Molecular Structural Changes of Plasticized PVC after UV Light Exposure

Abstract

Plasticized poly(vinyl chloride) (PVC) materials for industrial, medical, and household use are often intentionally exposed to UV light, though its impact on the molecular integrity and toxicity of the surface and bulk of PVC materials is still not well understood. This paper investigates the surface and bulk molecular changes of plasticized PVC films with 25, 10, or 0 wt % bis-2-ethylhexyl phthalate (DEHP) plasticizer after exposure to short wave (254 nm) or long wave (365 nm) UV light. Surface analytical techniques including sum frequency generation vibrational spectroscopy (SFG) revealed short wave UV exposure induced major molecular changes on the plasticized PVC surfaces, resulting in increased surface hydrophilicity and decreased CH3 content with increasing exposure time. Additionally, it was deduced from multiple techniques that the surface and the bulk of the plastic exposed to short wave UV contained phthalic monoesters and phthalic acid formed from multistep radical reactions. In contrast, when exposed to long wave UV, molecular content and ordering on the surfaces of the plastic remained relatively unchanged and the introduction of DEHP in plastic helped protect PVC chains from degradation. Results from this study demonstrate short wave UV exposure will result in plastic surfaces containing phthalates and phthalate-related products accessible to contact by living organisms.

Polyaniline nanorods/PVC composites with antistatic properties

“…Field emission scanning electron microscopy (FESEM) measurements were taken with a Hitachi S-3000N Scanning SEM. XRD patterns were performed 1 The article is published in the original. on a XD-6000 X-ray diffractometer using a CuK α radiation source (λ = 1.5418 Å).…”

“…Poly(vinyl chloride) (PVC) as one of the most common commodity plastics has been used in the automobile, building construction, and packaging field [1,2]. However, pure PVC is insulation, which especially limits its applications in antistatic field [3,4].…”

Evaluating UV/H2O2 exposure as a DEHP degradation treatment for plasticized PVC

“…We have previously studied the surface and bulk effects of short and long wave UV (254 and 365 nm, respectively) treatments on DEHP‐plasticized PVC materials in air to better understand what molecules remain present on the plastic surfaces after exposures to UV in industrial or natural environments. Exposure to short wave UV was found to rapidly degrade DEHP molecules on the surface of the plastic and in the bulk to form products including MEHP, phthalic acid, hydroxylation of phenyl rings, and complete breakdown of DEHP . From an environmental perspective, this demonstrates that plastics exposed to short wave UV over time will yield surfaces containing a number of different phthalate related molecules.…”

Photostability, thermal and mechanical properties of poly(vinyl chloride)/novel acrylate terpolymer blend

“…Unfortunately, PVC suffers from both poor heat and light stability, since it undergoes rapid autocatalytic dehydrochlorination process due to the evolution of HCl gas upon exposure to heat and light during its fabrication and use, respectively. The changes of the molecular structure of the PVC by the effect of UV light are important issue that has attracted the attention of many researchers . Formation of conjugated polyene sequences resulting from UV irradiation gives rise to discoloration of the polymeric matrix and other damaging effects in its physical properties .…”