An evaluation of the melt crystallisation behaviour of injection-moulded high-density polyethylene (HDPE) based on a solidification kinetics analysis

Abstract

Dynamical rheology, transient temperature measurement, and two-dimensional wide angle X-ray diffraction were performed in this work to investigate the effects of the solidification behaviour and crystallisation kinetics on the gradient structure formation of the injection-moulded high-density polyethylene (HDPE) samples across the thickness. The temperature profiles obtained via enthalpy transformation method were used to elucidate the effect of cooling rates on the solidification kinetics during the injection moulding process. A four-parameter model was proposed for the first time, based on the ‘three-parameter model’ of our previous research, and the former one is shown to have a better fitting effect. Heat transfer at locations χ ≤ 0.5 from the mould surface was found to be primarily dominated by a thermal conduction mechanism, unlike the situation when χ > 0.5. The degree of orientation of the HDPE samples was closely associated with the shear distributions and temperature fields.