Combined effect of hindered amine light stabilizer and ultraviolet absorbers on photodegradation of poly(vinyl chloride)

Abstract

The combined effect of a basic hindered amine light stabilizer (HALS) and ultraviolet absorbers (UVAs) on casted poly(vinyl chloride) (PVC) films, during photodegradation, was studied by color change, ultraviolet‐visible (UV–vis) spectroscopy, Fourier‐transform infrared (FTIR) spectroscopy, and viscosity‐average molecular weight. It was found that the basic amine groups in the HALS (T770) could promote the dehydrochlorination, thereby accelerating the photooxidation of PVC films. Meanwhile, T770 could scavenge the radicals formed and restrain the aging of PVC to some extent. The above‐mentioned aspects were competing factors: the former played a dominant role during the first 100 h, while the latter counteracted the former effect to some extent between 100 and 300 h. A benzotriazole derivative (UV326) absorbs more UV radiation in the UV‐A region (320–400 nm), which mainly causes the photodegradation of PVC samples, than a benzophenone derivative (UV531). Thus, UV326 is a more efficient UV absorber than UV531 in prohibiting the photooxidation and chain scission of PVC films. The combination of T770 and UV326 effectively protected PVC films from dehydrochlorination and photooxidation. The combination of T770 and UV531 accelerated the dehydrochlorination and discoloration of PVC films. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers

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

“…Then it slowly increases to 491% at 800 h, meaning that the rate of photooxidation slows down at the last 400 h of irradiation. The result is different with the extremely high value of CI of DOP‐plasticized PVC control samples (832%) in the previous work, [22] indicating that the NBR in the blends has some positive effect on protecting the blends from photooxidation. This may be because the commercial product NBR may contain some thermal stabilizers which protect the blends from photooxidation.…”

“…The results suggest that UVA plays a more important role than HALS in protecting the blends from dehydrochlorination. The lower value of Δ E of PVC/NBR with HALS/UV326 than that of PVC/NBR with HALS/UV531 indicates that UV326 is much more effective on the photostability of samples than UV531 [22].…”

Tailoring the desired optical and mechanical performance of polyester‐plasticized PVC films: the role of different light stabilizers on the photo‐degradation

“…Stabilizers may retard photo‐degradation of PVC in two ways. First, the stabilizers may interact with photo‐excited polymer chains and transfer the excitation energy to the stabilizer by scavenging of chain‐propagating alkylperoxyls and deactivation of hydroperoxides, such as hindered amine light stabilizer (HALS) . Alternatively, the stabilizers themselves may screen or absorb most of the UV light and transform the absorbed radiation energy into less harmful thermal energy via a photophysical process involving ground state and excited state molecules, thereby leaving little to be absorbed by PVC.…”

Flame retardant plasticized poly(vinyl chloride) film with selective solar spectral transparent properties

“…1,2 Among the thermoplastics, it ranks in the top ve in total worldwide production volume. 3,4 The relatively high chlorine content (56.8%) makes PVC more resistant to ignition and burning than most conventional organic polymers, 5 which offers PVC a number of applications. Although the limiting oxygen index (LOI) of PVC is 45% to 49%, it can generate high levels of black smoke during burning.…”