6.1 Introduction

Rigid polyvinyl chloride (PVC) foam (flexible PVC Foam is covered in Chapter 7 of this book) was first produced some thirty years ago, when it was heralded as the wood of the future [1, 2]. Now this material has a well-established market in Western Europe of about 300 ktonnes. The product range covers diverse applications such as window sills, sewer pipes and advertising boards. The reasons for the success of this material are its ability to compete with wood and also the benefits that it offers over solid PVC.

Many of the applications for extruded PVC foam profile (in the density range 500 to 800 kg/m ³) are for wood-replacement products. It can be sawn, nailed or screwed without splitting or cracking, thus allowing use of woodworking methods. Foamed extrudates can be produced to resemble wood in terms of structure, colour and appearance. Hence rigid PVC foam profile is often used as a direct substitute for wood. This is being driven [3] by environmental pressure to protect forests, the rising price of timber and the advantages of a maintenance-free product. On a cost/volume basis PVC foam is more expensive than wood but becomes more cost effective when wood finishing operations are taken into account. PVC foam can be extruded into complex shapes (some of which are not possible with wood) without the finishing operations and scrap associated with the manufacture of wood trim.

In addition PVC foam offers the following advantages over wood [4,...