Hydrolysis of polyurethane

Example 1. Hydrolysis of Polyurethane in a Pyrex Hydrolysis Reactor.54 A... 

PURs. See Polyurethanes (PUs, PURs) Pyrex hydrolysis reactor, hydrolysis of polyurethane in, 573 Pyrolysis, 208... 

Hydrolysis of Polyurethanes by Lipase. Effects of Mn of PCL-diol moiety on the hydrolysis of polyurethanes, which were composed of... 

The effects of chemical structure of diisocyanate component on the hydrolysis of polyurethanes by R. delemar lipase were examined (Figure 8). The rates of hydrolysis of the polyurethanes containing MDI or tolylene-2,U-diisocyanate (TDI) were smaller than that of the polyurethane containing 1,6-hexamethylene-diisocyanate (HDI). 

Figure T. Effects of molecular weight of PCL-diol parts on the hydrolysis of polyurethanes by R. delemar lipase. Each reaction mixture for biodegradability assay contained 15.6-37.2 mg of polyurethane film (i4.U-2T.1 mg as polyester moiety) on the cover glass (3.2 cm ) in a total volume of 10 ml. In this condition, no effect of amount of polyurethane was observed. (Mn)s of PCL-diols parts of polyurethanes I, II, III and IV were 530, 1250, 2000, 3000 respectively. The dashed lines show PCL-diol (Mn 2000) ( ) and PCL-diol (Mn 3000) ( ).

Figure 8. Effects of chemical structure of diisocyanate component on the hydrolysis of polyurethanes by R. delemar lipase.

Mahoney et a/.87 have described the reaction of polyurethane foam and superheated water at 200 °C for 15 min, which leads to toluene diamines and polypropylene oxide. Hydrolysis of polyurethane and rubber mixtures has been used as a method not only of recovering valuable chemicals from the polyurethane fraction, but also to separate the polymers because rubber is inert to hydrolysis.89 The degradation takes place by contact with saturated steam at 200 °C for 12 h. This process may find particular applications in the treatment of rubber/polyurethane laminations. 

Tin compounds do not catalyze hydrolysis of polyurethanes. Many, especially the divalent tin types, are, however, susceptible to hydrolytic attack and are therefore unstable in the presence of water. 

As a class of compounds, nitriles have broad commercial utility that includes their use as solvents, feedstocks, pharmaceuticals, catalysts, and pesticides. The versatile reactivity of organonitnles arises both from the reactivity of the C=N bond, and from the abiHty of the cyano substituent to activate adjacent bonds, especially C—H bonds. Nitriles can be used to prepare amines, amides, amidines, carboxyHc acids and esters, aldehydes, ketones, large-ring cycHc ketones, imines, heterocycles, orthoesters, and other compounds. Some of the more common transformations involve hydrolysis or alcoholysis to produce amides, acids and esters, and hydrogenation to produce amines, which are intermediates for the production of polyurethanes and polyamides. An extensive review on hydrogenation of nitriles has been recendy pubHshed (10). 

Almost all IDA derived chain extenders are made through ortho-alkylation. Diethyltoluenediamine (DE I DA) (C H gN2) (53), with a market of about 33,000 t, is the most common. Many uses for /-B I DA have been cited (1,12). Both DE I DA and /-B I DA are especially useful in RIM appHcations (49,53—55). Di(methylthio)-TDA, made by dithioalkylation of TDA, is used in cast urethanes and with other TDI prepolymers (56). Styrenic alkylation products of TDA are said to be useful, eg, as in the formation of novel polyurethane—polyurea polymers (57,58). Progress in understanding aromatic diamine stmcture—activity relationships for polyurethane chain extenders should allow progress in developing new materials (59). Chlorinated IDA is used in polyurethane—polyurea polymers of low hysteresis (48) and in reinforced polyurethane tires (60). The chloro-TDA is made by hydrolysis of chloro-TDI, derived from TDA (61). 

Effect of chain structure on the hydrolysis of polyester polyurethanes... 

Meluch et al.10 reported that high-pressure steam hydrolyzes flexible polyurethane foams rapidly at temperatures of 232-316°C. The diamines are distilled and extracted from the steam and the polyols are isolated from the hydrolysis residue. Good results were obtained by using reclaimed polyol in flexible-foam recipes at file 5% level. Mahoney et al.53 reported the reaction of polyurethane foams with superheated water at 200°C for 15 min to form toluene diamines and polypropylene oxide. Gerlock et al.54 studied the mechanism and kinetics of the reaction... 

PCL-diol and diphenylmethane-i -diisocyanate (MDI), by R. delemar lipase were examined. These polyurethanes have both the hydrogen bonds among polymer chains and aromatic rings in the polymer molecules. R. delemar lipase could hydrolyze the polyurethanes though the rate of hydrolysis toward polyurethanes decreased as compared to that ward PCL-diol. The rate of hydrolysis decreased with decreasing the Mn of PCL-moiety of polyurethanes (Figure T). 

Marans and Preckel " synthesized both the mononitrate (95) and the dinitrate (92) esters of metriol by using a similar strategy to that used for pentaerythritol trinitrate. Thus, nitration of both the mono- (90) and the di- (93) acetate esters of metriol, followed by selective hydrolysis of the acetate groups, yields (92) and (95) respectively the latter could be useful as a monomer for the synthesis of energetic polyurethane polymers. 

Huang, T.C. and Chen, D.H., Kinetic studies on urea hydrolysis by immobilized urease in a batch squeezer and flow reactor, Biotechnol. Bioeng., (1992) 40,10,1203-09. Storey, K.B., Duncan, J.A., and Chakrabarti, A., Immobilization of amyloglucosidase using two forms of polyurethane polymer, Appl. Biochem. Biotechnol., (1990) 23, 3, 221-36. 

LeJeune et al. - - investigated this stabilizing effect of immobilization at the expense of activity. They immobilized an organophosphorus hydrolase by emulsifying a solution of the enzyme with a hydrophilic polyurethane prepolymer. They intended to study the enzymatically catalyzed hydrolysis of organophosphate nerve... 

Recycling. The methods proposed for the recycling of polyurethanes include pyrolysis, hydrolysis, and glycolysis. Regrind from polyurethane RIM elastomers is used as filler in some RIM as well as compression molding applications. The RIM chips are also used in combination with rubber chips in the construction of athletic fields, tennis courts, and pavement of working roads of golf courses. 

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