Wood substitute

Rigid vinyl foams ia constmction markets have grown substantially due to improved techniques to manufacture articles with controlled densities and smooth outer surfaces. Wood mol ding substitute for door frames and other wood products is an area that has grown. Rigid vinyl foams are also used ia the manufacture of pipes and wines as resia extenders and ia sidings and wiadows as the replacement of wood or wood substitutes. 

World production of unsaturated polyester resins in 1997 was of the order of 1.7 X 10 tonnes, with the USA accounting for about 45% and Western Europe 27%. Over 75% is used in reinforced plastics, with the rest being used for such diverse applications as car repair putties, cultured marble , wood substitution and surface coatings. The pattern of consumption in 1993 of reinforced polyesters in the USA was reported as ... 

In order to prepare wood substitutes and materials with open-cell structures, the so-called water-filled oligomeric foams are used These foams are obtained by mixing the OFM-monomeric composition with water until an emulsion is formed which is hardened after the addition of an initiator and activator. As a result, a white rigid material is obtained which is a spatial network copolymer with uniformly distributed micro-inclusions of water (2—5 nm). Optimal strength is reached at 50-60% of water, although the amount of water may be as high as 90%. At optimal water concentration, the cell walls withstand cryolitic destruction till 34 K. At 7 mass % of water the apparent denaty of the material reaches 250—9(X) kg/m and it resembles natural wood in appearance and in some properties. 

Possible applications of foamed composites include buUding insulation, wood substitutes for applications which require corrosion resistance, high physical strength and light weight. Very recently, a large market for foamed composites has appeared in the automotive industry. One example is a door-trim panel (7). 

In foam injection-molded parts the anooth-skinned resilient foam produces a tough energy-absorbing structure that is being used as a wood substitute in athletic products such as lacrosse-stick heads and hockey-stick blades. Protective structures for helmets and automotive parts are under development. All are being produced in densities ranging for 0.35 to 0.7 g/cc (22 to 44 Ib/ft ). In those applications where added sti ess is desirable the use of glass or titanate fiber reinforcement with the foamed structure is very effective (6). 

These processes provide a way of making produets over the whole range of densities. While MDF started its life as a panel eompeting with partieleboard as a wood substitute, it has become a new material in its own right. The ability to eontrol density profile so that the surface density of the sanded panel is uniform has... 

From low MW oligo-polyols (400-1000 daltons polyethers, polyesters, Mannich polyols, aromatic polyesters, oleochemical polyols, etc.), are obtained rigid, hard polyurethane structures (rigid PU foams, wood substitutes, etc). 

Polystyrene packaging foam, loose fill, wood substitute, sorbent polymers. 

The decisive criterion in the case of wood substitution is the life expectancy ratio (LER) of the compared products made of mixed plastics or wood, respectively. Only above a certain limit value (in the examined case LER = >3.3) — that is, a clearly longer life cycle of the plastic product as compared with the wooden product—is the level of resource reduction in feedstock recycling/energy recovery reached. The situation is similar as far as acidification and eutrophication are concerned. Advantages are found only with regard to waste minimization. 

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 building industry is under enormous pressure and is unable to meet the demands from different construction sectors. Wood is in short supply, and it is difficult to procure seasoned timber in required quantities. There is a serious need to combat wood scarcity. Existing wood substitutes such as reconstituted panel products particle/fiber boards, ply wood, and other materials cannot meet the increasing demand for wood without the development of wood substitutes. One important option is to promote development and utilization of natural fibers for the development of composites. 

Natural fiber (jute fabric) and industrial wastes are used along with polymer to make composite wood substitute products. In this process, processed fabric of jute fiber and industrial wastes such as fly ash/red mud/marble sluny dust with polymer were synthesized in molds of required length and width. The composite laminates were fabricated with requisite pressure and cured at room temperature. Various products such as full size door shutters and panels can be fabricated and designed according to requirement. The industrial waste-based polymer composite products are comparable to natural wood and thus could be used as a wood substitute for doors, windows, ceilings, flooring, partitions, and furniture, etc. The products are cost-effective and no further maintenance is required. This is an environment friendly product with fruitful utilization of fly ash/red mud/marble slurry dust (Table 22.14). The salient features of the products are ... 

Wood substitute Poly coir Coir fiber NIIST, Tiruvananthapiiram... 

The developed composites have the potential to be used in a variety of engineering applications, for instance, as wood substitutes, which will help in reduction of deforestation and enviromnental poUutiOTi. 

Fig. 22.10 Natural fiber based wood substitute products...

Tipco Industries Ltd., in Bombay, India, produces Tip wood, a composite material from mixed plastic waste and 20% filler for use as a wood substitute for applications such as pallets, benches, fencing, and road markers. 1 ... 

As discussed previously, one approach to the use of commingled plastics is to use them in wood-substitute and similar applications where the incompatibility between the various ingredients of the mix does not present severe problems. A different approach is to make the resins compatible in some way, hence improving the performance characteristics of the blend. The compatibilization can be done by the way the blend is processed, perhaps including some degree of control over the resins in the mix, or by additives. 

Xanthos and co-workers [12] did some research in which LDPE was melt blended with either automotive shredder residue, carpet hacking residue or mixtures of the two and prototype blocks were intrusion moulded from them. These blocks were evaluated for use as a wood substitute for the building industry by conducting tests to determine their short-term and long-term mechanical properties, flammability, thermal conductivity and heavy metal and total organic carbon leaching behaviour. The performance of these prototypes was compared with that of wood and the composites containing carpet residue were found to be favourable as replacements for wood thermal barrier components in a steel-based stud assembly. 

Window frames and doors PVC, foamed PVC (wood substitute), ABS (coextruded with vinyl modified ASA or polyolefins modified styrene acrylonitrile copolymer (SAN) -glass-fibre reinforced plastic (GFRP), composite based, ABS (thermoformed panels for high quality doors and window profiles)... 

Plastic lumber and wood substitutes Waste (PET), HDPE, PE (HD /LD), all with wood fibres) and co-extruded capstock (ABS/PVC with. PVDF cover)... 

The reaction conditions, particularly the acidity and the temperature, have a profound effect on the character of the resultant products. In general, three stages can be identified formaldehyde addition to phenol, prepolymer formation below 100°C, and crosslinking at temperatures above 100°C. The reactions between phenols and aldehydes were first described by Bayer, who also obtained the first patent on the preparation of methylolphenols. The first kinetic studies in alkaline media were reported by Lederer and Manasse. The first patents on resin produc s were issued to Smith, for an ebonite and wood substitute, and to Blumer, for a shellac substitute. However, not until Baekeland s famous heat and pressure patent did phenolic resins become prominent and widely used polymers. 

Alkali treated (mercerized) pine needle furnishes bonded with isocyanate prepolymer can be effectively used as panel products for wood substitute in buildings applications, mainly under wet conditions when a good bonding with resin adhesive is required (Gupta et al. 2010). 

Chemical foaming agents Physical foaming agents Insulation, packaging, wood substitutes... 

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