New opportunities with wood-flour-foamed PVC

Composites of wood with polyethylene, polypropylene, and poly(vinyl chlorid e) represent an emerging class of materials that combine the favor-able per formance and cost attributes of both wood and thermoplastics. One of the ma jor disadvantages, however, of these materials is a relatively high specifi c gravity compared with those of many natural wood products. A PVC-wood com posite, for example, has a specific gravity of about 1.3 g/cc. This paper l ooks at producing cellular PVC-based wood composites and the properties tha t are achieved as the foam density is reduced. Overall, even with densities as low as 0.6 g/cc, the physical properties should be adequate for many wo od replacement applications. The composites also offer the aesthetics of wo od and economics that are favorable compared to those of both rigid and cel lular PVC.