Photoacoustic study of UV, UV–thermal, and weathering degradation of rigid foam polyurethane

Abstract

synopsisDegradation of polyurethane samples by UV, combination of W-thermal, and natural weathering were studied by photoacoustic spectroscopy. This study reveals that degradation of polyurethane could be initiated at a relatively low temperature of 40°C and low W dosage. It was also found that the effect of heat is more pronounced than the effect of W. The reaction mechanism of polyurethane degradation is fully in agreement with photoacoustic absorption spectra.

Photostabilization of Polymers

“…Section 6,2) all the possible )NOR + POO·-)NO' + POOR (6,70) It is important to stress that hindered amines react neither fast enough nor efficiently enough with peroxy radicals and simple peroxides at ambient conditions to be responsible for major stabilizing mechanisms,650 (ii) Reactions which are significant in photostabilization mechanisms: Section 6.1) and nitroxy radicals (cf.…”

“…6 Time to embrittlement (0·06 carbonyl units) for polypropylene films containing various hydroxybenzophenones exposed in a Microscal Unit [(Weatherometer Microscal Ltd, UK), employing a 500 W high-pressure fluorescent lamp (50°C, relative humidity, ambient)J66…”

Preparation and properties of MDI/H12MDI‐based water‐borne poly(urethane‐urea)s—Effects of MDI content and radiant exposure

“…The secondary factors are atmospheric pollutants, biological agents, acts of nature, high‐energy radiations, and mechanical stress (accelerates physical damage). A number of authors have investigated the harmful effects of UV exposure on polyurethanes 9–13. For polyurethanes based on MDI, the photosensitivity is thought to be due to an aromatic diurethane bridge.…”

“…A number of authors have investigated the harmful effects of UV exposure on polyurethanes. [9][10][11][12][13] For polyurethanes based on MDI, the photosensitivity is thought to be due to an aromatic diurethane bridge. The monoquinone-imide structure is a chromophore that is thought to be responsible for the yellowing of polyurethane during exposure, whereas the diquinone-imide is responsible for the brownish or amber color that polyurethanes exhibit after longer periods of exposure.…”

Effect of Quasi‐nanometer zirconium carbide on the physical characterization of zirconium carbide/polyurethane composite films irradiated under ultraviolet light

“…The carbonyl index is used to determine the degree of photooxidation under irradiation. 16 Abu-Zeid et al 17 revealed that the PU polymer can be easily degraded under UV irradiation even with a low dosage. Govorčin Bajsić and Rek 18 attributed the degradation of PU under UV irradiation to two steps: the degradation of the hard segment and the degradation of the soft segment.…”