纳米蒙脱土/聚丙烯复合材料热氧老化动力学

Thermal-oxidative aging kinetics of montmorillonite/polypropylene nanocomposites

对熔融插层法所制备的纳米蒙脱土/聚丙烯(OMMT1/PP)复合材料,分别在100℃、110℃、120℃进行0～12 d的热氧老化,考察其热性能、热稳定性、拉伸强度的衰减及其动力学。TG、DSC、FTIR分析结果表明:纳米OMMT1/PP复合材料比PP的热分解温度升高37℃,结晶度由51%提高到71%,而且有机化的纳米MMT片层与PP之间存在较强的作用,因此热氧作用的C O吸收峰明显弱化,表面轻微开裂。100～120℃老化后OMMT1/PP的强度保持率大大优于纯聚丙烯材料(8～22倍),OMMT1/PP 110℃老化12 d后拉伸强度仍然达54%。建立了以拉伸强度为参数的OMMT1/PP热氧老化的一级反应动力学方程,其热氧老化反应的活化能为52.3 kJ/mol,为PP的1.7倍。分析认为:OMMT1/PP较高的活化能值以及优良的抗热氧老化能力来自其剥离型纳米化MMT片层对PP的力学保护作用、物理阻隔效应以及OMMT1与PP之间化学交互作用的综合结果。

Organ montmorillonite（OMMT1）/polypropylene（PP） nanocomposites were prepared by the melt intercalation method.After thermal-oxidative aging for 0 ～ 12d at the temperature of 100℃,110℃ and 120℃,the thermal property,thermal stability,the attenuation of tensile strength and kinetics were studied.The results of TG,DSC and FTIR show that,compared with PP,the thermal decomposition temperature of OMMT1/PP increases by 37℃,the crystallinity increases from 51% to 71%,and there is stronger interaction between nano-OMMT lamellar and PP.So CO vibration absorption peaks of OMMT1/PP weaken significantly in FTIR spectra and surface cracks slightly during thermal-oxidative aging.After aging at 100～120℃,strength retention of OMMT1/PP is much superior to pure polypropylene material（8～22 times）,and its tensile strength was 54% after 12 d aging at 110℃.The first-order kinetics equation of OMMT1/PP thermal-oxidative aging was established with tensile strength as parameter,its activation energy was 52.3kJ/mol（1.7 times of PP）.The higher the activation energy values and excellent resistance to thermal-oxidative aging of OMMT1/PP can be contributed to the mechanical protection of exfoliated nano-MMT lamella,physical barrier effect to PP and the chemical interaction between MMT and PP.