Isothermal crystallization behavior of high-density polyethylene (HDPE) was studied experimentally by using a rotary rheometer with parallel plates fixtures.It was found that the crystallization rate depended on the surface roughness of the fixtures with the same chemical composition.As the surface roughness increased,the crystallization rate first increased then decreased which meant that there was a range of surface roughness where the crystallization rate could reach a maximum value.Surface roughness effectively enhanced the interfacial area and decreased heat resistance, but possibly trapped air pockets in the valley of the rough surface produced a considerable interfacial heat resistance,both affecting the crystallization rate of HDPE.The isothermal crystallization rate decreased in sequence as the HDPE specimen contacted with aluminum,brass and stainless steel plates whose surface roughness were on the same level.The sample crystallizes more quickly on the fixtures with higher heat conduction coefficient, thus lowering heat resistance.
