Polymer polyethylene

The material in use as of the mid-1990s in these components is HDPE, a linear polymer which is tough, resiUent, ductile, wear resistant, and has low friction (see Olefin polymers, polyethylene). Polymers are prone to both creep and fatigue (stress) cracking. Moreover, HDPE has a modulus of elasticity that is only one-tenth that of the bone, thus it increases the level of stress transmitted to the cement, thereby increasing the potential for cement mantle failure. When the acetabular HDPE cup is backed by metal, it stiffens the HDPE cup. This results in function similar to that of natural subchondral bone. Metal backing has become standard on acetabular cups. 

F. Polyethylene polymer autoclav e type reactors usually contain 8 to 120 impellers of the same or different circulation designs on a single shaft to ensure rapid total homogeneous mixing in the reactor, w hich contains a gas at about 30,000 psi and, hence, the fluid is neither a gas or a liquid because the densities are about the same. 

Intentional hranching may improve the properties of the product polymer through grafting. A graft copolymer can he obtained by creating active sites on the polymer backbone. The addition of a different monomer then reacts at the active site and forms a branch. For example, polyethylene irradiated with gamma rays and then exposed to a reactive monomer, such as acrylonitrile, produces a polyethylene-polymer with acrylonitrile branches ... 

Polymerizations catalyzed with coordination compounds are becoming more important for obtaining polymers with special properties (linear and stereospecific). The first linear polyethylene polymer was prepared from a mixture of triethylaluminum and titanium tetrachloride (Ziegler catalyst) in the early 1950s. Later, Natta synthesized a stereoregular polypropylene with a Ziegler-type catalyst. These catalyst combinations are now called Zieglar-Natta catalysts. 

De Sarkar M., De P.P., and Bhowmick A.K., New polymeric blends from hydrogenated styrene-butadiene rubber and polyethylene. Polymer, 39, 1201, 1998. 

Semiquantitative Determination of Chimassorb 944 in Low Density Polyethylene Polymer by Infrared Spectroscopy. Analytical Method No. C-259, Ciba-Geigy, Ardsley, NY (1981). 

Extended chain crystal (ECC) Folded chain crystal (FCC) Growth Growth rate Induction period Melt relaxation Molecular weight Nucleation Nucleation rate Nucleus Optical microscope (OM) Polyethylene Polymer Power law ... 

Polyethylene particle growth, over Ziegler-Natta catalysts, 26 530-531 Polyethylene polymer properties, control of, 17 703... 

Polyethylene polymers history of, 17 701-702 simulations of, 16 747 Polyethylene products, Ziegler-Natta catalysts for, 26 540-543 Polyethylene resins, 17 700-703 applications for, 17 703 Polyethylenes, classification of, 17 701t. 

See also Polyethylene polymer entries Polyethylene shrink film wrapping, 18 37 Poly(ethylene-stal-a-olefin), glass... 

Epacher, E., Krohnke, C. and Pukhanszky, B., Effect of Catalyst Residues on the Chain Structure and Properties of a Phillips Type Polyethylene, Polym. Eng. Set, 40, 1458 (2000)... 

Alternatively, polystyrene-based solutions were developed. Best results for immobilization were found when TADDOL derivatives (6) and (7) containing phenolic hydroxy groups were prepared in solution and anchored to Merrifield resin (Scheme 4.4) [66]. The authors managed to couple (7) to PS-DVB polymers with different loading and cross-Hnking degrees as weU as on polyethylene polymer which contained polyvinylbenzyl chloride chains (SMOP-3-resins). 

S.S. Cherukupalli and A.A. Ogale, Online measurements of crystaUinity using Raman spectroscopy during blown film extrusion of a linear low-density polyethylene, Polym. Eng. Sci, 44, 1484—1490 (2004). 

Calibration. The accepted method of calibrating a GPC system was used. Narrow molecular-weight distribution high-density polyethylene polymers were characterized by light scattering, osmometry, and sedi-... 

Wintle, H. J. Radiation induced conductivity in irradiated polyethylene. Polymer 2, 444 (1961),... 

Obviously, the polymerization of ethylene does not involve isotactic steric control, since no isomers are possible in the linear polyethylene polymer. However, as the simpliest member of the vinyl monomer series, ethylene should be considered along with the substituted ethylenes. Where does the Ziegler catalyst, which produces polyethylene, lie in relation to the polypropylene catalysts ... 

Banks, M., Ebdon, J. R., and Johnson, M., Influence of covalently bound phosphorus-containing groups on the flammability of poly(vinyl alcohol), poly(ethylene-co-vinyl alcohol) and low-density polyethylene, Polymer, 1993, 34, 4547 1556. 

Bourbigot, S., Le Bras, M., Delobel, R., Breant, P., and Tremillon, J.-M. 1996. 4A Zeolite synergistic agent in new flame retardant intumescent formulations of polyethylenic polymers—Study of the constituent monomers. Polym. Deg. Stab. 54 275-283. 

Yeh, J.T., Yang, H.M., and Huang, S.S., Combustion of polyethylene filled with metallic hydroxides and crosslinkablc polyethylene, Polym. Deg. Stab., 50, 229-234, 1995. 

Kole S et al. (1995) Grafting of silicone rubber onto polypropylene or polyethylene. Polym Networks Blend 5(3) 117—122... 

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