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Special Issue on Biobased Polymers

There has been a strong and continued interest in the use of the so-called “bioplastics” in recent years. The definition of bioplastic has been deformed and extended to suit all sorts of interests. The “bio” prefix refers sometimes to the synthesis process (natural vs synthetic), to the feedstock (renewable biomass vs petroleum derivatives) or to the ability of the polymer to biodegrade at a certain rate. To understand the motivations behind the development and research in this area, it is important to distinguish between biobased and biodegradable polymers. Biobased polymers are defined as polymers naturally or synthetically synthesized from a biomass feedstock. Biodegradable polymers are polymers that will be assimilated by microorganisms leading to their degradation and transformation into carbon dioxide and biomass. Thus, the term biobased refers to the origin of the material while biodegradable refers to a specific property and to a potential disposal method. The development of biobased plastics has been mainly driven by the desire to increase the use of renewable biomass, or its corollary, to reduce petroleum consumption in the fabrication of polymeric materials. To a large extent it is motivated by the potential cost reduction and by the sustainability of the feedstock. This quest has led to unprecedented ventures between agricultural-based companies and traditional synthetic plastics industries. The most famous example is the successful commercial development of polylactide (Initiated by Cargill and Dow). This has recently been followed by the introduction of biobased propane diol, a monomer for use in polyesters and polyurethanes (Tate & Liles and Dupont). A similar commercial introduction is expected shortly in polyhydroxyalcanoates. On the other hand, the drive for biodegradable materials has come mainly from niche applications such as agricultural films and from the positive public perception toward biodegradation as a litter control method and eventually as a waste management solution. The long-term sustainability of this approach for large-scale use of biodegradable materials is largely dependant on the development of industrial composting facilities. For the moment, the debate is still open on the environmental benefits since the highly visible benefits of biodegradation for litter control have to be weighed against the extra carbon dioxide and methane emission and the lost opportunity for recycling and energy-recovery. Whether durable biobased materials or short-lived biodegradable materials are necessary in a given application, the role of the polymer scientist/engineer is to provide the necessary material options in order, in the long run, to minimize environmental impacts. This special issue gathers contributions from main players in the biobased polymer area. Several papers deal with polylactide and investigate the structure and rheology of this material as well as the properties of various PLA-based composites. Other papers will deal with natural polymers such as bacterial cellulose, proteins, PHA and thermoplastic starch. Finally, a few papers deal with hybrid materials which combine a synthetic polymer with a bio-based or biodegradable component. I hope this issue can give IPP readers a good sense of the wide variety of research that is being pursued and of the role of polymer processing expertise in the development of biobased materials. Guest Editor Michel A. Huneault National Research Council of Canada