Direct stamp forming of flexible hybrid fibre preforms for thermoplastic composites

Abstract

Hybrid fibres combine individual reinforcing filaments with a precise amount of thermoplastic polymer matrix, providing an alternative solution to pre-consolidated blanks in stamp forming of thermoplastic composites. Preforms made from such fibres remain flexible at ambient conditions. This study investigates the consolidation behaviour of unidirectional arrangements made from E-glass monofilaments clad in polycarbonate sheaths (69 vol% glass). It assesses the influence of pre-heating temperature, press temperature, and holding time inside the press on the resulting laminates’ void content. The results prove that preforms made from hybrid fibres can be directly stamp formed while achieving void contents below 0.35 vol% with dwell times inside the press as low as 5 s for 1 mm thick laminates.