Interface strength in glass fibre–polypropylene measured using the fibre pull-out and microbond methods

Interface strength in glass fibre–polypropylene was measured using both fibre pull-out and microbond methods. Excellent correlation between two methods was obtained. Data from microbond test could be divided into two groups according to whether or not there was constant interfacial friction after debonding. Microscopy observation on tested microbond samples which had exhibited decreasing interfacial friction after debonding revealed considerable residual resin around the debonded area of samples. Further investigation indicated that this unexpected difference was caused by the variation in mechanical properties of the matrix due to thermal degradation during sample fabrication.