Pre-mould processing technique for syntactic foams: Generalised modelling, theory and experiment

Pre-mould processing for syntactic foams made of starch and ceramic hollow microspheres was studied. A statistical model to relate various parameters such as volume expansion rate (VER) of initial bulk volume of microspheres (IBVMS), microsphere size, microsphere volume fractions, minimum inter-microsphere distance (MID), and mixing ratio of microspheres was developed for theoretical relations. The statistical model consists of cubic cells which can optionally be simple cubic (SC) or face centered cubic (FCC) or body centered cubic (BCC) cells. The theoretical relations were verified with experimental/numerical data for various mixtures of microspheres and found to be capable of predicting effects of microsphere size and mixture ratio of microsphere size groups on VER under various conditions arising from starch content in binder and IBVMS. Volume shrinkage for mixture of microspheres and binder after moulding but before forming syntactic foam was found to be high for high contents of small microspheres in mixture.