Wood with plastic offers cost performance benefits

Tom Shelley reports on a class of materials that combine the benefits of wood and other natural products with polymers The latest range of low cost materials to become available to designers are polymer bonded woods, appreciably cheaper than plastic on its own while more durable than wood, and much more durable than chipboards and similar materials. Target markets are mainly in the built environment, but they also offer potential for use in car interiors and consumer products. Three completely different products from three different sources have recently come to our attention, each based on the same underlying philosophy, but with widely different properties and applications. MWood, which comes from Miru Enterprise in Korea, is made from 40 to 50% recycled PVC, 40 to 50% "Organic fibres", 8 to 12% calcium carbonate plus an "Impact modifier", lubricant, colourants and up to 1% chemical binder. It is more durable than wood because the plastic encapsulates and binds the fibres together to resist moisture penetration and fungal rot. It incorporates no preservatives but is still resistant to attack by insects and the effects of ultra violet light. International Building Code (IBC) fire rating is claimed to be Class 1, the highest. The material is available in various extruded cross sections including hollow cellular and can also be injection moulded. It does not splinter, crack or swell. MK Profile systems in Preston is offering extruded 85% wood 15% polypropylene profiles made by Maschinenbau Katz in North Rhein Westfalia. Sales manager Tom Murphy told Eureka that while they are primarily limited to indoor (or in vehicle) use, they are "Significantly cheaper" than aluminium profiles with the same dimensions. The slot dimensions are based on those of the MK 40 series of aluminium profiles, widely used in many industrial and non industrial applications. The common slot geometry means than many of the existing components such as slot nuts, plates and other connecting elements can be used in either system, and aluminium sections can also be included in constructions where strength is critical. The wood-plastic profiles are lighter than their aluminium equivalents and can be used where metal parts are discouraged, such as electronic measurement systems, magnetic devices, metal detection and protective packaging. A range of new components has been designed for the wood profiles with shelving specifically in mind. Another German company, Berleburger Schaumstoffwerk - BSW, based on Bad Berleburg, has developed a wood based material which they call, "Recoflex" which is elastic. Made of wood granules, latex, cork and polyurethane, it is press compacted to produce boards or rolls that can be bent in all directions. Its main application at present is in the manufacture of curved wooden mouldings. The material is placed between high density fibreboard (HDF), medium density fibreboard (MDF) or high pressure laminate (HPL) sheets and pressed. This reduces the work processes otherwise involved in gluing several layers, and reduces product weight because the material only has a density of 440kg/cu m. In a pilot project, Lang Formholz -Service is co-operating with Concavex and the architect's bureau, Marcus in Detmold, to produce small pieces of furniture and partitions with Recoflex as a filler. BSW believes that the material additionally has good to excellent sound proofing properties, although test results are not yet available at time of writing. Miru Enterprise MK Profiles Berleburger Schaumstoffwerk Pointers * MWood is an almost 50-50 mixture of organic fibres and recycled PVC suitable for outdoor use * MK wood profiles are 85% wood and 15% polypropylene suitable mainly for indoor use, but significantly cheaper and lighter in weight than corresponding aluminium profiles * Recoflex is made of wood granules, latex, cork and polyurethane and is flexible, allowing its use as a filler in moulded wooden objects and as a sound absorbing material