Characterization and reprocessing of greenhouse films

Films for greenhouses are an attractive source of post-consumer plastic mat erials because they are mainly made of polyethylene and can be easily colle cted in large amounts in small zones. The types of polymers for this applic ation are, however, increasing and the films contain not only additives and stabilisers, but also fertiliser and pesticide residues. Finally, the exte nt of photooxidative degradation undergone during the use can strongly infl uence the recycling operations and the final properties of the secondary ma terial. In this work, a complete characterisation of post-consumer films fo r greenhouses has been carried out and the properties of the recycled mater ial have been correlated with the number of reprocessing steps and compared with those obtained by reprocessing virgin scraps of the same composition. The presence of small amounts of low molecular weight compounds (photooxid ized species and pesticide residues) does not compromise the use of the rec ycled plastic in many applications. The mechanical properties decrease with the number of reprocessing steps and with increasing level of photooxidati ve degradation but are good enough for many applications. (C) 2001 Elsevier Science Ltd. All rights reserved.