Changes in colour and mechanical properties of wood polypropylene composites on natural weathering

Abstract

This comparative study focused on understanding the effect of coupling agent and particle size on weathering behaviour of wood polypropylene composite. Two coupling agents, namely maleic anhydride grafted polypropylene and m-TMI (m-Isopropenyl-α,α− dimethylbenzyl isocyanate) grafted polypropylene were used in preparation of the composites. The composites were exposed to outdoor conditions for one year and changes in surface colour and mechanical properties were measured after 2, 4, 8 and 12 months of natural weathering. During the initial four months of weathering considerable colour change was observed with increase in lightness. Mechanical properties were unaffected largely for the initial four months and thereafter started declining. Overall, tensile strength decreased by about 15 % and flexural strength decreased by about 8 % after one year of weathering. The flexural modulus also decreased by about 10 %. Wood particle size was found to affect the aesthetic and strength of the composites after natural weathering. Coupling agents had a positive impact on mechanical properties however their influence on weathering degradation was not noticeable.

Bioactive Propolis-Silane System as Antifungal Agent in Lignocellulosic-Polymer Composites

“…An extensive review of the effects of weathering on the properties of WPCs was presented by Friedrich [ 36 ]. The effect of coupling agents (maleic anhydride-grafted polypropylene and m-TMI grafted polypropylene) on the mechanical properties of WPCs after UV was investigated by Gunjal et al [ 42 ]. The influence of fungi on WF/HDPE composites in the presence of various compounds was also investigated by Feng et al [ 19 ].…”

“…The issue of WPC aging has been addressed in many previous works [ 37 , 38 , 39 , 40 , 41 ]. The change in the properties and color of composites depending on the size of the filler particles is presented in the work of Gunjal et al It was noticed that the most exposed to the color change are composites containing smaller sizes of filler particles, while the greatest deterioration of mechanical properties was observed in samples with larger filler particles [ 42 ]. The discoloration and decay of some of the properties of WPCs were also noticed by Kuka et al In order to eliminate the destructive effect of UV, they proposed a thermal modification of the lignocellulosic filler.…”

Crystallinity and impact strength improvement of wood-polylactic acid biocomposites produced by rotational and compression molding

“…The behavior of PLA and its biocomposites was also studied under accelerated weathering to determine any changes in these materials' long-term properties. This information would be useful to increase their range of applications and their lifetime (Gunjal et al 2020. Regardless of the processing method, the materials that were not subjected to thermal annealing presented significant changes in their dimensional stability after accelerated weathering.…”

Insights into the processing, structure, and mechanical performance of polyethylene/gypsum composites

“…Nonetheless, their long-term exposure to environmental conditions often limits their use owing to the hydrophilicity and potential decomposition of plantbased materials [12]. To overcome this issue, inorganic waste fillers can be incorporated to improve the sustainability of plant-based composites without affecting their environmental resistance.…”