Flame Retardant Epoxy Composites on the Road of Innovation: An Analysis with Flame Retardancy Index for Future Development

Nowadays, epoxy composites are elements of engineering materials and systems. Although they are known as versatile materials, epoxy resins suffer from high flammability. In this sense, flame retardancy analysis has been recognized as an undeniable requirement for developing future generations of epoxy-based systems. A considerable proportion of the literature on epoxy composites has been devoted to the use of phosphorus-based additives. Nevertheless, innovative flame retardants have coincidentally been under investigation to meet market requirements. This review paper attempts to give an overview of the research on flame retardant epoxy composites by classification of literature in terms of phosphorus (P), non-phosphorus (NP), and combinations of P/NP additives. A comprehensive set of data on cone calorimetry measurements applied on P-, NP-, and P/NP-incorporated epoxy systems was collected and treated. The performance of epoxy composites was qualitatively discussed as Poor, Good, and Excellent cases identified and distinguished by the use of the universal Flame Retardancy Index (FRI). Moreover, evaluations were rechecked by considering the UL-94 test data in four groups as V0, V1, V2, and nonrated (NR). The dimensionless FRI allowed for comparison between flame retardancy performances of epoxy composites. The results of this survey can pave the way for future innovations in developing flame-retardant additives for epoxy.

A brief yet informative view of the effect of the used P family of FRs on the flame retardancy performance of epoxy resins is given in Figure 1. It is apparent from the figure that all sorts of behavior, including Poor, Good, and Excellent flame-retardant performance, are achieved. This is the characteristic of dependency of flame retardancy performance on both the type and the content of the P type of FR. It can be observed that the majority of epoxy systems contains less than 20 wt.% of phosphorus flame retardants. For instance, a compromise between FRI and FR loading percentage was achieved by incorporation of encapsulated ammonium polyphosphate (APP- A brief yet informative view of the effect of the used P family of FRs on the flame retardancy erformance of epoxy resins is given in Figure 1. It is apparent from the figure that all sorts of ehavior, including Poor, Good, and Excellent flame-retardant performance, are achieved. This is the haracteristic of dependency of flame retardancy performance on both the type and the content of e P type of FR. It can be observed that the majority of epoxy systems contains less than 20 wt.% of hosphorus flame retardants. For instance, a compromise between FRI and FR loading percentage as achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with n FRI value of 19. Detailed information about the type of phosphorus flame retardants was rovided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P pe FR for epoxy should carefully meet the requirements based on the lesson learned from the ultivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection f the performance of each class of P-type FR in this table from one side and the chemical structure of e used FR from the other side should be balanced towards a high-performance FR for developing ame-retardant epoxy composites.  Table 1 as a to l notes. Here: FP1-4, FP1-6, FP1-8 [24], DPO-PHE-11.68, DOPO-PHE-12.03 [25], DOPO-T-2.34, DOPO-T-4.67, DOPO-T-6.99, DOPO-T-9.34 [26], AEPP-5, AEPP-10, AEPP-15 [27], DiDOPO-3 [28], DiDOPO-10, DiDOPO-11 [29], DiDOPO-7 [30], DiDOPO-1, DiDOPO-5, DiDOPO-10 [31], DiDOPO-1, DiDOPO-5, DiDOPO-10, DiDOPO-15, DiDOPO-20 [32], PPMS-15, PPMS-EG-15 [33], PPMS-MWCNT-5, PPMS-MWCNT-10, PPMS-MWCNT-15, PPMS-15 [34], DPIPP-7.5, DPIPP-15, DPPIO-7.5, DPPIO-15 [35], IDOP-5, IDOP-10, IDOP-15 [36], PPAP-5 [37], AlPBu-10, AlPBu-11, AlPBu-12 [38], MPL-DOPO-2.5, MPL-DOPO-5, DDM-DOPO-2.5, DDM-DOPO-5 [39], ATZ-6 [40], P-KC-30, DOPO-30 [41], DHPP-OH-BAC-5, DHPP-OH-BAC-10, DHPP-OH-BAC-15 [42], PPAP-5, PPAP-10, PPAP-20 [ [46], AlPi-7, MPP-7 [47], A-BP-9 [48], CLEP-DOPO-POSS-2.91 [19],  Table 1 as a to l notes. Here: was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants wa provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from th multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure o