New Powder Coating Equipment to Produce Continuous Fibre Thermoplastic Matrix Towpregs

Abstract

Thermoplastics are replacing traditional thermosetting resins as matrices in composite materials in many applications due to their enhanced properties. Thermoplastics exhibit better toughness, durability and damping properties and provide the options of continuous processing, reshaping, and reparability, as well as more favourable recycling and processing routes that do not involve chemical reactions [1]. However, their high melt viscosity makes it difficult to impregnate continuous fibres, which restricts commercial applications. Recently developed dry coating techniques allow the production of long fibre thermoplastic matrix towpregs without most of the previous impregnation problems [2, 3]. In this work, a new coating line was developed to produce long fibre dry coated thermoplastic matrix towpregs at rates compatible with industrial production. The polymer deposition rate was considerably increased to allow processing towpregs at greater speeds (approx. 10 m/min) than current equipment. A new coating chamber was used to allow improved control of the fibre and polymer contents and the towpreg impregnation quality. Other general improvements were also made in the equipment to allow better monitoring of the towpreg processing. Glass or carbon fibres with polypropylene towpregs (GF/PP and CF/PP, respectively) were produced on the new coating line which were then submitted to extensive tests to verify their polymer content and impregnation quality. This paper presents the results of the tests and discusses the optimization of the new dry coating line. The results show that the new deposition chamber allows production of economical thermoplastic matrix towpregs with improved efficiency that may be used in the industrial production of composites for commercial markets.