摘要
采用分子动力学模拟方法研究纳米SiO2以及甲基苯基二甲氧基硅烷改性酚醛树脂的物理性能.研究表明:300 K下未改性酚醛树脂玻璃转化温度为362 K,弹性模量、剪切模量分别为5.45 GPa和2.19 GPa,热导率和热膨胀系数分别为0.37 W·(m·k)-1和3.8 × 10-5 K-1,添加纳米SiO2后玻璃转化温度提高了1.6％,弹性模量、剪切模量分别提高了34.9％和28.8％,热导率和热膨胀率分别降低了11％和31.6％.SiO2表面接枝3％、5％、7％和10％硅烷偶联剂以及甲基苯基二甲氧基硅烷改性酚醛树脂玻璃转化温度分别提高了10.5％、15.2％、16.8％、19.3％和1.5％,弹性模量分别提高了44.4％、53.2％、53.8％、63.5％和13.4％,而热导率分别降低了12.4％、13.5％、11.2％、7％和10％.此外甲基苯基二甲氧基硅烷改性的酚醛树脂的热膨胀系数较未改性酚醛树脂提高15.7％.研究表明:掺杂纳米SiO2、SiO2表面接枝硅烷偶联剂以及甲基苯基二甲氧基硅烷改性都能够提高酚醛树脂的玻璃转化温度,机械性能同时降低热导率,而对于热膨胀系数,纳米SiO2掺杂使其减小,甲基苯基二甲氧基硅烷改性则会使其明显增大.
Abstract
The physical properties of modified nano-SiO2 and methyl-phenyl-dimethoxy-silane modified phenolic resin are studied by molecular dynamics simulation.The results show that the glass transition temperature of unmodified phenolic resin at 300 K is 362 K,the elastic modulus and shear modulus are 5.45 GPa and 2.19 GPa,the thermal conductivity and thermal expansion coefficients are 0.37 W·(m·k)-1 and 3.8 × 10-5K-1,respectively.The addition of nano-SiO2 increases the glass transition temperature by 1.6％,the elastic modulus and shear modulus by 34.9％and 28.8％,and the thermal conductivity and thermal expansion by 11％and 31.6％,respectively.The thermal conductivity and thermal expansion are reduced by 11％and 31.6％,respectively.SiO2 surface grafting 3％,5％,7％and 10％silane coupling agent and methyl-phenyl-dimethoxy-silane modified phenolic resin,the glass transition temperature increased by 10.5％,15.2％,16.8％,19.3％and 1.5％respectively,the elastic modulus increased by 44.4％,53.2％,53.8％,63.5％and 13.4％respectively,and the thermal conductivity decreased by 12.4％,13.5％,11.2％,7％and 10％respectively.Moreover,the thermal expansion coefficient of phenol formaldehyde resin modified by methyl phenyl dimethoxy silane increased by 51.8％compared with the unmodified phenol formaldehyde resin.The study show that the doping of nano-SiO2,the grafting of silane coupling agent on the SiO2 surface,and the modification of methyl-phenyl-dimethoxy-silane can improve the glass transition temperature,and mechanical properties and reduce the thermal conductivity of phenolic resin.Only nano-SiO2 doping can reduce the thermal expansion coefficient,whereas the modification of methyl-phenyl-dimethoxy-silane will increase substantially.
基金项目
环境友好能源材料国家重点实验室项目(21fksy27)
四川省自然科学基金重点项目(2022NSFSC0031)
NETL
NSTL
万方数据