the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  Table 1 as a to l notes. Here: FP1-4, FP1-6, FP1-8 [24], DPO-PHE-11.68, DOPO-PHE-12.03 [25], DOPO-T-2.34, DOPO-T-4.67, DOPO-T-6.99, DOPO-T-9.34 [26], AEPP-5, AEPP-10, AEPP-15 [27], DiDOPO-3 [28], DiDOPO-10, DiDOPO-11 [29], DiDOPO-7 [30], DiDOPO-1, DiDOPO-5, DiDOPO-10 [31], DiDOPO-1, DiDOPO-5, DiDOPO-10, DiDOPO-15, DiDOPO-20 [32], PPMS-15, PPMS-EG-15 [33], PPMS-MWCNT-5, PPMS-MWCNT-10, PPMS-MWCNT-15, PPMS-15 [34], DPIPP-7.5, DPIPP-15, DPPIO-7.5, DPPIO-15 [35], IDOP-5, IDOP-10, IDOP-15 [36], PPAP-5 [37], AlPBu-10, AlPBu-11, AlPBu-12 [38], MPL-DOPO-2.5, MPL-DOPO-5, DDM-DOPO-2.5, DDM-DOPO-5 [39], ATZ-6 [40], P-KC-30, DOPO-30 [41], DHPP-OH-BAC-5, DHPP-OH-BAC-10, DHPP-OH-BAC-15 [42], PPAP-5, PPAP-10, PPAP-20 [ [46], AlPi-7, MPP-7 [47], A-BP-9 [48], CLEP-DOPO-POSS-2.91 [19], FP1-4, FP1-6, FP1-8 [24], mise between FRI and FR loading percentage nium polyphosphate (APP-) at 15 wt.% with e type of phosphorus flame retardants was s, innovations in design and manufacture of P ements based on the lesson learned from the bout by P-type FR additives. Precise detection ble from one side and the chemical structure of owards a high-performance FR for developing ntaining phosphorus flame retardants in terms t. Symbols are indicative of different types of re indicative of fiber-incorporated composites to l notes. Here: FP1-4, FP1-6, FP1-8 [24], OPO-T-2.34, DOPO-T-4.67, DOPO-T-6.99, [27], DiDOPO-3 [28], DiDOPO-10, DiDOPO-5, DiDOPO-10 [31], DiDOPO-1, [32], PPMS-15, PPMS-EG-15 [33], T-15, PPMS-15 [34], DPIPP-7.5, DPIPP-15, DOP-15 [36], PPAP-5 [37], AlPBu-10, OPO-5, DDM-DOPO-2.5, DDM-DOPO-5 [39], DHPP-OH-BAC-5, DHPP-OH-BAC-10, P-20 [43], [Dmim]Tos-2.4, [Dmim]Tos-4, [45], MDOP-0.96, MDOP-1.9, MDOP-3.75, -9 [48], CLEP-DOPO-POSS-2.91 [19], DPO-PHE-11.68, DOPO-PHE-12.03 [25], was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.   [26], was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  Table 1  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of  the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of  the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  Table 1  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  Table 1  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of  the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  AlPBu-10, AlPBu-11, AlPBu-12 [38], was achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with an FRI value of 19. Detailed information about the type of phosphorus flame retardants was provided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P type FR for epoxy should carefully meet the requirements based on the lesson learned from the multivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection of the performance of each class of P-type FR in this table from one side and the chemical structure of the used FR from the other side should be balanced towards a high-performance FR for developing flame-retardant epoxy composites.  Table 1  as achieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with n FRI value of 19. Detailed information about the type of phosphorus flame retardants was rovided to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P ype FR for epoxy should carefully meet the requirements based on the lesson learned from the ultivariable behavior of flame retardancy brought about by P-type FR additives. Precise detection f the performance of each class of P-type FR in this table from one side and the chemical structure of he used FR from the other side should be balanced towards a high-performance FR for developing lame-retardant epoxy composites.  Table 1  hieved by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with I value of 19. Detailed information about the type of phosphorus flame retardants was ed to the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P R for epoxy should carefully meet the requirements based on the lesson learned from the ariable behavior of flame retardancy brought about by P-type FR additives. Precise detection performance of each class of P-type FR in this an FRI value of 19. Detailed information about th provided to the reader in the caption of Figure 1. Thu type FR for epoxy should carefully meet the requir multivariable behavior of flame retardancy brought of the performance of each class of P-type FR in this ta the used FR from the other side should be balanced flame-retardant epoxy composites.  