The role of particle size and polymer molecular weight in the formation and properties of an organo-ceramic composite

The role of particle size and polymer molecular weight in the formation and properties of a calcium aluminate cement-poly(vinyl alcohol) composite was investigated. Banbury mixing studies, in combination with poly(vinyl alcohol) solution rheology, showed paste formation to be dependent on the degree of polymerisation and concentration of the polymer. Both polymer molecular weight and cement particle size have an effect on the mechano-chemistry, the "window of processibility", and mechanical properties of the hardened matrix. Increasing the polymer chain length appears to accelerate the mechanically induced crosslinking reactions between the polymer and cement hydration phases, thereby diminishing the processing window. Decreasing the cement mean particle size has a similar effect. Polymer degree of polymerisation and cement particle size distribution are shown to be important factors in the mechanical properties of the hardened composite. SEM micrographs show that wide polydispersity in the grain phase is important in attaining a macro-defect-free microstructure. 16 refs.