Abiotic and biotic degradation of post-consumer polypropylene/ethylene vinyl acetate: Wood flour composites exposed to natural weathering

Abstract

The effects of natural weathering on the visual appearance and chemical changes of wood plastic composite (WPC) formulations based on post‐consumer polypropylene/ethylene vinyl acetate (PP‐EVA) matrix were investigated. The WPC composition used was 70/30 (w/w) (recycled PP‐EVA/wood flour). Besides, the effectiveness of using coupling agent on adhesion of WPC and its influence in degradation were evaluated. Colorimetry, scanning electron microscopy, Fourier transform infrared spectroscopy, mechanical test, and biodegradation in simulated soil after natural weathering were used in this research. The results showed the samples with longer exposure time to natural weathering presented significant color change, increased in carbonyl index, and wood loss on weathered WPC surfaces. Weathered WPC exhibited decreased in mechanical properties, higher mass loss after biodegradation test when compared with no weathering WPC, reaching to 15.0% mass loss against 3.7%, respectively. Climatic conditions directly affect the characteristics of all composites, thus indicating a significant photo‐oxidation of the samples with a longer time of exposure to weathering, and this natural ageing has facilitated the WPC biodegradation. POLYM. COMPOS., 38:571–582, 2017. © 2015 Society of Plastics Engineers

Effect of natural ageing on the properties of recycled polypropylene/ethylene vinyl acetate/wood flour composites

“…The natural ageing is initiated by sunlight that is abundantly present in outdoor environment, especially by ultraviolet (UV) radiation. Photo-degradation of WPC, also understood as the ageing of the major components of WPC (wood and polymer), results from the combined effects of light, water, oxygen, and heat [7].…”

“…Photo-yellowing of weathered wood has been attributed to the breakdown of lignin into water soluble products, which eventually leads to the formation of chromophores groups such as carboxylic acids, quinones, and hydroperoxy radicals. The presence of chromophores in polymer and wood usually enhances the absorption of ultraviolet (UV) light, which later causes photodegradation of WPC [7,8].…”

Resistance of Conifer Needle Polyolefin Composites (CNPCs) Against Biodecomposition Caused by Fungi

“…The quantitative changes of the surface area at 1774-1491 cm −1 (typical for lignin groups) and 1186-912 cm −1 (band specific for cellulose groups) [44,69,70] are presented in Table 4. As expected, the noncomposted samples showed the increase in the intensity of the 1774-1491 cm −1 band compared to composites with mercerized flour and 10 wt% of sandarac, caused by a high proportion of resin acids in the sandarac.…”

Conifer Needles as Thermoplastic Composite Fillers: Structure and Properties

“…Table 6 presents the collected data on the intensity of peaks in the spectra of all three composites. Emandi et al (2011);Xu et al (2013), andCatto et al (2015) The band at 1735 cm -1 represents hemicellulose. PEHD_P/50 had the highest relative peak height in relation to the internal standard peak (2020 cm -1 ) at this wavenumber.…”