Assessment of processibility and properties of raw post-consumer waste polyethylene in the rotational moulding process

This paper presents work from an ongoing study into the use of post-consumer waste polymer in the rotational moulding process. Raw plastic recyclate, predominantly consisting of polyethylene, was processed into polymer powders containing an additive package suitable for rotational moulding, with and without the addition of a compatibiliser. Rheological studies on the materials showed very high viscosities at low shear rates in comparison with materials typically used in rotational moulding, which has significant implications for melt flow and bubble removal during the process. It was possible to mould the materials successfully, but poor surface finishes were achieved. Impact strength was drastically lower for recyclate mouldings compared with virgin material. Flexural and tensile strengths of the recyclate mouldings were reduced compared to virgin polyethylene, but results indicated that optimising the processing conditions could lead to improvements. This work gives some baseline indicators to inform further planned work on optimising processing conditions and identifying viable material compositions.