Recycling and Durability of PVC Materials Focusing on Pre- and Post-consumer Wastes from Building Products

Doctoral thesis, 2003

The potential for recycling various polymeric materials contained within buildings constructed in the late 1960s and 1970s in Sweden was investigated during the course of this work. Three residential blocks were studied to establish the quantity of materials available for recycling, to investigate the difficulty in and time needed for the dismantling of the buildings, the degree of purity of the materials, and the possibility of separating the materials. The focus of the experimental work was on studies of various types of polyvinyl chloride (PVC), which is the dominant polymeric material in the buildings. The important properties and the durability of new plasticised and rigid PVC materials were investigated, as well as the properties of older products collected from the buildings. The study had several facets. First, there was an investigation into the degradation processes that occur during the initial processing of virgin material and during reprocessing. Then there was examination of changes in properties during service life. Following this was the process of establishing the remaining lifetime of the used and reprocessed materials. Finally there was an investigation into fundamental degradation mechanisms that can take place during the long service life of PVC materials in buildings under various environmental conditions. In particular, stabiliser consumption and dehydrochlorination, depletion of plasticiser, and deterioration of the tensile properties were examined. Evaluation was carried out by means of physical and chemical analysis and characterisation was achieved on a molecular level, in addition to evaluation of the mechanical properties, including attempts at recycling some materials on the laboratory scale. Accelerated ageing of the materials was performed to simulate the natural service life conditions. The decisive degradation mechanisms in the new and model materials were mapped and compared with older materials. An attempt was also made at recovering energy from flooring.