An extensive study of the fracture behaviour of an injection-moulded PET (polyethylene terephthalate)/glass-composite system has recently been completed [1-8]. The PET matrix is generally considered to be ductile, while PPS (polyphenylene sulphide) is considered brittle. Therefore, for comparative purposes, a study of the brittle PPS matrix reinforced by short glass fibres would be of interest. This is the thrust of the present investigation. A PPS matrix reinforced with 40 wt % E-glass fibres was made by injection molding. The mechanical lifetime data were obtained by stressrupture testing [4, 5]. The microstructure was examined by scanning electron microscopy (SEM). The through-thickness microstructure is shown in Fig. 1. The surface of this SEM micrograph was cut parallel to the mold-fill direction (MFD) and to the thickness of the plaque. Near the surfaces of the plaque, the glass fibres are oriented approximately parallel to the MFD, whereas in the centre the fibres lie more nearly normal to the MFD. Two kinds of compact tension specimens are used: the L specimen is cut so that the fibre axis lies parallel to the loading axis; the T specimen has the fibre axis normal to the stress axis. Thus, in the L configuration, the main crack must run perpendicular to the fibres and in the T configuration, parallel to the fibres. A dead load is applied to the specimen until the specimen fails by part-through failure. The environment is controlled by a corrosion cell, within which the specimen is immersed during the whole lifetime of stress-rupture testing. Two kinds of aggressive environments are used, 10 vol. % HCI solution and 10 wt % NaOH solution, and compared with stress-rupture under air. Data for mechanical lifetime under air, 10% HC1 and 10% NaOH are shown in Fig. 2. Both the L (Fig. 2a) and the T (Fig. 2b) geometries are shown. The curves in Fig. 2 are the 0.25 and 0.75 reliability (R) curves, representing a law of the form [4]