Hydrolic degradation

Polyurethane is subject to hydrolic degradation at its higher temperature limits. Polyurethane is machinable. It does not seal as well as rubber, and additional 0-rings and gaskets are needed when switching from rubber to polyurethane lined parts. Polyurethane is available in thermoset and thermoplastic forms. A new generation of glass-reinforced polyurethane thermoplastic materials are available from different manufacturers. The properties of polyurethane are presented in Tables 10-17 and 10-18. 

Kjeldsen, P., Kjelholt, J., Schultz, B., Christensen, T.H., and Tjell, J.C. Sorption and degradation of chlorophenols, nitrophenols and organophosphorus pesticides in the subsoil under landfills, / Contam. Hydrol, 6(2) 165-184, 1990. 

Johnson, T.L. Eish,W. GorhyYA. Tratnyek, P.G. (1998) Degradation of carbon tetrachloride by iron metal Complexation effects on the oxide surface. J. Contam. Hydrol. 29 379-398... 

Furthermore, it is worth remarking that Kulicke, Haas (1984) have found that the critical Reynolds number, which defines the onset of tensional stress, is strongly shifted in the case of PAAm if the measurement is repeated (2nd run), i.e., the molecule is degraded, whereas in the case of partially saponified PAAm/AAcNa, no pronounced change of Re0 is to be found, as shown in Fig. 38. This phenomenon has been attributed to the relatively high rigidity of the partially hydrolized polyacrylamide. 

Ether-insoluble hydrol lignin from the acid-catalyzed product seems to be a highly condensed guaiacyl type of preparation which has not been severely degraded during the isolation process. 

Flyvbjerg J, Arvin E, Jensen BK, et al. 1993. Microbial degradation of phenols and aromatic hydrocarbons in creosote-contaminated groundwater under nitrate-reducing conditions. J Contain Hydrol... 

Schmidt TC, Schirmer M, Weiss H, Haderlein SB (2004) Microbial degradation of methyl tert-butyl ether and tert-butyl alcohol in the subsurface. J Cont Hydrol 70 173-203... 

FIGURE 10.5 Hydrol)Tic and oxidative degradation of sulfur mustard. ... 

Kjeldsen, R, J. Kjolholt, B. Schultz, T.H. Christensen, and J.C. Tjell. Sorption and Degradation of Chlorophenols, Nitrophenols and Otganophosphorus Pesticides in the Subsoil Under Landfills, J. Contam. Hydrol., 6(2) 165-184 (1990). 

Rahaman, M.H., Tsuji, H., 2013. Hydrol)4ic degradation behavior of stereo multiblock and diblock poly(lactic acid)s effects of block lengths. Pol)Tner Degradation and Stabihty 98,709—719. 

Intact and partially hydrolized PA undergo heavy biotranstormation by resident colonic microflora and are degraded to phenolic acids, hippuric acids, simple phenols and valerolactones, that are effectively absorbed... 

One more successful example is the preparation of covalently bound antibiotics onto various amino-acid-ester-substituted polyphosphazenes [99]. The amino acid ester groups could be used to fine-tune the rate of hydrol)n ic degradation and thus drug release, and the antibiotics ciprofloxacin and norfloxacin could be covalently attached to the polyphosphazene backbone via the piperazinyl groups. In aqueous media, the antibiotics released were measured to be between 4 and 30% over a 6-week period for films prepared from... 

Hrapovic, L. and Rowe, R.K., Intrinsic degradation of volatile fatty acids in laboratory-compacted clayey soil, /. Contam. HydroL, 58, 221, 2002. 

The dye interaction technique was used to follow polymer degradations in in vivo and in vitro studies as well as to establish a viscosity-molecular weight relationship for racemic poly(lactide). In order to assure the presence of one carboxyl group per chain partially hydrolized polymers of high initial molecular weights were used in the latter case. The polymers were hydrolyzed with deionized water either in form of solid powder or in tetrahydrofuran or acetone solution with complete agreement of data obtained in both ways. 

The hydrolic stability of glass-flber-reinforced PBT, PET and PC was studied by Kelleher et al. [42] following the changes in MFI during the process of hydrolytic degradation. Their entire approach was similar to that used earlier for reinforced PBT [43] and PC [44]. Because MFI is related to the degree of polymerization, the following relationship was developed [44] to study the rate of hydrolysis ... 

Polyesters which solely contain aromatic acid components such as PET or PBT are commodity materials for many technical applications and are commonly regarded as quite resistant to any hydrol)n ic degradation. Only by applying very drastic chemical treatments, (e.g., sulfuric acid at 150 °C), which are a long way away from any physiological conditions, hydrolysis of such polymers can be achieved at reasonable rates, which can be used for recycling purposes [32]. Furthermore, chemical hydrolysis was applied in some cases for the analysis of aromatic polyesters [33]. 

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