Fine Structure of UHMWPE Reactor Powder and its Change in Mechanical and Thermal Fields pp. 93-151
Authors: (Liubov Myansikova, Yury Boiko, Victor Egorov, Elena Ivaníkova, Dmitrii Lebedev, Vycheslav Marikhin, Elena Radovanova, Goerg Michler, Volker Seidewitz, Sylviya Goerlitz)
Abstract: Aiming at better understanding the influence of reactor powder morphology of ultrahigh- molecular-weight polyethylene (UHMWPE) on its processing ability, the transformation of a number of lab-scale and commercial polyethylene reactor powders to mechanically coherent film by sintering of pre-compacted powders at temperature lower than that of melting point is studied. The dependence of mechanical properties of UHMWPE films on parameters of compaction/sintering process is investigated. Nascent morphology and structural rearrangements in the nascent particles during compaction/sintering are considered. A whole complex of modern techniques for structural investigations (X-ray analysis in wide and small angles (WAXS/SAXS), Fourier transform infrared spectroscopy (FTIR), scanning and transmission electron microscopy (SEM/TEM), broad line nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Raman spectroscopy in longitudinal acoustic mode (LAM) and a.o.) is used. A special attention is paid to investigation of nascent particle surface structure and its influence on particle coalescence. Molecular dynamics in ultrathin surface layers of nascent particles was first studied with the help of a unique device, Nanoluminograph (designed and patented by employees of PlasmaChem, GmbH, (Germany), Ioffe Physico-Technical Institute of Russian Academy of Sciences and The Russian Institute of Radionavigation and Time). Its work is based on the thermoluminescence phenomena. It is shown that compaction/sintering process results in a marked change in both crystalline and disordered regions of reactor powders, the properties of the end product being dramatically dependent on the initial structure of nascent morphology.
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