INFLUENCE OF WATER-ABSORPTION ON TRANSVERSE TENSILE PROPERTIES AND SHEAR FRACTURE-TOUGHNESS OF GLASS POLYPROPYLENE/

Water absorption characteristics, and developments of transverse tensi le modulus and strength, and mode II fracture toughness with water abs orption of a unidirectional glass/polypropylene (PP) composite have be en examined, Immersion times up to 5 months at 50 degrees C were emplo yed. Overall, very small amounts of water were absorbed. The absorptio n of water was more rapid in distilled water than in seawater No signi ficant change in the transverse tensile modulus was observed after imm ersion, which is attributed to negligible softening of the highly crys talline PP matrix. The transverse tensile strength, very low initially , was also virtually unaffected by water absorption. The mode II fract ure toughness, G(IIc), decreased significantly after water absorption. The reduction of G(IIC) is attributed to degradation of the matrix du e to water absorption as observed in the scanning electron microscope.