Thesis Abstracts 2003
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Consolidation of a Woven Commingled Roving
By: Danny J.Y.S. Pagé PhD (Chem Eng.)
Supervisors: Dr. P.J.Bates, Dr. H.W.Bonin and Dr. V.T. Bui
Abstract
The consolidation of thermoplastic composites is an important industrial process that insures that the resin carefully wets the reinforcement and eliminate voids in order to optimise mechanical properties. A study was conducted on the consolidation of a woven commingled roving under biaxial tension, compressive stress, and heat. The material was a 2-2 twill fabric composed of 60% glass fibres by weight and 40% polypropylene fibres. The study of this complex process was divided into three parts. The first part consisted in measuring and modelling the transverse compressibility of an aligned commingled roving at ambient temperature. This work allowed measuring the fibre volume fraction in the roving as a function of compressive stress. The second part consisted in measuring and modelling changes in the thickness of a woven commingled roving under biaxial tension. This work provided the mean to define regions of low and high permeability in the fabric to be used in a consolidation process. The third part consisted in measuring the resin flow during consolidation at 210°C, and, the flexural properties, fibre volume fraction and void volume fraction of the consolidated material. The results were compared as a function of consolidation conditions such as applied pressure (0.2-2 MPa), consolidation time (10-100 seconds) and biaxial tension (10-40 MPa). The mechanical properties showed a strong dependence on fibre volume fraction, which increased with applied pressure and consolidation time. Biaxial tension also increased mechanical properties due to improved fibre orientation. The void decreased rapidly during the first moments of consolidation and minimum void contents of 2% were observed at higher pressures. The model predicted the resin flow trends observed during consolidation and the fibre and void volume fractions of the consolidated parts.
