Synthetic Environmentally Friendly Castor Oil Based-Polyurethane with Carbon Black as a Microphase Separation Promoter

This study created water polyurethane (WPU) prepolymer by using isophorone diisocyanate, castor oil, dimethylolpropionic acid, and triethanolamine (TEA) as the hard segment, soft segment, hydrophilic group, and neutralizer, respectively. TEA, deionized water, and carbon black (CB) were added to the prepolymer under high-speed rotation to create an environmentally friendly vegetable-oil-based polyurethane. CB served as the fortifier and promoter of microphase separation. Fourier transform infrared spectroscopy was performed to elucidate the role of H-bond interactions within the CB/WPUs. Additionally, atomic force microscopy was conducted to determine the influence of H-bond interactions on the degree of microphase separation in the WPU. Furthermore, this study used four-point probe observation to discover the materials’ conductivity of CB in the WPU. Thermogravimetric analysis and dynamic mechanical analysis were performed to measure the thermal properties of the CB/WPUs. The mechanical properties of CB/WPUs were measured using a tensile testing machine. The CB/WPUs were also soaked in 1 wt.% NaOH solution for different amounts of time to determine the degradation properties of the CB/WPUs. Finally, scanning electron microscopy was performed to observe the topography of the CB/WPUs after degradation.


Introduction
The promotion of green materials has attracted global attention to the development of environmentally friendly polymers. Numerous studies have investigated vegetable oils [1,2], such as castor oil (CO) [3,4] and soybean oil [5]. CO is extracted from the seeds of caster plants. Because every CO molecule consists of three -OH groups, CO can serve as a cross-link agent [6]. Scholars have imported CO into polyurethane (PU) structures [7,8], and even implemented the postmodified ester [9,10] and alkenyl [11,12] groups of CO in PU. PU has outstanding mechanical properties, abrasion resistance, and stiffness [13,14]. Therefore, this study synthesized green PU by using natural materials and isocyanate [15]. Water polyurethane (WPU) has inferior mechanical properties 5 to oil PU [16]. The mechanical properties of PU are mainly determined by the degree of microphase separation during

Synthesis of CB/WPUs
First, CB was added to 10 mL of MEK and dispersed using an ultrasonicator. Subsequently, CO and IPDI were added to the 500-mL three-necked flask. Nitrogen was passed through the flask to heat it to 75 °C . A mechanical mixer was employed to mix the content at 300 rpm. After 2 h of reaction had passed, DMPA was added for prepolymerization. When the stickiness of the mixture had increased, butanone containing CB was added to moderate the stickiness of the mixture. The WPU prepolymer was then cooled to 50 °C and neutralized using TEA for 20 min. Deionized water and ethylenediamine (EDA) were added to the mixture for 1 h to disperse the CB/WPUs (Scheme 1). The obtained CB/WPU solution was poured into a serum bottle and stored under a vacuum to defoam for 1 day. Finally, the CB/WPU solution was poured onto a Teflon plate and placed in an

Synthesis of CB/WPUs
First, CB was added to 10 mL of MEK and dispersed using an ultrasonicator. Subsequently, CO and IPDI were added to the 500-mL three-necked flask. Nitrogen was passed through the flask to heat it to 75 • C. A mechanical mixer was employed to mix the content at 300 rpm. After 2 h of reaction had passed, DMPA was added for prepolymerization. When the stickiness of the mixture had increased, butanone containing CB was added to moderate the stickiness of the mixture. The WPU prepolymer was then cooled to 50 • C and neutralized using TEA for 20 min. Deionized water and ethylenediamine (EDA) were added to the mixture for 1 h to disperse the CB/WPUs (Scheme 1). The obtained CB/WPU solution was poured into a serum bottle and stored under a vacuum to defoam for 1 day. Finally, the CB/WPU solution was poured onto a Teflon plate and placed in an oven to dry. The recipe, symbols, and theoretical contents of the hard and soft segments for the CB/WPUs films are shown in Table 1.

Fourier Transform Infrared Spectroscopy (FT-IR)
Fourier transform infrared spectroscopy measurements were performed on a Digilab (Hopkinton, MA, USA) (model (FTS-1000)). The spectra of the samples was obtained by averaging 16 scans in a range of 4000 to 650 cm −1 with a resolution of 2 cm −1 .

