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19 pages, 6379 KiB  
Article
Enhanced Flame Retardancy of Unsaturated Polyester Resin via Simultaneously Using a Novel DOPO-Based Organic Flame Retardant and Modified Silicon Carbide
by Piye Wu, Jingjie Hu, Chanyu Liu, Ping He, Feng You, Hao Yang and Man Xu
Coatings 2025, 15(4), 376; https://doi.org/10.3390/coatings15040376 - 23 Mar 2025
Viewed by 481
Abstract
Unsaturated polyester (UP) resin is widely utilized in the construction and automotive industries. The flammable nature of UP must be constrained when its products are manufactured. A novel organic flame retardant has been synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and triallyl isocyanate (TAIC). This DOPO-TAIC [...] Read more.
Unsaturated polyester (UP) resin is widely utilized in the construction and automotive industries. The flammable nature of UP must be constrained when its products are manufactured. A novel organic flame retardant has been synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and triallyl isocyanate (TAIC). This DOPO-TAIC additive has been used to reduce the flammability of a matrix. Additionally, this flame retardant was then combined with dopamine-modified silicon carbide (M-SiC) to further diminish the flammability of UP. The limiting oxygen index (LOI) value combustion of a UP/DOPO-TAIC/M-SiC blend was 30.8% when the filler contents of DOPO-TAIC and M-SiC was 15 wt.% and 30 wt.%, respectively. These materials exhibited a UL 94 V-0 rating for combustion. Compared to the values for combustion of the neat UP, the peak heat release rate (Pk-HRR) and total heat release rate (THR) for this blend were reduced by 51% and 35%, respectively. The mode of action for flame retardant of UP blends containing DOPO-TAIC and M-SiC has been composed. The presence of a flame retardant containing P-Si elements can significantly reduce flammability compared to that of unmodified resin. Full article
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17 pages, 3084 KiB  
Article
Wheat Chromatin Remodeling Protein TaSWP73 Contributes to Compatible Wheat–Powdery Mildew Interaction
by Yixian Fu, Zige Yang, Jiao Liu, Xiaoyu Wang, Haoyu Li, Pengfei Zhi and Cheng Chang
Int. J. Mol. Sci. 2025, 26(6), 2590; https://doi.org/10.3390/ijms26062590 - 13 Mar 2025
Viewed by 519
Abstract
Wheat powdery mildew disease caused by the obligate biotrophic fungal pathogen Blumeria graminis forma specialis tritici (B.g. tritici) seriously threatens global wheat production. Although improved powdery mildew resistance is an aim in wheat breeding, the regulatory mechanism underlying the wheat–B.g. [...] Read more.
Wheat powdery mildew disease caused by the obligate biotrophic fungal pathogen Blumeria graminis forma specialis tritici (B.g. tritici) seriously threatens global wheat production. Although improved powdery mildew resistance is an aim in wheat breeding, the regulatory mechanism underlying the wheat–B.g. tritici interaction remains poorly understood. In this study, the wheat chromatin remodeling protein TaSWP73 was identified as a negative regulator of post-penetration resistance against B.g. tritici. The transient overexpression of TaSWP73 attenuates wheat post-penetration resistance against B.g. tritici, while the silencing of TaSWP73 potentiates salicylic acid (SA) biosynthesis and activates post-penetration resistance against B.g. tritici. Importantly, chromatin in the promoter regions of TaSARD1, an activator gene of SA biosynthesis, is marked by high nucleosome occupancy in the TaSWP73-silenced wheat leaves. The silencing of TaSARD1 could suppress SA biosynthesis and attenuate post-penetration resistance against B.g. tritici with a lack of TaSWP73. In addition, TaICS1 was characterized as an essential component of wheat SA biosynthetic machinery. Potentiated SA biosynthesis and increased post-penetration resistance against B.g. tritici with a lack of TaSWP73 could be suppressed by the silencing of TaICS1 expression. These results collectively support the hypothesis that the wheat chromatin remodeling protein TaSWP73 contributes to the compatible wheat–powdery mildew interaction presumably via the suppression of the TaSARD1-TaICS1-SA pathway. Full article
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15 pages, 5375 KiB  
Article
Changes in Heat Resistance and Mechanical Properties of Peroxide Cross-Linking HDPE: Effects of Compounding Cross-Linkers
by Shunquan Liu, Run Zhang, Chenchao Fu, Tianshuo Zheng and Ping Xue
Polymers 2025, 17(4), 535; https://doi.org/10.3390/polym17040535 - 19 Feb 2025
Cited by 1 | Viewed by 1040
Abstract
Due to excellent chemical resistance and impermeability, high-density polyethylene (HDPE) is widely used in petrochemical transportation, product packaging, sports equipment, and marine applications. Yet, with the wide variety of service environments, its mechanical and thermal properties do not meet the demand. In the [...] Read more.
