Influence of UV absorber on photodegradation processes of poly(vinyl chloride) with different average degrees of polymerization

The influence of UV absorber (Chimassorb81) on the photodegradation mechanism of different average degrees of polymerization (DP) of poly (vinyl chloride) (PVC) with UV‐irradiation time was investigated by viscosity‐average molecular weight determination, UV‐vis spectroscopy, FTIR, contact angle mea...

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Bibliographic Details
Published in:Polymer engineering and science 2007-09, Vol.47 (9), p.1480-1490
Main Authors: Shi, Wei, Zhang, Jun, Shi, Xu-Ming, Jiang, Guo-Dong
Format: Article
Language:English
Subjects:
Absorption of light
Ageing
Applied sciences
Chemical properties
Compounding ingredients
Evaluation
Exact sciences and technology
Fireproof agents
Influence
Methods
Optical properties
Photolysis
Physical properties
Polymer industry, paints, wood
Polymerization
Polyvinyl chloride
Properties and testing
Spectrum analysis
Technology of polymers
Ultraviolet radiation
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Summary:The influence of UV absorber (Chimassorb81) on the photodegradation mechanism of different average degrees of polymerization (DP) of poly (vinyl chloride) (PVC) with UV‐irradiation time was investigated by viscosity‐average molecular weight determination, UV‐vis spectroscopy, FTIR, contact angle measurement, and scanning electron microscopy (SEM). The PVC films with different DP (1000 and 3000), which contained 0.3 or 0.5 phr Chimassorb81, were prepared by solution casting. It was carried out by exposing specimens to xenon‐arc light source with a spectral irradiance of 0.68 W/(m2 nm) at 63°C. It is found that the Chimassorb81 is efficient photostabilizer for PVC with different DP. Although the Chimassorb81 delays the photodegradation of PVC, it does not influence the photodegradation mechanisms of PVC with different DP. The main photodegradation reaction for the lower DP of PVC is dehydrochlorination in the initial stage of UV‐irradiation, and then the crosslinking and chain scission reactions occurred after long irradiation. However, the main reaction of the higher DP of PVC is not dehydrochlorination but crosslinking and chain scission in the initial stage of UV‐irradiation. The results of carbonyl index, CCl index, contact angle measurement, and SEM also show that the photostability of Chimassorb81 is more effective for the higher DP of PVC, especially in the presence of higher concentration of Chimassorb81. POLYM. ENG. SCI., 47:1480–1490, 2007. © 2007 Society of Plastics Engineers
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.20851