Degradation of polyurethanes

A number of studies have dealt with the photo-induced discoloration and degradation of polyurethanes based on aromatic diisocyanates such as toluene diisocyanate (TDI - represents a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate isomers) and methylene 4,4-diphenyl diisocyanate (MDI) Cl, 2, 3,... 

Figure 4. Relationship between logarithmic heating rate (log0) and reciprocal absolute temperature (1/T) for the degradation of polyurethane (PU) with 20 wt% of lignin in air. Weight loss, Or 5%, 10%, 15% and...

Table I. Calculated Activation Energies (E s) for Thermal Degradation of Polyurethanes (PU s) and Lignin...

There are many reports in the literature describing photodegradation sensitized by aromatic ketones and quinones. Beachell and Chang (24) showed that triplet excited benzophenone accelerates degradation of polyurethanes by hydrogen abstraction. Harper and McKellar (25) showed the same effect with benzophenone on opolypropylene, and Amin and Scott (26) on polyethylene. Rabek and Ranby (27) have demonstrated that triplet excited quinones enhance... 

Nakajima-Kambe, T., Shigeno-Akutsu, Y., Nomura, N., Onuma, F. Nakahara, T. (1999). Microbial degradation of polyurethane, polyester polyurethanes and polyether polyurethanes. Applied Microbiology and Biotechnology, 51, 134-40. 

Determination of 4,4/-methylenedianiline (5a) in hydrolyzed human urine may serve as a biomarker for exposure to methylenebis(4-phenyl isocyanate) produced on thermal degradation of polyurethane foam. The urine is hydrolyzed with H2SO4 and 4,4 -methylenedianiline (5a) is derivatized to the corresponding pentafluoropropionamide. 

Le Bras, M. Bourbigot, S. Delobel, R. Camino, G. Eling, B. Lindsay, C. Reels, T. Thermal degradation of polyurethane and polyurethane/ expandable graphite coatings. Polym. Degrad. Stab. 2001, 74, 493-499. 

In the degradation of polyurethanes, the dominant process changes markedly during the course of the reaction. The activation energy vs. extent of reaction plots provide useful information on the effects of sample geometry (Fig. la), the dominant processes (Fig. la vs, Fig. lb) and the extent to which processes are (Fig. la), or are not (Fig. 2a) separated. However, as the initial activation energy is not determined by the factor jump method, it provides little Information of value for use in extrapolating from test to service conditions. 

S Hirose, K Kobashigawa, Y Izuta, H Hatakeyama. Thermal degradation of polyurethanes containing lignin smdied by TG-FTIR. Polym International 47 247-256, 1998. 

Figure 2.7 Flow diagram of the Ford hydroglycolysis process for the degradation of polyurethanes,94...

Tinnerberg H., Spanne M., Dalene M., Skarping G. (1997) Determination of complex mixtures of airborne isocyanates and amines. Part 3. Methylenediphenyl diisocyanate, methylenediphenylamino isocyanate and methylenediphenyldiamine and structural analogues after thermal degradation of polyurethane. Analyst, 122, 275-278. 

She also confirmed fungal degradation of polyurethane cable sheathing in the marine environment [85]. 

Kerr, N. and Batcheller, J. (1993). Degradation of polyurethanes in 20th-century museum textiles. In Postprints of Saving the Twentieth Century The Conservation of Modem Maierials Ottawa, 15-20 September 1991 (D. Grattan, ed.), pp. 189-206. Canadian Conservation Institute. 

Simha, R., Ingham, J. D., Rapp N. S., Hardy J., Polymer degradation IB. Carbon-14 as a tracer for studies of the thermal degradation of polyurethanes. Journal of Polymer Science Part B-Polymer Physics, 2(7), pp. 675-679 (1964). 

Ratner, B. D., Gladhill, K. W, Horbett, T. A. Analysis of in vitro enzymatic and oxidative degradation of polyurethanes. 

S. McCarthy, G. Meijs, N. Mitchell, P. Gunatillake, G. Heath, A. Brandwood, K. Schindhelm, In-vivo degradation of polyurethanes transmission-FTIR microscopic characterization of polyurethanes sectioned by cryomicrotomy. Biomaterials 18 (21) (1997) 1387-1409. 

J.P. Santerre, R.S. Labow, G.A. Adams, Enzyme-biomaterial interactions effect of biosystems on degradation of polyurethanes. J. Biomed. Mater. Res. 27, 97-109 (1993)... 

Potential for metal ion oxidation (Fig. 1.16a), an oxidative degradation of polyurethane insulation, true for both kinds (80A and 55D)... 

San Francisco, Ca., 26th-30th March 2000, p.404-5 DEGRADATION OF POLYURETHANES AND EPOXIES STEP-SCAN PHOTOACOUSTIC FTIR AND IR/RAMAN IMAGING Kim H Urban MW... 

No.21, 1997, p.1387-409 BV-VIVO DEGRADATION OF POLYURETHANES TRANSMISSION-FTIR MICROSCOPIC CHARACTERISATION OF POLYURETHANES SECTIONED BY CRYOMICROTOMY... 

Tang, Y.W., Santerre, J.P., Labow, R.S. and Taylor, D.G. 1997a. Application of macromo-lecular additives to reduce the hydrolytic degradation of polyurethanes by lysosomal enzymes. Biomaterials 18 37-45. 

Nakajima-Kambe T et al. (1999) Microbial degradation of polyurethane, polyester pol50irethanes and polyether pol50irethanes. Applied microbiology and biotechnology. 51(2) 134-140. 

Special methods are necessary for the production of polyurethane dispersions because of the thermodynamically unstable nature of these two-phase systems. A simple application of the emulsion polymerization techniques for isocyanate polyaddition reactions is not possible, due to the reactivity of the NCO group with water. The extreme water sensitivity of all polyurethane preparation procedures which calls for the complete absence of water is obviously a major problem to be overcome in their preparation. It is surprising, given the basic hydrolytic degradability of polyurethane elastomers, to find that polyurethane latex has good long-term stability when it is a two-phase system. This is in contrast to the situation that applies when it is present in a one-phase system. 

Griesser, H. J. (1991) Degradation of polyurethanes in biomedical applications a review. Polymer Degradation and Stability, 33, 329-354. 

A similar degradation mechanism has been proposed for the thermal degradation of polyurethanes which also dissociate into their isocyanate and diol constituents. ... 

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