Poly diol polyurethanes prepared from

Kinetic studies have been made on the thermal decomposition of a poly(oxypropylene)triol-toluene di-isocyanate copolymer foam. Following a diffusion rate-controlled step, the cellular structure collapses to a viscous liquid and degradation then occurs on a random scission basis. Products of degradation of A-monosubstituted and A A-disubstituted polyurethanes have been analysed by direct pyrolysis in the ion source of a mass spectrometer. The mono-substituted polymers depolymerize quantitatively to di-isocyanates and diols, whereas the disubstituted materials decompose selectively to secondary amines, olefins, and carbon dioxide. The behaviour of the monosubstituted polymers has been confirmed in an i.r. study of the degradation of model compounds. A study of the thermal degradation in vacuum of polyurethanes prepared from butanediol, methylene bis(4-phenylisocyanate), and hexanedioic acid-ethylene glycol-propylene glycol polyesters has been reported and reaction mechanisms proposed. ... 

Figure 9. Williams plasticity of polyurethanes prepared from poly-(propylene ether) diols at d erent ratios of 2,4-tolylene diisocyanate...

Studies have been made of the elastic (time-independent) properties of single-phase polyurethane elastomers, including those prepared from a diisocyanate, a triol, and a diol, such as dihydroxy-terminated poly (propylene oxide) (1,2), and also from dihydroxy-terminated polymers and a triisocyanate (3,4,5). In this paper, equilibrium stress-strain data for three polyurethane elastomers, carefully prepared and studied some years ago (6), are presented along with their shear moduli. For two of these elastomers, primarily, consideration is given to the contributions to the modulus of elastically active chains and topological interactions between such chains. Toward this end, the concentration of active chains, vc, is calculated from the sol fraction and the initial formulation which consisted of a diisocyanate, a triol, a dihydroxy-terminated polyether, and a small amount of monohydroxy polyether. As all active junctions are trifunctional, their concentration always... 

Polyurethane bulk and thin-film samples are prepared from a two-part PU adhesive formed by polyaddition of Bayer Desmodur CD (89% diphenylmethane-4,4 -diisocyanate 1 with 11% uretoneimine triisocyanate 2 as additive) with a polyol mixture of Bayer Desmophen 2060BD (linear poly(propylene ether) diol... 

Millable polyurethane elastomers are prepared from bi-functional castor oil or its blends, with poly(propylene glycol) at two different ratios of 1 4-butane diol as a chain extender and TDI. Castor oil-based polyurethane nanoparticles with an average diameter of 300 nm are prepared by a... 

For polyurethane production, Donnelly [109] has carried out the synthesis of copolyurethanes based on mixtures of commercial poly(THF diol)s with glucose. Complex products resulted, which can be represented by mono- or bis(glucoside) structures. From a variety of polyol blends, solid polyurethanes were prepared which ranged from linear, soluble, weak elastomers to polymers of higher transition temperature and stiffness, low solubility, and low extension under tensile load [110]. 

Despite the improvements, a more durable elastomer was clearly needed. A battery of polyurethane elastomers including Pellethane were prepared and implanted subcutaneously in rats. Before implantation, the polymers were extruded into tubes and elongated over mandrels to 400%. The implants were left in place for 6 months and examined under a scanning electron microscope. One of the better performing polyurethanes was based on poly(l,6-hexyl 1,2-ethyl carbonate) diol. Polyesters typically are considered less durable due to the presence of esterase enzymes in vivo. From the data recovered during the implant period, it was determined... 

Besides aliphatic diisocyanates, an aromatic isocyanate was also used to prepare polyurethanes. A new renewable copolymer (Scheme 17) was synthesized from reactive bis-hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers (PHBHV-diol), isosorbide, and 1,4-phenylene diisocyanate. The molar number-average molecular weights (M of most of the copolyesters were about... 

Kuo et al. recently studied in detail the synthesis of segmented polyurethane from poly(dimethylsiloxane diol) with poly(ethylene glycol) 83 (PEG) and 4,4 -methylene diphenyl diisocyanate 70 (Scheme 32). Polymer fUms were prepared by casting the polymer from solution. The electrolyte was prepared by dipping the polymer films in LIClOVpropylene carbonate solutions of different concentrations and for different time intervals. They obtained an ionic conductivity of 2.33 X 10 S/cm at 80°C. Moreover, the conductivity of the composite electrolyte increased with an increase in the content of PEG, which attracts a larger quantity of Li" ions. 

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