坡缕石/硅烷交联聚乙烯复合材料的制备及热降解动力学计算

Preparation and kinetics of thermal degradation of the composite palygorskite/silane grafted crosslinked polyethylene

以坡缕石黏土为添加剂，低密度聚乙烯为基体，采用熔融共混法制备出坡缕石／硅烷接枝交联聚乙烯（PGS／XLPE）新型复合材料．利用动态热重分析法研究了硅烷接枝交联聚乙烯（XLPE）及坡缕石／硅烷接枝交联聚乙烯在不同升温速率下的热稳定性及热降解动力学，并通过扫描电镜（SEM）、万能试验机及极限氧指数仪分别对材料形貌、力学性能及阻燃性能进行了表征．结果表明，当0．2≤α≤0．9时，XLPE的表观活化能E在59．5～75．2kJ·mol^-1之间，而PGS／XLPE的表观活化能E在97．1～145．6kJ·mol^-1之间；相同升温速率下，PGS／XLPE在550℃下的残留量略高于XLPE；坡缕石黏土的引入不但提高了材料的力学性能，而且也提高了材料的热稳定性．

With nano-scale palygorskite as additives and low-density polyethylene as matrix, the composite palygorskite/silane grafted crosslinked polyethylene materials is prepared by melt-blending method. Dynamic thermo gravimetric analysis（TG） is used to study the stability and kinetics of thermal degradation on XLPE and PGS/XLPE under different heating rates. The material morphology, mechanical properties and flame retardant properties of the composite material have been characterized by means of SEM, universal strength tester and limiting oxygen index instrument, respectively. The results show that the apparent activation energy is between 59.5 kJ · mol^-1 and 75.2 kJ · mol^-1 when 0.2≤α≤0.9, while the apparent activation energy of PGS/XLPE is between 97.1 kJ· mol^-1 and 145.6 kJ· mol^-1 The residues of PGS/XLPE under 550 ℃ is slightly higher than the pure one;; the introduction of palygorskite not only increase mechanical properties of the materials but also improve the thermal stability of the materials.