Due to excellent chemical resistance and impermeability, high-density polyethylene (HDPE) is widely used in petrochemical transportation, product packaging, sports equipment, and marine applications. Yet, with the wide variety of service environments, its mechanical and thermal properties do not meet the demand. In the present study, a compounding cross-linker comprising di-tert-butyl peroxide (DTBP) and triallyl isocyanurate (TAIC) is employed by combining with a two-step preparation process. High-quality cross-linking reactions are achieved for HDPE. In this study, the cross-linking of DTBP is first examined separately. A peak cross-linking degree of 74.7% is achieved, and there is a large improvement in thermal resistance and mechanical properties. Subsequently, the composite cross-linking system of DTBP and TAIC is investigated. The peak cross-linking degree is 82.1% (10% increase compared to DTBP). The peak heat deformation temperature is 80.1 °C (22% increase compared to DTBP). The peak impact strength is 104.73 kJ/m2 (207% increase compared to neat HDPE). The flexural strength is 33.6 MPa (22% increase compared to neat HDPE). The results show that this cross-linking system further improves the cross-linking degree, heat resistance, and mechanical properties of HDPE, indicating its potential application in engineering materials for high performance. Full article
(This article belongs to the Special Issue Advances in Polymer Composites II)
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12 pages, 6331 KiB  
Article
Preparation and Space Charge Properties of Functionalized Zeolite/Crosslinked Polyethylene Composites with High Thermal Conductivity
by Bai Han, Jinghui Dai, Wanliang Zhao, Wei Song, Zhi Sun and Xuan Wang
Polymers 2023, 15(22), 4363; https://doi.org/10.3390/polym15224363 - 9 Nov 2023
Cited by 1 | Viewed by 1465
Abstract
Nanocomposite doping is an effective method to improve the dielectric properties of polyethylene. Meanwhile, the introduction of thermal conductivity groups in crosslinked polyethylene (XLPE) is also an effective way to improve the thermal conductivity. Nano-zeolite is an inorganic material with a porous structure [...] Read more.
Nanocomposite doping is an effective method to improve the dielectric properties of polyethylene. Meanwhile, the introduction of thermal conductivity groups in crosslinked polyethylene (XLPE) is also an effective way to improve the thermal conductivity. Nano-zeolite is an inorganic material with a porous structure that can be doped into polyethylene to improve the insulation performance. In this paper, hyperbranched polyarylamide (HBP) with a high thermal conductivity and an auxiliary crosslinking agent (TAIC) was grafted on the surface of ZSM-5 nano-zeolite successively to obtain functionalized nano-zeolite (TAICS-ZSM-5-HBP) (the “S” in TAICS means plural). The prepared functionalized nano-zeolite was doped in polyethylene and grafted under a thermal crosslinking reaction to prepare nanocomposites (XLPE/TAICS-ZSM-5-HBP). The structural characterization showed that the nanocomposite was successfully prepared and that the nanoparticles were uniformly dispersed in the polyethylene matrix. The space charge of the TAICS-ZSM-5-HBP 5wt% nanocomposite under a high electric field was obviously inhibited. The space charge short-circuit test showed that the porous structure of the nano-zeolite introduced more deep traps, which made the trapped charge difficult to break off, hindering the charge injection. The introduction of TAICS-ZSM-5-HBP particles can greatly improve the thermal conductivity of nanocomposites. The thermal conductivity of the XLPE/5wt% and XLPE/7wt% TAICS-ZSM-5-HBP nanocomposites increased by 42.21% and 69.59% compared to that of XLPE at 20 °C, and by 34.27% and 62.83% at 80 °C. Full article
(This article belongs to the Special Issue Synthesis and Applications of Polymer-Based Nanocomposites)
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17 pages, 4514 KiB  
Article
Thermal, Mechanical and Tribological Properties of Gamma-Irradiated Plant-Derived Polyamide 1010
by Maiko Morino, Yosuke Nishitani, Tatsuya Kitagawa and Shinya Kikutani
Polymers 2023, 15(14), 3111; https://doi.org/10.3390/polym15143111 - 21 Jul 2023
Cited by 3 | Viewed by 1817
Abstract
In this study, we investigated the influence of the gamma-irradiation dose and the addition of the cross-linking agent (triallyl isocyanurate (TAIC)) on the thermal, mechanical and tribological properties of plant-derived polyamide 1010 (PA1010). PA1010 and PA1010/TAIC were extruded using a twin screw extruder [...] Read more.