Table 1 as a DPO-PHE-11.68, DOPO-PHE-12.03 [25], D DOPO-T-9.34 [26], AEPP-5, AEPP-10, AEPP-1 DiDOPO-11 [29], DiDOPO-7 [30], DiDOPO-1 DiDOPO-5, DiDOPO-10, DiDOPO-15, DiDOPO-2 PPMS-MWCNT-5, PPMS-MWCNT-10, PPMS-MWCN DPPIO-7.5, DPPIO-15 [35], IDOP-5, IDOP-10, I by incorporation of encapsulated ammonium polyphosphate (APP-) at 15 wt.% with e of 19. Detailed information about the type of phosphorus flame retardants was the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P epoxy should carefully meet the requirements based on the lesson learned from the e behavior of flame retardancy brought about by P-type FR additives. Precise detection mance of each class of P-type FR in this table from one side and the chemical structure of from the other side should be balanced towards a high-performance FR for developing ant epoxy composites.  19. Detailed information about the type of phosphorus flame retardants was the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P epoxy should carefully meet the requirements based on the lesson learned from the e behavior of flame retardancy brought about by P-type FR additives. Precise detection mance of each class of P-type FR in this table from one side and the chemical structure of from the other side should be balanced towards a high-performance FR for developing ant epoxy composites.
. Flame retardancy analysis of epoxy resins containing phosphorus flame retardants in terms RI values as a function of P type and content. Symbols are indicative of different types of rus flame retardant used. Hollow symbols are indicative of fiber-incorporated composites ails earlier given in the bottom of Table 1 19. Detailed information about th provided to the reader in the caption of Figure 1. Thu type FR for epoxy should carefully meet the requir multivariable behavior of flame retardancy brought a of the performance of each class of P-type FR in this ta the used FR from the other side should be balanced t flame-retardant epoxy composites.   19. Detailed information about the type of phosphorus flame retardants was the reader in the caption of Figure 1. Thus, innovations in design and manufacture of P epoxy should carefully meet the requirements based on the lesson learned from the le behavior of flame retardancy brought about by P-type FR additives. Precise detection mance of each class of P-type FR in this table from one side and the chemical structure of from the other side should be balanced towards a high-performance FR for developing ant epoxy composites.
Although variation of FRI values according to the composition reflects the flame retardancy of epoxy composites from cone calorimetry angle (the most reliable test among those normally used for analysis of performance of flame retardants), other types of flame tests would give more insights into the real effect of one or complementary actions of two or more P type FR additives in epoxy. Based on available data, a brief view of the effect of the used P-based FRs on the flame retardancy performance of epoxy resins as a function of UL94 results is given in Figure 2. The distribution of data in this figure gives useful information about the efficiency of the FR system in harsh conditions. For instance, this figure suggests that V-0 performance in UL94 can be achieved even at the Poor category of flame retardancy performance in terms of FRI. It appears that it is not possible to roughly correlate the obtained results in UL94 to those obtained in cone calorimetry tests. performance of epoxy resins as a function of UL94 results is given in Figure 2. The distribution of data in this figure gives useful information about the efficiency of the FR system in harsh conditions. For instance, this figure suggests that V-0 performance in UL94 can be achieved even at the Poor category of flame retardancy performance in terms of FRI. It appears that it is not possible to roughly correlate the obtained results in UL94 to those obtained in cone calorimetry tests.  Table 1 as a to l notes. The vertical variation in each category, i.e., V-0, V-1, V-2, and NR, is schematically representative of the amount of additive used. For example, among two data distinguished by different symbols having the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), which have different vertical quantity both revealed V-1 behavior in UL-94 test, but the upper was an FR used in more quantity in preparation of epoxy composites.
