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

Abstract

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/(m 2 nm) at 638C. It is found that the Chimas-sorb81 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, CÀ ÀCl 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.

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the polyvinyl chloride/powder nitrile rubber blends during photodegradation

“…Degradation and crosslinking are the main reactions in PVC and NBR during irradiation [13]. Degradation may induce the scission of macromolecular chains and make the tensile strength decrease.…”

“…Photostabilizers are usually added into PVC to prolong the lifetime [11–13]. However, the photostabilization of PVC/NBR blends with photostabilizers such as hindered amine light stabilizer (HALS) and ultraviolet absorber (UVA) [9] has not been well researched.…”

Kinetic study of the poly(vinyl chloride)/titanium dioxide nanocomposites photodegradation under accelerated ultraviolet and visible light exposure

“…It is well known that two chain reactions occur in UV‐degraded PVC simultaneously: dehydrochlorination and photo‐oxidative degradation . The elimination of HCl molecules (dehydrochlorination) is followed by production of conjugated polyene sequences (R4).…”

“…Weathering of polymeric materials has been the most challenging issue in recent years and due to the increasing use of these substances, their degradation or stability processes has become an area of intense investigations . Among these materials, poly(vinyl chloride) (PVC) with a huge production rate (34 million tons per year) and its good properties such as low production cost, good process ability, and easy modification have been the most interested polymeric materials in research area to study its degradation and stability features . Hence, to increase PVC photostability, the use of some additives like titanium dioxide (TiO 2 ) has been suggested and used …”

Effect of UV absorbers and hindered amine light stabilizers on the photodegradation of ethylene–octene copolymer

“…Generally, this could be accomplished by appropriately introducing a single additive or a combination of special additives (e.g. [32][33][34][35][36] However, the photodegradation behavior of EOC added with UV absorber or hindered amine light stabilizer has not been reported yet. 27 The chemical nature of the additives strongly influenced the long-time photostabilizing efficiency.…”