In this study, we investigated the influence of the gamma-irradiation dose and the addition of the cross-linking agent (triallyl isocyanurate (TAIC)) on the thermal, mechanical and tribological properties of plant-derived polyamide 1010 (PA1010). PA1010 and PA1010/TAIC were extruded using a twin screw extruder and injection molded. These specimens were then irradiated with gamma-ray in air with doses of 20 and 50 kGy. After gamma-irradiation, the specimens were heat-treated to remove the free radicals generated in the polymer. The combination of gamma-irradiation and the addition of TAIC significantly changed the crystal structures of PA1010. Glass transition temperature increased with the addition of TAIC and, in particular, with increasing gamma-irradiation dose. Moreover, PA1010/TAIC showed a rubbery plateau originating from cross-links by gamma-irradiation, which was observed in the temperature regions above the melting point in DMA measurements. Mechanical properties such as strength, modulus and hardness, and tribological properties such as frictional coefficient, specific wear rate and limiting pv (pressure p × velocity v) value of PA1010 improved with change in the internal microstructure with the gamma-irradiation and addition of TAIC. Full article
(This article belongs to the Special Issue Eco-Friendly Polymers and Polymer Composites)
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16 pages, 4053 KiB  
Article
Evaluation of Cross-Linked Polyamide 6 Micro-Indentation Properties: TAIC Concentration and Electron Radiation Intensity
by Martin Ovsik, Michal Stanek and Martin Bednarik
Materials 2023, 16(6), 2391; https://doi.org/10.3390/ma16062391 - 16 Mar 2023
Cited by 2 | Viewed by 2165
Abstract
Nowadays, technical practice puts emphasis on improving selected material properties of polymers which could lead to new applications. Material properties can be modified in numerous ways, among which is radiation treatment. This study looks into the influence of beta radiation on several properties [...] Read more.
Nowadays, technical practice puts emphasis on improving selected material properties of polymers which could lead to new applications. Material properties can be modified in numerous ways, among which is radiation treatment. This study looks into the influence of beta radiation on several properties of polyamide 6, e.g., indentation hardness, modulus and creep. Main changeable parameters were the concentration of triallyl isocyanurate (TAIC), which promotes cross-linking, and intensity of radiation. The concentration was in the range from 2 to 6 wt.%, while the radiation dose was 0, 66, 99 and 132 kGy. The treated materials were measured for indentation hardness, modulus and creep. Degree of cross-linking was verified by thermo-mechanical analysis (TMA), while degradation processes was investigated by Fourier-transform infrared spectroscopy (FTIR). The results indicate that electron radiation positively affects the tested material properties. The best results were seen in polyamide with 6 wt.% of TAIC, which demonstrated a 38% improvement in mechanical properties after exposure to 132 kGy. This improvement in properties affects the final parts and their application (e.g., in the automotive industry—engine parts; in electrical engineering—insulation of wires and cables; and in industry—pipes for underfloor heating, etc.). Full article
(This article belongs to the Special Issue Application, Processing, and Testing of New Progressive Materials)
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14 pages, 3017 KiB  
Article
Tumor Budding Is an Independent Prognostic Factor in Pancreatic Adenocarcinoma and It Positively Correlates with PD-L1 Expression on Tumor Cells
by Rafał Pęksa, Michał Kunc, Piotr Czapiewski, Michał Piątek, Stanisław Hać, Barbara Radecka and Wojciech Biernat
Biomedicines 2022, 10(7), 1761; https://doi.org/10.3390/biomedicines10071761 - 21 Jul 2022
Cited by 4 | Viewed by 2842
Abstract
Pancreatic adenocarcinoma is one of the leading causes of cancer-related death in developed countries. Only 15% of patients are candidates for radical surgery, and adequate prognostication may guide proper postsurgical management. We aimed to retrospectively assess the prognostic significance of the immunohistochemical expression [...] Read more.
