Recycled polyolefins. Material properties and means for quality determination

Recycling of polymers has come to be a necessary part of the development of a sustainable society. Recycling of low price bulk polymers, to which group the polyolefins belong, is seen by many as a waste of time and resources when they simply may be energy recovered. Several life-cycle assessments (LCA) have, however, proven that it is also valuable to material recycle bulk polymers such as polyolefins. In many instances, polyolefins are inplant recycled and used again in similar products, but they may also be separated and sorted from municipal solid waste. This paper will discuss recycled polyolefins, in particular their change in material properties and how to characterise these properties and show that these analyses are a basis for quality determination. In fact, an important vehicle for the success of recycled polymeric materials is to use a quality concept. Accurate determination of a series of polymeric properties will be the only way recycled polymeric materials can compete with virgin ones. Analytical methods useful in the quality concept are presented and discussed. In particular, three parameters are important for quality measurements. These are degree of degradation, polymer composition and presence of low molecular weight compounds (degradation products of polymer matrix and additives, initiator/catalysts, solvents, use-related e.g. fragrance or flavour etc.). For the future it is important to give recycled polymeric materials status as resources besides the fossil and renewable ones.