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Opinion Article

Opinion Article contributed by Miriam Wehrli, Project Manager and Dr. Markus A. Meier, Head Market Platform Packaging Market Platform Packaging, Ciba Inc., Basel, Switzerland Biopolymers as an option for sustainability – Quo vadis? Sustainability has become the new buzzword in our modern and environmentally aware society. Government authorities, organizations and companies all over the world are increasingly coming up with initiatives to improve sustainable development while striking the right balance between environmental, social and economic concerns. Specifically relating to the packaging market, the focus is on reducing carbon footprint and in this regard, biopolymers are consistently in the spotlight. When compared to traditional plastics, these new types of emerging polymers bring numerous modified properties such as a higher water-vapor transmission rate (WVTR) and biodegradability. The latter, however, often leads to confusion and consumers too often do not know how to deal with this new feature, what makes them unsure of the real benefits of biopolymers. Do we need biodegradable polymers? Biodegradability is an attribute which is often associated on the one hand with environmental friendliness but on the other hand, also with instability of the polymer and low performance. Currently biodegradability is frequently used as a marketing tool, although not all aspects of biodegradability are known and therefore hardly foreseeable. 32 bioplastics MAGAZINE [07/04] Vol. 2

Opinion Life-cycle: Oil-based polymers Net CO 2 Exploration Refinery Use Collection Incineration with energy recovery 0 Recycling + + Life-cycle: Biopolymers Growth Processing Use Collection Incineration with energy recovery - Recycling + 0 No significant difference between polymers Net CO 2 production (+) Overall target: CO 2 reduction by process optimization Figure 1: CO 2 balance comparison of oil-based polymers and biopolymers. Legend: + : CO 2 production and release to the atmosphere (emission), - : CO 2 elimination of plants during growth (photosynthesis), 0 : CO 2 neutral (overall no emission nor elimination) Already today we are confronted with headlines pointing at the rising prices for corn tortillas in Mexico due to increasing demand of bio-resources causing corn shortages. Feedstock and farmland for biopolymers are in competition with biofuels as well as land capacity which could be used to feed people. The benefits of biopolymers capable of being chemically recycled rather than composted are therefore obvious. Collecting industrial and post consumer waste of polylactic acid (PLA), for instance, and converting it back to lactic acid by depolymerization results again in a purified base material for the polylactic acid production. In doing so, corn production, corn wet milling and fermentation could be avoided and leading to an overall reduction of costs and energy consumption. Furthermore, when considering the high efforts presently made to improve the mechanical and technical properties of biopolymers, future biopolymer solutions will most probably end up losing the biodegradability at the expense of strength. In essence, the development of biobased polymers should target a polymer which is recyclable rather than biodegradable. Carbon footprint In this context, the main driver for biopolymers on the market turns out to be the fact that they are based on renewable raw materials. This is presumably linked with the increasing pressure to reduce the environmental impact of products and furthermore to comply with internal sustainability commitments. Biopolymer resin producers especially enhance their life cycle studies by purchasing renewable energy credits, but this option is certainly independent of the polymer produced. For the time being, Ciba’s market analysis in collaboration with Pira International and life cycle assessment (LCA) studies of biopolymers in cooperation with the Swiss Federal Institute of Technology (ETH Zurich) show neither clear advantages nor disadvantages of biopolymers compared with traditional mineral oil based polymers. As processing, use, collection and even waste management (except composting) do so far not show significant difference and are comparable for all kind of polymers in terms of energy demand and greenhouse gas emissions, a fully greenhouse gas neutral option (from cradle-tograve) can only be achieved by using renewable resources. Even if 100% recycling could be feasible, traditional plastics would still need crude oil as a feedstock and therefore release net CO 2 to the atmosphere. So, the long-term vision for a sustainable solution points to biopolymers which are 100% recyclable. If this is considered not feasible, then at least incineration with heat recovery should be the option and not composting, in which, neither energy nor base material can be recovered (destroying value). Alternatives – biobased polyethylene (PE) Biopolymers like PLA and starch-based solutions still show performance drawbacks in end-use packaging applications compared with traditional polymers. While the higher WVTR of biopolymers could be a benefit for several fresh produce packaging applications, they then shortly bioplastics MAGAZINE [07/04] Vol. 2 33

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