Polyurethane prepared from poly

The most frequently encountered acid is adipic, but others are also employed in polyurethanes. Polyurethanes prepared from poly(ethylene glycol) adipate and 1,5-naphthalene diisocyanate produce two strong absorptions at 750 cm and 735 cmwhile the urethane from poly(ethylene glycol) sebacate and 1,5-naphthalene diisocyanate shows crystallinity bands at 722, 729, 754, 860, 881 and 895cm" ... 

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

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. ... 

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... 

Polyesters [2] find use in fibers [poly(ethylene terephthalate), poly(ethylene oxybenzoate), poly(ester ethers), poly(ester amides), etc.] [1], coatings (especially unsaturated polyesters) [4], plasticizers, adhesives, polyurethane base resins, films, etc. Cross-linked polyesters prepared from glycerol and phthalic anhydride (alkyd resins) have been reviewed [20], High-melting poly aryl esters have been investigated for high-temperature applications. 

In order to control the pore texture in carbon materials, blending of two kinds of carbon precursors, the one giving a relatively high carbonization yield and the other having a very low yield, was proposed and called polymer blend method [112], This idea gave certain success to prepare macroporous carbons from poly(urethane-imide) films prepared by blending poly(amide acid) and phenol-terminated polyurethane prepolymers [113]. By coupling this polymer blend method with... 

The value of a for poly(propylene oxide) was obtained from the data of Moacanin 189) for polyurethanes prepared by condensation of toluene-2,4-diisocyanate with atactic polypropylene glycols of molecular weights about 1000 and 2000. The small quantity of diisocyanate present in these compositions can make only a negligible effect on the chain dimensions (less than one per cent on the freely rotating chain, as is... 

Before going into the methods for radical reactions it most be said tlmt polycondensation or polyaddition have led to more industrial preparation. In this connection epoxy resins, the polyurethanes obtained from prepolymers and, more recently, more specialized polymers such as the PEB AC (ATOCHEM), amid-ether or polyimids (KHERIMIDE from RHONE POULENC must be mentioned). Moreover, it is interesting to note that the ionic methods (cationic or anionic ones) have not produced industrial products (except dihydroxy poly (dimethyl siloxanes), poly (tetrahydro-furanes)) but they have facilitated theoretical studies both on the analytical aspects and the materials we can obtain. 

Nylon block copolymers were previously synthesized from the anionic polymerization of caprolactam in the presence of polyurethane prepolymers. (11) The prepolymers, prepared from the reaction of diisocyanates with polyether glycols, contained Isocyanate end groups which initiated caprolactam polymerization. Sodium caprolactam was used to catalyze the reaction. This copolymer system is the basis for some current areas of nylon 6 RIM research. (12) NYRIM nylon block copolymers are formed from stoichiometric mixtures of polymeric polyols and caprolactam using poly acyllactam initiation which was described previously. The reactions are as follows ... 

A new family of linear polyurethanes and poly(ester-urethanes), prepared from both aliphatic and aromatic diisocyanates and isorbide [21] or conveniently protected sugar alditols, has recently been reported and the properties of... 

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... 

Polyurethane elastomers, prepared from (i) polyether macrodiols that contain a reduced number of ether linkages compared with PTMO [poly(tetramethylene oxide)],... 

Segmented polyurethane elastomers, prepared from diisocyanates, macrodiols and chain extenders, are frequently used in the construction of implantable medical devices, such as cardiac pacemakers, heart valves, catheters, and heart assist devices, because of their excellent mechanical properties and haemocompatibility. Polyether macrodiols, such as poly(tetramethylene oxide) (PTMO), are used to prepare polyurethanes for implant, since they offer an increased resistance to enzymatic hydrolysis compared with polyester-based polyurethanes. 

Using this technique, a large variety of polyurethanes have been prepared from different vegetable oils. Natural polyols like castor oil (generally trifunctional) are directly reacted with diisocyanates to obtain branched polyurethanes, although it is difficult to control the reactivity. However, bifunctional castor oil can be polymerised with diisocyanates in the presence of suitable chain extenders and catalysts to produce polyurethanes in a more controlled manner (Fig. 6.4). A castor oil polyol-based polyurethane network can also be prepared from epoxy terminated polyurethane pre-polymer with 1,6-hexamethylene diamine. Epoxy terminated pre-polymer is obtained by the reaction of glycidol and isocyanate terminated polyurethane pre-polymer of castor oil polyol, poly(ethylene glycol) (PEG) and 1,6-hexamethylene diisocyanate. ... 

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... 

Using a mixture of castor oil and hydroxyether of bisphenol-A (HBA) as the polyol and reacting with TDI in the presence of DBTDL catalyst at 35°C, a series of polyurethanes are prepared in an air-circulating oven for 48 h. A series of poly(urethane urea)-vinyl polymer hybrid aqueous dispersions are prepared. Waterborne poly(urethane urea) is synthesised from castor oil and polyoxypropylene polyol M = 1000 g moL ), dimethylol propionic acid and isophorone diisocyanate and then neutralised with tertiary amine. The hybrid aqueous dispersion with high oil content poly(urethane urea) exhibits excellent compressive mechanical strength. Sunflower oil-modified waterborne polyurethane resin may also be prepared. The waterborne resin is synthesised from the monoglyceride of the oU, poly(propylene-ethylene) triol, tartaric acid and toluene diisocyanate, then neutralised with triethyl amine. 

Water-blown low density rigid polyurethane foams have been prepared with poly(ether polyol)s, polymeric isocyanates, DSF, water, a catalyst mixture, and a surfactant the immiscible character of the blend composites. Soy flour and the initial water content were varied from 0 to 40 per cent and from 4.5 to 5.5 per cent of the poly(ether polyol) content, respectively. The addition of soy flour in the rigid polyurethane foam system contributed to a higher glass transition temperature, and increasing the initial water content also resulted in an increase in the glass transition temperature [85]. 

Figure 7.9. Hardness vs. composition for SINs, pseudo-IPNs, and linear blends, prepared from polyurethane and poly(methyl methacrylate).

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