Chain Mobility in Polymer Systems:  On the Borderline between Solid and Melt. 2. Crystal Size Influence in Phase Transition and Sintering of Ultrahigh Molecular Weight Polyethylene via the Mobile Hexagonal Phase

1998 ◽  
Vol 31 (15) ◽  
pp. 5022-5031 ◽  
Author(s):  
S. Rastogi ◽  
L. Kurelec ◽  
P. J. Lemstra
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Crystal Size ◽  
Hexagonal Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polymer Systems ◽  
Chain Mobility ◽  
Ultrahigh Molecular Weight

Phase Transition during Heating of Nanostructured Ultrahigh Molecular Weight Polyethylene Membranes

2015 ◽  
Vol 119 (52) ◽  
pp. 15909-15918 ◽  
Author(s):  
Hiroki Uehara ◽  
Takuya Tamura ◽  
Hideyuki Yamashita ◽  
Takeshi Yamanobe ◽  
Hiroyasu Masunaga
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Ultrahigh Molecular Weight

scholarly journals Enhancing Chain Mobility of Ultrahigh Molecular Weight Polyethylene by Regulating Residence Time under a Consecutive Elongational Flow for Improved Processability

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2192
Author(s):  
Xiaochuan Chen ◽  
Xiaotong Wang ◽  
Yanhong Feng ◽  
Jinping Qu ◽  
Dingshan Yu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Molecular Weight ◽  
Residence Time ◽  
Elongational Flow ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polymeric Chain ◽  
Thermal Oxidative Degradation ◽  
Chain Entanglement ◽  
Chain Mobility ◽  
Ultrahigh Molecular Weight

Improving the processability of ultrahigh molecular weight polyethylene (UHMWPE) and understanding the effect of the polymeric chain mobility has long been a challenging task. Herein, we show that UHMWPE without any processing aids can be processed at a lower temperature of 180 °C compared to conventional processing temperatures (~250 °C) under a continuous elongational flow (CEF) by using an eccentric rotor extruder (ERE). By probing the effect of the residence time of UHMWPE samples under a CEF on the morphology, rheological behavior and molecular orientation, we find that the long polymer chains of UHMWPE are apt to orientate under a consecutive volume elongational deformation, thereby leading to a higher residual stress for the extruded sample. Meanwhile, the residence time of samples can regulate the polymeric chain mobility, giving rise to the simultaneous decrease of the melting defects and residual stress as well as Hermans orientation function with increasing residence time from 0 to 60 s. This also engenders the enhanced diffusion of UHMWPE segments, resulting in a defect-free morphology and higher entanglement with lower crystallinity but without causing obvious thermal oxidative degradation of UHMWPE. This interesting result could originate from the fast chain entanglement and particle welding enabled by a desirably short residence time, which could be explained by the empirical, entropy-driven melting explosion mechanism.

scholarly journals Тепловой эффект перехода моноклинной фазы в орторомбическую в сверхвысокомолекулярном полиэтилене

2019 ◽  
Vol 61 (10) ◽  
pp. 1965 ◽  
Author(s):  
В.М. Егоров ◽  
В.А. Марихин ◽  
Л.П. Мясникова ◽  
А.К. Борисов ◽  
Е.М. Иванькова ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Solid State ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Effects ◽  
Ultrahigh Molecular Weight

AbstractWe analyze heat effects associated with the solid-state phase transition in ultrahigh molecular weight polyethylene from the unstable monoclinic phase into thermodynamically stable orthorhombic phase. The model proposed here for the structure of supramolecular formations of monoclinic phase does not contradict to earlier X-ray diffraction data for this polymer.

Heat Effect Due to Monoclinic-to-Orthorhombic Phase Transition in Ultrahigh Molecular Weight Polyethylene

2019 ◽  
Vol 61 (10) ◽  
pp. 1927-1932 ◽  
Author(s):  
V. M. Egorov ◽  
V. A. Marikhin ◽  
L. P. Myasnikova ◽  
A. K. Borisov ◽  
E. M. Ivan’kova ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Heat Effect ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Ultrahigh Molecular Weight
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