Pancreatic adenocarcinoma is one of the leading causes of cancer-related death in developed countries. Only 15% of patients are candidates for radical surgery, and adequate prognostication may guide proper postsurgical management. We aimed to retrospectively assess the prognostic significance of the immunohistochemical expression of immune checkpoint receptors (PD-L1 and VISTA), markers of systemic inflammation, thrombosis in the tumor area, and the tumor budding in the group of 107 patients diagnosed with pancreatic adenocarcinoma in a single center. The high expression of PD-L1 on tumor cells (TCs) was associated with worse overall survival (OS, p = 0.041, log-rank). On the contrary, high PD-L1 or VISTA on tumor-associated immune cells (TAICs) was correlated with better OS (p = 0.006 and p = 0.008, respectively, log-rank). The joint status of PD-L1 on TCs and TAICs stratified patients into three prognostic groups. The cases with high-grade budding were characterized by higher PD-L1 expression on TCs (p = 0.008) and elevated systemic inflammatory markers. Moreover, budding was identified as the independent prognostic factor in multivariate Cox regression analysis (HR = 2.87; 95% CI = 1.75–4.68; p < 0.001). To conclude, the pattern of PD-L1 and VISTA expression was associated with survival in univariate analysis. Tumor budding accurately predicts outcomes in pancreatic cancer and should be incorporated into routine histopathological practice. Full article
(This article belongs to the Special Issue Advances on Pancreatic Cancer)
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15 pages, 10910 KiB  
Article
Inclusion/Exclusion Behaviors of Small Molecules during Crystallization of Polymers in Miscible PLLA/TAIC Blend
by Lu Yin, Jiayao Wang, Taotao Lin and Jichun You
Polymers 2022, 14(13), 2737; https://doi.org/10.3390/polym14132737 - 4 Jul 2022
Cited by 3 | Viewed by 2286
Abstract
In this work, PLLA/TAIC has been taken as a model system to investigate the inclusion and exclusion of small molecules during the crystallization of polymers in their miscible blend. Our results indicate that it is the growth rate and diameter of PLLA spherulites [...] Read more.
In this work, PLLA/TAIC has been taken as a model system to investigate the inclusion and exclusion of small molecules during the crystallization of polymers in their miscible blend. Our results indicate that it is the growth rate and diameter of PLLA spherulites that dominate the localization of TAIC. On the one hand, crystallization temperature plays an important role. Crystallization at higher temperature corresponds to higher growth rates and a greater diameter of PLLA spherulites. The former improves the ability of PLLA crystals to trap TAIC while the latter leads to a lower volume fraction of space among neighboring PLLA spherulites. The combination of the two contributes to the enhanced inclusion behaviors. On the other hand, when compared to melt crystallization, cold crystallization results in much smaller spherulites (from higher nucleation density) and sufficient space among spherulites, which accounts for the enrichment of TAIC in interspherulitic regions and for its enhanced exclusion. In the adopted polymer–small molecule blend, TAIC can enrich in interspherulitic regions even in its miscible blend with PLLA, which can be attributed to its stronger diffusion ability. Full article
(This article belongs to the Special Issue Mechanical and Dynamic Characterization of Polymeric Composites)
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10 pages, 2683 KiB  
Article
Triallyl Isocyanurate as an Efficient Electrolyte Additive for Layered Oxide Cathode Material-Based Lithium-Ion Batteries with Improved Stability under High-Voltage
by Chang-Ming Zhang, Feng Li, Xue-Quan Zhu and Jin-Gang Yu
Molecules 2022, 27(10), 3107; https://doi.org/10.3390/molecules27103107 - 12 May 2022
Cited by 13 | Viewed by 3910
Abstract
In this study, a new electrolyte additive 1,3,5-tri-2-propenyl-1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione (TAIC) for lithium-ion batteries is reported. The additive is introduced as a novel electrolyte additive to enhance electrochemical performances of layered lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LiCoO2 [...] Read more.
