The Fracture Toughness of a Highly Filled Polymer Composite

Fracture toughness values are given for an ATH-PMMA composite for filler volume fractions ranging from 0.35 to 0.49 and tested over the temperature range from 0 to 90 degrees C. The toughness decreased with increasing filler content contrary to expectations. A toughness model based on debonding, and subsequent plastic void growth was extended from a low volume fraction form to accommodate interaction between particles. From the fitted data it was possible to calculate the adhesion energy of the particles and the average particle size. The former was somewhat less than the matrix toughness and the latter agreed quite well with the sizes found from particle size measurements on the filler and surface roughness measurements on the fracture surfaces.