Study On The Preparation And Degradable Properties Of Photo-Biodegradable PE Films

This subject was proposed for the severe environmental pollution aroused from the hard degradable plastics, which has lead to "white pollution". The synthesis and the optimum conditions of the photosensitizers contained ferric stearate (FeSt3) and ferric dimethyldithiocarbamate (FeDBC) were mainly studied in this subject. The processing technology, the ultraviolet accelerated photo-degradation, the micro-biological degradation and the natural degradation of the photo-biodegradable LLDPE film were studied in this subject. The carbonyl index (CI) and the molecular weight of the photo-biodegradable LLDPE film were detected in this subject. The relationship between the carbonyl index, the molecular weight and the types, the contents of photosensitizers were proposed in this paper.The results of this research showed that the ferric stearate (FeSt3) and the ferric dimethyldithiocarbamate (FeDBC) were excellent photosensitizers. The photocatalytic oxidation reaction of LLDPE was photo-initiated by FeSt3 and FeDBC, which can cause LLDPE chain interruption, carbonyl index increased, the molecular weight decreased and then the LLDPE film thoroughly degraded. Compared with the LLDPE film contained FeSt3, the LLDPE film contained FeDBC needed a much longer degradable induction period, and the photocatalytic activity of LLDPE film contained FeSt3 was much better than the LLDPE film contained FeDBC with the same contents and the same degradable time, which showed that the photosensitive activity of FeSt3 was much better than FeDBC. The degradable rates of LLDPE films contained FeDBC with different contents were different, and the inflection point was emerged in this relationship, which showed that the degradable time of the LLDPE film could be controlled by the contents of FeDBC. The service properties of LLDPE films were excellent after natural exposure and natural buried in 60 days. The LLDPE films contained photosensitizers were thoroughly degraded, while the blank film was no change, which showed that the LLDPE films contained photosensitizers were thoroughly degraded under the precondition of the films with good service life. The LLDPE film contained 0.6% FeSt3 and UV aged 144 hours could be thoroughly micro-biological degraded when the molecular weight down to less than 10000. The Aspergillus Niger was screened out from the microorganism in this bio-degradable experiment, which has the bio-degradable function on the LLDPE film. The holes were emerged in photo-biodegradable films after bio-degradable experiments, which showed that the photo-biodegradable films could be thoroughly bio-degraded after photo-degradation.