Silica aerogel modified PVDF / FKM thermoplastic elastomer and preparation method thereof

Abstract

The invention provides a silica aerogel modified PVDF / FKM thermoplastic elastomer and a preparation method thereof, specifically, silica aerogel is pretreated with a coupling agent KH570, ultraviolet light modification is performed, the silica aerogel is used for preparing modified fluororubber (FKM), and finally PVDF and the modified FKM are prepared into the PVDF / FKM thermoplastic elastomer in a torque rheometer. Performance testing is carried out on the PVDF / FKM thermoplastic elastomer, and results show that the crosslinking degree of the FKM is favorably improved through ultraviolet light treatment, the crosslinking degree of the FKM treated for 20 minutes is the maximum, the S '(MH) value is 20.56 dN.m, the tensile strength of the PVDF / FKM thermoplastic elastomer is the maximum and 24.5 MPa when the use amount of KH570 is 3%, and a positive correlation relation exists between the tensile strength and a torque value; and the heat conductivity coefficient of the elastomer modified by ultraviolet light is obviously reduced. The material can be used for corrosion-resistant cables and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of materials, in particular to a modified PVDF / FKM thermoplastic elastomer of silica aerogel and a preparation method thereof. BACKGROUND

[0002] Fluorine rubber (FKM) is a kind of high-performance rubber material with excellent chemical resistance, high-temperature resistance, oil resistance and weather resistance. It is widely used in aerospace industry, chemical industry, automobile industry, medicine and food industry. Due to its excellent chemical properties, it is a key material in the national defense industry.

[0003] Thermoplastic elastomer (TPE) is a special elastomer material with the characteristics of showing rubber elasticity within a certain temperature range and being able to be processed into shape like plastic by heating. TPE is a new type of polymer material, which is between rubber and resin, and can replace part of rubber and modify plastic. The dual properties of rubber and plastic and the wide characteristics of TPE make it widely used in the manufacture of various industrial products such as rubber shoes, rubber cloth and rubber pipes, rubber strips, rubber plates, rubber parts, and adhesives, and it has a wide application space in the rubber industry.

[0004] TPE is usually composed of hard segments with crystallization or high glass transition temperature (Tg) and soft segments with low Tg. Due to the large difference in chemical composition and physical properties between the hard segments and the soft segments of TPE, microphase separation phenomenon occurs. At room temperature, the hard segments in TPE form a physical crosslinking network through inter-chain interaction, constrain the activity of macromolecular chains, and play the role of physical crosslinking and reinforcing filler in the glass microzone, so that TPE has good dimensional stability and thermal mechanical properties without vulcanization and external filler. The molecular chains in the soft segment have strong free rotation ability, which gives TPE high elasticity.

[0005] The vulcanization of synthetic rubber is a curing process, which is an irreversible process. TPE does not need a vulcanization process, and it is a physical reversible material processing process. According to the production method, thermoplastic elastomer (TPE) can be divided into two types: chemical synthesis type and blending type. The former usually refers to block copolymers with ABA or (AB)n structure, where A represents the hard segment and B represents the soft segment. This type of TPE also includes graft copolymers such as polyisobutylene-G-polystyrene, and anti-1,4-polyisoprene homopolymer. Blending TPE includes polyvinyl chloride / acrylonitrile rubber, polyvinyl chloride / copolyester, polyvinyl chloride / polyurethane elastomer, and other co-continuous phase blends, as well as EPDM / PP thermoplastic vulcanization dynamic glue and other dynamic vulcanization blends, and polypropylene / polycarbonate binary copolymer interpenetrating network type blending.

[0006] The PVDF / FKM thermoplastic elastomer processed by the FKM has higher production efficiency and processing performance than traditional vulcanized rubber. Since it can be manufactured into a shape by a thermoplastic processing mode, it has better forming precision and surface finish, and can realize batch production and automatic production. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide a silica aerogel modified PVDF / FKM thermoplastic elastomer and a preparation method thereof. The technical scheme adopted by the present application is as follows: A preparation method of a silica aerogel modified PVDF / FKM thermoplastic elastomer, comprising the following steps: S1. Dissolve the coupling agent in an organic solvent and mix with the silica aerogel uniformly; S2. Modify the silica aerogel mixed with the coupling agent by ultraviolet light irradiation; S3. Mix the fluororubber and the mixing aid uniformly, then add the modified silica aerogel and mix again, and finally add Armeen and mix until uniform to obtain modified fluororubber; S4. Add PVDF in a torque rheometer for processing, then add the modified fluororubber for processing to obtain a PVDF / FKM thermoplastic elastomer.

