The durability of controlled matrix shrinkage composites

Abstract

Controlled matrix shrinkage composites have resin matrices in which the cure shrinkage is controlled by adding expanding monomers to epoxy (and other) resins. The shrinkage stresses can be reduced to about one third of their normal values, accompanied by a 50% increase in impact resistance of the composites, with no corresponding loss of shear strength. Tensile and compressive properties of the composites are slightly reduced, although the resin matrices themselves have slightly improved properties as a result of the addition of the expanding monomer. In contrast to this, the addition to the resin matrix of a compatible solvent, dimethyl formamide, had very little effect on the shrinkage stress or composite impact strength but caused losses of resin properties which were manifested in a decrease in composite shear strength.