Polyurethan VC, a Virtually Crosslinked Elastomer

Abstract

Many of the outstanding physical properties that characterize elastomeric Polyurethans have been realized in a soluble, thermoplastic variety, Polyurethan VC, which displays the superficial properties of a rubbery vulcanizate at room temperature and so is considered to be virtually crosslinked. High tensile strength as well as good tear, abrasion, solvent, oil, and ozone resistance characterizes this polymer. Since these properties are realized in the unvulcanized state, many useful applications of the readily processable polymer can be made, avoiding the complications which attend the use of conventional (vulcanizing) urethan elastomers. Outdoor exposure and indoor accelerated weathering studies demonstrated a deficiency in the weather resistance of the raw polymer. Weather-induced changes, believed to be due to ultraviolet-initiated autoxidation, have been estimated by noting changes in the stress-strain properties as well as the ultraviolet and infrared absorption spectra of the polymer on exposure to natural and artificial weather conditions. The beneficial effects of certain carbon blacks, conventional antioxidants, and ultraviolet absorbers on the weather resistance of the polymer have been described.

Synthesis and characterization of polyurethane

“…To improve performance, the polyester polyurethane rubber with adding fillers and softeners, would be very homogeneous polymers. It had good-working performance, resistance oil resistance and insulation, can be used in machinery industry, construction industry and special industry [4,5] . The angiography guide wire of Terumo Corporation, the surface and internal were hydrophilic polyurethane coating, which reduced sliding resistance of guide wire surface.…”

Property correlations for dynamically cured rice husk ash filled epoxidized natural rubber/thermoplastic polyurethane blends: Influences of RHA loading

“…Typically, the crystallization in the hard segments of TPU acts as physical crosslinking and reinforcement that promotes excellent performance properties, while the soft segments contribute to high flexibility of the TPU [3e5]. The first commercial thermoplastic polyurethane was manufactured by Bayer-Farbenfabriken and B.F. Goodrich [6]. The blending of TPU with other polymers has been widely studied with focus on the improvement of mechanical properties, wear resistance, thermal stability, toughness and other related properties.…”

Selected topics in biomedical polyurethanes. A review

“…A methylene group in MDI is also susceptible to oxidation via a proton abstraction mechanism, involving auto-oxidation of the aromatic urethane groups to a form of quinoneimide [17]. Resistivity of the urethane group against thermal, oxidative and UV degradation can be improved by substitution of the liable hydrogen atom by groups such as the methyl and benzyl groups [18].…”

“…Sterilization may lead to hydrolytic, thermal, chemical or radiation-induced degradation [8,17,226,229]. In vivo degradation is in general hydrolytic, although tissue enzymes may also participate in the degradation process [8,[231][232][233][234].…”

“…Polymer processing, e. g., melt-processing or solution-processing can cause thermal and chemical degradation [8,17,[226][227][228][229]. Sterilization may lead to hydrolytic, thermal, chemical or radiation-induced degradation [8,17,226,229].…”