In this study, a new electrolyte additive 1,3,5-tri-2-propenyl-1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione (TAIC) for lithium-ion batteries is reported. The additive is introduced as a novel electrolyte additive to enhance electrochemical performances of layered lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LiCoO2) cathodes, especially under a higher working voltage. Encouragingly, we found protective films would be formed on the cathode surface by the electrochemical oxidation, and the stability of the cathode material–electrolyte interface was greatly promoted. By adding 0.5 wt.% of TAIC into the electrolyte, the battery exhibited outstanding performances. The thickness swelling decreased to about 6% after storage at 85 °C for 24 h, while the capacity retention of cycle-life performances under high temperature of 45 °C after the 600th cycle increased 10% in comparison with the batteries without TAIC. Due to its specific function, the additive can be used in high energy density and high voltage lithium-ion battery systems. Full article
(This article belongs to the Section Nanochemistry)
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18 pages, 6808 KiB  
Article
Effects of Peroxide Initiator on the Structure and Properties of Ultralow Loss Thermosetting Polyphenylene Oxide-Based Composite
by Xueyi Yu, Zeming Fang, Qianfa Liu, Dan Li, Yundong Meng, Cheng Luo, Ke Wang and Zhiyong Lin
Polymers 2022, 14(9), 1752; https://doi.org/10.3390/polym14091752 - 26 Apr 2022
Cited by 15 | Viewed by 4640
Abstract
Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition–process–structure–property relationships of the systems. In this [...] Read more.
Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition–process–structure–property relationships of the systems. In this work, the effects of peroxide initiator concentration on the structure and dielectric properties of a free radical cured ultralow loss PPO/Triallyl isocyanate (TAIC) composite system were studied. As expected, the glass transition temperature (Tg) and storage modulus increased with the advancing of crosslinking, whereas the dielectric loss showed an “abnormal” rise with the increase in crosslink density. Extensive studies were carried out by varying the initiator contents and characterizing the structure with spectroscopy, thermal analysis, and positron annihilation lifetime spectrum (PALS) techniques. The results show that the competition of polarity, crosslink density, free volume, and free TAIC are the key factors determining the dielectric properties of the composites. Full article
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21 pages, 5981 KiB  
Article
Genome-Wide Identification and Analysis of bZIP Gene Family and Resistance of TaABI5 (TabZIP96) under Freezing Stress in Wheat (Triticum aestivum)
by Yi Liang, Jingqiu Xia, Yunshuang Jiang, Yuzhuo Bao, Huichan Chen, Duojia Wang, Da Zhang, Jing Yu and Jing Cang
Int. J. Mol. Sci. 2022, 23(4), 2351; https://doi.org/10.3390/ijms23042351 - 21 Feb 2022
Cited by 53 | Viewed by 5461
Abstract
The basic leucine zipper (bZIP) regulates plant growth and responds to stress as a key transcription factor of the Abscisic acid (ABA) signaling pathway. In this study, TabZIP genes were identified in wheat and the gene structure, physicochemical properties, cis-acting elements, [...] Read more.
The basic leucine zipper (bZIP) regulates plant growth and responds to stress as a key transcription factor of the Abscisic acid (ABA) signaling pathway. In this study, TabZIP genes were identified in wheat and the gene structure, physicochemical properties, cis-acting elements, and gene collinearity were analyzed. RNA-Seq and qRT-PCR analysis showed that ABA and abiotic stress induced most TabZIP genes expression. The ectopic expression of TaABI5 up-regulated the expression of several cold-responsive genes in Arabidopsis. Physiological indexes of seedlings of different lines under freezing stress showed that TaABI5 enhanced the freezing tolerance of plants. Subcellular localization showed that TaABI5 is localized in the nucleus. Furthermore, TaABI5 physically interacted with cold-resistant transcription factor TaICE1 in yeast two-hybrid system. In conclusion, this study identified and analyzed members of the TabZIP gene family in wheat. It proved for the first time that the gene TaABI5 affected the cold tolerance of transgenic plants and was convenient for us to understand the cold resistance molecular mechanism of TaABI5. These results will provide a new inspiration for further study on improving plant abiotic stress resistance. Full article
(This article belongs to the Topic Plant Functional Genomics and Crop Genetic Improvement)
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14 pages, 2169 KiB  
Article
Histologic-Based Tumor-Associated Immune Cells Status in Clear Cell Renal Cell Carcinoma Correlates with Gene Signatures Related to Cancer Immunity and Clinical Outcomes
by Chisato Ohe, Takashi Yoshida, Junichi Ikeda, Toyonori Tsuzuki, Riuko Ohashi, Haruyuki Ohsugi, Naho Atsumi, Ryosuke Yamaka, Ryoichi Saito, Yoshiki Yasukochi, Koichiro Higasa, Hidefumi Kinoshita and Koji Tsuta
Biomedicines 2022, 10(2), 323; https://doi.org/10.3390/biomedicines10020323 - 29 Jan 2022
Cited by 9 | Viewed by 3555
Abstract
The three-tier immunophenotype (desert, excluded, and inflamed) and the four-tier immunophenotype (cold, immunosuppressed, excluded, and hot) have been linked to prognosis and immunotherapy response. This study aims to evaluate whether immunophenotypes of clear cell renal cell carcinoma, identified on hematoxylin and eosin-stained slides, [...] Read more.
