engleski

Photodegradation of Polyurethane

This chapter is a review of the investigations of photooxidative degradation of polyurethane, PUR. The mechanism of photooxidative degradation and secondary crosslinking reactions in PUR are presented. The course and the intensity of the changes in molecular, supermolecular and morphological structures of PUR due to photooxidative degradation are reviewed. These structural changes were followed by comparative spectroscopic measurements (IR, NMR, UV), as well as by DSC analysis, DMA, X-ray measurements, electron microscopy and GPC measurements samples of PUR samples before and after various times of photooxidative degradation. The influence of the nature of the polyols and the isocyanate components used in the syntheses of PUR on the photooxidative process and changes in PUR structures mentioned above as well as on the rate of yellowing of PUR samples are discussed. The correlation between intensities of structural changes of PUR and its mechanical properties are presented. The influence of the physical state of PUR and the thickness of the PUR samples on the photooxidative stability of PUR are also described.

polyurethane; mechanism of photooxidative degradation; supermolecular; structures; spectroscopic measurements; yellowing

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