表面接枝防老剂的白炭黑在天然橡胶中的应用

为了提高白炭黑与橡胶的相容性,同时防止防老剂的挥发,采用γ-缩水甘油醚氧丙基三甲氧基硅烷与对氨基二苯胺(PPDA)的反应物对白炭黑进行表面改性,得到表面接枝防老剂的白炭黑。将改性白炭黑应用于天然橡胶(NR)中考察其增强与防老性能,并与炭黑/NR、未改性白炭黑/NR和Si69改性白炭黑/NR复合材料相比较(均添加防老剂4020)。结果表明,改性白炭黑/NR复合材料的焦烧时间延长,硫化时间缩短,白炭黑在橡胶中的分散性提高,同时具备更出色的力学性能。随着表面接枝防老剂含量的增加,改性白炭黑/NR复合材料的拉伸强度和撕裂强度比未改性白炭黑和Si69改性白炭黑/NR均有大幅提高。当接枝的PPDA含量达到5.27%(与白炭黑的质量比)时,其拉伸强度比未改性白炭黑/NR提高了90%,比Si69改性白炭黑/NR提高了73%,并接近炭黑/NR; 其撕裂强度是未改性白炭黑/NR的5倍,Si69改性白炭黑/NR的2.5倍,炭黑/NR的2倍。另外,表面接枝防老剂的白炭黑/NR复合材料具有优异的抗热氧、抗臭氧和湿热老化性能;其抗臭氧老化性能优于添加通用防老剂4020的对比复合材料。

Application of antioxidant functionalized silicas in natural rubber

Antioxidant functionalized silica was designed and prepared from N-phenyl-1, 4-phenylenediamine(PPDA), (3-Glycidyloxypropyl)trimethoxysilane and silica to improve the dispersion of silica in the rubber matrix and to avoid the volatility and extractability of the antioxidants. The reinforcement and antioxidation effects of the modified silica in natural rubber (NR) were studied and compared with those of carbon black/NR, neat silica/NR and Si69 modified silica/NR (the latter three composites added with N-(1, 3-dimethylbutyl)-N-phenyl-1, 4-phenylenediamine (4020) as antioxidant). The results show that the use of antioxidant functionalized silica can prolong the scorch time, shorten the optimum curing time, improve the dispersion of silica in NR network, and improve the mechanical properties of the composites. The tensile strength and tear strength of the antioxidant functionalized silica/NR increase with increasing PPDA grafting content. When the PPDA content reaches 5.27% (mass fraction to silica), its tensile strength increases 90% and 73% to those of the neat silica/NR and Si69 modified silica/NR, respectively, and is closed to that of the carbon black/NR; its tear strength is 5, 2.5 and 2 times of those of neat silica/NR, Si69 modified silica/NR and carbon black/NR, respectively. Furthermore, the antioxidant functionalized silica/NR composites show great resistance in thermal oxidative ageing and damp heat ageing. Their stability is improved in ozone ageing compared with those used 4020 as antioxidant.