Surface Roughness Analysis
Scanning was performed using a Bruker dimension icon atomic force microscope (Billerica, MA, USA), which is generally operated in two imaging modes: tapping and contact. The tapping mode was used in this study, and the tip of the oscillation probe cantilever made only intermittent contact with the sample. Regarding the phase of the sine wave that drives the cantilever, the phase of the tip oscillation is extremely sensitive to various sample surface characteristics; therefore, the topography and phase images of a sample's surface can be detected.

Thermogravimetric Analysis (TGA)
Thermogravimetric analysis was performed on a TA instrument Q-500 (New Castle, DE, USA). The samples (5-8 mg) were heated from room temperature to 700 • C under nitrogen at a rate of 10 • C/min.

Conductivities
The sheet resistances of the CB/WPUs were measured with a Keithley 2400 digital source meter equipped with a four-point probe. Every resistance was tested 3 times and the average value was obtained. Generally speaking, the conductive materials used in the antistatic materials can be divided into three grades. The first one is basic antistatic grade with a 10 9~1 0 12 of surface impedance. The second one is antistatic grade (static dissipation) with 10 6~1 0 9 of surface impedance. The third one is conductive grade with 10 4~1 0 6 of surface impedance.

Dynamic Mechanical Analysis (DMA)
Dynamic mechanical analysis was performed on DMA Q800 machine (TA Instruments, New Castle, DE, USA) at 1 Hz with a 5 µm amplitude over a temperature range of −50 to 50 • C at a heating rate of 3 • C/min. Specimens with dimensions of 35.6 × 12.7 × 2 mm 3 were used in these tests. The Tg was taken as the peak temperature of the glass transition region in the tan δ curve.

Stress-Strain Testing
Tensile strength and elongation at break were measured using a universal testing machine (model CY-6040A8, Chun Yen Testing Machine Co., Ltd., Taichung, Taiwan). Testing was conducted with ASTM D638. The dimension of the film specimen was 45 mm × 8 mm × 0.2 mm.

Hydrolytic Degradation Tests
Hydrolytic degradation evaluation of the specimens was conducted in a 1% aqueous NaOH solution [30,31]. In order to accelerate the tests, all samples were tested at 45 • C. The specimens with dimensions of 2 × 2 cm 2 were tested for various days, washed with distilled water, and dried completely in a vacuum oven at 70 • C for 3 h. The degree of degradation was determined from the weight loss in Equation (1): where W 0 is the dry weight before degradation, and W t is the dry weight at time t.

Morphology Analysis
Morphology of the specimens after hydrolytic degradation was observed by using a high resolution field-emission scanning electron microscope (FESEM), model JSM-6500F(JEOL, Tokyo, Japan). Specimens of 2 × 2 cm 2 were fixed on a sample holder using conductive adhesive tape and were then coated with a thin layer of platinum to improve image resolution. The samples were photographed with 1.00 K magnification Figure 2a displays the FTIR analysis results and reveals that the curve of the CB/WPUs is within 4000-650 cm −1 . The FTIR curve contains the characteristic peak of PU (-COONH-). The stretching vibration peaks of the -NH and -OH groups are located at 3100-3550 cm −1 , whereas the stretching vibration peak of CH 2 is located at 2800-3000 cm −1 (the asymmetric and symmetric stretching vibration peaks of CH 2 are located at 2923 and 2856 cm −1 , respectively). The stretching vibration peak of C=O is located at 1600-1800 cm −1 and represents the ordered H-bonded carbonyl groups (C=O order ), disordered H-bonded carbonyl groups (C=O disorder ), and free carbonyl groups (C=O free ). The stretching vibration peaks for amide II (δN-H + νC-N + νC-C) and III (νC-N, N-H bending, and C-Cα) are located at 1529 and 1234 cm −1 , respectively. These results are consistent with those in other reports [6,32]. This study conducted curve fitting of the C=O curve section (1620-1740 cm −1 ) to determine changes in the number of H-bonds and reveal the influence of adding CB to the WPU on H-bond interactions ( Figure 2b). The results revealed that the stretching peaks of C=O order , C=O disorder , and C=O free are located at 1644, 1703, and 1738 cm −1 , respectively. After calculating the curve area of C=O order , C=O disorder , and C=O free , the percentage of total H-bond content within the C=O functional group of each CB/WPU was determined ( Table 2). The calculations indicated that the C=O functional group comprised 79.96%, 88.27%, 92.28%, and 84.90% of the total H-bond content in WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03, respectively. The original C=O comprised 79.96% of the total H-bond content of the WPU. These H-bonds were located in the hard section of the C=O· · · H-N. When the amount of CB added was 0-2 wt.%, higher amounts of CB resulted in more total H-bonds in the C=O functional group, with the maximum difference being 12.32%. These H-bonds were located in the C=O· · · H-O section between WPU and CB. When 3 wt.% CB was added, the total number of H-bonds was lower. This was possibly due to severe clustering of CB that prevented the formation of H-bonds.

