无机掺杂纳米粒子/天然乳胶纳米复合材料的制备及耐热老化性能研究

目前,有关纳米碳酸钙和纳米二氧化硅共同填充并协同增强天然乳胶(NRL)的研究鲜有报道。利用十二烷基三甲氧基硅烷(DDES)分别对纳米碳酸钙和纳米二氧化硅2种颗粒状无机纳米粒子进行表面改性,采用乳胶共混法制备改性无机纳米粒子/天然乳胶纳米复合材料,并对制备所得的复合材料进行不同时间的热氧老化。通过红外光谱(FTIR)、热重分析(TG)、接触角测定仪(CAMI)研究了改性前后纳米颗粒的结构和性能变化。采用橡胶加工分析仪(RPA)和扫描电镜(SEM)对天然乳胶复合材料的力学性能和微观结构进行了测试分析。结果表明:DDES的硅氧烷基团与颗粒状无机纳米粒子表面的羟基反应,在M-CaCO3、M-SiO2表面形成DDES接枝改性层,修饰后的纳米颗粒均匀地分散在天然乳胶中,并形成填料-乳胶交联网络结构;其中2种改性无机纳米粒子共同填充制备的CaCO3/SiO2/NRL样品性能较优,断面形貌均匀,储能模量(G’)大;经70℃,480 h热氧老化后拉伸强度及撕裂强度保持率分别为81.45%、38.54%,表现出优异的耐热氧老化性能。

Preparation and Heat-Resistant Ageing Performance of Inorganic Doped Nanoparticles/Natural Rubber Latex Nanocomposites

The surface modification of nano-calcium carbonate( nano-CaCO3) and nano-silica( nano-SiO2) was carried out by using silane coupling agent DDES,which were further used to prepare inorganic nanoparticles/natural rubber latex( NRL) nanocomposites. Subsequently,the prepared composite material was subjected to thermal oxygen aging for different durations. The structures and properties of nano-particles before and after modification were studied by infrared spectroscopy( FTIR),thermogravimetric analysis( TG) and contact angle meter( CAMI). The mechanical properties and microstructures of natural rubber latex composites were tested by rubber processing analyzer( RPA)and scanning electron microscopy( SEM). Results showed that modification inorganic nano-particles/natural rubber latex nano-composites were prepared by latex blending method. The infrared analysis showed that the siloxane groups of DDES reacted with hydroxyl groups on the surface of nanoparticles and formed DDES graft modified layer on the surface of M-CaCO3 and M-SiO2. The properties of CaCO3/SiO2/NRL samples prepared by M-CaCO3 and M-SiO2 co-filled NRL were still good. In this case,the granular fillers uniformly dispersed within the NRL matrix and formed the granular filler-rubber network together with NRL,which performed good nano-synergistic enhancement effect. It led to the increase of the energy storage modulus( G’) and uniform cross-section. Meanwhile,after aging at 70 ℃ for 480 h,the tensile strength and tear strength retention rates were 81.45% and 38.54%,respectively,showing excellent heat-resistant oxygen aging resistance.