Study of Particle Loaded Composites Fabrication Using Liquid Composite Moulding Technique

Abstract

The particle loaded composites are being used widely for enhanced/tailor-made properties (mechanical, thermal, electrical, etc.) in the end product. Although the particle loaded composites find application in a number of areas, very little information is available on the fabrication of particle loaded composites using liquid composite moulding techniques, the experimental results and characterisation of particle filtration. Also, the effect of filler addition on shape distortion (warpage and spring-in) has not been reported in the literature. Therefore, this study focusses on the three aspects of particle loaded composites, i.e. fabrication process (flow and filtration), product shape (warpage and spring-in) and properties (mechanical). Composite plates were fabricated by VIM process from glass woven fabric and vinyl ester resin, using line injection under the action of vacuum, with different concentrations (0, 0.5%, 1.0%, 1.5% and 2.0%) of silica microparticles (1.128 μm). It was observed that the mould filling time increases as the concentration of filler particles increases in the suspension. It was observed that the front progresses more rapidly near the entrance, and then its movement slows down during the filling. The effect of particle filtration on the thermal expansion coefficient (CTE) along the composite length was also observed. This phenomenon has not been studied/reported in the literature, as a measure of particle filtration. It was found that the CTE was low at the inlet indicating a high particle concentration. Then a gradual decrease in the particle concentration was observed from the inlet towards the outlet. Near outlet, the particle concentration was found to slightly increase due to particle deposition. COMSOL Multiphysics® Modelling Software (v5.3) was also used for the numerical study of flow process and filtration. The numerical and experimental results were found to be in accordance with each other. In the next part, the effect of fillers on shape distortion in flat and angled part composites was studied. For this purpose, composite plates and angled parts reinforced with UD glass fabric were prepared from vinyl ester resin, both with and without fillers. The experimental results showed a 51.6% decrease in the curvature in thin plates by the addition of 5% silica particles. Similarly, the spring-in angle was also found to decrease by 65% in the angled composite parts. The curvature and spring-in were also simulated using COMSOL Multiphysics® Modelling Software (v5.3), and results were in close correlation with the experimental values. The mechanical properties (tensile, flexural, impact and shear) of composite materials were also found to increase after the addition of particles.