The ablative behavior of high linear chains and its role in the thermal stability of polyethylene: a combined P‐TREF−TGA study

Abstract

AbstractEthylene copolymers contain short chain branches (SCBs) which have great influence on their properties. An ethylene/1‐hexene copolymer distinguished in terms of the number of butyl SCBs was precisely separated based on differences in crystallizability using the preparative temperature‐rising elution fractionation (P‐TREF) method and was then studied via TGA and DSC. A comparison between the results obtained and the literature suggested a short chain branch distribution (SCBD) functionality for a included in the general linear form Tm (°C) = −a(SCBD) × (SCB) + b. P‐TREF−TGA results showed that the highly linear chains acted as ablative layers which could increase the thermal stability and durability of polyethylene in the absence of any mineral additive. Furthermore, the P‐TREF−TGA data displayed an interesting interrelationship between temperature at maximum rate of degradation (Tmax) and the number of butyl SCBs over all the heating rates (10, 25, 50 and 100 °C min‐1). The role of the number of butyl SCBs in thermal degradation was exhausted by higher heating rates, whereas the ablation capability was enhanced. Kinetic studies demonstrated that the activation energy dropped on increase in butyl branch content within the backbone. © 2015 Society of Chemical Industry