Solid epoxy resin systems for automated composite manufacturing

Neptun Yousefi,Anthony D Evans,Lee T Harper,Henry A Maples,Thomas James,Alexander Bismarck

doi:10.1016/j.compositesa.2020.106205

Neptun Yousefi, Anthony D Evans + Show 4 more

Open Access

https://doi.org/10.1016/j.compositesa.2020.106205

Copy DOI

Abstract

Thermosetting resins were formulated by mixing solid epoxy components, hardener and accelerator at elevated temperature. These mixtures were ground into uncured, solid resin powders and dispensed onto carbon fibres using a powder printer prior to vacuum curing. Using accelerators reduced curing time from 8 h to 16 min. Manufactured cross-ply carbon fibre laminates (0°/90°/0°) had comparable mechanical properties to composites manufactured using a liquid resin system. Tack behaviour of solid epoxy resin formulations was investigated and results compared to a conventional liquid resin system. Master curves of the storage and loss moduli of both solid and liquid resin formulations were generated by applying time-temperature superposition to shear moduli between 1 and 100 rad/s at multiple temperatures. This approach was used to determine optimum processing parameters to enable resin tack for automated fibre placement, demonstrating the importance of temperature control with respect to deposition rates.

Highlights

Carbon fibre composites could potentially be used in a wider range of sectors if significant cost savings can be made [1,2,3], for example by using less expensive precursors to manufacture carbon fibres [4,5] or utilising recycled materials [6,7,8]
The use of low cost feedstock materials in technologies such as automated tape laying (ATL) and automated fibre placement (AFP) [9,10,11], which are typically limited to the aerospace industry, could significantly broaden the application areas of automated manufacturing of composites for high volume production
We describe a low cost solid epoxy resin formulation and a composite manufacturing method utilising this solid epoxy resin

Summary

Introduction

Carbon fibre composites could potentially be used in a wider range of sectors if significant cost savings can be made [1,2,3], for example by using less expensive precursors to manufacture carbon fibres [4,5] or utilising recycled materials [6,7,8]. The use of low cost feedstock materials in technologies such as automated tape laying (ATL) and automated fibre placement (AFP) [9,10,11], which are typically limited to the aerospace industry, could significantly broaden the application areas of automated manufacturing of composites for high volume production. These tech nologies use wide (ATL) and narrow (AFP) prepreg tapes for material lay-down. ADFP preforms suitable for liquid composite moulding require heavily processed dry fibre tapes, resulting in high intermediate material costs [25,26] They suffer from much lower tack than prepreg tapes, significantly limiting pro duction rates

Methods

Results

Conclusion