Multiphysics modelling and experimental investigations of the filling and curing phases of bi-injection moulding of thermoplastic polymer/liquid silicone rubbers

Liquid silicone rubber (LSR) is a family of high-technology elastomer materials. The member of this family has been identified as being very promising for development in the coming decades due to their unique properties and ease of generation in large series by the injection moulding process. In particular, the over-moulding of LSR on other materials, such as thermoplastic polymers, metals and ceramics, is possible today, which leads to the possibility of obtaining multi-material, functional multi-colour and newly featured components. The work presented in this paper focuses on the transformation of liquid silicone rubber to better understand the phenomena involved to improve production processes and to optimize the processing conditions for bi-material components in well-defined geometry and functional properties. The rheological, rheo-kinetic and thermal behaviours of silicone elastomers were investigated and characterized under real conditions of manufacture with different combined methods. A thermo-rheo-kinetic model was then developed and implemented using the moulding simulation software Cadmould(A (R)) 3D to simulate two-component injection moulding of silicone rubber into a thermoplastic polymer. For the validation of the models chosen and the parameters identified, bi-material injection moulding tests of a two-component standard peel test specimen (polyamide thermoplastic polymer/liquid silicone rubber) were performed and compared to numerical results.