[0008] Preferably, in step S3, the mixing aid includes zinc oxide, magnesium oxide, calcium hydroxide, TAIC, and TX101-50D.

[0009] Preferably, in step S1, the coupling agent is of type KH570, and the amount of the coupling agent is 3%-5%.

[0010] Preferably, in step S2, the ultraviolet light irradiation time is 5-20 min.

[0011] Preferably, in step S2, the ultraviolet light irradiation time is 5 or 20 min.

[0012] Further, the silica aerogel modified PVDF / FKM thermoplastic elastomer is prepared by the above-mentioned preparation method.

[0013] The beneficial effects of the present application are as follows: the present application pretreats the silica aerogel with coupling agent KH570, then performs ultraviolet light modification, and is used to prepare modified fluororubber (FKM), finally PVDF and modified FKM are prepared into PVDF / FKM thermoplastic elastomer in a torque rheometer, and the performance is tested, the results show that: ultraviolet light treatment helps to improve the crosslinking degree of FKM, the crosslinking degree of FKM treated for 20 minutes is the largest, the S'(MH) value is 20.56 dN·m, the tensile strength of PVDF / FKM thermoplastic elastomer is the largest when the amount of KH570 is 3%, the tensile strength is 24.5 MPa, and there is a positive correlation between the tensile strength and the torque value; the thermal conductivity of the elastomer is significantly reduced. It can be used for corrosion-resistant cables and other purposes, and at the same time, the renewable use of thermosetting rubber FKM can be realized, which has high economic significance. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings obtained according to these drawings without creative labor are still within the scope of the present application.

[0015] Figure 1 S' of FKM under different modification conditions, (a) ultraviolet light modification for different times, (b) different amounts of KH570 Figure 2 Electrical conductivity of PVDF / FKM thermoplastic elastomer under different modification conditions, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 3 Tensile properties of PVDF / FKM thermoplastic elastomer, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 4 Hardness of PVDF / FKM thermoplastic elastomer, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 5 Thermal conductivity of PVDF / FKM thermoplastic elastomer, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 6 Density of FKM, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 7 Torque of PVDF / FKM thermoplastic elastomer, (a) ultraviolet light modification for different times, (b) modification with different amounts of KH570 Figure 8 TG of PVDF / FKM thermoplastic elastomer, (a) DTG of the PVDF / FKM thermoplastic elastomer modified by ultraviolet light for different times, (b) DTG of the PVDF / FKM thermoplastic elastomer modified by different amounts of KH570, (c) TG of the PVDF / FKM thermoplastic elastomer modified by ultraviolet light for different times, (d) local enlarged view of TG of the PVDF / FKM thermoplastic elastomer modified by ultraviolet light for different times, (e) TG of the PVDF / FKM thermoplastic elastomer modified by different amounts of KH570; Figure 9 DSC of PVDF / FKM thermoplastic elastomer, (a) crystallization temperature of the PVDF / FKM thermoplastic elastomer modified by ultraviolet light for different times, (b) crystallization temperature of the PVDF / FKM thermoplastic elastomer modified by different amounts of KH570, (c) melting temperature of the PVDF / FKM thermoplastic elastomer modified by ultraviolet light for different times, (d) melting temperature of the PVDF / FKM thermoplastic elastomer modified by different amounts of KH570; Figure 10 XRD diffraction pattern, (a) XRD diffraction pattern of PVDF / FKM thermoplastic elastomer, (b) XRD diffraction pattern of silica aerogel, FKM; Figure 11 XRD diffraction pattern of PVDF. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0017] EMBODIMENT The raw materials used in the embodiment of the present application are shown in Table 1, and the instruments used are shown in Table 2.

[0018] Table 1 Experimental raw materials Table 2 Experimental instruments Before preparing the thermoplastic elastomer, the fluororubber was modified. The fluororubber was modified by silica aerogel modified by different ultraviolet light irradiation times and different amounts of coupling agent. The specific scheme is shown in Table 3 and Table 4.

