Photo-sensitivity of recycled photo-degraded polystyrene

Blends have been made containing various combinations of (polystyrene) virgin polymer, recycled polymer and photo-degraded polymer to investigate whether recycled polymer prepared from photo-degraded waste has increased sensitivity to photo-degradation after recycling. Bars injection moulded from virgin material were used to generate photo-degraded material using laboratory ultraviolet (UV) exposure. Recycled polystyrene was prepared from (i) sprues and runners from the mouldings made with virgin material and (ii) single polymer waste that contained other grades and some material that had already been recycled at least once. Mixtures of virgin polymer and photo-degraded polymer showed accelerated degradation when compared with similar blends of virgin polymer with recyclate from mouldings that had not been exposed to UV. This effect was greatest for short exposure times (<6 weeks) but the seeding effect of the photo-degraded material was less severe at longer exposure times. (C) 2002 Kluwer Academic Publishers.