Another test of importance is the limiting oxygen index (LOI), which is demonstrative of flammability. A self-extinguishing behavior is expected when the LOI value is higher than 28. A brief overview of the effect of the used phosphorus-type flame retardants on the flame retardancy performance of epoxy resins as a function of LOI results is given in Figure 3. Surprisingly, the highest value obtained in LOI testing is located in the Good zone of FRI. The collection of data with FRI values below 5, where LOI% varies depending on the type of phosphorus additive and undoubtedly the content, is hidden behind these symbols.  Table 1 as a to l notes. The vertical variation in each category, i.e., V-0, V-1, V-2, and NR, is schematically representative of the amount of additive used. For example, among two data distinguished by different symbols having the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), which have different vertical quantity both revealed V-1 behavior in UL-94 test, but the upper was an FR used in more quantity in preparation of epoxy composites.
Another test of importance is the limiting oxygen index (LOI), which is demonstrative of flammability. A self-extinguishing behavior is expected when the LOI value is higher than 28. A brief overview of the effect of the used phosphorus-type flame retardants on the flame retardancy performance of epoxy resins as a function of LOI results is given in Figure 3. Surprisingly, the highest value obtained in LOI testing is located in the Good zone of FRI. The collection of data with FRI values below 5, where LOI% varies depending on the type of phosphorus additive and undoubtedly the content, is hidden behind these symbols.   Table 1 as a to l notes.

Epoxy Resins Containing Nonphosphorus Flame Retardants
According to the literature, a variety of nonphosphorus FRs have been used in epoxy resins. Table 2 summarizes pHRR, THR, and TTI and the FRI values of epoxy/NP systems. The percentage of incorporated FR as well as the results of LOI and UL-94 test are also given for comprehensive determination of the behavior of this family of epoxy composites.   Table 1 as a to l notes.

Epoxy Resins Containing Nonphosphorus Flame Retardants
According to the literature, a variety of nonphosphorus FRs have been used in epoxy resins. Table 2 summarizes pHRR, THR, and TTI and the FRI values of epoxy/NP systems. The percentage of incorporated FR as well as the results of LOI and UL-94 test are also given for comprehensive determination of the behavior of this family of epoxy composites.      [195] protonated magadiite reaction with silane coupling agent (S-H-magadiite)  3  38  1416  114 2.14 -- [195] organo-modified magadiite (OM-magadiite) 3   From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR.
The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, (fabric); e Matrix: six layers of IM-7 carbon fiber fabrics reinforced epoxy; f Matrix: eight layers of woven E-glass reinforced epoxy; g Matrix: six layers of IM-7 carbon fiber fabrics reinforced epoxy; h Matrix: eight layers of woven glass Fiber Reinforced epoxy.
From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.   Table 1 as notes a to h. Here: From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy. From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ , GNO-1, GNO-3, GN-Cu-1, GN-Cu-3 [178], AlO(OH)-20 [147], AlO(OH)-20, SiO2-20 [127], α-MnO2-0.5, HNT-5, HNT-10, HNT@PDA-5, HNT@PDA-10, HNT@PDA@Fe(OH) 3 -5, HNT@PDA@Fe(OH) 3 -10 [172], From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ effective in terms of the flame retardanc The effect of the used NP-type FR on visually assessed in Figure 4. Moreov provided to the reader in the caption o additives suggests that even at high loa informative case, alumina Trihydrate development of flame-retardant epoxy to 30 wt.%), it gives the best results, Exc additives are not individually responsib From the comparison between Tables 1 and 2, one can simply infer that the NP family is less effective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. The effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be visually assessed in Figure 4. Moreover, detailed information about the type of NP additives is provided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP additives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an informative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in development of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up to 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of additives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less ffective in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. he effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be isually assessed in Figure 4. Moreover, detailed information about the type of NP additives is rovided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP dditives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an nformative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in evelopment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up o 30 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of dditives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less tive