engleski

The Review of the Investigations of Ageing of Polyurethane Polymers

The paper is the review of the investigations of photooxidative degradation of polyurethane, PUR. The investigations were performed on PUR prepolymer and on the commercial polyurethane product i.e. on the integral foam, produced by factory of polyurethane shoe soles. The effects of the nature of the polyols used in synthesis on the structural transformations after ageing by UV irradiation has been studied. The obtained relation between the structure and the stability as well as the course of the degradation processes are reviewed. To evaluate the stability of PUR in application, the changes in PUR structure, the viscosities and mechanical properties were followed. Spectroscopical measurements and electronic micrographyof aged samples show that a photo and oxidative degradation of PUR is a very complex phenomenon in which the new structures appeared through simultaneous decomposition of PUR and through the crosslinking reactions due to the interactions of newly formed radicals and structures. In consequence of that, the mechanical properties, solubilities and viscosities decreased. The processes of photooxidative degradation is less expressed in polyesterurethane than in polyurethane based on polyether, under the same conditions of experiments. Different structures of polyester diols caused the various ageing behaviour of PUR too. The degradation and oxidation occurred at the polymer surface in polyesterurethane, while PUR based on polyether shows the photooxidative degradation in to interior layers too.

polyurethane; photooxidative degradation; integral foam; polyols; course of the degradation processes

nije evidentirano