Analysis of the effect of mechanical recycling upon tensile strength of a short glass fibre reinforced polyamide 6,6

The effect of mechanical recycling upon tensile strength of an injection moulded polyamide 6,6 reinforced with 35% by weight of glass fibres has been experimentally investigated. Tensile tests have been conducted on specimens made of virgin material and containing different percentages of mechanically recycled material. Mechanical recycling consisted of regrinding of specimens and further injection moulding the granules into specimens of the same type. The main effect of this type of recycling is fibre breakage with consequent decrement of fibres contribution to composite strength. The results from the experimental tests have been compared with predictions obtained by applying a micro-mechanical model, which allowed taking into account the fibre length distribution and the properties of the phases of the composite. The model appeared to be a useful tool in the eco-design methodology, where the knowledge of property change of recycled material against those of the virgin one is necessary in the assessment of the environmental impacts of different recovery options.