Effect Of Composite Additives On Weather Resistance Properties Of Polyurethane Films

In this article, two organic ultraviolet absorbers such as UV-531and UV-327areadded to the polyurethane in the separate and complex ways, respectively. The modifiedpolyurethane films are obtained. The tests for the films exposured to UV radiation, O3andUV/O3atmosphere are performed by using self-developed accelerated aging devices,respectively. The colour difference, yellowness index, UV-Vis spectra, infrared spectrumand SEM images are recorded, respectively. The results are used to study theweather-resistance properties of the polyurethane films. Effect of composite additives onweather resistance properties of polyurethane films is discussed and whether there issynergism between UV and O3in polyurethane films aging is also analyzed.During exposure to UV environment, colour difference, yellowness index, UVabsorbance, carbonyl index and photo oxidation index of the various polyurethane filmsgradually increase with the exposure time.–NH and–C=O absorption peaks graduallyincrease and broaden with the exposure time. C–C stretching peak, C–O absorption peak,and the coupling peak of–NH bending and–CN stretching motion gradually decreasewith the exposure time. The obvious effect exists on yellowing resistance of thepolyurethane films modified by the composite ultraviolet absorbers. The obvious effectexists on photodegradation resistance of the polyurethane films modified by UV-327.During exposure to O3environment, colour difference, yellowness index, UVabsorbance, carbonyl index and photo oxidation index of the various polyurethane filmsgradually increase with the exposure time.–NH and–C=O absorption peaks graduallybroaden with the exposure time. C–C and C–N absorption peaks gradually decrease withthe exposure time. UV-327, UV-531and the composite ultraviolet absorbers aggravateyellowing of the polyurethane films. The obvious effect exists on degradation resistance ofthe polyurethane films modified by UV-327.During exposure to constant UV radiation with O3atmosphere, colour difference,yellowness index, UV absorbance, carbonyl index and photo oxidation index of thevarious polyurethane films significantly increase with the exposure time.–NH and–C=O absorption peaks significantly broaden with the exposure time. C–C,–C–O and–CNabsorption peaks significantly decrease, and–NCO peak gradually appears with theexposure time. The obvious effect exists on yellowing resistance of the polyurethane filmsseparately modified by UV-531and the composite ultraviolet absorbers. The obviouseffect exists on photodegradation resistance of the polyurethane films modified by UV-327.It can be seen from the changes in various performance of the films after exposure to threedifferent environments that a obvious synergism between UV and O3in the polyetherpolyurethane films aging is observed.