[0019] Table 3 Scheme 1 Modification of fluororubber Note: The modified aerogel was modified by 5% KH570.

[0020] Table 4 Scheme 2 Modification of fluororubber Note: The treatment time of the aerogel was 20 min.

[0021] On the basis of the modification of the fluororubber, FKM modified by different light irradiation times and different amounts of coupling agent was selected to prepare PVDF / FKM thermoplastic elastomer with PVDF. The specific scheme is shown in Table 5 and Table 6.

[0022] Table 5 Scheme 3 PVDF / FKM thermoplastic elastomer Preparation 1 Table 6 Scheme 4 PVDF / FKM thermoplastic elastomer Preparation 2 1. Modification of silica aerogel An amount of aerogel was weighed, and 5% of KH570 was weighed according to the weight of the aerogel, the KH570 was fully dissolved in anhydrous ethanol, then the weighed aerogel was added and mixed uniformly, and then 5 aliquots of aerogel were prepared according to the above steps, and were modified under ultraviolet light for 1, 2, 5, 10, 15, and 20 minutes, respectively, and were marked as A1, A2, A3, A4, A5, and A6, respectively.

[0023] An amount of aerogel was weighed, and 5% of KH570 was weighed according to the weight of the aerogel, the KH570 was fully dissolved in anhydrous ethanol, then the weighed aerogel was added and mixed uniformly, and then 5 aliquots of aerogel were prepared according to the above steps, and were modified under ultraviolet light for 1, 2, 5, 10, 15, and 20 minutes, respectively, and were marked as A1, A2, A3, A4, A5, and A6, respectively.

[0024] 2. Preparation of FKM The roller distance was set to 2.1 mm, the roller temperature was 50°C, FKM was added, and the pre-mixed zinc oxide (ZnO), magnesium oxide (MgO), calcium hydroxide (Ca(OH)2), TAIC, TX101-50D were added uniformly on both sides for 3 times of cutting, the cutter and the thin pass were triangularly wrapped, and after uniform mixing, the modified aerogel was added and uniformly mixed, and finally Armeen (octadecylamine) was added as a surfactant. After uniform mixing, the first group was marked as A1, A2, A3, A4, A5, and A6, respectively. The second group was marked as B1, B2, B3, B4, and B5, respectively.

[0025] 3. Preparation of PVDF / FKM thermoplastic elastomer The temperature was set to 180°C and the rotation speed was set to 120 r / min in the torque rheometer. 70 parts of PVDF were added and treated for 5 minutes, then different rubbers modified in Tables 3 and 4 were added, each taking 30 parts of rubber, and treated for 8 minutes. The prepared PVDF / FKM thermoplastic elastomer was pressed on a flat vulcanizing machine. The thermoplastic elastomer treated by ultraviolet light for different times was marked as C1-C5, and the thermoplastic elastomer with different amounts of coupling agent KH570 was marked as D1-D4, as shown in Tables 5 and 6.

[0026] Test Examples The test and characterization methods used in the present application are shown in Table 7.

[0027] Table 7 Test Methods 1. Vulcanization Performance 1.1 Vulcanization Performance of Group A The present application explores the processing properties of FKM composite materials under different conditions by using RPA 2000 rubber processing analyzer.

[0028] Figure 1 is the vulcanization performance of FKM of different ultraviolet light time modified aerogels, from which it can be seen that the minimum torque S'(ML) of sample A3 is the smallest, with a value of 0.48 dN·m, and the minimum torque of the vulcanization characteristics will affect the processing performance of the FKM material, the smaller the minimum torque, the more excellent the processing performance, so sample A3 has the best processing performance, and the S'(ML) value of sample A4 is significantly different from that of other groups, and the processing performance is poor. In addition, the data of other samples are less different, and the processing difficulty is not much different.

[0029] The maximum elastic torque S'(MH) affects the physical properties of the material, and the S'(MH) of sample A4 is greater than that of other samples, which is 19.44 dN·m. Thus, the vulcanization performance of sample A4, i.e., the fluororubber modified by ultraviolet light for 10 minutes, is better, and the S'(MH) of sample A1 is less than that of other samples due to the shorter ultraviolet light modification time of only 1 minute, which is less than that of other samples. The S'(MH) of other samples increases first and then decreases with the change of the modification time of the aerogel, indicating that the vulcanization performance of the FKM material will first increase and then decrease with the change of the modification time of the aerogel.

