Abstract
The effect of fibre concentration, temperature and mould thickness on tensile strength of single- and double-gated injection-moulded polypropylene copolymer reinforced with 0, 10, 20, 30 and 40 wt% short glass fibre was studied at a fixed strain-rate of 7.58 × 10−3 s−1 between 23 and 100 °C. It was found that tensile strength of single-gated mouldings, σc, increased with increasing volume fraction of fibres, ϕf in a nonlinear manner and decreased with increasing temperature in a linear manner. However, for ϕf values in the range 0–10% a simple additive rule-of-mixtures adequately described the variation of σc with ϕf over the entire temperature range 23–100 °C studied here. Tensile strength of double-gated mouldings like their single-gated counterparts decreased linearly with increasing temperature. The presence of weldlines significantly reduced tensile strength of double-gated composite mouldings but had little effect on tensile strength of the matrix. Weldline integrity factor, F σ, defined as weldline strength divided by unweld strength, decreased with increasing ϕf but increased with increasing temperature. A linear dependence was found between F σ and temperature. Mould thickness had no significant effect upon weld and unweld tensile strengths and consequently had no significant effect upon weldline integrity factor.
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Hashemi, S., Onishi, P. Effect of fibre concentration, temperature and mould thickness on weldline integrity of short glass-fibre-reinforced polypropylene copolymer composites. J Mater Sci 44, 5588–5594 (2009). https://doi.org/10.1007/s10853-009-3786-z
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DOI: https://doi.org/10.1007/s10853-009-3786-z