Novel tooling for direct melt impregnation of textile with variotherm injection moulding: Methodology and proof of concept

Abstract

Thermoplastic compression resin transfer moulding coupled with injection moulding is an appealing process for the production of thermoplastic composites. However, its implementation at an industrial scale remains challenging as variotherm injection moulding could prevent solid skin formation in the parting line, making cavity sealing difficult. In this study, a tool for thermoplastic compression resin transfer moulding and the related methods and process parameters for an implementation at an industrial scale are presented. The validity of the concept is proved by producing and characterizing composite plates with elevated fibre volume fractions and advantageous mechanical properties at a range of production temperatures within a cycle time not exceeding 20 min. The best mechanical properties were obtained at a production temperature of 270°C with a bending strength of 477 MPa, a flexural modulus measured at 25.7 GPa and a fibre volume content of 67%.

A model for the consolidation of hybrid textiles considering air entrapment, dissolution and diffusion

“…Since the importance of air diffusion has been proven to play a major role in this study, the ability of polymers to dissolve air could become a major selection criterion in the production of hybrid textiles based thermoplastic composites. Instead of focusing heavily on the development of very low viscosity thermoplastics such as the PP used in this study or the polyamide 6 ''Evolite HF XS1480'' from Solvay [3,4], their ability to absorb and diffuse air should also be weighed. In addition, the possibility to use existing additives or develop new ones should be considered.…”

“…An increasing attention has therefore been given lately to alternative manufacturing techniques as more cost-effective manufacturing techniques for structural parts are sought. Thus, novel techniques such as direct-thermoplastic melt impregnation [3,4], stamp forming of hybrid bicomponent fibres [5] or resin transfer moulding with spacers and high-fluidity thermoplastics [6] have been investigated. Other manufacturing routes generally rely on hybrid systems, meaning that the fibres and thermoplastic are blended at different scales, usually mesoscopically at the ply or microscopically at the tow level.…”

Direct In-Mold Impregnation of Glass Fiber Fabric by Polypropylene with Supercritical Nitrogen in Microcellular Injection Molding Process

“…The injection was delayed by 30 s, so that the fiber tapes could be preheated in the cavity. Werlen et al [ 25 ] presented a novel tool for thermoplastic compression resin transfer molding combined with injection molding. A variotherm process was successfully implemented with glass fabric and PA6, to produce plates at different temperatures.…”