[0030] ΔM, i.e., (MH)-(ML), reflects the degree of crosslinking of the FKM material, and the value of sample A4 is the largest, which is 18.63 N·m, i.e., ultraviolet light modification for 10 minutes can determine that the crosslinking degree of sample A4 is the highest, and from Table 8 it can be seen that the change rule of the crosslinking degree and the S'(MH) value of the rubber is basically the same, i.e., the vulcanization performance is good, and the crosslinking degree of the corresponding rubber is also relatively high.

[0031] Table 8 is the vulcanization time of FKM of different ultraviolet light time modified aerogels, and by comparing the scorch time, half vulcanization time T50, and vulcanization time T90 of Table 9, it can be found that except that A1 has a small vulcanization time related value due to the short ultraviolet modification time, A4 has a slightly smaller vulcanization time than other samples, which indicates that the vulcanization speed of ultraviolet light treatment for 10 minutes is faster, and the rest of the ultraviolet irradiation time less than or greater than 10 minutes will increase the vulcanization time of the sample.

[0032] Therefore, in terms of time cost and material cost, the modification time of 10 min or 15 min is better.

[0033] Table 8: Cure time of FKM modified by different UV treatment time 1.2 Cure performance of group B Figure 1 (b) is the cure performance of FKM modified by different amount of KH570, from which it can be seen that the S'(ML) of sample B1 is the smallest, which is 0.66 dN·m, so sample B1 has the best processing performance, in addition, the data of other samples are larger than that of sample B1, and the processing difficulty of sample B1 is slightly larger.

[0034] The S'(MH) of sample B5 is larger than that of other samples, which is 20.56 dN·m. The AM value of B5 is the largest, which can be determined that the cure performance of sample B5 is better, and the crosslinking degree is the highest. The S'(MH) of sample B1 is relatively smaller than that of other samples, so the cure performance of sample B1 is relatively poor. With the increase of the amount of KH570, the S'(MH) of other samples first increases and then decreases, which shows that with the increase of the amount of KH570, the cure performance of FKM material will first increase and then decrease.

[0035] Table 9 is the cure time of FKM modified by different amount of KH570, by comparing the scorch time, half cure time and cure time in table 11, it can be found that the difference between samples is not very large, which shows that the increase of the amount of KH570 has an increasing effect on the crosslinking degree of FKM, but has little effect on the cure time.

[0036] Table 9: Cure time of FKM modified by different amount of KH570 2. Conductive performance Figure 2 is the conductivity of PVDF / FKM thermoplastic elastomer under different modification conditions. Among them Figure 2 (a) is the effect of aerogel on the conductive performance of PVDF / FKM thermoplastic elastomer under the condition of adding a certain amount of aerogel and different UV treatment time. From the figure, it can be seen that the conductive performance of sample C1 is the lowest, which is 5.72×10 -15 s / cm, with the increase of treatment time, when the treatment time reaches 10 min, the conductivity almost does not change, which is 4.92×10 -16 s / cm, which decreases by nearly 1 order of magnitude.

[0037] Figure 2(b) is the effect of different amounts of KH570 on the electrical conductivity of PVDF / FKM thermoplastic elastomer under the condition of aerogel treated by ultraviolet light for a certain time. As can be seen from the figure, with the increase of the amount of KH570, the electrical conductivity of PVDF / FKM thermoplastic elastomer gradually decreases, and the minimum is 5.22 x 10 -16 s / cm, the maximum is 4.86 x 10 -16 s / cm, and the conductivity decreases.

[0038] The above can show that the effect of aerogel treatment time on PVDF / FKM thermoplastic elastomer becomes small, but the difference between the maximum and the minimum is one order of magnitude. With the increase of the amount of KH570, the electrical conductivity gradually decreases, but it is still within one order of magnitude, so the ultraviolet irradiation time has a certain influence on the electrical conductivity of PVDF / FKM thermoplastic elastomer. The amount of KH570 has little effect on the electrical conductivity of the elastomer.

