Study on Crystallization Kinetics of Partially Melting Polyethylene Aiming To Improve Mechanical Properties
writer：Haili Zheng,? Bo Wang,? Guoqiang Zheng（通訊作者）, Zhigang Wang
keywords：extrusion
source：期刊
specific source：Industrial Engineering and Chemical Research
Issue time：2014年
Partially melting high-density polyethylene (HDPE) is investigated by differential scanning calorimetry and in situ
Fourier transform infrared spectroscopy (FTIR) measurements. The results show that some incompletely molten crystals can be
preserved in the partially melting HDPE, thus accelerating subsequent crystallization. Moreover, quantitative calculation of such
incompletely molten crystals has been done based on the FTIR results. Interestingly, the kinetically enhanced crystallization
results from the improved nucleation rate because of the incompletely molten crystals. Furthermore, such interesting selfnucleation
originating from the partially melting HDPE has been deliberately applied to practical polymer processing, i.e.,
extrusion, aiming to investigate the influence of partially melting HDPE on the microstructural development and the resultant
mechanical properties of the extruded products. Unexpectedly, an increment in tensile strength has been achieved in the sheets
extruded from partially melting HDPE compared with that extruded from completely melted HDPE. Wide-angle X-ray
diffraction and small-angle X-ray scattering results show that the crystallinity, long period, and lamellar thickness increase for the
sheets extruded from the partially melting HDPE. These increases are considered to be responsible for the mechanical increment.
This work opens a new gateway for applying the self-nucleating effect of partially melting polymer melt into practical processing
with the purpose of preparing high-performance polymer products.