The effect of processing temperature on wedge peel strength of CF/PA 6 laminates manufactured in a laser tape placement process

Abstract

High-performance thermoplastics such as PEEK have been most commonly studied for thermoplastic ATP. Engineering thermoplastics such as PA 6 have comparatively low melt viscosities and different processing behaviour. The effect of processing temperature on the quality of CF/PA 6 laminates manufactured with a near-infrared laser ATP system is investigated. The inter-laminar bond strength is characterised by wedge peel tests on samples manufactured at different process temperatures from 200 °C to 460 °C at a placement rate of 100 mm/s. Thermal degradation of the polymer was investigated by DSC and DMA. Optical microscopy of cross-sections revealed significant squeeze-out of the matrix for process temperatures exceeding 320 °C, corresponding with a rapid decrease of wedge peel strength. No significant thermophysical changes were detected for temperatures up to 380 °C. Reduction of wedge peel strength at high temperatures was attributed to matrix squeeze-out caused by the low melt viscosity of the polymer and not thermal degradation of the PA 6.