[0039] 3. Tensile strength and elongation at break Figure 3 The tensile properties of PVDF / FKM thermoplastic elastomer. Figure 3 (a) is the change curve of the tensile strength and elongation at break of PVDF / FKM thermoplastic elastomer modified by ultraviolet for different times. With the increase of ultraviolet treatment time, the tensile strength of the thermoplastic elastomer increases as a whole, and the maximum value appears when the aerogel is treated for 15 min, and the tensile strength is 22.4 MPa. At the same time, the change trend of the elongation at break is basically the same as that of the tensile strength, and both increase. The improvement of the tensile strength and the elongation at break of PVDF / FKM thermoplastic elastomer may be due to the enhancement of FKM by aerogel after ultraviolet modification.

[0040] Therefore, the effect of ultraviolet modification for 5 min or 15 min is better.

[0041] Figure 3 (b) is the change curve of the tensile strength and elongation at break of PVDF / FKM thermoplastic elastomer modified by different amounts of KH570. As can be seen from the figure, with the increase of the amount of KH570, the tensile strength of the thermoplastic elastomer shows a trend of first increasing and then decreasing, and the elongation at break shows a trend of first decreasing and then increasing and then decreasing. Among them, when the amount of KH570 is 3%, the tensile strength of PVDF / FKM thermoplastic elastomer is the maximum, which is 24.5 MPa. The elongation at break is 37%. The maximum value of the elongation at break appears when the amount of KH570 is 5%, which is 47%, an increase of nearly 88%.

[0042] It can be seen that the amount of KH570 is in the preferred range of 3%-5%.

[0043] 4. Hardness Figure 4 is the hardness of PVDF / FKM thermoplastic elastomer. As shown in Figure 4 (a), under the condition of aerogel modification by ultraviolet light at different times, the hardness of PVDF / FKM thermoplastic elastomer first increases, then suddenly decreases, and finally increases again. It is shown that within 15 minutes of ultraviolet light treatment, the hardness of the sample does not increase significantly. After 20 minutes of treatment, the hardness of PVDF / FKM thermoplastic elastomer increases significantly.

[0044] Figure 4 (b) shows that under the condition of different amounts of KH570, the hardness of the sample first increases, then suddenly decreases, and then increases again. It is shown that under the condition of different amounts of KH570, with the increase of the amount of KH570, the hardness will first increase and then decrease. Figure 4 It can be found that with the increase of ultraviolet light treatment time and the amount of KH570, the hardness of the sample first increases, then decreases, and then increases again, and finally reaches a maximum. But the overall trend is that the hardness of the thermoplastic elastomer increases after modification by KH570.

[0045] 5. Thermal conductivity Figure 5 is the thermal conductivity of PVDF / FKM thermoplastic elastomer. As shown in Figure 5 (a), under the condition of aerogel modification by ultraviolet light at different times, the thermal conductivity of the sample generally increases from 0.148 w / (m.k) to 0.205 w / (m.k), an increase of about 38.5%. The thermal conductivity of PVDF / FKM thermoplastic elastomer modified by aerogel treated at different times has a certain influence. It is possible that the structure of the aerogel treated by ultraviolet light will have a certain influence, which ultimately leads to the increase of the thermal conductivity of PVDF / FKM thermoplastic elastomer.

[0046] Figure 5 (b) shows that under the condition of different amounts of KH570, the thermal conductivity of the sample decreases. From 0.205 w / (m.k) to 0.162 w / (m.k), the thermal conductivity decreases by about 40%. It is shown that under the condition of different amounts of KH570, the high amount of KH570 has a decreasing effect on the thermal conductivity of PVDF / FKM thermoplastic elastomer. The decrease of thermal conductivity helps to improve the heat preservation performance of the material, so the amount of KH570 can be controlled at about 5%.

[0047] 6. Density Figure 6 is the density of FKM thermoplastic elastomer. Figure 6 (a), Figure 6(b) Density of FKM modified by different UV treatment time and different amount of coupling agent KH570, overall, the change is not big, but the numerical difference is small. Due to the small amount of aerogel, the change of rubber density is mainly related to the crosslinking degree of the rubber itself.

