Introduction

WPCs (Wood Plastic Compounds) are blends of plastics (mainly cheaper polyolefins or PVC and more recently also bioplastics such as PLA) with wood fibers or flour. Wood plastics are one of the first examples of sustainable materials invented in the 1960s, as they were made with recycled plastics and the waste products of the wood industry, resulting in a very low CO ₂ footprint. Particularly in North America and northern Europe, WPCs are a popular alternative in buildings and construction. WPCs are sensitive to heat due to the wood component, which typically makes up to 70% of the compound. They are also prone to UV light and heat exposure, where besides the plastic degradation, the oxidation of the wood cellulosic component tends to cause strong staining and release of low molecular weight polar molecules (VOCs).

Recommendation

As WPCs are considered as cheaper alternatives for the building industry, light stabilizers need to guarantee the durability of the material with a reasonable overall cost position. UniteChem LS 770 is widely used in WPCs for its optimum cost/performance, with the possibility to be combined with a UV absorber such as UniteChem UV 531 to enhance UV protection. UniteChem LS 791 and UV P are alternative solutions. For bio-degradable WPCs based on PLA, UniteChem LS 622 is recommended in combination with UV P. UniteChem AO blends of AO 1010 and AO 168 such B215 are commonly used to protect WPCs during processing, reducing both polymer viscosity variation and cellulosic decomposition.