Effects of Photostabilizers and Surface Treatments

Matuana et al. [76] also reported that rutile titanium dioxide was an effective UV stabilizer for wood/PVC composites. 

Similar results were reported by Butylina et al. [78] who carried out a more extensive study of the natural weathering properties of wood-PP composites with and without pigments. Samples were exposed to natural weathering for one year in a Finnish climate and their color changes monitored. Darker pigments (such as brown and grey) were 

Kumar et al. [83] studied the weathering properties of ethylene-propylene copolymer (EPC) matrix composites with three different reinforcement materials, namely, 3% NaOH-treated jute fibers, 17.5% NaOH-treated jute fibers and commercial microcrystalline cellulose powder, using maleated EPC as a compatibilizer. The samples were subjected to UV radiation at 60°C in air for 150 hours. Again, the neat polymer samples were more resistant to weathering than the composites. The samples reinforced with commercial microcrystalline cellulose were the most stable of the composites and those made with fibers treated with the lower concentration of NaOH were the most susceptible to photo-oxidation. It was concluded that optimizing the durability and mechanical properties of the natural fiber-reinforced composites was closely dependent on selecting the appropriate treatment for the fibers. 

Lignocellulosic thermosets have also been studied for their weathering properties, although not to the same extent as lignocellulosic thermoplastics. 

O Dell [84] studied the weathering properties of jute fiber/unsaturated polyester composites and compared them with glass fiber/unsaturated polyester composites. Samples were exposed to cycles of continuous UV exposure for 102 min, followed by 18 min of water spray for a total of 1200 hours. It was noted that there were no observable visual differences between weathered glass and jute fiber specimens in color changes or surface erosion effects. 

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