Realizing the simultaneously improved toughness and strength of ultra-thin LLDPE parts through annealing
writer：Suyu Shi, Yamin Pan, Bo Lu, Guoqiang Zheng(通訊作者), Chuntai Liu, Kun Dai, Changyu Shen
keywords：Microinjection molding Annealing LLDPE
source：期刊
specific source：Polymer
Issue time：2014年
Ultra-thin LLDPE parts were prepared by microinjection molding. Mechanical properties and microstructure
of samples before and after annealing at different temperatures (60, 80, 100 C) were analyzed.
Tensile test indicates that toughness has been enhanced at least 7 times after being annealed in parallel
with significant increase of tensile strength. Microstructure characterizations, including differential
scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS),
scanning electronic microscope (SEM) and polarized Fourier transform infrared spectroscopy (FTIR) were
performed to investigate the variations of microstructure and to further establish the relationship between
microstructure and mechanical properties. It is suggested that the increased crystallinity and
perfection of crystals upon annealing are beneficial to the reinforcement. Formation of a stronger
physical cross-linking network due to the increase of connecting points is in favor of the enhanced
strength as well. Moreover, the notable improvement of toughness in the annealed ultra-thin LLDPE
parts is ascribed to combined effects of microvoids developed in both the annealing and deformation
process. This work offers a simple approach to prepare ultra-thin LLDPE parts with excellent toughness
and strength.