TWI Industrial Member Report Summary 481/1993
By S M Tavakoli
Polymers are susceptible to deterioration when subjected to various agents during processing or service, and previous work has shown that welding can affect not only short term mechanical properties but also the long term performance of polymeric components.
Polyethersulphone (PES) is one of the most important heat-resistant engineering thermoplastics, and can perform satisfactorily at elevated temperatures (up to 200C), under stress and on exposure to moisture and other environmental factors. The effects of welding on the structure and ageing properties of PES are not known. This work evaluated the effects of hot plate and linear friction welding on ageing properties of both unreinforced and glass fibre reinforced PES. Tensile properties were determined before and after ageing in air at 220 and 230°C and in boiling water. Variations in chemical and physical properties were investigated using Fourier transform infrared (FTIR)-microspectrometry, Fourier transform Raman (FTR) spectroscopy and dynamic mechanical thermal analysis (DMTA). Fractographic examination was carried out using a scanning electron microscope (SEM).