[0048] 7. Torque Figure 7 Torque of PVDF / FKM thermoplastic elastomer. The highest torque data is sample C2 and sample D2, both 22.90 N.m. It shows that the internal binding force of these two thermoplastic elastomers is larger, so the torque is increased. The processing difficulty is higher than other samples.

[0049] 8. Thermogravimetric analysis Table 10 and Table 11 are the weight loss rate and carbon residue rate of PVDF / FKM thermoplastic elastomer. It can be seen that when the first 1% weight loss rate is reached, the lowest is sample D2, the temperature is 328.5 ℃, and the highest is sample D1, the temperature is 427.7 ℃. The sample with the highest carbon residue rate is D1, which is 38.28%, and the lowest is sample D4, which is 24.06%. The carbon residue rate shows a downward trend in group D, indicating that as the amount of KH570 increases, the decomposition temperature of PVDF / FKM thermoplastic elastomer is advanced, resulting in a decrease in carbon residue rate.

[0050] Figure 8 DTG and carbon residue rate of modified PVDF / FKM thermoplastic elastomer, from Figure 8 (a) (b) can be seen that the temperature when the maximum weight loss rate is reached, the highest sample is C2, the temperature is 474.8 ℃, and the lowest sample is D2, the temperature is 472.4 ℃. Overall, the temperature when the maximum weight loss rate is reached is around 473.0 ℃, with little difference. The samples in group C have certain improvement in thermal stability.

[0051] Table 10 Thermal gravimetric analysis of aerogel modified PVDF / FKM thermoplastic elastomer with different UV treatment time Table 11 Thermal gravimetric analysis of PVDF / FKM thermoplastic elastomer modified by different amount of KH570 Note: D1, D2, D3, D4 correspond to the amount of coupling agent KH570 2%, 3%, 5%, 8% respectively.

[0052] 9. Melt crystallization analysis Figure 9The crystallization temperature and the melting temperature of the PVDF / FKM thermoplastic elastomer. The crystallization temperature of the samples C1, C2, C3, C4, C5 is 145.29, 145.30, 145.04, 146.02, 145.40 ℃ respectively, and the melting temperature is 170.83, 171.29, 170.33, 169.88, 170.33 ℃ respectively. The crystallization temperature of the samples D1, D2, D3, D4 is 145.28, 145.85, 145.85, 145.90 ℃ respectively, and the melting temperature is 171.62, 171.23, 170.33, 170.23 ℃ respectively.

[0053] From the above, it can be seen that the different treatment time of ultraviolet light and different amount of KH570 have little effect on the crystallization temperature and the melting temperature of the PVDF / FKM thermoplastic elastomer. The crystallization temperature is about 145 ℃, and the melting temperature is about 170 ℃.

[0054] 10. XRD diffraction pattern Figure 10 The XRD patterns of the PVDF / FKM thermoplastic elastomer, the silica aerogel, and the fluororubber FKM respectively. Figure 11 The XRD pattern of the PVDF.

[0055] From Figure 10 As can be seen from (b), the diffraction angle 2θ of the silica aerogel shows 12°, 30°, 42° respectively, and the diffraction angle 2θ of the FKM shows 17.4°, 40.56° respectively.

[0056] Figure 10 (a) is the XRD diffraction pattern of the PVDF / FKM thermoplastic elastomer. The diffraction angle 2θ of the PVDF in the PVDF / FKM thermoplastic elastomer shows 20°, 36°, 38°, 57° in the samples C1, C2, C3, C4, C5 respectively. The diffraction angle 2θ of the silica aerogel in the PVDF / FKM thermoplastic elastomer shows 12°, 30°, 42° respectively. The diffraction peak of the FKM in the PVDF / FKM thermoplastic elastomer is not completely reflected in the PVDF / FKM thermoplastic elastomer. It may be that the content of the FKM in the elastomer is low, and the diffraction peak is covered. The crystallinity of the PVDF / FKM thermoplastic elastomer is 20.95%, 22.75%, 32.78%, 34.31%, 34.61% respectively. Among them, the crystallinity of the sample C1 is the lowest, only 20.95%, and the crystallinity is the highest when treated for 20 min, which is 34.16%. With the increase of the treatment time of the aerogel, the crystallinity of the C group also gradually rises, indicating that the increase of the ultraviolet light treatment time is helpful to the crystallization of the PVDF / FKM thermoplastic elastomer.