in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be ally assessed in Figure 4. Moreover, detailed information about the type of NP additives is ided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP itives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an rmative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in elopment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of itives are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, TNB-10, TNB-15, TNB-20 [ From the comparison between Tables 1 and 2, one can simply infer that the NP family is less ctive in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. effect of the used NP-type FR on the flame retardancy performance of epoxy resins can be ally assessed in Figure 4. Moreover, detailed information about the type of NP additives is vided to the reader in the caption of Figure 4. The quality of epoxy composites containing NP itives suggests that even at high loading levels it is difficult to attain very high efficiencies. As an rmative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in elopment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up 0 wt.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of itives are not individually responsible for high fire resistance of epoxy.  , GNO-1, GNO-3, GN-Cu-1, GN-Cu-3 [178], AlO(OH)-20 [147], AlO(OH)-20, SiO2-20 [127], α-MnO2-0.5, ACS@SnO 2 @NiO-5 [125], effective in terms of the flame retardancy of the The effect of the used NP-type FR on the flam visually assessed in Figure 4. Moreover, deta provided to the reader in the caption of Figure  additives suggests that even at high loading lev informative case, alumina Trihydrate (ATH, development of flame-retardant epoxy nanocom to 30 wt.%), it gives the best results, Excellent in additives are not individually responsible for h  rom the comparison between Tables 1 and 2, one can simply infer that the NP family is less ive in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. ffect of the used NP-type FR on the flame retardancy performance of epoxy resins can be lly assessed in Figure 4. Moreover, detailed information about the type of NP additives is ded to the reader in the caption of Figure 4. The quality of epoxy composites containing NP ves suggests that even at high loading levels it is difficult to attain very high efficiencies. As an ative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in opment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up t.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of ves are not individually responsible for high fire resistance of epoxy.  Table 1 as notes a to h. Here: 3TT-3BA-20 [169], GN-3 [28], MWCNT-0.8 [29], OMMT-7 [30], OLDH-1, OLDH-5, OLDH-10 [31], MgAl-LDH-2, IF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-LDH-2 [170], TAT-20 [52], TNB-1, TNB-5, NB-10, TNB-15, TNB-20 [ , GNO-1, GNO-3, N-Cu-1, GN-Cu-3 [178], AlO(OH)-20 [147], AlO(OH)-20, SiO2-20 [127], α-MnO2-0.5, CP-10, CP-15 [130], om the comparison between Tables 1 and 2, one can simply infer that the NP family is less e in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. fect of the used NP-type FR on the flame retardancy performance of epoxy resins can be y assessed in Figure 4. Moreover, detailed information about the type of NP additives is ed to the reader in the caption of Figure 4. The quality of epoxy composites containing NP es suggests that even at high loading levels it is difficult to attain very high efficiencies. As an ative case, alumina Trihydrate (ATH, ) has been used in a wide range of content in pment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up t.%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of es are not individually responsible for high fire resistance of epoxy.   Tables 1 and 2, one can simply infer that the NP family is less e in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. ect of the used NP-type FR on the flame retardancy performance of epoxy resins can be assessed in Figure 4. Moreover, detailed information about the type of NP additives is d to the reader in the caption of Figure 4. The quality of epoxy composites containing NP s suggests that even at high loading levels it is difficult to attain very high efficiencies. As an tive case, alumina Trihydrate (ATH, ) has been used in a wide range of content in ment of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up .%), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of s are not individually responsible for high fire resistance of epoxy.  , GNO-1, GNO-3, -Cu-1, GN-Cu-3 [178], AlO(OH)-20 [147], AlO(OH)-20, SiO2-20 [127], α-MnO2-0.5, CP-10, CP-15 [130], effective in terms of the flame retardancy of the com The effect of the used NP-type FR on the flame r visually assessed in Figure 4. Moreover, detailed provided to the reader in the caption of Figure 4. T additives suggests that even at high loading levels it informative case, alumina Trihydrate (ATH, ) h development of flame-retardant epoxy nanocompos to 30 wt.