Surface Roughness and Electrical Resistance Analysis
The hydrogen bond is one of the key factors promoting the microphase separation of PU. So on the whole, it can be said that the hydrogen bond influences the surface roughness and also influences the distribution of microphase separation at the same time. The left and right parts of Figure 3 display the three-dimensional morphology and phases of the CB/WPUs. The average surface roughness of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 is 1.58, 2.07, 4.32, and 2.84 nm, respectively. Up to CB addition of 2 wt.%, an increase in the CB added caused an increase in the

Surface Roughness and Electrical Resistance Analysis
The hydrogen bond is one of the key factors promoting the microphase separation of PU. So on the whole, it can be said that the hydrogen bond influences the surface roughness and also influences the distribution of microphase separation at the same time. The left and right parts of Figure 3 display the three-dimensional morphology and phases of the CB/WPUs. The average surface roughness of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 is 1.58, 2.07, 4.32, and 2.84 nm, respectively. Up to CB addition of 2 wt.%, an increase in the CB added caused an increase in the surface roughness of the WPU. However, adding an excessive amount of CB resulted in lower average surface roughness due to the H-bond interaction produced by the -OH group of CB and -C=O group of PU. The FTIR results revealed that CB/WPU-02 had the most H-bonds, causing an unstable film-forming process and increasing the average surface roughness. The phase figure indicates that WPU had similar microphase separation conditions as PU. When 1 wt.% of CB was added, the number of surface hard segments was increased. The hard segments (i.e., the white dots in Figure 3) showed the presence of CB. Because in the phase diagram of AFM, it is able to identify the soft or hard degree of the film, and when the values are higher (white dots), it represents the film is harder. The microphase separation in PU can promote the separation of soft segment and hard segment. The hard segment belongs to the harder area in the film. So the white dots represent the hard segment (IPDI), but they can also represent CB (because CB is relatively harder compared to the film). This indicates that CB promotes microphase separation. When 2 wt.% of CB was added, the hard segments began to cluster and the soft segments (i.e., darker area) were evenly distributed. This result indicated that the degree of microphase separation was greater in CB/WPU-02 than in CB/WPU-01. The phase figure of CB/WPU-03 indicates that when the amount of CB added was 3 wt.%, the white dots were clustered. Microphase separation in PU is caused by the different polarity of hard and soft segments. Additionally, hard segment clustering is caused by H-bond interactions between hard segments. Because the CB/WPU-02 film exhibited the most H-bond interactions, it had the greatest degree of microphase separation. surface roughness of the WPU. However, adding an excessive amount of CB resulted in lower average surface roughness due to the H-bond interaction produced by the -OH group of CB and -C=O group of PU. The FTIR results revealed that CB/WPU-02 had the most H-bonds, causing an unstable film-forming process and increasing the average surface roughness. The phase figure indicates that WPU had similar microphase separation conditions as PU. When 1 wt.% of CB was added, the number of surface hard segments was increased. The hard segments (i.e., the white dots in Figure 3) showed the presence of CB. Because in the phase diagram of AFM, it is able to identify the soft or hard degree of the film, and when the values are higher (white dots), it represents the film is harder. The microphase separation in PU can promote the separation of soft segment and hard segment. The hard segment belongs to the harder area in the film. So the white dots represent the hard segment (IPDI), but they can also represent CB (because CB is relatively harder compared to the film). This indicates that CB promotes microphase separation. When 2 wt.