Polyolefins are normally resistant against oxidation as commercial products thanks to the use of stabilisers. They are also very resistant to biodegradation due to the high molecular weight and their strong hydrophobic character. They can however be made biodegradable by adding so-called pro-degradants.
With the help of those pro-degradants they are degraded by a chain reaction by a free radical mechanism including oxygen in the air. This leads to chain scission and the build-up of low molecular oxidation products suitable for assimilation by microorganisms. The goal of our work is to develop biodegradable materials based on mainly PE and PP. The work comprises optimisation of the pro-degradant system and studies of the kinetics and mechanisms in the oxidative degradation processes in different environments. The degradation is studied using different evaluation methods: mechanical tests, IR- and UV-VIS-NIR-spectroscopy, ESCA, etc. Differences in degradation mechanisms in different environments are mapped.
Polymeric nano composites (PNC)
In spite of the fact that PNC has been interesting for a long time it is still few that can offer commercial products. One of the reasons is the large number of parameters that have to be optimised to get a material with the properties asked for. Our projects within the area include development of polymeric materials in which specially modified mineral particles are added to certain thermoplastics (mainly PVC, PE, PP and PA) under conditions leading to the build up of nanocomposites with exfoliated structure. The aim is to develop materials with markedly better properties like mechanical stability, heat resistance, barrier properties, etc. The project is run in cooperation with the polymer industry, the packaging industry, SIK Swedish Institute for Food and Biotechnology, Chalmers University of Technology and the University College of Borås.
Wood/plastics composites (WPC)
Biolab and SP Trätek have together studied wood products, such that are modified with new methods – tall oil derivates, heat treatment, furfurylation – and wood-plastics composites (WPC). The wood within the composites can consist of waste from other wood technical industry, for example rest products from manufacturing of the modified products above. In such a way the waste amounts can be largely decreased. Biolab evaluates the new products concerning biodegradability in soil and compost and also how they manage an attack from wood decaying fungi according to international standards (EN 113 among others). An important part of the work concerns evaluation of the ecotoxicological effect of these products.