Diisocyanate Elastomer

Dinitrotoluene Hexamethylene diisocyanate Methylene bis (4-cyclohexylisocyanate) Toluene-2,4-diisocyanate Toluene-2,6-diisocyanate elastomer mfg., abrasive wheels Toluene diisocyanate elastomer mfg., adhesives Toluene diisocyanate elastomer mfg., cast Poly (diethylene adipate) polyester elastomer mfg., film Toluene diisocyanate elastomer mfg., high strength Bitoluene diisocyanate elastomer mfg., linings Toluene diisocyanate elastomer mfg., mechanical items Toluene diisocyanate... 

Methylenebis(4-phenyl isocyanate). This compound is also known as methyl diisocyanate [101-68-8] (MDI) and is produced by the condensation of aniline and formaldehyde with subsequent phosgenation. Its principal end use is rigid urethane foams other end uses include elastic fibers and elastomers. Total formaldehyde use is 5% of production (115). 

Following this work, the y -12F-diol was used for the direct reaction with hexamethylene-1,6-diisocyanate in the presence of dibutyltin dilaurate to produce a cross-linked elastomer or a reactive prepolymer which was terminated with either isocyanate or hydroxyl groups, depending on which reactant was in excess (142,143). 

The addition polymerization of diisocyanates with macroglycols to produce urethane polymers was pioneered in 1937 (1). The rapid formation of high molecular weight urethane polymers from Hquid monomers, which occurs even at ambient temperature, is a unique feature of the polyaddition process, yielding products that range from cross-linked networks to linear fibers and elastomers. The enormous versatility of the polyaddition process allowed the manufacture of a myriad of products for a wide variety of appHcations. 

Thermoplastic polyurethane elastomers are produced from prepolymers by polycondensation (12,13). A relatively high molecular-weight polyester or polyether with terminal hydroxy groups (a polyglycol) first reacts with an excess of a diisocyanate. 

In the late 1990s high quality elastomers were produced using p-phenylene diisocyanate (PPDI) but because of its high vapour pressure it has to be used in a prepolymer formulation. 

Hie most representative member of this class of polyesters is the low-molar-mass (M 1000-3000) hydroxy-terminated aliphatic poly(2,2/-oxydiethylene adipate) obtained by esterification between adipic acid and diethylene glycol. This oligomer is used as a macromonomer in the synthesis of polyurethane elastomers and flexible foams by reaction with diisocyanates (see Chapter 5). Hydroxy-terminated poly(f -caprolactonc) and copolyesters of various diols or polyols and diacids, such as o-phthalic acid or hydroxy acids, broaden the range of properties and applications of polyester polyols. 

Singer S.M. and Allot M.T., Thermoplastic polyurethane elastomer based on a saturated hydroxyl terminated polyol, difunctional aromatic chain extender and 1,5-naphthalene diisocyanate, US Patent 5 599 874, 1997. 

In a polyurethane elastomer analysed by isobutane CI-MS and CI-MS/MS in TD/Py-CIMS (TD, 20-200°C Py, 200-300 °C) mode MDI (diisocyanate), BDO (chain extender), Stabaxol P (stabiliser), AA/ BDO/HDO (cyclic adipate) and residual cyclic ester oligomers were identified [65]. 

Step polymerization is used to synthesize multiblock copolymeric elastomers (referred to as segmented elastomers). An example is the polyester-polyurethane system produced by the reaction of a diisocyanate with a mixture of macro diol and smallsized diol (Eq. 14). The macro diol (usually referred to as a... 

The equilibrium shear modulus of two similar polyurethane elastomers is shown to depend on both the concentration of elastically active chains, vc, and topological interactions between such chains (trapped entanglements). The elastomers were carefully prepared in different ways from the same amounts of toluene-2,4-diisocyanate, a polypropylene oxide) (PPO) triol, a dihydroxy-terminated PPO, and a monohydroxy PPO in small amount. Provided the network junctions do not fluctuate significantly, the modulus of both elastomers can be expressed as c( 1 + ve/vc)RT, the average value of vth>c being 0.61. The quantity vc equals TeG ax/RT, where TeG ax is the contribution of the topological interactions to the modulus. Both vc and Te were calculated from the sol fraction and the initial formulation. Discussed briefly is the dependence of the ultimate tensile properties on extension rate. 

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... 

Elastomers Prepared. The three elastomers discussed herein were prepared from PPG, toluene-2,4-diisocyanate (TDI), and either LHT-240 or TIPA. Elastomers prepared by a one-step procedure are designated LHT-240 and TIPA, indicative of the triol used. A third elastomer, designated Tri-NCO, was prepared by first reacting LHT-240 with all of the required TDI for two hours at 50°C to obtain a triisocyanate (or essentially... 

Elastomers resulting from a series of organic reactions, e.g., a polyglycol ester of adipic acid reacted with an aromatic diisocyanate and cured with water, glycol or further reaction with an aromatic diisocyanate. These elastomers have high tensile strength, very high abrasion resistance, and lower hysteresis than natural rubber. A major use is in the manufacture of foamed polymers. 

The most important reactions for the production of elastomers, however, utilise diisocyanates and polyols, and the elastomeric products formed can be of the following types. 

The diisocyanates and polyols are reacted to form a high molecular weight hydroxyl terminated millable gum. These millable gums are compounded and processed as conventional elastomers, both sulphur and peroxides being used to cure the polymers. Here again, polyether and polyester types are available, and the differences between these two types referred to above also apply here. 

TOXICITY AND SAFE HANDLING OF DIISOCYANATES AND ANCILLARY CHEMICALS A CODE OF PRACTICE FOR POLYURETHANE FLEXIBLE FOAM MANUFACTURE AND ELASTOMER MANUFACTURE (Rapra Technology Ltd. British Rubber Manufacturers Assn.)... 

Castor oil-urethane elastomers were prepared by reacting 2,4 tolylene diisocyanante, TDI, 80/20 2,4/2,6 TDI, or hexamethylene diisocyanate (HDI) with castor oil. The last reaction was rather slow and thus dibutyltin dilaurate, 0.001 gm per gm of HDI, was used as a catalyst. Since TDI hydrolyses significantly in the presence of trace amounts of water, DB grade castor oil from the Baker Castor Oil Company (NL Industries) was employed. 

Two other derivatives of toluene are the important explosive trinitrotoluene (TNT) and the polyurethane monomer toluene diisocyanate (TDI). TNT requires complete nitration of toluene. TDI is derived from a mixture of dinitrotoluenes (usually 80% o,p and 20% o,o) by reduction to the diamine and reaction with phosgene to the diisocyanate. TDI is made into flexible foam polyurethanes for cushioning in furniture (35%), transportation (25%), carpet underlay (20%), and bedding (10%). A small amount is used in polyurethane coatings, rigid foams, and elastomers. 

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