% of CB was added, the hard segments began to cluster and the soft segments (i.e., darker area) were evenly distributed.   The amount of CB substantially influences the conductivity of CB/WPUs. The resistive properties of the CB/WPUs are displayed in Table 3. The standard WPU did not exhibit conductivity. When 1 wt.% CB was added, the resistive value was 2.01 × 10 6 , indicating that the addition of 1 wt.% CB gave the WPU static conductivity. CB/WPU-02 and CB/WPU-03 had resistive values of 8.41 × 10 5 and 3.99 × 10 4 , respectively. This was because more CB was present in the WPU and indicates that all samples had static conductivity.  .43 • C. Thus, when 3 wt.% CB was added to the WPU, the temperature required to reach T onset or T 50 was increased by 10 • C. This was because CB has greater thermostability than WPU. Therefore, the thermostability of WPU was increased by adding more CB. Furthermore, the 700 • C residue masses of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 were 1.81%, 2.24%, 2.30%, and 2.45%, respectively. The increase of residue mass in CB/WPUs with CB content again indicates that more CB has remained in WPU. The amount of CB substantially influences the conductivity of CB/WPUs. The resistive properties of the CB/WPUs are displayed in Table 3. The standard WPU did not exhibit conductivity. When 1 wt.% CB was added, the resistive value was 2.01 × 10 6 , indicating that the addition of 1 wt.% CB gave the WPU static conductivity. CB/WPU-02 and CB/WPU-03 had resistive values of 8.41 × 10 5 and 3.99 × 10 4 , respectively. This was because more CB was present in the WPU and indicates that all samples had static conductivity.   to the WPU, the temperature required to reach Tonset or T50 was increased by 10 °C. This was because CB has greater thermostability than WPU. Therefore, the thermostability of WPU was increased by adding more CB. Furthermore, the 700 °C residue masses of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 were 1.81%, 2.24%, 2.30%, and 2.45%, respectively. The increase of residue mass in CB/WPUs with CB content again indicates that more CB has remained in WPU.  Figure 5 displays the tanδ of the WPUs obtained when different amounts of CB were added. The dynamic glass transition temperature is denoted Tgd. Table 3 lists the maximum Tgd and tanδ for the different CB/WPUs. The Tgd of the standard WPU was 52.66 °C. Adding 2 wt.% CB to WPU resulted in a higher Tgd of 59.41 °C. This was possibly due to H-bond interactions between the -OH groups in CB and C=O groups in WPU. This H-bond interaction prevents WPU molecular chains from moving, causing a higher Tgd. However, when 3 wt.% CB was added, the Tgd was lower. This may have been caused by the extensive clustering of CB, which restrained the -OH groups of CB and prevented them from forming H-bonds with the C=O groups, as was demonstrated in the FTIR   Figure 5 displays the tanδ of the WPUs obtained when different amounts of CB were added. The dynamic glass transition temperature is denoted T gd . Table 3 lists the maximum T gd and tanδ for the different CB/WPUs. The T gd of the standard WPU was 52.66 • C. Adding 2 wt.% CB to WPU resulted in a higher T gd of 59.41 • C. This was possibly due to H-bond interactions between the -OH groups in CB and C=O groups in WPU. This H-bond interaction prevents WPU molecular chains from moving, causing a higher T gd . However, when 3 wt.% CB was added, the T gd was lower. This may have been caused by the extensive clustering of CB, which restrained the -OH groups of CB and prevented them from forming H-bonds with the C=O groups, as was demonstrated in the FTIR analysis. Additionally, the maximum tanδ of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 0.403, 0.400, 0.398, and 0.384, respectively. The tanδ is obtained from the loss modulus divided by the storage module. So, lower tanδ value means harder membrane. Thus, the maximum tanδ decreased with an increase of CB. This was because the addition of CB increased the hardness of the CB/WPUs, reducing the flexibility and increasing the stickiness of the WPUs.   