Flexure and water sorption properties of wood thermoplastic composites made with polymer blends

A Review on Flexural Properties of Wood-Plastic Composites

Wood–plastic composite (WPC) is a kind of composite material that is made of plastic and wood fiber or wood powder. Because it is mothproof, is resistant to corrosion, and has plasticity, among other advantages, it has been researched and used increasingly in building materials. The flexural property of WPC is an important subject in evaluating its mechanical properties. In this paper, wood–plastic raw materials and processing technology are introduced; the internal and external factors of WPC which affect the flexural properties are analyzed; the different ways of enhancing the bending capacity, including the surface pretreatment, addition of different modifiers (compatibility agent and coupling agent) etc. are summarized; and the methods of operation and strengthening effect are analyzed. This work provides a reference for further research in related fields.

Preparation and Characterisation of Wood Polymer Composites Using Sustainable Raw Materials

In recent years, composites consisting of polymers and cellulosic materials have attracted increasing research attention. Polypropylene (PP) is among the most common polymer types found in excavated waste from landfills. Moreover, wood waste generated from wood products manufacturing such as sawdust (SD) offers a good potential for the fabrication of composite materials, and it is readily available in the environment. In this paper, wood polymer composites (WPC) consisting of recycled PP (rPP) and (SD) were prepared and characterised. A range of mechanical properties, including tensile strength, flexural properties, creep and hardness were studied, along with morphology, thermal properties, water degradation and contact angle. The results showed that the mechanical and thermal properties of rPP increased with an increase in 40 wt% of the SD content. Furthermore, the SD content significantly influenced the water uptake of the composites. Time–temperature superposition (TTS) was applied to predict the long-term mechanical performance from short-term accelerated creep tests at a range of elevated temperatures. The short-term creep test showed efficient homogeneity between the fillers and matrix with increasing temperature. The produced wood polymer composites displayed a comparable physical property to virgin polymer and wood and could potentially be used for various structural materials.

Effects of Coupling Agent and Thermoplastic on the Interfacial Bond Strength and the Mechanical Properties of Oriented Wood Strand-Thermoplastic Composites

Wood-plastic composites (WPC) with good mechanical and physical properties are desirable products for manufacturers and customers, and interfacial bond strength is one of the most critical factors affecting WPC performance. To verify that a higher interfacial bond strength between wood and thermoplastics improves WPC performance, wood veneer-thermoplastic composites (VPC) and oriented strand-thermoplastic composites (OSPC) were fabricated using hot pressing. The effects of the coupling agent (KH550 or MDI) and the thermoplastic (LDPE, HDPE, PP, or PVC) on the interfacial bond strength of VPC, and the mechanical and physical properties of OSPC, were investigated. The results showed that coupling agents KH550 and MDI improved the interfacial bond strength between wood and thermoplastics under dry conditions. MDI was better than KH550 at improving the interfacial bond strength and the mechanical properties of OSPC. Better interfacial bonding between plastic and wood improved the OSPC performance. The OSPC fabricated using PVC film as the thermoplastic and MDI as the coupling agent displayed the highest mechanical properties, with a modulus of rupture of 91.9 MPa, a modulus of elasticity of 10.9 GPa, and a thickness swelling of 2.4%. PVC and MDI are recommended to fabricate WPCs with desirable performance for general applications.

Characterization and Vibro-Acoustic Modeling of Wood Composite Panels

Natural fiber-filled polymers offer good mechanical properties and economic competitiveness compared to traditional materials. Wood flour is one of the most widely used fillers, and the resulting material, known as wood plastic composite (WPC), has already found a wide applicability in many industrial sectors including automotive and building construction. This paper, as a followup of a previous study on a numerical-based approach to optimize the sound transmission loss of WPC panels, presents an extensive numerical and experimental vibro-acoustic analysis of an orthotropic panel made out of WPC boards. Both structural and acoustical excitations were considered. The panel radiation efficiency and its transmission loss were modeled using analytic and semi-analytic approaches. The mechanical properties of the structure, required as input data in the prediction models, were numerically determined in terms of wavenumbers by means of finite element simulations, and experimentally verified. The accuracy of the predicted acoustic performances was assessed by comparing the numerical results with the measured data. The comparisons highlighted a significant influence of the junctions between the WPC boards, especially on the panel's transmission loss. The radiation efficiency results were mostly influenced by the boundary conditions of the plate-like structure. This latter aspect was further investigated through a finite element analysis.