%), it gives the best results, Excellent in term additives are not individually responsible for high f  Table 1 as notes MWCNT-0.8 [29], OMMT-7 [30], OLDH ZIF8-2, ZIF8@MgAl-LDH-2, ZIF67-2, ZIF67@MgAl-L TNB-10, TNB-15, TNB-20 [ the comparison between Tables 1 and 2, one can simply infer that the NP family is less in terms of the flame retardancy of the composite epoxy with respect to the P family of FR. t of the used NP-type FR on the flame retardancy performance of epoxy resins can be assessed in Figure 4. Moreover, detailed information about the type of NP additives is to the reader in the caption of Figure 4. The quality of epoxy composites containing NP suggests that even at high loading levels it is difficult to attain very high efficiencies. As an ive case, alumina Trihydrate (ATH, ) has been used in a wide range of content in ent of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up ), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of are not individually responsible for high fire resistance of epoxy.  the comparison between Tables 1 and 2, one can simply infer that the NP family is less terms of the flame retardancy of the composite epoxy with respect to the P family of FR. of the used NP-type FR on the flame retardancy performance of epoxy resins can be sessed in Figure 4. Moreover, detailed information about the type of NP additives is o the reader in the caption of Figure 4. The quality of epoxy composites containing NP uggests that even at high loading levels it is difficult to attain very high efficiencies. As an e case, alumina Trihydrate (ATH, ) has been used in a wide range of content in nt of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up ), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of re not individually responsible for high fire resistance of epoxy.   Tables 1 and 2, one can simply infer that the NP family is less rms of the flame retardancy of the composite epoxy with respect to the P family of FR. the used NP-type FR on the flame retardancy performance of epoxy resins can be ssed in Figure 4. Moreover, detailed information about the type of NP additives is the reader in the caption of Figure 4. The quality of epoxy composites containing NP gests that even at high loading levels it is difficult to attain very high efficiencies. As an case, alumina Trihydrate (ATH, ) has been used in a wide range of content in t of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up t gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of not individually responsible for high fire resistance of epoxy.
. the comparison between Tables 1 and 2, one can simply infer that the NP family is less terms of the flame retardancy of the composite epoxy with respect to the P family of FR. of the used NP-type FR on the flame retardancy performance of epoxy resins can be sessed in Figure 4. Moreover, detailed information about the type of NP additives is o the reader in the caption of Figure 4. The quality of epoxy composites containing NP uggests that even at high loading levels it is difficult to attain very high efficiencies. As an e case, alumina Trihydrate (ATH, ) has been used in a wide range of content in nt of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up ), it gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of re not individually responsible for high fire resistance of epoxy. effective in terms of the flame retardancy of the compo The effect of the used NP-type FR on the flame reta visually assessed in Figure 4. Moreover, detailed inf provided to the reader in the caption of Figure 4.  e comparison between Tables 1 and 2, one can simply infer that the NP family is less erms of the flame retardancy of the composite epoxy with respect to the P family of FR. f the used NP-type FR on the flame retardancy performance of epoxy resins can be ssed in Figure 4. Moreover, detailed information about the type of NP additives is the reader in the caption of Figure 4. The quality of epoxy composites containing NP gests that even at high loading levels it is difficult to attain very high efficiencies. As an case, alumina Trihydrate (ATH, ) has been used in a wide range of content in t of flame-retardant epoxy nanocomposites. It can be seen that at high loading rate (up t gives the best results, Excellent in terms of FRI. It can be concluded that the NP class of not individually responsible for high fire resistance of epoxy.
A brief overview of the effect of the NP used as FR in epoxy composite preparation and on the flame retardancy performance of epoxy resins as a function of UL-94 results is given in Figure 5. Since data are limited and spread over the plot, there is no conclusion about the relationship between FRI (cone calorimetry) and UL-94 analysis to be highlighted. Nevertheless, all sorts of behavior can be seen in the plot, depending on the type and content of NP type of FRs. It is worthy of note that the NR category of UL-94 constitutes a high proportion of the results.   Table 2 as notes a to h. The vertical variation in each category, i.e., V-0, V-1, V-2, and NR, is schematically representative of the amount of additive used. For example, among two data distinguished by different symbols having the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), which have different vertical quantity both revealed V-1 behavior in UL-94 test, but the upper was an FR used in greater quantity in preparation of epoxy composites.