The three-tier immunophenotype (desert, excluded, and inflamed) and the four-tier immunophenotype (cold, immunosuppressed, excluded, and hot) have been linked to prognosis and immunotherapy response. This study aims to evaluate whether immunophenotypes of clear cell renal cell carcinoma, identified on hematoxylin and eosin-stained slides, correlate with gene expression signatures related to cancer immunity, and clinical outcomes. We evaluated tumor-associated immune cells (TAICs) status using three methodologies: three-tier immunophenotype based on the location of TAICs, four-tier immunophenotype considering both the location and degree of TAICs and inflammation score focusing only on the degree of TAICs, using a localized clear cell renal cell carcinoma cohort (n = 436) and The Cancer Genome Atlas (TCGA)-KIRC cohort (n = 162). We evaluated the association of the TAICs status assessed by three methodologies with CD8 and PD-L1 immunohistochemistry and immune gene expression signatures by TCGA RNA-sequencing data. All three methodologies correlated with immunohistochemical and immune gene expression signatures. The inflammation score and the four-tier immunophenotype showed similarly higher accuracy in predicting recurrence-free survival and overall survival compared to the three-tier immunophenotype. In conclusion, a simple histologic assessment of TIACs may predict clinical outcomes and immunotherapy responses. Full article
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19 pages, 36691 KiB  
Article
Mechanically Robust and Flame-Retardant Polylactide Composites Based on In Situ Formation of Crosslinked Network Structure by DCP and TAIC
by Yajun Chen, Xingde Wu, Mengqi Li, Lijun Qian and Hongfu Zhou
Polymers 2022, 14(2), 308; https://doi.org/10.3390/polym14020308 - 13 Jan 2022
Cited by 13 | Viewed by 2617
Abstract
The addition of intumescent flame retardant to PLA can greatly improve the flame retardancy of the material and inhibit the dripping, but the major drawback is the adverse impact of the mechanical properties of the material. In this study, we found that the [...] Read more.
The addition of intumescent flame retardant to PLA can greatly improve the flame retardancy of the material and inhibit the dripping, but the major drawback is the adverse impact of the mechanical properties of the material. In this study, we found that the flame retardant and mechanical properties of the materials can be improved simultaneously by constructing a cross-linked structure. Firstly, a cross-linking flame-retardant PLA structure was designed by adding 0.9 wt% DCP and 0.3 wt% TAIC. After that, different characterization methods including torque, melt flow rate, molecular weight and gel content were used to clarify the formation of crosslinking structures. Results showed that the torque of 0.9DCP/0.3TAIC/FRPLA increased by 307% and the melt flow rate decreased by 77.8%. The gel content of 0.9DCP/0.3TAIC/FRPLA was 30.8%, indicating the formation of cross-linked structures. Then, the mechanical properties and flame retardant performance were studied. Results showed that, compared with FRPLA, the tensile strength, elongation at break and impact strength of 0.9DCP/0.3TAIC/FRPLA increased by 34.8%, 82.6% and 42.9%, respectively. The flame retardancy test results showed that 0.9DCP/0.3TAIC/FRPLA had a very high LOI (the limiting oxygen index) value of 39.2% and passed the UL94 V-0 level without dripping. Finally, the crosslinking reaction mechanism, flame retardant mechanism and the reasons for the improvement of mechanical properties were studied and described. Full article
(This article belongs to the Special Issue Fire-Safe Polymer Composites: Structure and Application)
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24 pages, 10596 KiB  
Article
Influence of Cross-Linking Agent Concentration/Beta Radiation Surface Modification on the Micro-Mechanical Properties of Polyamide 6
by Martin Ovsik, Michal Stanek, Adam Dockal, Jiri Vanek and Lenka Hylova
Materials 2021, 14(21), 6407; https://doi.org/10.3390/ma14216407 - 26 Oct 2021
Cited by 5 | Viewed by 2065
Abstract
This study focuses on the problematic of polyamide 6 containing various concentrations of cross-linking agent that was exposed to electron radiation. It is important to improve the material properties of polymers as much as possible. This endeavor can be realized by numerous methods, [...] Read more.
