Correlation between interfacial bond strength and degree of healing in overprinting PAEK on CF/PAEK composites

Overprinting is a new emerging hybrid manufacturing process that combines composite manufacturing and additive manufacturing, offering the dual advantages of cost-effectiveness and design freedom. This study presents the first endeavour of overprinting high temperature polymers. The joint strength was measured by the rib-on-plate test. A modified non-isothermal healing model was developed to predict the interfacial bond strength, based on thermal history at the interface during overprinting. The model captures how crystallisation impedes interfacial diffusion. The degree of intimate contact was employed to evaluate the true interfacial strength. A positive linear correlation was identified between the interfacial bond strength and the final degree of healing. This study reveals the critical effect of crystallisation on diffusion when the processing temperature is above the glass transition temperature, offering a more comprehensive understanding of the bonding mechanism of high temperature semi-crystalline polymers.