The effect of thermo-oxidative ageing on crystallization, dynamic and static mechanical properties of long glass fibre-reinforced polyamide 10T composites

The performances and microstructure of long glass fibre-reinforced polyamide 10T (PA10T/LGF) composites that experienced different ageing temperatures (160 and 200°C) with increasing ageing time are characterized by differential scanning calorimetry (DSC), mechanical analysis, thermogravimetric analysis (TGA) and scanning electron microscopy to probe the correlation between properties of the composites and thermo-oxidative ageing. The DSC results show that PA10T/LGF composites occur on degradation, the fracture of molecular chains and the destruction of crystallization structure, which leads to the crystallization and melting peaks of PA10T/LGF composites to shift to high temperature. On the basis of dynamic mechanical analysis data, the reduction of the interfacial bonding between the glass fibre and PA10T matrix and the motion of molecular chain segments result in the thermo-oxidative ageing of composites. According to the calculation of activation energy (E), thermo-oxidative temperature and ageing time can bring about the decline of the E value, proving the deterioration in performance of PA10T/LGF composites. In view of TGA, the increase in the thermo-oxidative temperature and ageing time promotes the degradation of PA10T/LGF composites. The tensile, flexural and notched impact strengths of PA10T/LGF composites decline with prolonging the ageing temperature and time. The surface of materials produces some microcracks and the cross-section surface of PA10T/LGF composites becomes rougher.