Value-added Wood Composites Made from Waste Polystyrene as a Binder: a Review

Wood composites is a growing field of products that are increasingly present for a variety of applications, with an undiminished upward trend now for very many decades. It must be clearly pointed out that one cannot speak about wood composites without speaking in depth of the polymer binders used to hold them together. Synthetic adhesives do still dominate this market and are mostly based on formaldehyde. There are also several biobased adhesives based on renewable natural materials that are at the forefront of new developments. Some of these are already industrial, sometime for many years, such as tannin adhesives and some soy adhesives, while others are on the way of industrialization, and many others are, as yet, at the experimental stage. Nowadays, the products manufactured from recycled materials are especially paid attention in the view-point of environmental problems. Polystyrene is a synthetic, aromatic, thermoplastic polymer made from the monomer styrene. Waste polystyrene poses serious environmental risks especially in developing countries where disposal facilities are lacking and its management is a serious problem because it is easy to recycle. Due to the lack of effective strategies of polystyrene waste recycling, most of it is discarded in recycling plants, landfills or incinerated. In this context, an option to successfully utilize waste polystyrene and at the same time to avoid the environmental problems that formaldehyde adhesives cause, is its application as a binder in order to produce value-added wood composites. This paper reviews the research milestones in this area and discusses the potential of using waste polystyrene as a binder in producing value-added wood composites.