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An experimental study of the thermorheological behavior of polypropylene (PP) reinforced with short glass fibers during the injection processing is described in this paper. This study was carried out using a proprietary rheometer which was designed and developed within our laboratory and is mounted on the injection machine. We have studied the variations of PP viscosity and elasticity, during isothermal flow, as a function of temperature, shear rate and glass fiber content. Furthermore we have studied the influence of the injection thermomechanical parameters during non-isothermal flowing and a pressure drop inside the feed channels and within a molding cavity of cylindrical cross section.

Our work deals with the viscoelastic behavior and the evolution of the morphology of polypropylene samples reinforced with short glass fibers and molded with an injection machine. The influences on polymer properties of the mold temperature, of the rate of fibers and of the embedding are studied. We determine the existence of typical relations between the microstructure, the thermomechanical parameters of the injection and the viscoelastic properties of the composite. All these results contribute to optimize the mechanical resistance of molded objects thanks to a better knowledge of the action of injection molding parameters.

This study deals with fibre orientation during injection moulding of polyarylamide and polypropylene/polyarylamide matrices reinforced with 30% of short glass fibres. The rheological behaviour of these two composites has been investigated with a capillary rheometer. The composites have also been injected into a rectangular plate cavity using two threshold gate geometries and several plate thicknesses, and the orientation of the fibres has been determined at given coordinates inside the plate. The effects of speed injection, moulding temperature and flow geometry on fibre orientation have been investigated.

Thermoplastic polymer alloys or composites present a structural anisotropy after injection molding. The evolution of such an anisotropy depends on the type and on the concentration of components and also on the thermodynamical conditions of processing. Thermomechanical properties of such materials evolute taking into account typical microstructures. In this paper, we study the influence of injection and mold temperatures and of injection speed on stress-strain, impact resistance and viscoelastic behaviour of 30% short glass fibers reinforced polypropylene/polyarylamide mixtures.

This study deals with the compatibility of a poly(vinyl chloride) mixed separately with two industrial chlorinated poly(vinyl chlorides), denoted PVC/C1 and PVC/C2 (chlorine contents of 65.2 and 67.5%, respectively). The technique of mixing, examined for different compositions, is the main parameter for the compatibility of the resins. The mixtures were prepared either with a Brabender plastograph, with a milling cylinder at 190°C (the mixture being fluid), or by sintering at a temperature between 180 and 200°C under pressure. We determined the complex components of the elasticity modulus as a function of temperature (from 50 to 170°C at a frequency of 110 Hz) for each mixture, using a Rheovibron viscoelastometer. The study of the structure of the mixtures, based on the variation of the tangent of the loss modulus, allows us to say that the compatibility of polymers depends on the chlorine contents in chlorinated PVC; thus, at 65.2% the chlorinated polymer seems to be compatible with PVC, but at ...