Wood-polymer composite materials

The book opens with a paper on the structure and composition of wood to define the material under discussion and then considers molds, permeability, wood preservation, thermal deterioration and fire retard-ance, dimensional stability, adhesion, reconstituted wood boards such as fiberboard and particleboard, plywood, laminated beams, wood finishes, wood-polymer composites, and wood softening and forming. A final paper treats the common theme of wastewater management. Only one of the papers presented at the meeting is not included in this volume, and its subject of conventional wood preservation methods is adequately treated in detail elsewhere (e.g., Nicholas, D. D., Ed Wood Deterioration and Its Prevention by Preservative Treatments, 2 vols., Syracuse University Press, 1973). 

It may also be possible to eventually extend this bonding concept to the preparation of flakeboards and other wood-base composite materials. If plastics like polystyrene are incorporated into the composite matrix, and successful bonding between the wood and plastic is developed through the graft polymers, the three-dimensional network of plastic material throughout the composite matrix may lead to enhanced physical and mechanical properties as well as improvements in dimensional stability (Figure 2). 

Figure 2 Creep-recovery tests of chemically treated woods. U, untreated wood Fs, vapor phase formalization F, liquid phase formalization A, acetylation PO, etherification with propylene oxide MG, treatment with maleic acid and glycerol PFl, impregnation with low molecular weight phenol-formaldehyde resin PEG-ICP, impregnation with polyethylene glycol (PEG-IOOO) WPC, formation of a wood- polymer composite (PMMA) WIC, formation of a wood-inorganic material composite.

In order to develop natural fiber-reinforced polymer composites, the primary focus should be given to the nature of the interface between the natural fiber and the polymer matrix. A fundamental understanding of fiber-fiber and fiber-matrix interface is critical to the design and manufacture of polymer composite materials because stress transfer between load-bearing fibers can occur at the fiber-fiber interface and fiber-matrix interface. In wood-polymer composite systems there are two interfaces that exist, one between the wood surface and the interphase and one between the polymer and interphase [1]. Therefore, failure in a composite or bonded laminate can occur as follows (i) adhesive failure in the wood-interphase interface, (ii) the interphase-polymer... 

A. Hassan, A.A. Salema, EN. Ani, and A.A. Bakar, A review on oil palm empty fruit bunch fiber-reinforced polymer composite materials. Polym. Compos. 31(12), 2079-2101 (2010). M. Zaini, M.A. Fuad, Z. Ismail, M.S. Mansor, J. Mustafah, The effect of filler content and size on the mechanical properties of polypropylene/oil palm wood flour composites. Polym. Int. 40(1), 51-55 (1996). 

The wood-polymer composite industry has the greatest growth potential in building products that have limited structural requirements and the materials selected depend very much on the intended end product and cost, availability, market value, and product performance requirements. The main composite product is decking or splintering [304]. Other areas of activity are outdoor furniture such as picnic tables, park benches, naturetrails/walkways, fencing piers, boardwalks, window and door... 

The enthusiasm in this field is explained by the number of potential applications. For example wood-polymer composites (WPC), mostly manufactured through extmsion and injection moulding processes are used in automotive (dashboards or screen-doors of the vehicles) and construction applications (interior floor coverings, profiles for doors and windows, ornamental panels, external shutters, pavements, garage, or entrance doors). Replacement of wood products for building applications such as particleboard and fiberboard materials or injection mouldable wood is another area where natural fibers are generating increased interest. 

According to the definition by American Society for Testing and Materials (ASTM), the term WPCs refer to composite materials that contain wood fiber/floiu and various thermoplastics or thermosets. Traditionally, there are two definitions of WPCs, wood-plastic composites and wood polymer composites. 

Q. Wu, K. Chi, Y. Wu, and S. Lee, MechcUiiccil, thermal expansion, and flammability properties of co-extruded wood polymer composites with basalt fiber reinforced shells. Materials ( Design 60,334-42 (2014). 

---