Photooxidative weathering of biodegradable nanocomposite films containing halloysite

Abstract

This study reports the results of photodegradation experiments performed on biodegradable nanocomposite blown films based on a commercial grade of poly(3-hydroxybutyrate-co−3-hydroxyvalerate)/poly(butylene adipate-co-terephthalate) blend added with different amounts (3, 5, and 10 wt%) of tubular halloysite nanoclays, natural and organomodified. The films, subjected to photooxidative weathering in a climatic chamber under UV exposure, were systematically analyzed to check the chemical and physical changes induced by the aging protocol, taking the as-produced films as the reference materials. In particular, the samples were characterized using several techniques [colorimetry, water contact angle tests, UV–vis, attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectrophotometry, X-ray diffraction, oxygen permeability, and mechanical tests]. The experiments demonstrated that all nanocomposite films, when compared with the unfilled one, show higher changes in the total color difference ΔE* and higher reduction in the average transparency due to the changes in the molecular structure of the polymer (hydrolysis of the ester linkage, multiple chain scissions, and crosslinking), as observed from ATR-FTIR analysis. The phenomenon, which basically involves the amorphous phase, tends to increase with the nanofiller percentage in the films and is more relevant in the presence of the organomodified halloysite. As a consequence of the photodegradation of the amorphous polymer chains that increase their molecular mobility, the oxygen permeability worsens, even in the presence of nanofillers. Instead, in terms of mechanical response, the addition of pure and organomodified halloysite to polymer matrix had positive effects on tensile properties both before and after photooxidation

Photooxidation Behavior of a LDPE/Clay Nanocomposite Monitored through Creep Measurements

“…The faster photooxidation kinetics of the nanocomposite has been reported also in previous studies [16,26,27,28,29,30,31] and has been explained by demonstrating that the photodegradation, induced by the UV irradiation, is favored by the iron ions contained in the clay.…”

Controlled biodegradation of polymers using nanoparticles and its application

“…The process of degradation occurs mainly through the scission of backbone / side chains of the polymer. The structural changes during aging of polyesters are accredited to the series of chain scission and [43]. Biotic system include microbes, enzyme or combination of both which perform biological activity for their growth employing polymers as carbon source.…”

Enhanced Photodegradation Stability in Poly(butylene adipate-co-terephthalate) Composites Using Organically Modified Layered Zinc Phenylphosphonate

“…The peaks at 1268, 1250, 1166, 1118, and 1103 cm −1 were attributed to the ester group. The peaks at 720 cm −1 were attributed to the methylene groups, while those at 1505 and 875 cm −1 were attributed to the benzene ring [ 38 , 39 ]. The intensities of these peaks became insignificant after irradiation, which indicated the chemical decomposition of the PBAT via photodegradation.…”