Particulate reinforced rotationally moulded polyethylene composites – Mixing methods and mechanical properties

In order to investigate the mechanical properties of particulate reinforced polyethylene when using rotational moulding process, different mathematical models are used to predict the tensile properties. A series of micro-sized particles at various volume fractions are used as fillers for Liner Medium Density Polyethylene (LMDPE) to verify those theoretical models. A comparison with the experimental results finds that the theoretical models of Halpin–Tsai–Nielsen and Nicolais–Narkis can be used to predict the tensile moduli and the tensile strengths, respectively, for the particulate reinforced composites produced by the rotational moulding process when uniform distribution of reinforcement is achieved. The scanning electron microscopic images show that an even distribution of particles within the product wall can be achieved in two ways: direct manual mixing method for bigger sized particles (90–240 μm) and melt compounding method for smaller particles (6.5–35 μm). It is also found that with around 2 vol% of the smallest Spheriglass 5000 beads added by the melt compounding method, the tensile strength remains almost the same and the tensile modulus reaches a 20% improvement above that of pure LMDPE.