No abstract

The widespread use of conventional petrochemical-based plastics and their low biodegradability led to a growing pollution issue. Among the class of the aliphatic polyesters, poly(propylene/neopentyl cyclohexanedicarboxylate) [P(PCExNCEy)] random copolymers combine promising physical-chemical properties and biodegradability features but they are characterized by slow degradability. The effect of gamma radiation on both chemical-physical properties and compostability was evaluated by several techniques on different samples irradiated in air at absorbed doses up to 500 kGy and in water or under oxidative atmosphere up to 100 kGy. According to the results obtained, exposure to radiation significantly affects polymer molecular weight and hydrophilicity, while crystallinity remains unaltered and biodegradability is only slightly influenced. In particular, among the different irradiation environments used, irradiation in water seems to favor the polymer degradation in compost.

Characterization of PAGAT dose response upon different irradiation conditionsPolymer gel dosimeters represent a promising instrument for tridimensional radiation dose measurement for highly conformal radiation therapy techniques. In this study, the dependence of the dose response of the polymeric gel dosimeter PAGAT was investigated as a function of different irradiation conditions and time elapsed after irradiation. An X-ray tube and 60 Co sources were used for irradiation. This allowed to assess variations in system dose response under different irradiation energies and dose rates -ranging from 1.4 Gy h -1 up to 0.14 kGy h -1 . Analysis of irradiated samples was performed by UV-Vis optical measurements at different time intervals after irradiation. Significant variability in PAGAT dose response was observed for different irradiation conditions and considered dose rates.

No abstract

Plastic waste has become a major worldwide environmental threat. In this view, six different polymer films, characterized by a different biodegradation rate, were exposed to gamma radiation and their surface properties along with the effect on their biodegradation rate in compost has been investigated. In particular two polyesters, poly(butylene succinate) (PBS) and poly(propylene cyclohexane dycarboxylate) (PPCE), have been selected as biodegradable and slow degrading polymers, while, as recalcitrant polymers, commercial films of high density polyethylene (HDPE), low density polyethylene (LDPE) and polyethylene terephthalate (PET). Polymers have been irradiated in air and water at absorbed doses up to hundreds of kGy. Surface properties have been analyzed by means of water contact angle (WCA) measurements and the composting tests have been performed up to 180 days.WCA measurements revealed positive changes that could affect the polymer biodegradability. For polyesters, the wettability is highly increased when the samples are irradiated in water. PE wettability is increased for all the absorbed doses, while PET is not affected. In general, the degradability in compost of the considered systems is increased: PBS tends to degrade faster when irradiated in water while PPCE in both irradiation conditions. HDPE and LDPE did not evidence relevant variations in the surface morphology after 180 days in compost but a difference in the thermal properties suggests a beginning of the degradation process. PET degradability appeared to be not affected after 180 days in compost, even after irradiation up to 1 MGy. The research suggests that the radiation-induced degradation could be an effective pre-treatment to enhance the biodegradation rate of some polymeric systems.