engleski

UV Degradation of Polyurethane

The course and intensity of polyurethane, PUR, photodegradation depend on the dyiisocianate and polyol nature. In the paper the structural changes of PUR on the base of the two different types of polyester polyol used in PUR synthesis were studied. Linear polyurethane prepolymers were synthesized starting from diphenylmethane-4, 4'-diisocianate, MDI, and polyester polyols. Two different types of polyester diols were used: poly(ethylene adipate) and poly(ethylene/butylene adipate). The effects of UV irradiation on the photooxidative degradation of prepared PUR prepolymer were studied. The changes in the chain length and their distribution as well as the changes in chemical structure were followed. Comparative investigations were performed by gel permeation chromatography, GPC, by spectroscopic and viscometric measurements. The results show pronounced heterogenity of the degradative reactions. The GPC results show that the photooxidative decomposition is followed by a decrease in molecular mass together with an increase in polydispersity. This indicates a very inhomogenous degradation, which is a consequence of the specific course and of the intensity of photooxidative degradation. This was confirmed by means of comparative IR and NMR measurements. Conclusions on the difference in behaviour of the different types of polyester polyols used in PUR synthesis were discussed.

Photodegradation, Polyurethane, Molecular Mass, Spectroscopic measurements

nije evidentirano