A brief overview of the effect of NP-type FR on the flame retardancy performance of epoxy resins as a function of LOI results is given in Figure 6. Surprisingly, the highest value obtained in LOI testing is located in Poor zone of FRI. On the other hand, Excellent flame retardancy seen at high FRI values has LOI of about 22%. From this perspective, it can be concluded that cone calorimetry is not monotonically representative of the character of FR when used in epoxy.  Table 2 as notes a to h. The vertical variation in each category, i.e., V-0, V-1, V-2, and NR, is schematically representative of the amount of additive used. For example, among two data distinguished by different symbols having the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), which have different vertical quantity both revealed V-1 behavior in UL-94 test, but the upper was an FR used in greater quantity in preparation of epoxy composites.
A brief overview of the effect of NP-type FR on the flame retardancy performance of epoxy resins as a function of LOI results is given in Figure 6. Surprisingly, the highest value obtained in LOI testing is located in Poor zone of FRI. On the other hand, Excellent flame retardancy seen at high FRI values has LOI of about 22%. From this perspective, it can be concluded that cone calorimetry is not monotonically representative of the character of FR when used in epoxy.  Table 2 as notes a to h.

Epoxy Resins Containing Combinatorial Flame Retardant Systems
Assessing the flame retardancy performance of P-and NP-incorporated epoxy systems unraveled the inadequacy of using one FR additive alone when a high performance is required. The antagonism or synergism may be the result of using two or more FR systems in a given polymer matrix. In the case of epoxy, there have been some attempts towards combinatorial use of P and NP additives for the sake of higher performance. Table 3 summarizes pHRR, THR, TTI, and FRI values of epoxy/P/NP combinatorial flame-retardant systems. The percentage of incorporated FR as well as the results of LOI and UL-94 tests are also given.   Table 2 as notes a to h.

Epoxy Resins Containing Combinatorial Flame Retardant Systems
Assessing the flame retardancy performance of P-and NP-incorporated epoxy systems unraveled the inadequacy of using one FR additive alone when a high performance is required. The antagonism or synergism may be the result of using two or more FR systems in a given polymer matrix. In the case of epoxy, there have been some attempts towards combinatorial use of P and NP additives for the sake of higher performance. Table 3 summarizes pHRR, THR, TTI, and FRI values of epoxy/P/NP combinatorial flame-retardant systems. The percentage of incorporated FR as well as the results of LOI and UL-94 tests are also given.    Octaphenyl polyhedral oligomeric silsesquioxane/9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10    To give a more meaningful overview of the effect of combined P and NP additives on flame retardancy performance of epoxy, FRI values are calculated by using calorimetric data given in Table 3 and plotted in Figure 7. In this figure, the vertical axis shows the amount of additive system used in preparation of epoxy composites. The plot also reveals that three types of flame retardancy performances are observed, depending on the type of combinatorial systems as well as the amount of FR additives used. Attention should be paid to the fact that even at lower loading levels, careful coupling of one or more P and NP additives could lead to superiority of the FR system used, and there was a possibility for attaining higher performances compared to highly-filled systems (FR content ≥ 40). Thus, careful selection of complementary additives with disciplined loading can result in high flame retardancy performance.    Table 1 as a to i notes category, i.e., V-0, V-1, and NR, is schematically representative of the example, two data distinguished by different symbols have the s (horizontal quantity) in a given category (e.g., V-1), but higher V-1 be the FR was used in greater quantity.
When looking at the UL-94 test results (considering the fact that for some systems to be plotted and discussed in Figure 8), it can be the whole systems take Poor and Good labels based on FRI values. It i a given category, e.g., V-0, the amount of additive changes the FRI, a sense of such variations.  Table 1 as a to i notes. category, i.e., V-0, V-1, and NR, is schematically representative of the example, two data distinguished by different symbols have the sa (horizontal quantity) in a given category (e.g., V-1), but higher V-1 be the FR was used in greater quantity.  Table 1 as a to i notes. The ve category, i.e., V-0, V-1, and NR, is schematically representative of the amoun example, two data distinguished by different symbols have the same or (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior i the FR was used in greater quantity.  Table 1 as a to i notes. The vertical category, i.e., V-0, V-1, and NR, is schematically representative of the amount of a example, two data distinguished by different symbols have the same or very (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in ULthe FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.
