改性白炭黑在天然橡胶中的分散性及防老作用

Dispersion and Aging Resistance of Modified-SiO_2 in Nature Rubber

采用γ-氨丙基三乙氧基硅烷(KH550)与3,5-二叔丁基-4-羟基苯乙酸为改性剂,通过两步法改性白炭黑(SiO_2),制备得到一种具有防老功能的白炭黑,将防老白炭黑添加到天然橡胶(NR)中,制备防老SiO_2/NR复合材料,并与未改性SiO_2/NR复合材料进行对比。结果表明,防老SiO_2/NR的焦烧时间变化不大,正硫化时间缩短了35.43%;橡胶加工分析仪与扫描电镜测试结果显示,白炭黑经过接枝改性后在天然橡胶中的分散性得到改善。在100℃下,随着老化时间的不同,防老SiO_2/NR的断裂伸长率变化率与拉伸强度变化率降幅小于未改性SiO_2/NR复合材料。最后,采用FlynnWall-Ozawa法考察了防老SiO_2/NR硫化胶的热氧化活化能,发现白炭黑接枝了防老剂后,SiO_2/NR的热氧化活化能有所提高,起始热失重温度提高了13.4℃。

Employing 3-triethoxysilyl-1-propanamine and 2- [ 3, 5-di （ tert-butyl）-4-hydroxyphenyl ] acetic acid as modifiers to modify silica and preparing for silica with anti-aging function by a two-step method. Modified silica was added to natural rubber （NR） to prepare for anti-aging SiO2/NR composites which were compared with the unmodified-SiCh/NR composites. The results show that the scorch time of anti-aging SiO2/NR composites has a little change and the curing time is shortened by 35.43%. Results of rubber process analyzer （RPA） and SEM test show that the dispersion of the modified silica in nature rubber is improved. At 100 ℃, with the different aging time, the decreasing amplitude of tensile strength and elongation at break of anti-aging SiO2/NR composites is less than that of unmodified SiOz/NR composites. Finally, the thermal oxidation activation energy of vulcanized rubber was investigated by Flynn-Wall-Ozawa method. The result shows that after the silica is grafted with antioxidant, the thermal oxidation activation energy of SiO2/NR composites increases and the initial mass loss temperature is increased 13.4 ℃.