Figure 6 displays the stress-strain curve of the various CB/WPUs. Table 4 records the maximum tensile strength, breaking strain, and Young's modulus of each CB/WPU. The maximum tensile strength of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 9.7, 12.9, 13.8, and 10.4 MPa, respectively, whereas their breaking strains were 123%, 108%, 69%, and 60%. CB/WPU-02 thus had the greatest tensile strength. Possible reasons for this include the dispersibility of CB when 2 wt.% CB was added to WPU and the H-bond interactions between CB and WPU. In these two situations, the degree of microphase separation was increased. This microphase separation result was also shown in the AFM results. When an excessive amount of CB (i.e., 3 wt.%) was added, the CB in the WPU was severely clustered. This clustering increased the stress concentration point of the WPU and caused more defects in the material, reducing the maximum tensile strength and breaking strain. The Young's modulus of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 0.85, 1.39, 3.64, and 1.77 MPa, respectively. CB/WPU-02 thus exhibited the greatest Young's modulus. This result is consistent with the aforementioned description.   Figure 6 displays the stress-strain curve of the various CB/WPUs. Table 4 records the maximum tensile strength, breaking strain, and Young's modulus of each CB/WPU. The maximum tensile strength of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 9.7, 12.9, 13.8, and 10.4 MPa, respectively, whereas their breaking strains were 123%, 108%, 69%, and 60%. CB/WPU-02 thus had the greatest tensile strength. Possible reasons for this include the dispersibility of CB when 2 wt.% CB was added to WPU and the H-bond interactions between CB and WPU. In these two situations, the degree of microphase separation was increased. This microphase separation result was also shown in the AFM results. When an excessive amount of CB (i.e., 3 wt.%) was added, the CB in the WPU was severely clustered. This clustering increased the stress concentration point of the WPU and caused more defects in the material, reducing the maximum tensile strength and breaking strain. The Young's modulus of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 0.85, 1.39, 3.64, and 1.77 MPa, respectively. CB/WPU-02 thus exhibited the greatest Young's modulus. This result is consistent with the aforementioned description. analysis. Additionally, the maximum tanδ of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 0.403, 0.400, 0.398, and 0.384, respectively. The tanδ is obtained from the loss modulus divided by the storage module. So, lower tanδ value means harder membrane. Thus, the maximum tanδ decreased with an increase of CB. This was because the addition of CB increased the hardness of the CB/WPUs, reducing the flexibility and increasing the stickiness of the WPUs.  Figure 6 displays the stress-strain curve of the various CB/WPUs. Table 4 records the maximum tensile strength, breaking strain, and Young's modulus of each CB/WPU. The maximum tensile strength of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 9.7, 12.9, 13.8, and 10.4 MPa, respectively, whereas their breaking strains were 123%, 108%, 69%, and 60%. CB/WPU-02 thus had the greatest tensile strength. Possible reasons for this include the dispersibility of CB when 2 wt.% CB was added to WPU and the H-bond interactions between CB and WPU. In these two situations, the degree of microphase separation was increased. This microphase separation result was also shown in the AFM results. When an excessive amount of CB (i.e., 3 wt.%) was added, the CB in the WPU was severely clustered. This clustering increased the stress concentration point of the WPU and caused more defects in the material, reducing the maximum tensile strength and breaking strain. The Young's modulus of WPU, CB/WPU-01, CB/WPU-02, and CB/WPU-03 was 0.85, 1.39, 3.64, and 1.77 MPa, respectively. CB/WPU-02 thus exhibited the greatest Young's modulus. This result is consistent with the aforementioned description.

