Validation of micromechanics models including imperfect interfaces for short fiber thermoplastic composites

Micromechanics models proposed by Nairn et al. and Hashin, which can treat imperfect bonded interfaces between fibers and polymer matrix, are evaluated for use in predicting the equivalent stiffness of a short fiber reinforced thermoplastic composite. Treatment of the imperfect interfaces is fundamentally important to address differences of interface connections that affect the mechanical properties of the composite. We first compare the Nairn–Hashin (NH) models with the Mori–Tanaka (MT) model under the condition of a perfect interface. Elastic moduli calculated from the NH models almost agree with that from the MT model. The NH models are then evaluated using elastic moduli measured for randomly fiber-oriented films of short glass fiber reinforced polypropylene. By considering the imperfect interface parameters estimated from pull-out tests of a single glass fiber embedded in a polypropylene matrix, the NH models predict the measured elastic moduli.