The fracture toughness of reinforced polyurethane foam

Abstract

A microscopic study of the fracture processes occurring in rigid, closed-cell polyurethane foam has been combined with an assessment of toughness using fracture mechanics in order to investigate the reinforcement capability of chopped glass fibres. One aspect of fibre reinforcement is seen as an extension of a mechanism that could be responsible for the relatively high surface energy of the base foam. There is also an increase in modulus, and a further contribution to toughness is derived from fibre pull-out. An optimum, though unspecified, fibre length exists that gives the most efficient reinforcement of the foam considered.