Hydrolytic Degradation
This study sought to develop an environmentally friendly and degradable material. Figure 7 displays the mass loss of the CB/WPUs after degradation in 1 wt.% NaOH. The mass loss of all samples exceeded 15% after 12 h of degradation. After 16 h of degradation, most of the polymer structure was fractured, causing difficulties in sampling. CB/WPU-02 exhibited the lowest degradation speed. This was because the CB/WPU-02 had the most H-bond interactions. When the amount of CB added was 3 wt.%, the CB was severely clustered within the WPU, increasing the number of defects in the material. This enabled 1 wt.% NaOH to enter the CB/WPU-03 film more easily and caused the CB/WPU-03 to lose more mass.

Hydrolytic Degradation
This study sought to develop an environmentally friendly and degradable material. Figure 7 displays the mass loss of the CB/WPUs after degradation in 1 wt.% NaOH. The mass loss of all samples exceeded 15% after 12 h of degradation. After 16 h of degradation, most of the polymer structure was fractured, causing difficulties in sampling. CB/WPU-02 exhibited the lowest degradation speed. This was because the CB/WPU-02 had the most H-bond interactions. When the amount of CB added was 3 wt.%, the CB was severely clustered within the WPU, increasing the number of defects in the material. This enabled 1 wt.% NaOH to enter the CB/WPU-03 film more easily and caused the CB/WPU-03 to lose more mass.  Figure 8 displays the SEM surface topology of CB/WPUs after degradation in 1 wt.% NaOH for different amounts of time. After 12 h, numerous holes had developed on the WPU sample containing no CB, whereas CB/WPU-01 had considerably fewer holes. This was because the H-bond interactions between CB and WPU prevented the 1 wt.% NaOH solution from infiltrating the WPU film. The surface topography of CB/WPU-02 is rougher than the other samples. This was possibly because more H-bond interactions were causing the greatest degree of microphase separation within the CB/WPU-02 (such as AFM). The high degree of microphase separation promoted the clustering of degradable casotor oil segments, so after CB/WPU-02 was immersed in 1 wt.% NaOH solution, the clustered soft segments on CB/WPU-02 surface were degraded and the shape was changed. After being degraded for 12 h, large cavities formed on CB/WPU-03. This was because of severe CB clustering in the WPU, which caused numerous defects in the CB/WPU-03 film. In summary, from the degradation loss rate and SEM, it was known that CB/WPU-02 had less degradation loss rate and no formation of cavities, and this was possibly because the H-bond interactions inhibited 1 wt.% NaOH, permeating into CB/WPUs film.  Figure 8 displays the SEM surface topology of CB/WPUs after degradation in 1 wt.% NaOH for different amounts of time. After 12 h, numerous holes had developed on the WPU sample containing no CB, whereas CB/WPU-01 had considerably fewer holes. This was because the H-bond interactions between CB and WPU prevented the 1 wt.% NaOH solution from infiltrating the WPU film. The surface topography of CB/WPU-02 is rougher than the other samples. This was possibly because more H-bond interactions were causing the greatest degree of microphase separation within the CB/WPU-02 (such as AFM). The high degree of microphase separation promoted the clustering of degradable casotor oil segments, so after CB/WPU-02 was immersed in 1 wt.% NaOH solution, the clustered soft segments on CB/WPU-02 surface were degraded and the shape was changed. After being degraded for 12 h, large cavities formed on CB/WPU-03. This was because of severe CB clustering in the WPU, which caused numerous defects in the CB/WPU-03 film. In summary, from the degradation loss rate and SEM, it was known that CB/WPU-02 had less degradation loss rate and no formation of cavities, and this was possibly because the H-bond interactions inhibited 1 wt.% NaOH, permeating into CB/WPUs film.

Conclusions
This study successfully synthesized an environmentally friendly vegetable-oil-based PU. FTIR analyses revealed that CB/WPU-02 had the most H-bond interactions. The AFM and conductivity test results revealed that 2 wt.% CB was the optimal amount of CB to add to promote microphase separation. This was due to CB microclustering when 2 wt.% CB was employed. The CB microclustering and H-bond interactions caused CB/WPU-02 to exhibit the highest degree of microphase separation. Additionally, TGA revealed that greater amounts of CB in the WPU resulted in higher initial degradation temperatures. The DMA and tensile test revealed that the CB/WPU-02 film had the highest Tgd and most favorable mechanical properties. When the amount of CB added was 3 wt.%, the CB clustered severely and numerous defects were created. The degradation experiment and SEM results revealed that CB/WPU-02 exhibited the greatest degradation stability of all samples. NaOH was found to not easily infiltrate the CB/WPU-02 film, causing the degradation process to commence from the film surface. In summary, when 1 wt% of CB is added (CB/WPU-01), it has already become the static conductive material (such as Table 3). So the cost has already been reduced, it is much more suitable to be used in the application of operation room and weapon storehouse. As for the raise of benefit, 2 wt% of CB addition (CB/WPU-02) will be the most appropriate addition level.

Conclusions
This study successfully synthesized an environmentally friendly vegetable-oil-based PU. FTIR analyses revealed that CB/WPU-02 had the most H-bond interactions. The AFM and conductivity test results revealed that 2 wt.% CB was the optimal amount of CB to add to promote microphase separation. This was due to CB microclustering when 2 wt.% CB was employed. The CB microclustering and H-bond interactions caused CB/WPU-02 to exhibit the highest degree of microphase separation. Additionally, TGA revealed that greater amounts of CB in the WPU resulted in higher initial degradation temperatures. The DMA and tensile test revealed that the CB/WPU-02 film had the highest T gd and most favorable mechanical properties. When the amount of CB added was 3 wt.%, the CB clustered severely and numerous defects were created. The degradation experiment and SEM results revealed that CB/WPU-02 exhibited the greatest degradation stability of all samples. NaOH was found to not easily infiltrate the CB/WPU-02 film, causing the degradation process to commence from the film surface. In summary, when 1 wt.% of CB is added (CB/WPU-01), it has already become the static conductive material (such as Table 3). So the cost has already been reduced, it is much more suitable to be used in the application of operation room and weapon storehouse. As for the raise of benefit, 2 wt.% of CB addition (CB/WPU-02) will be the most appropriate addition level.