Improvement of selected properties of Wood-Polymer Composites (WPC) - Silane modification of wood particles

Wood Polymer Composites are a new group of hybrid materials, which combine the advantages

of synthetic polymers such as polyolefines and natural polymers such as wood; whereas the

synthetic polymer is used as matrix material and the wood as reinforcement material or filler. As

matrix material, principally every thermoplastic polymer with a processing temperature below

200°C can be used due to the temperature sensivity of wood. Wood Polymer Composites are

processed typically with processing technologies from the plastic industry such as extrusion and

injection molding.

The present study was conducted to explore the possibility of wood particle modification with

different types of silanes. It was the aim to contribute the silanes as compatibilizers or coupling

agent and therefore improve the mechanical properties and the resistance against water. Norway

spruce (Picea abies) as representative wood species was used in three different particle types. The

size distribution for the wood particles ranges from 70-2500 µm. Four commercial available

silanes with various functional groups (amino, di-amino, alkyl) were used as modification agents.

The concentrations varied between 1.5%, 3.0%, 4.5% and 7.5%. As reference system commonly

used maleated acid anhydride based coupling agents were used. The pre-treated wood particles

were compounded via extrusion with polypropylene and samples were produced via injection and

compression molding. The following properties were tested; tensile, bending, and impact

strength, water uptake (cold and boiling water test), descent rate, weathering tests and durability

test against basidiomycetes.