POLYETHER-URETHANE

Polyether-urethane 200 Better hydrolytii z stability and resistance to fungal ... 

Hydrolysis studies compared a polycarbonate urethane with a poly(tetramethyl-ene adipate) urethane and a polyether urethane based on PTMEG. After 2 weeks in 80°C water, the polycarbonate urethane had the best retention of tensile properties [92], Polycarbonates can hydrolyze, although the mechanism of hydrolysis is not acid-catalyzed, as in the case of the polyesters. Polycarbonate polyurethanes have better hydrolysis resistance than do standard adipate polyurethanes, by virtue of the highest retention of tensile properties. It is interesting to note in the study that the PTMEG-based urethanes, renowned for excellent hydrolysis resistance, had lower retention of physical properties than did the polycarbonate urethanes. 

The polyether-PDMS soft segments in segmented polyurea-urethanes have been synthesized to combine the good mechanical properties of PUs and the excellent blood-contacting properties of PDMS. The most widely recognized material in this category is Avcothane [Arkles BC, Med Device Diagn Ind 3 30(1981)], which is characterized as a block copolymer of aromatic polyether urethane and PDMS. 

Elastomeric fibres based upon both polyester-urethane and polyether-urethane structures followed. The early work by Bayer led to the use of highly polar solvents such as dimethyl formamide. Formation of fibres by reactive spinning, where the isocyanate-ended polymer is extruded into an aqueous solution of a chain-coupling agent, was described in 1949 [75] and by dry-spinning a solution of the chain-coupled polymer in 1951 [76], However, Bayer did not immediately use their technology to produce commercial fibres [77],... 

The most widely studied synthetic polymers for blood contact applications are polyether urethane ureas ( Biomer (Ethicon)). These materials have been used in artificial hearts, as coatings for lead wires in pacemakers, have been used and are being considered for blood vessel prostheses. The success of these materials is believed to be due to preferential adsorption of albumin rather than globulin or fibrinogen which promote a clotting response. However, these materials are hydrophobic and questions of long-term effectiveness are unresolved. Particularly, these materials may shed emboli or may be susceptible to surface calcification. Thus, it may be desirable to have synthetic polymers which are hydrophilic and better resemble blood vessels [475]. 

Santerre and collaborators [72,73] also found that the plasma interaction of polyether urethanes was significantly altered by incorporation of sulfonate groups [73] which could be derivatized with amino adds [72]. The synergistic effect of pendant PEO and sulfonate groups grafted onto polyurethanes resulted in prolonged ex vivo occlusion times [482]. These results corresponded well with... 

Table 3. Spin-spin relaxation parameters for crosslinked polyether urethanes ...

Jahangir AR, McClung WG, Cornelius RM, McCloskey CB, Brash JL, Santerre JP. Fluorinated surface-modifying macromolecules modulating adhesive protein and platelet interactions on a polyether-urethane. Journal of Biomedical Materials Research 2002, 60, 135-147. 

The chemical structure of the prepolymer influences its chemical resistance. As a result of their structure, polyesters have inherently better oil resistance but lower hydrolytic stability. The ether groups in the polyether urethanes... 

Early work by Athey (1965) and Magnus et al. (1967) evaluated a range of polyurethanes for their resistance to moisture and dry and moist air environments. Athey showed that polyether urethanes were 5 to 10 times more... 

The solubility data in Table I may be used to test the log P correlations in poly(ethylene-co-vinyl acetate) and polyether-urethanes. The correlations in Equations 19 and 20 are derived by combining this data with the reported (20) water solubilities and octanol-water partition coefficients of the steroids (22-24). 

Ebdon JR, Hourston DJ, Klein PG (1984) Polyurethane-polysiloxane interpenetrating polymer networks. 1. A polyether urethane-poly(dimethylsiloxane) system. Polymer 25( 11) 1633—1639... 

Polyurethane (poly- ester/polyether urethane) Hygenic Corp. (HC480ARJ Nalgene 8030 Contains no plasticizers. Can be used both for vacuum or pressure systems. Has higher chemical resistance to fuels, oils, and some solvents than does PVC tubing. Not autoclavable, stiffer than PVC, flammable, not recommended with strong acids or alkalis. 

A = Polyester-urethane B = Fluorinated polyacrylate C = Polyether urethane D = Anhydride cured epoxy 1 E = Anhydride cured epoxy 2 F = One-component epoxy 1 ... 

Preliminary studies of the interphase between respective domains by Van Bogart et al. (53) indicate the thickness of this region, assuming a linear density gradient, is on the order of 10-20 A for polyester and polyether urethanes (MDI-BD based). Theoretically, the interfacial thickness is inversely related to the square root of the hard segment-soft segment interaction parameter (54). 

Forsyth, M., Meakin, P., MacFarlane, D.R., Hill, A.J. (1993) Free volume and conductivity of plasticized polyether-urethane solid polymer electrolytes . J. Phys. Condens. Matter 7, 7601. 

Test I3 determines (1) the loss of force support at 40% IFD (indentation force deflection), (2) loss in thickness, and (3) structural breakdown as determined by visual inspection. This vocedure describes tests that deflect the material by a flat-horizontal indentation exerting a force of 750 +/- 20 N in the test specimen. Test I3 is similar to ISO 3385 and BS 4443 Method 13 and is used jximaiily to determine the loss in thickness and in hardness of flexible cellular materials intended for use in load- bearing upholstery. The test involves repeated indentation of a specimen by an indentor smaller in area than the test piece. The flexible cellular materials tested are usually latex and polyether urethanes. 

AMS 3568-83 Foam Sheet, Polyether Urethane (EU) Elastomer, Shock Absorbing, 12 pp (DOD Adopted) (FSC 9320) (AS)... 

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