Description

This study examined the effect coextruding a clear HDPE cap layer onto HDPE/wood-flour composites has on the discoloration of coextruded composites exposed to accelerated UV tests. Chroma meter, FTIRATR, XPS, SEM, and UV vis measurements accounted for the analysis of discoloration, functional groups, and degree of oxidation of both uncapped (control) and coextruded composites before and after UV exposures. Two separate discoloration characteristics occurred in the discoloration of composites. For uncapped WPCs (control), chemical changes due to photooxidation resulted in darkening followed by physical changes, including loss of colored wood components from the surface, as well as increased roughness on the surface, which led to lightening of WPCs. By contrast, because a hydrophobic cap layer prevented the loss of colored components from the surface, coextruding a clear hydrophobic HDPE cap layer over WPCs significantly decreased the discoloration during the weathering process. Photooxidation of wood components at the interface accounted for the discoloration of coextruded WPCs before the failure of cap layer. Moreover, as the cap layer absorbed a specified amount of UV light and reduced oxygen available to interface, it decreased the photooxidation rate at the interface compared to that at the WPCs surface.

Publication Notes

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Citation

Matuana, Laurent M.; Jin, Shan; Stark, Nicole M. 2011. Ultraviolet weathering of HDPE/wood-flour composites coextruded with a clear HDPE cap layer. Polymer degradation and stability. Vol. 96, no. 1 (Jan. 2011): p. 97-106.

Cited

Keywords

Wood-plastic composites, polyethylene, composite materials, deterioration, weathering, accelerated life testing, wood flour, extrusion process, injection molding of plastics, color fading, ultraviolet radiation, stabilizing agents, light absorption, plastics, extrusion, oxidation, Fourier transform infrared spectroscopy, surface roughness, X-ray photoelectron spectroscopy, HDPE, high density polyethylene, discoloration, wood-plastic materials, accelerated testing, photostabilizers, durability, surface properties, ultraviolet absorber, light absorption, coextrusion, FTIR, XPS

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