engleski

Durability of HDPE-wood plastic composites

In recent years wood-plastic composites (WPCs) have emerged as an important group of engineering materials due to overall interest and need in renewable materials from bio-resources. This type of composite is typically comprised of wood or other natural lignocellulosic fibers in a thermoplastic matrix. For that reason WPCs are often called “green composites” because the wood flour is a natural material and can be successfully recycled together with the polymer matrix. For many applications WPCs show better properties in comparison to wood so they have successfully proven their application in various fields such as lumber, decking and railing, window profiles, wall studs, door frames, furniture, pallets and automotive components. Furthermore, wood fibers or wood flour act as a reinforcing material or filler and WPCs represent the good alternative for the use of glass or carbon fibers and inorganic fillers. Due to such widespread use WPCs often need many additives for preserving their stability in different application conditions. For example, when used in exterior applications, it is needed to ensure wood–plastic composites’s durability against atmospheric influences. Namely, WPCs undergo cyclic dimensional changes caused by UV degradation and periodic absorption and desorption of moisture resulting in loss of mechanical integrity and aesthetic properties. The objective of this study was to investigate the durability of the high density polyethylene-wood composites under the atmospheric conditions. For this purpose WPCs were prepared by extrusion and the samples were prepared with different content of UV stabilizer. In order to simulate outdoor weathering conditions composites were exposed to elevated temperatures and UV light in UV chamber and their moisture absorption was also studied. To study the changes in composite’s surface after weathering samples were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). The water absorption degree was also determined. Thermogravimetric analysis (TGA) was used for determination of composites’ thermal stability. The results show relatively good resistance of WPCs to outdoor weathering conditions. It can be concluded that the UV stabilizer’s content of 0.25 phr is the optimal one, ensures the most efficient stability of WPCs and delays their degradation.

wood plastic composites; HDPE; durability; UV stability

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