02524nas a2200217   4500008004100000022001400041245016000055210006900215260000800284300000900292490000700301520172900308653001102037653002402048653002102072653000902093653002602102100002702128700002102155856013002176       2020                        eng d  a0148-605500aRheological quantification of the extent of dissolution of ultrahigh molecular weight polyethylene in melt-compounded blends with high density polyethylene0 aRheological quantification of the extent of dissolution of ultra  cJAN  a1-120 v643 a<p>Melt compounding of ultrahigh molecular weight polyethylene (UHMWPE) with high density polyethylene (HDPE) promises to be an alternative route to prepare bimodal polyethylene grades. However, complete dissolution of UHMWPE in HDPE cannot be guaranteed during melt compounding. Indeed, in an earlier work [K. Chaudhuri et al., Polym. Eng. Sci. 59, 821-829 (2019)], it was shown that a fully entangled UHMWPE did not mix well with commercial HDPE. However, a disentangled UHMWPE (dPE) could be melt-mixed in the same HDPE as evidenced qualitatively by rheological measurements. The present work is focused on quantifying the extent of dissolution of dPE in HDPE. The proposed method involves fitting rheological models for linear viscoelasticity of entangled bimodal blends of polydisperse polymers to dynamic oscillatory shear data and extracting information on the extent of dissolved species. The time-dependent diffusion model of des Cloizeaux is used along with the theory of double reptation (DR) to describe the dynamics of polydisperse homopolymers and also to extract the molecular weight distribution of the UHMWPE sample. A quadratic mixing rule, consistent with the DR model, is used to describe the dynamics of bimodal blends. Melt-mixed dPE/HDPE blends were prepared and characterized for their linear viscoelastic response by frequency sweep tests. The blends showed complex behavior with multiple crossover points, especially for the higher content of dPE. The bimodal model was then fit to the experimental frequency sweep data to determine the only unknown parameter, namely, the extent of dissolved dPE. It was found that a considerable fraction of dPE is dissolved in HDPE during melt compounding.</p>
10ablends10aDisentangled UHMWPE10adouble reptation10aHDPE10aMathematical modeling1 aChaudhuri, Krishnaroop1 aLele, Ashish, K.  uhttps://library.ncl.res.in/content/rheological-quantification-extent-dissolution-ultrahigh-molecular-weight-polyethylene-melt02005nas a2200229   4500008004100000022001400041245010700055210006900162260000800231300001100239490000800250520119300258653002501451653002401476653002101500653002201521653004101543100001701584700002401601700002501625856012501650       2020                        eng d  a0079-670000aUltrahigh molecular weight polyethylene: catalysis, structure, properties, processing and applications0 aUltrahigh molecular weight polyethylene catalysis structure prop  cOCT  a1012900 v1093 a<p>Ultrahigh molecular weight polyethylene (UHMWPE) belongs to an emerging class of high-performance specialty polymers with a unique set of properties and applications. The field has witnessed many scientific and technological advances in recent years. However, synthesis of UHMWPE is not a trivial exercise and presents several challenges. This review addresses these fundamental challenges and provides an overview of recent developments in the field of UHMWPE. The nature of catalysts, reaction conditions that favor its formation, their physical properties, methods of processing them into products, and their applications are discussed. Recent developments in formation of UHMWPE in a disentangled state by use of appropriate catalysts and reaction conditions are also discussed. This has elicited considerable interest as a means of enabling melt processing of UHMWPE. This review provides a comprehensive source of information and understanding of the multifaceted aspects of UHMWPE with specific reference to chemistry, catalysis, processes for manufacturing, and an analysis of catalyst structure-polymer property relationships. (C) 2020 Elsevier B.V. All rights reserved.</p>
10aCatalysts for UHMWPE10aDisentangled UHMWPE10aEntangled UHMWPE10apolyethylene (PE)10aUltrahigh molecular weight (UHMW) PE1 aPatel, Ketan1 aChikkali, Samir, H.1 aSivaram, Swaminathan  uhttps://library.ncl.res.in/content/ultrahigh-molecular-weight-polyethylene-catalysis-structure-properties-processing-and