Effect of the morphology of reactor powders on the structure and mechanical behavior of drawn ultra-high molecular weight polyethylenes

Tsobkallo, Katherina; Vasilieva, V. V.; Khizhnyak, S. D.; Пахомов, П. М.; Galitsyn, V. P.; Rühl, E.; Egorov, V. M.; Tshmel, A.

doi:10.1016/s0032-3861(02)00909-6

Cited by 12 publications

(10 citation statements)

References 18 publications

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“…In contrast, the crystals that recrystallized after melting during compression molding become thinner [14,15]. The cause of such thicker crystallization of the former reactor powder was attributed to the less-entangled morphology formed during polymerization [14][15][16][17][18]. The single endotherm located at the lower T m indicated complete melting during molding at 150-190 • C. Similar recrystallization temperatures after compression mold- ing gave the constant value of the resultant crystallinity ( Table 1).…”

Section: Characterization Of the Uhmw-pe Disks Molded At Different Tementioning

confidence: 95%

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Tribology of ultra-high molecular weight polyethylene disks molded at different temperatures

Aoike

Yokoyama

Uehara

et al. 2007

Wear

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Section: Characterization Of the Uhmw-pe Disks Molded At Different Tementioning

confidence: 95%

“…It is known that less-entangled reactor powder morphologies with the higher crystallinity are formed during polymerization for PE [14][15][16][17][18]. These reactor powders are utilized for preparing high-performance films with higher crystallinity [14,19,20].…”

Section: Introductionmentioning

confidence: 99%

Tribology of ultra-high molecular weight polyethylene disks molded at different temperatures

Aoike

Yokoyama

Uehara

et al. 2007

Wear

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“…13.1.1 Such behavior is at least partly attributable to the mixture of chain lengths of molecules that make up a polymeric material.…”

Section: Thermal Properties Of Polymersmentioning

confidence: 99%

Polymer Properties through Structure

Agarwal¹

2005

Handbook of Polymer Reaction Engineering

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Since polymers display an incredible range of properties, their potential for applications is ever increasing. The link between polymer structure and the resulting properties has long been realized, and emerged as the concept of tailor making of polymers. In earlier times, developments were largely targeted on achieving the desired properties through new monomers, copolymer and blend compositions, physical and chemical additives, and control of polymer molecular weights, as well as through structural changes derived from processing. In recent years, the increased expertise in anionic polymerization and the emergence of controlled radical polymerization techniques have led to relatively easy access to several precisely controlled topologies such as those of telechelic, block, graft, star-shaped, and several other branched homoploymers and copolymers with controlled molecular weights. For example, phenomenal growth has been recorded in the area of synthesis of block copolymers, as well as in examination of their self-assembling characteristics leading to unique control of nanoscale morphology. This is providing tools for development of properties suitable for applications extending from those requiring mechanical toughness to electronic and biological uses. Another rapidly developing area is nanocomposites, where the attainable range of properties is further expanded by incorporating inorganic and organic nanoparticles in polymeric matrices.In this chapter we aim to demonstrate the relationship of the structure of polymers with their thermal, solution, and rheological behavior. Besides providing a general review of such behavior, we will emphasize some of the recent developments in these areas. Thermal Properties of PolymersThe thermal behavior of polymers is different from that of simple compounds in that, on heating, the transition of polymers from solids to liquids occurs not at

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“…Thus, despite the fact that the supramolecular structure of the RP is completely lost upon dissolution [1], the properties of the final product (in this instance fiber) depend on the morphology and molecular characteristics of the RP (grain size, grain connectivity, molecular structure of the ordered phase, etc.) that are formed under the influence of the CT [2][3][4][5][6].…”

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Optimization of the synthesis of uhmwpe for preparing high-strength fibers from spinning solution

et al. 2013

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Data on the possibility of preparing in high yield reactor powders of ultra-high-molecular-weight polyethylene deposited on titanium-magnesium catalysts were presented. The powders had controlled morphology, supramolecular structure, and molecular weight and were suitable for producing highstrength fibers by gel formation.Ultra-high-molecular-weight polyethylene (UHMWPE) of molecular weight (MW) (1-5)·10 6 g/mol is used as starting raw material in gel technology for producing high-strength fibers. Reactor powders (RP) of UHMWPE that are synthesized using Ziegler-type catalysts (CT) usually act as such raw material. The required MW for the UHMWPE can be obtained by adjusting the synthesis conditions. However, the MW is not the only parameter that determines the fiberforming properties of a spinning solution. These properties depend considerably on the solution homogeneity, the degree of crystallinity, and structural features of the RP macromolecule. These determine the uniformity and strength of the molecular network that will be transformed into a highly ordered structure during orientational drawing. Thus, despite the fact that the supramolecular structure of the RP is completely lost upon dissolution [1], the properties of the final product (in this instance fiber) depend on the morphology and molecular characteristics of the RP (grain size, grain connectivity, molecular structure of the ordered phase, etc.) that are formed under the influence of the CT [2-6].The principal trends in the relationship of the parameters of the primary synthesized polymer and the synthesis conditions are well known {e.g., as the polymerization temperature decreases, the polyethylene (PE) MW increases, the bulk RP density decreases, etc.[7]}. However, it is extremely difficult to predict that properties of the final product, in this instance highly oriented fiber, at the synthesis stage without establishing even just the general trends in the change of fiber properties as a function of the CT and the polymerization process parameters.Herein data on the effect of several UHMWPE RP synthesis parameters on the mechanical properties of highly oriented fibers produced under identical conditions from gel precursors and obtained by spinning from solutions are presented in order to identify such trends. The RP were synthesized on titanium-magnesium CT using a polymerization suspension of ethylene in a hydrocarbon diluent at 45-65°C. The active component of the CT was TiCl 4 deposited on highly disperse (activated) MgCl 2 modified by additional components that enabled the RP morphology and polymer MW to be controlled.Three groups of RP samples designated arbitrarily A, B, and C (Table 1) were investigated using three CT modifications TMK-A, TMK-B, and TMK-C, respectively. The temperature and time of the polymerization were varied within each group in order to produce PE with the required MW and in sufficiently high yield.

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Effect of the morphology of reactor powders on the structure and mechanical behavior of drawn ultra-high molecular weight polyethylenes

Cited by 12 publications

References 18 publications

Tribology of ultra-high molecular weight polyethylene disks molded at different temperatures

Tribology of ultra-high molecular weight polyethylene disks molded at different temperatures

Polymer Properties through Structure

Optimization of the synthesis of uhmwpe for preparing high-strength fibers from spinning solution

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