The influence of hygrothermal ageing on the mechanical properties and thermal degradation kinetics of long glass fibre reinforced polyamide 6 composites filled with sepiolite

Abstract

In this article, the influence of relatively long hygrothermal ageing on long glass fibre reinforced polyamide 6 (LGF/PA6) composites filled with sepiolite (Sep) are analyzed. The composites with different weight fractions of Sep are exposed in a hygrothermal environment of 80 °C and RH 95% for 0–20 days. The mechanical properties with different ageing time show a decrease in tensile strength and an increase in impact strength. The scanning electronic microscopy (SEM) photos of the impact fracture indicate better adhesion of the interface between the glass fibre and polymer matrix in the composites filled with Sep after the ageing process. Then the thermal stability and degradation kinetics of the composites with different filler fractions and ageing times are studied by thermal gravimetric analysis (TGA) with the methods of Kissinger, Friedman and Flynn–Wall–Ozawa in dynamic measurements. Calculated apparent activation energy (E) by the three methods shows that the composites without Sep have an obvious decrease in the value of E after ageing, however, the E values of the composites filled with Sep have a slight increase.