[0057] In summary, the present application modifies FKM on the basis of ultraviolet light modified silica aerogel, prepares PVDF / FKM thermoplastic elastomer, and tests and analyzes the vulcanization performance of FKM, the mechanical properties, the electric conductivity, the thermal conductivity, the thermal stability of the PVDF / FKM thermoplastic elastomer, and the microstructure in the PVDF / FKM thermoplastic elastomer.

[0058] By controlling the ultraviolet light treatment time and the amount of KH570, the mechanical properties of the prepared PVDF / FKM thermoplastic elastomer, the torque data and the mechanical properties are positively correlated, when the ultraviolet irradiation time is 20 min, the PVDF / FKM thermoplastic elastomer with the KH570 amount of 3% has the highest tensile strength, the tensile strength is 24.5 MPa, and the KH570 amount of 5% has the maximum elongation at break, which is 47%, and the elongation is increased by nearly 88%.

[0059] By controlling the aerogel treatment time and the amount of KH570, the electric conductivity and the thermal conductivity of the prepared PVDF / FKM thermoplastic elastomer are found to increase, the electric conductivity of the modified thermoplastic elastomer increases, the thermal conductivity increases with the increase of the ultraviolet light treatment time, the maximum value is 0.205 w / (m.k), and the thermal conductivity decreases with the increase of the amount of coupling agent, the minimum value is 0.162 w / (m.k), and the thermal conductivity is reduced by about 40%.

[0060] With the increase of the ultraviolet light modification time, the thermal stability of the PVDF / FKM thermoplastic elastomer is improved to a certain extent, and the residual carbon rate of the elastomer modified by the coupling agent KH570 is reduced, which reduces the thermal stability.

[0061] The longer the ultraviolet light treatment aerogel treatment time, the greater the crystallinity of the PVDF / FKM thermoplastic elastomer, and when the treatment time is 20 min, the crystallinity is the maximum, which is 34.16%.

[0062] Overall, the ultraviolet light method is used to modify the aerogel, which can realize the rapid modification of the silica aerogel, and is used to modify the fluorine rubber, improve the mechanical, thermal, and crystallization properties of the prepared PVDF / FKM thermoplastic elastomer, and can be used as a reference method for modifying the thermoplastic elastomer.

[0063] The above only discloses the preferred embodiments of the present application, and of course cannot limit the scope of the present application, therefore the equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A method for the preparation of a silica aerogel modified PVDF / FKM thermoplastic elastomer, characterized in that, The method comprises the following steps: S1. After the coupling agent is dissolved in an organic solvent, it is mixed with silica aerogel uniformly; S2. The silica aerogel mixed with the coupling agent is modified by ultraviolet light irradiation; S3. After the fluororubber is mixed with mixing aids uniformly, the modified silica aerogel is added and mixed again, and finally Armeen is added and mixed until uniform to obtain modified fluororubber; S4. In a torque rheometer, PVDF is added first and treated, and then the modified fluororubber is treated to obtain a PVDF / FKM thermoplastic elastomer.

2. The method for preparing a silica aerogel modified PVDF / FKM thermoplastic elastomer according to claim 1, characterized in that: In step S3, the mixing aids include zinc oxide, magnesium oxide, calcium hydroxide, TAIC, and TX101-50D.

3. The method for preparing a silica aerogel modified PVDF / FKM thermoplastic elastomer according to claim 1, characterized in that: In step S1, the coupling agent is of type KH570.

4. The method for preparing a silica aerogel modified PVDF / FKM thermoplastic elastomer according to claim 1, characterized in that: In step S1, the amount of the coupling agent is 3%-5%.

5. The method for preparing a silica aerogel modified PVDF / FKM thermoplastic elastomer according to claim 1, characterized in that: In step S2, the ultraviolet light irradiation time is 5-20 min.

6. The method for preparing a silica aerogel-modified PVDF / FKM thermoplastic elastomer according to claim 5, characterized in that: In step S2, the ultraviolet light irradiation time is 5-20 min.

7. A silica aerogel modified PVDF / FKM thermoplastic elastomer prepared by the method according to any one of claims 1-6.

Images