退火与偶联剂对PMMA/SiO_2纳米复合材料性能的影响

Effects of Annealing and Coupling Agents on Properties of PMMA/SiO-_2 Nanocomposites

首先利用3-氨丙基三乙氧基硅烷(KH550)对纳米二氧化硅(Si O2)进行表面接枝改性,将未改性或改性的Si O2分别与聚甲基丙烯酸甲酯(PMMA)按照95∶5的质量比进行熔融共混,利用注塑成型制备一系列PMMA/Si O2和PMMA/改性Si O2共混物。采用物理沉降法、傅里叶变换红外光谱(FTIR)测试了Si O2接枝状态。结果表明,表面改性后的Si O2沉降量和沉降速率较低,红外谱图也表明物理包覆现象;采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、悬臂梁冲击试验机与万能实验机进行了表面形态、玻璃化转变温度(Tg)及力学性能测试。结果表明,在不同的退火处理下,表面改性后的PMMA/Si O2纳米复合材料有着良好的分散性和相容性,其Tg和拉伸强度较高,而冲击强度较未改性的低;同时随着退火处理的温度升高,未改性或改性的PMMA/Si O2纳米复合材料的Tg和拉伸强度先升高再降低。

Nano-silica （SiO2 ） was firstly modified using aminopropyhriethoxysilane （KH550）, and then the modified and unmodified SiO2 with poly（ methyl methacrylate） （PMMA） by the ratio of 95 ： 5 were melt-blended via twin-screw extruder, respectively. A series of PMMA/Si02 and PMMA/modified SiO2 blends were prepared by injection molding. Physical sedimentation method and Fourier transform infrared spectrum were adopted to test the graft state of SiO2. The results showed that, the modified SiO2 presented low subsidence and sedimentation rate, the infrared spectrogram also showed obvious physical coating phenomenon. Scanning electron microscope （SEM）, differential scanning calorimeter （ DSC ）, cantilever beam impact testing machine and universal testing machine were used to study the surface morphology, glass transition temperature and mechanical properties, respectively. The results showed that, modified PMMA/ SiO2 nanocomposite based on different annealing treatment had good dispersibility and compatibility, and the glass transition temperature and tensile strength were higher but the impact strength was lower. Moreover, with increasing annealing treatment temperature, the glass transition temperature and tensile strength of unmodified and modified PMMA/SiO2 nanocomposites increased first and then decreased.