Wood-plastic composites extrusion

Gardner, D. J. 2002. Wood Plastic Composite Extrusion-Processing Systems, www.umaine. edu/adhesion/gardner/5502002/wpc%20ext%20pro%203-11-02.pdf. 

V. Hristov, E. Takacs, and J. Vlachopoulos. Extrudate surface tearing in extrusion of wood plastic composites, In ANTEC 2006, Charlotte, NC, May 7-11, 2006. 

Figure 16.3 Fading of UltraDeck wood-plastic composite deck board, according to the manufacturer s data ( Midwest Manufacturing Extrusion).

After the introduction of processing facilities for wood-plastic composites (WPC) by extrusion and later by injection moulding techniques, WPC production and its use increased almost exponentially. 

Lei and Wu [40] prepared wood plastic composites based on in-sifw-formed polyethylene terephthalate (PET) sub-micro-fibril (less than 500 nm in diameter) reinforced high-density polyethylene (HDPE) matrices through strand die extrusion and hot strand stretching. The PET fibrils obviously increased mechanical properties of the... 

Processing wood plastic composites (WPG) into profiles by extrusion for building and construction applications is one of the most exciting bnsinesses of recent years. Growth observed is such that WPG applications are already very high (at least 30% a year in... 

Weinrich, C. Direct extrusion of wood flour/ plastics composites on conical counterrotating twin screw extruders. In Wood-Plastic Conference, Conference Proceedings, Baltimore, MD, December 5-6, 2000 207-215. 

M. Bengtsson, N.M. Stark, and K. Oksman. Crosslinked wood-thermoplastic composites—profile extrusion and properties. In Progress in Wood Fibre Plastic Composites 2006 International Conference, Toronto, Canada, May 1-2, 2006. 

The fluidity of plastic is chosen on the basis of the molding method (molded machine and type of mold) and composition (content of wood flour). In extrusion molding, low fluidity has a bad influence on the productivity, and high fluidity induces the problem of stability of forming. Furthermore, depending on the fluidity of the plastic and the shape of wood flour, the orientation of wood flour must be also taken into account. In the case of wood/oleflnic resin composite with wood flour content of 50%, the plastic with fluidity (melt flow rate, MFR) of O.l-lOg/lOmin is general used. 

Vinyl wood fiber composites are now common in decking, railings, moldings, picture frames, and other profile extrusions. Such products are sold by, among others, Andersen Window, Certain Teed, Compos-A-Tron, Crane Plastics, Lida Plastics of Japan, Marley Mouldings, Profile Solutions, Royal, Tri-Ex Composites, and Youngstown Plastics. Most of the expansion in this rapidly growing area has come about in the last two decades. It is worthwhile to consider how this has happened. 

Moreover, wood has limited thermoplasticity. Although it can be bent under steam and chemical treatment, wood normally bums before it melts or becomes sufficiently plastic for heat molding or extrusion. These two techniques are important ways of shaping materials in high-speed composite production and are therefore keys to the cost-efficient penetration of lignocellulosic materials into the composites market. Chemical modification of wood offers a means of improving its thermoplasticity. 

Westlane Plastics (USA) [45] uses an extrusion method to produce rods of up to 31.75 mm diameter, stri K, pipes with 9.52-12.7 mm wall thickness and other profile artides from compositions based on phenol, melamine, carbamide, and alkyd resins. Fillers used incluse wood crush, cellulose, chalk, talc, clay, mica, silica, coke, graphite, and carbon fibers. 

Many carpet manufacturers, fiber and chemical suppliers, recycling companies, and academic institutions are actively pursuing various methods to recycle fibrous waste. The approaches include chemical processes to depolymerize nylon and other polymers, recovery of plastic resins from carpet fibers, direct extrusion of mixed carpet waste, composites as wood substitutes, fibers for concrete and soil reinforcement, waste-to-energy conversion, and carpet as feedstock for cement kilns. 

The main stream of wood fiber PP composites is short fiber reinforced, suitable for typical thermoplastic processing. The main steps of this technology are (1) pre-mixing, (2) plastic transformation of the melt (typically sheet extrusion), and (3) thermoforming (vacuum- or pressureforming) of the sheet. 

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