Influence of water absorption on transverse tensile properties and shear fracture toughness of glass/polypropylene

Water absorption characteristics, and developments of transverse tensile modulus and strength, and mode II fracture toughness with water absorption of a unidirectional glass/polypropylene (PP) composite have been examined, Immersion times up to 5 months at 50 degrees C were employed. Overall, very small amounts of water were absorbed. The absorption of water was more rapid in distilled water than in seawater No significant change in the transverse tensile modulus was observed after immersion, which is attributed to negligible softening of the highly crystalline PP matrix. The transverse tensile strength, very low initially, was also virtually unaffected by water absorption. The mode II fracture toughness, G(IIc), decreased significantly after water absorption. The reduction of G(IIC) is attributed to degradation of the matrix due to water absorption as observed in the scanning electron microscope.