Compartmentalized polymerization in aqueous and organic media to low-entangled ultra high molecular weight polyethylene

2021 ◽  
Author(s):  
Florian P. Wimmer ◽  
Viktoria Ebel ◽  
Felix Schmidt ◽  
Stefan Mecking
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Functional Group ◽  
Aqueous Media ◽  
Organic Media ◽  
Catalytic Polymerization ◽  
Ultra High Molecular Weight

Catalytic polymerization in compartmentalized aqueous or non-aqueous media, respectively, with functional-group tolerant Ni(ii) catalysts yields low-entangled UHMWPE.

Titanium amidate complexes as active catalysts for the synthesis of high molecular weight polyethylene

2015 ◽  
Vol 93 (7) ◽  
pp. 775-783 ◽  
Author(s):  
Patricia Horrillo-Martinez ◽  
David C. Leitch ◽  
Scott A. Ryken ◽  
Robert K. Thomson ◽  
J. David Beard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
Catalytic Polymerization ◽  
Binding Motifs ◽  
Co Catalyst ◽  
Multiple Binding ◽  
Polymeric Chains ◽  
Ultra High Molecular Weight

A series of titanium and zirconium bis(amidate) complexes of the type L2MX2, where L is an amidate ligand, and X is either –NMe2 or –Cl, were prepared in 60%–83% yield and fully characterized. Multiple binding motifs are observed as the amidate ligand can bind in κ1- and κ2-modes. These complexes were then subjected to screening the catalytic polymerization of ethylene. All catalysts, after reaction with suitable co-catalyst, were functional for ethylene polymerization, though not for the copolymerization of ethylene and longer linear 1-alkenes. Polyethylene was formed in the range of 1000–4000 kDa, and with PDI values as low as 1.3. These long polymeric chains are considered as ultra-high molecular weight polyethylene (UHMWPE).

Application of ultra-high molecular weight polyethylene in a hydraulic drive

2020 ◽  
pp. 77-78
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
High Molecular Weight ◽  
Hydraulic Drive ◽  
Control Valve ◽  
Hydraulic Control ◽  
Hydraulic Motor ◽  
Hydraulic Pump ◽  
Hydraulic Oil ◽  
Ultra High Molecular Weight

The use of ultra-high molecular weight polyethylene (UHMW PE) for the manufacture of various parts, in particular cuffs for hydraulic drives, is proposed. The properties and advantages of UHMW PE in comparison with other polyethylene materials are considered. Keywords ultra-high molecular weight polyethylene, hydraulic pump, hydraulic motor, hydraulic control valve, hydraulic oil, low temperature. [email protected]

scholarly journals Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 4: sporadic fatigue crack propagation

2020 ◽  
Vol 92 (9) ◽  
pp. 1521-1536
Author(s):  
Clive Bucknall ◽  
Volker Altstädt ◽  
Dietmar Auhl ◽  
Paul Buckley ◽  
Dirk Dijkstra ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
High Molecular Weight ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Individual Growth ◽  
Paris Equation ◽  
Number Of Cycles ◽  
Ultra High Molecular Weight

AbstractFatigue tests were carried out on compression mouldings supplied by a leading polymer manufacturer. They were made from three batches of ultra-high molecular weight polyethylene (UHMWPE) with weight-average relative molar masses, ${\overline{M}}_{\mathrm{W}}$, of about 0.6 × 106, 5 × 106 and 9 × 106. In 10 mm thick compact tension specimens, crack propagation was so erratic that it was impossible to follow standard procedure, where crack-tip stress intensity amplitude, ΔK, is raised incrementally, and the resulting crack propagation rate, da/dN, increases, following the Paris equation, where a is crack length and N is number of cycles. Instead, most of the tests were conducted at fixed high values of ΔK. Typically, da/dN then started at a high level, but decreased irregularly during the test. Micrographs of fracture surfaces showed that crack propagation was sporadic in these specimens. In one test, at ΔK = 2.3 MPa m0.5, there were crack-arrest marks at intervals Δa of about 2 μm, while the number of cycles between individual growth steps increased from 1 to more than 1000 and the fracture surface showed increasing evidence of plastic deformation. It is concluded that sporadic crack propagation was caused by energy-dissipating crazing, which was initiated close to the crack tip under plane strain conditions in mouldings that were not fully consolidated. By contrast, fatigue crack propagation in 4 mm thick specimens followed the Paris equation approximately. The results from all four reports on this project are reviewed, and the possibility of using fatigue testing as a quality assurance procedure for melt-processed UHMWPE is discussed.

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