When looking at the UL-94 test results (considering the fact that there were some data in Table 3 for some systems to be plotted and discussed in Figure 8), it can be seen that, except for some data, the whole systems take Poor and Good labels based on FRI values. It is also interesting to note that for a given category, e.g., V-0, the amount of additive changes the FRI, and UL-94 testing does not make sense of such variations.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.  Table 1 as a to i notes. The vertical variation in each category, i.e., V-0, V-1, and NR, is schematically representative of the amount of additive used. For example, two data distinguished by different symbols have the same or very close FRI values (horizontal quantity) in a given category (e.g., V-1), but higher V-1 behavior in UL-94 testing means the FR was used in greater quantity.
The more interesting outcome of this work is that LOI percent similarly detects Poor and Good behaviors, not principally Excellent performance (Figure 9). This suggests that development of innovative FR additives by combination of P and NP and using highly efficient synthesis routes is the essential step to be taken in the near future for developing flame retardant epoxy composites. The more interesting outcome of this work is that LOI percent similarly detects Poor and Good behaviors, not principally Excellent performance (Figure 9). This suggests that development of innovative FR additives by combination of P and NP and using highly efficient synthesis routes is the essential step to be taken in the near future for developing flame retardant epoxy composites.  Table 1 as notes a to i.

Concluding Remarks and Future Perspective
In previous sections, we categorized the flame-retardant properties of epoxy resins in terms of the universal FRI criterion and the content of flame retardants of three families. We also attempted to find possible correlations between cone calorimetry (reflected in FRI variations), UL-94, and LOI analyses. Since cone calorimetry is the best way to simulate real state combustion of polymers, here, we give a general picture of flame retardancy of epoxy resins ( Figure 10). The Poor, Good, or Excellent flame retardancy cases are the result of the P, NP, or P/NP types of flame retardants used in preparation of epoxy composites as well as the FR loading. Each kind of behavior can be visualized by providing a full snapshot of the Poor, Good, and Excellent regions of the FRI to see how closely the data are collected in each zone. Overall, it can be seen that Poor and Good are the cases for majority of data, while the Excellent zone contains limited data. This highlights the difficulty of achieving high flame-retardant efficiency in epoxy composites when merely using flame retardants. Thus, development of innovative flame retardants through blending different FR families and making them reactive towards epoxy may result in a fully cured 3D network with high flame resistance. This requires the knowledge and experience of chemists and engineers who can adjust the performance of the system in a very disciplined manner. Moreover, using bio-based epoxy resins with limited environmental threats would be another solution to the question of "which FR additive(s) meet the requirements of highly flame-retardant epoxy composites?".  Table 1 as notes a to i.

Concluding Remarks and Future Perspective
In previous sections, we categorized the flame-retardant properties of epoxy resins in terms of the universal FRI criterion and the content of flame retardants of three families. We also attempted to find possible correlations between cone calorimetry (reflected in FRI variations), UL-94, and LOI analyses. Since cone calorimetry is the best way to simulate real state combustion of polymers, here, we give a general picture of flame retardancy of epoxy resins ( Figure 10). The Poor, Good, or Excellent flame retardancy cases are the result of the P, NP, or P/NP types of flame retardants used in preparation of epoxy composites as well as the FR loading. Each kind of behavior can be visualized by providing a full snapshot of the Poor, Good, and Excellent regions of the FRI to see how closely the data are collected in each zone. Overall, it can be seen that Poor and Good are the cases for majority of data, while the Excellent zone contains limited data. This highlights the difficulty of achieving high flame-retardant efficiency in epoxy composites when merely using flame retardants. Thus, development of innovative flame retardants through blending different FR families and making them reactive towards epoxy may result in a fully cured 3D network with high flame resistance. This requires the knowledge and experience of chemists and engineers who can adjust the performance of the system in a very disciplined manner. Moreover, using bio-based epoxy resins with limited environmental threats would be another solution to the question of "which FR additive(s) meet the requirements of highly flame-retardant epoxy composites?".