Effect of gamma dose rate in the crosslinking of PVC composites used for radiation protection in radiology

Advances in Manufacturing a New Cable Coating Resistant to Thermal Aging and γ Rays by Cobalt-60 up to 50 KGy

Poly(vinyl chloride) (PVC) is widely used for covering electrical cables, but a decrease in its physicochemical, thermal, and mechanical properties has been observed over time. Poly(nitrile butadiene) rubber (NBR), due to its certain properties, was chosen to be blended with PVC to improve its specific properties, when used as insulation for electrical cables installed in nuclear power plants. Thus, this work focuses on the effect of γ radiation at doses ranging from 10 to 50 KGy on the physicochemical, thermal, morphological, and mechanical properties of PVC, as well as on the improvement of its properties by the incorporation of NBR in the PVC matrix as a blend. A series of PVC/NBR blends containing 10, 20, 30, 40, and 50 wt % NBR was prepared and subjected to thermal aging at 80 °C after adding appropriate additives. The results obtained reveal that thermal aging at 80 °C and exposure of the PVC/NBR blend to γ radiation up to 50 KGy do not practically affect the properties of this material.

Freshwater-Derived Streptomyces: Prospective Polyvinyl Chloride (PVC) Biodegraders

Polyvinyl chloride (PVC) is widely used in industrial applications, such as construction and clothing, owing to its chemical, physical, and environmental resistance. Owing to the previous characteristics, PVC is the third most consumed plastic worldwide and, consequently, an increasing waste accumulation-related problem. The current study evaluated an in-house collection of 61 Actinobacteria strains for PVC resin biodegradation. Weight loss percentage was measured after the completion of incubation. Thermo-gravimetric analysis was subsequently performed using the PVC incubated with the three strains exhibiting the highest weight loss. GC-MS and ionic exchange chromatography analyses were also performed using the culture media supernatant of these three strains. After incubation, 14 strains had a PVC weight loss percentage higher than 50% in ISP-2 broth. These 14 strains were identified as Streptomyces strains. Strains 208, 250, and 290 showed the highest weight loss percentages (57.6–61.5% range). The thermal stability of PVC after bacterial exposure using these three strains was evaluated, and a modification of the representative degradation stages of nonincubated PVC was observed. Additionally, GC-MS analysis revealed the presence of aromatic compounds in the inoculated culture media, and ionic exchange chromatography showed chloride release in the supernatant. A mathematical relation between culture conditions and PVC weight loss was also found for strains 208 and 290, showing an accuracy up to 97.99%. These results highlight the potential of the freshwater-derived Streptomyces strains as candidates for the PVC biodegradation strategy and constitute the first approach to a waste management control scale-up process.