Sintering and Densification of Fibre Reinforcement in Polymers during Rotational Moulding

In the present work, sintering and densification of fibrous composite structures produced by rotational moulding were investigated. Lack of pressurisation during the process of rotational moulding implies an absence of driving forces to strongly bond two materials together as necessary in composite structures. This means that sintering and densification are the fundamental phases in which two or more materials can create an interface together by which stresses can be transmitted. The sintering study comprised of a novel single-particle interaction test that was developed to study the dynamical interaction between an ideal single polymer particle and a glass fibre bundle. Results showed that, although compatibiliser, as well as particle morphology, have an effect on fibre-particle bonding characteristics at a mesoscale, fibre sizing was shown to be the most significant parameter that affects polymer-fibre compatibility the most. The densification investigation studied the void and bubble formation and disappearance during the rotational moulding cycle as these defects have a detrimental effect on the mechanical performance of rotomoulded composite structures. The results verified previous researchers’ conclusions that particle size, heating rate and peak temperature are the most fundamental parameters to control bubble size and bubble density. Images captured during densification show how formation and evolution of air trapped in bubbles can be controlled by particle size or processing temperature. Finally, work is ongoing to present conclusions as to what resin properties should be more suitable for the rotational moulding of fibrous composite structures.