Ultrahigh molecular weight properties

In a time when prices for oil are continuously rising, hafnocene catalysts enable production of high-tech materials in a relatively cheap way. Hafnocenes are the key to a family of high and ultrahigh molecular weight polypropylenes whose material properties can be individually and simply varied. To help comprehend the importance... 

ENTER Membranes LLC has developed Teklon— a highly porous, ultrahigh molecular weight polyethylene separator for lithium-ion batteries. At the writing of this publication, the separator is available in small quantities. Pekala et al. characterized Celgard, Setela, and Teklon separators in terms of their physical, mechanical, and electrical properties. ... 

K.A. Saum, W.M. Sanford, W.G. Dimaio, Jr., and E.G. Howard, Jr., Process for medical implant of cross-linked ultrahigh molecular weight polyethylene having improved balance of wear properties and oxidation resistance, US Patent 6017 975, January 25, 2000. 

Ting RY, Kim OK (1972) Drag reduction properties of ultrahigh molecular weight polyacrylamide and related polymers Am Chem Soc Div Org Coating Plastics Chem 32 270... 

The findings described above form a basis for our current work that examines the influence of the interphase on the structure and ultimately on the properties of linear polymers. In this chapter we will first show that, depending on the crystallization conditions, the amount of loops or entanglements in the interphase, and thus the deformation behavior of polymers, can be varied. We will initially consider the example of ultrahigh molecular weight polyethylene (UHMW-PE) and the role of entanglements upon its drawability. 

As illustrated above, selection of cocatalyst is often predicated on cost. In some cases, however, use of an alternative cocatalyst may transcend the cost factor. This could be because the alternative cocatalyst provides enhanced polymer properties or improved process performance. For example, use of TMAL as cocatalyst in place of TEAL in a gas phase process has been shown to provide linear low density polyethylene with lower hexane extractables and superior film tear strength (14). Ultrahigh molecular weight polyethylene and polyethylene with broader molecular weight distribution can be produced using "isopre-nylaluminum" as cocatalyst (15-17). 

Although radiation may raise the softening temperature because of the crosslinks produced, the thermodynamic melting point is hardly changed in PE as demonstrated by Dole and Howard (20) by means of accurate specific heat measurements. Ultrahigh molecular weight polyethylene, DHMWPE, is used as Implantable prosthetic devices such as total joint replacements because of its mechanical properties, resistance to chemicals and to abrasion. Irradiation enhances its creep resistance (21). 

The wear behaviour of polytetrafluoroethylene (PTFE), carbon-filled PTFE, high density polyethylene (HDPE), ultrahigh molecular weight polyethylene (UHMPE), low density polyethylene (LDPE) and polymethyl methacrylate (PMMA) was studied. To ensure consistent and controlled properties of the samples, many of the materials were processed in the authors laboratory. The details of sample preparation and processing techniques are reported elsewhere ( ). ... 

Ultrahigh molecular weight polyethylene (UHMW PE) is most commonly used for articulation surfaces in joints. It is also used for prosthesis components in total hip replacement. In the latter application, it may be reinforced with carbon fibers to increase wear properties. 

T.M. Ushakova, E.E. Starchak, V.G. Krasheninnikov, V.G. Grinev, T.A. Ladygina, L.A. Novokshonova, Influence of copolymer fraction composition in ultrahigh molecular weight polyethylene blends with ethylene/1-hexene copolymers on material physical and tensile properties. J. Appl. Polym. Sci. 131, 40151 (2014)... 

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