This study focuses on the problematic of polyamide 6 containing various concentrations of cross-linking agent that was exposed to electron radiation. It is important to improve the material properties of polymers as much as possible. This endeavor can be realized by numerous methods, one of which is radiation exposure. This study investigates the effect of electron beam radiation in doses ranging from 66 to 132 kGy on the micro-mechanical properties of polymers, specifically polyamide 6 filled with 1, 3 and 5 wt.% of cross-linking agent triallyl isocyanurate (TAIC). The changes in the material brought by the radiation exposure were quantified by measurements of indentation hardness and modulus, which were the main measured micro-mechanical properties. Furthermore, thermo-mechanical analysis (TMA) was chosen to confirm the results of the material cross-linking, while the effect of degradation was investigated by Fourier-transform infrared spectroscopy (FTIR). In pursuit of complete evaluation, the topography of the test subject’s surface was explored by atomic force microscopy (AFM). The optimal concentration/radiation ratio was found in polyamide 6 enriched by 5 wt.% concentration of TAIC, which was irradiated by 132 kGy. Material treated in such a way had its indentation hardness by 33% and indentation modulus improved by 26% in comparison with the untreated material. These results were subsequently confirmed by the TMA and FTIR methods. Full article
(This article belongs to the Section Polymeric Materials)
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12 pages, 3443 KiB  
Article
Novel Approaches to In-Situ ATR-FTIR Spectroscopy and Spectroscopic Imaging for Real-Time Simultaneous Monitoring Curing Reaction and Diffusion of the Curing Agent at Rubber Nanocomposite Surface
by Shun Muroga, Yu Takahashi, Yuta Hikima, Seisuke Ata, Sergei G. Kazarian, Masahiro Ohshima, Toshiya Okazaki and Kenji Hata
Polymers 2021, 13(17), 2879; https://doi.org/10.3390/polym13172879 - 27 Aug 2021
Cited by 3 | Viewed by 4893
Abstract
Here, we propose a novel attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy method for simultaneously monitoring the curing reaction and the diffusion behavior of curing agents at the surface of rubber in real-time. The proposed scheme was demonstrated by fluorine rubber (FKM) [...] Read more.
Here, we propose a novel attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy method for simultaneously monitoring the curing reaction and the diffusion behavior of curing agents at the surface of rubber in real-time. The proposed scheme was demonstrated by fluorine rubber (FKM) and FKM/carbon nanotube (CNT) nanocomposites with a target curing agent of triallyl-isocyanurate (TAIC). The broadening and the evolution of the C=O stretching of TAIC were quantitatively analyzed to characterize the reaction and the diffusion. Changes in the width of the C=O stretching indicated the reaction rate at the surface was even faster than that of the bulk as measured by a curemeter. The diffusion coefficient of the curing agent in the course of heating was newly calculated by the initial increase in the absorbance and our model based on Fickian diffusion. The diffusion coefficients of TAIC during curing were evaluated, and its temperature and filler dependency were identified. Cross-sectional ATR-FTIR imaging and in situ ATR-FTIR imaging measurements supported the hypothesis of the unidirectional diffusion of the curing agent towards the heated surface. It was shown that our method of in situ ATR-FTIR can monitor the degrees of cure and the diffusion coefficients of curing agents simultaneously, which cannot be achieved by conventional methods, e.g., rheological measurements. Full article
(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)
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