Composites of Poly(Acrylate) Copolymer filled with diatomaceous earth: morphology and mechanical behaviour

Abstract

Failure mechanisms of poly(acrylate) (PA) copolymer system filled with a diatom filler have been studied. The natural diatom filler is characterised by the original skeletal structure which allows high “inner” porosity and thus matrix penetration inside the filler particles and agglomerates of various shapes in PA composite. High diatom filler crystallinity influences the matrix re-structurization by changing the intensity ratio of matrix amorphous halos indicating the increased composite film inhomogeneity. Interactions at the interface between diatom filler and PA copolymer matrix, specially for coarse cylindrical-shaped particles are low, showing low adhesion in the composite. We see composite weakening with the increased filler volume fraction, i.e. lowering the composite strength at break as a consequence of lower degree of interactions. On the other hand, the composite modulus and the yield strength increased as a result of matrix hardening due to the pronounced matrix penetration inside the porous diatom filler. The mechanisms of failure depend on the location with the lowest product of composite module and break energy. Because dewetting occurred, it is the product EG in the interfacial region between PA matrix and diatom filler particles that was relevant. The effects of filler characteristics, may be followed through an interaction coefficients calculated from a model equations. The numerical values of coefficients in the model are only comparative, but the relative values can be connected with changes at the interface.

Keywords:

• Diatomaceous earth-Morphology
• Mechanical behaviour
• Poly(acrylate) composite