MechLab researchers (B. Eixerés, S. Sánchez-Caballero, M. A. Peydró, F. Parres and M. A. Sellés) have published a study in Alexandria Engineering Journal on the injection moulding of carbon-fibre-reinforced polyphenylene sulphide (CF-PPS). The material, with 30 wt% carbon fibre and 15 wt% PTFE, has mechanical properties similar to aluminium at a considerably lower density, which makes it of interest for the automotive and aerospace sectors. The paper was published online on 18 January 2025, in open access, and appears in volume 123 (June 2025).
Five parameters analysed together
Earlier work looked at some parameters separately and sometimes reached contradictory conclusions. Here, injection temperature, injection speed, holding pressure, mould temperature and a post-moulding annealing treatment are analysed together. The material was dried at 100 °C for 4 hours before moulding, and annealing was carried out at 180 °C for 1 hour with a controlled cooling rate of 25 °C per hour.
Processing conditions have a large effect on the result. Between the most and least favourable conditions in the experimental design, the authors report differences of up to 78.1% in tensile strength, 109.5% in impact strength and 72.9% in Young’s modulus. Fracture strength benefits from low injection speed, annealing, low injection temperature, low holding pressure and a hot mould. Modulus improves with a hot mould, higher injection temperature and higher holding pressure; impact strength with low speed, high holding pressure and a hot mould. Hardness increases with annealing and with high temperature, speed and pressure.
What it adds to our work
The study brings together two of MechLab’s lines of work: polymer injection moulding and carbon-fibre thermoplastic composites. It gives practical guidance for setting moulding conditions according to the property that matters most in a given part. PTFE acts as a solid lubricant, and the tribological behaviour of PPS is another line the group works on, with friction and wear testing.
Source: Eixerés, B.; Sánchez-Caballero, S.; Peydró, M. A.; Parres, F.; Sellés, M. A. Influence of injection molding process conditions on the mechanical properties of CF-PPS/PTFE composites. Alexandria Engineering Journal 123 (2025) 381-391. Published online on 18 January 2025. doi:10.1016/j.aej.2025.01.022 Image: graphical abstract of the paper, CC BY-NC-ND 4.0.