There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

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Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

A concerted survey is presented of the existing theories for predicting the strength and modulus of particulate-filled polymeric composites. The macroscopic behaviour of particulate composites is affected by the size, shape, and the distribution of the inclusions. The interfacial adhesion between the matrix and inclusion is also important. The limitation of theoretical models in describing these parameters and expressing the experimental data on the macroscopic behaviour is demonstrated.

A review of particulate reinforcement theories for polymer composites

Influence of interface interaction on the ultimate tensile properties of polymer composites

The investigation outlined in the preceding paper has been extended to cover the effect of particle/matrix adhesion upon crack propagation in an epoxy resin reinforced with spherical glass particles. The behaviour has again been interpreted in terms of crack pinning and blunting. It has again been shown that in the absence of blunting a critical crack opening displacement criterion can be applied. The strength of the particle/matrix interface is found to affect both the crack propagation behaviour and the appearance of the fracture surface. It is also found to have a profound effect upon the fracture strength of the composites. The best overall mechanical properties are obtained for composites containing particles treated with coupling agent.

Crack propagation in a glass particle-filled epoxy resin

Preparation and mechanical properties of nanocomposites of poly(D,L-lactide) with Ca-deficient hydroxyapatite nanocrystals.

The mechanical properties of glass bead (30 micron diameter glass spheres) filled epoxy and polyester resins have been studied as a function of volume fraction of filler and the strength of the interfacial bond. The bonding between glass and resin was varied by chemically surface treating the glass using a silicone mold release to prevent chemical bonding at one extreme and a silane coupling agent to maximize bonding at the other extreme. Theoretical predictions of the elastic modulus and tensile strength have been made utilizing a finite element method. Excellent agreement is obtained with the experimental results. Izod impact energies have been measured for these composites as a function of filler content and interface treatment.

S. Sahu

Papers

Mechanical properties of particulate composites