@article { ISI:000236076400015, title = {Biodegradation of gamma-sterilised biomedical polyolefins under composting and fungal culture environments}, journal = {Polymer Degradation and Stability}, volume = {91}, number = {5}, year = {2006}, month = {MAY}, pages = {1105-1116}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Polyolefin-based commodities are widely used as biomedical devices and food packaging after gamma-sterilisation. The aim of the present work was to study the effect of gamma-sterilisation on the biodegradation of polyolefins. Films of isotactic polypropylene, high-density polyethylene and ethylene-propylene (EP) copolymers were sterilised under gamma-radiation with doses of 10 and 25 kGy. Neat and sterilised samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and chain scission in polymer chains were characterized by FTIR spectroscopy, SEM and viscometric measurements, respectively. A gradual decrease in intrinsic viscosity [eta] and increase in carbonyl and hydroxyl regions in FTIR spectra were found for the gamma-sterilised samples as a function of increasing dose. Polypropylene was found to be more susceptible to both radio-oxidation and biodegradation. It was observed that in case of ethylene-propylene copolymers, extent of gamma-sterilisation and/or biodegradation depends on the composition and distribution of comonomers. Important surface erosion was detected by SEM, for higher sterilisation doses, after composting. (c) 2005 Elsevier Ltd. All rights reserved.

}, keywords = {Biodegradation, chain scission, Composting and fungal culture, gamma-sterilisation, Polyolefins}, issn = {0141-3910}, doi = {10.1016/j.polymdegradstab.2005.07.004}, author = {Alariqi, Sameh A. S. and Kumar, A. P. and Rao, B. S. M. and Singh, R. P.} } @article { ISI:000239458500013, title = {Photo-bio-degradability of agro waste and ethylene-propylene copolymers composites under abiotic and biotic environments}, journal = {Journal of Polymers and the Environment}, volume = {14}, number = {2}, year = {2006}, month = {APR}, pages = {203-212}, publisher = {SPRINGER/PLENUM PUBLISHERS}, type = {Article}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Composites were prepared by two methods, (i) graft copolymerization (GFC) of isotactic polypropylene (PP) with maliec anhydride, (MAH) followed by esterification with coir fiber and (ii) by direct reactive mixing (DFC) of polypropylene (PP) and ethylene-propylene (EP) copolymers with MAH and peroxide with coir fiber. These composites, after molding in films (5 x 5 cm, - 100 mu m thickness) were examined for susceptibility to biological attack by measuring the percentage weight loss in compost upto 6 months, periodically, and fungal colonization on surface of the samples, when kept as sole carbon source for the growth of Aspergillus niger in culture medium upto 40 days. Photodegradation was evaluated by monitoring the variations in FT-IR spectrum and crack formation after successive treatment with UV light (\>= 290 nm) for 0, 20, 50 and 100 h at 60 C in the presence of air. Specimens of virgin PP were taken as a reference during all period of photo and biodegradation studies. Significant changes were observed depending on the preparation methods during photodegradation and biodisintegration of composites. DFCs samples were disintegrated faster than GFCs during the composting whereas, in culture, GFCs were covered highly in well uniform way by fungi. It was observed that photo-oxidative ageing directly enhanced the biodegradability of composites as the increase in fungal growth rate and decrease in weight during composting were found. It was concluded that extent of compatibilization had a profound effect on photo-oxidation and biodisintegration of composite material; consequently ester bonds were main units during fungal consumption. Composition of monomers in copolymers was also showing significant effect on the degradability which decreased with increasing content of ethylene in ethylene-propylene (EP) copolymers.

}, keywords = {Biodegradation, biodisintegration and composting, composites, ethylene-propylene copolymers, photo-degradation}, issn = {1566-2543}, doi = {10.1007/s10924-006-0012-9}, author = {Kumar, A. Pratheep and Pandey, Jitendra K. and Kumar, Bijendra and Singh, R. P.} } @article { ISI:000284374500018, title = {Effect of gamma-dose rate on biodegradation of gamma-sterilized biomedical polyolefins}, journal = {Journal of Polymers and the Environment}, volume = {18}, number = {4}, year = {2010}, month = {DEC}, pages = {600-607}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

The aim of the present study is to study the effect of gamma-dose rate on the biodegradation of gamma-sterilized polyolefins. Films of isotactic polypropylene, high density polyethylene and ethylene-propylene (EP) copolymer were sterilized under gamma-radiation with doses of 10 and 25 kGy. Two different (60)Co sources were used with dose rate 600 and 780 Gy h(-1). Neat and sterilized samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and intrinsic viscosity in polymer chains were characterized by FT-IR spectroscopy, SEM and viscometric measurements, respectively. It was observed that both gamma-degradation and biodegradation processes depend on the dose rate of gamma-source. It was found that the biodegradation of gamma-sterilized polyolefins in composting and microbial culture environments increased with decreasing the gamma-dose rate.

}, keywords = {Biodegradation, Composting and fungal culture, gamma-Dose rate, Polyolefins, Sterilization}, issn = {1566-2543}, doi = {10.1007/s10924-010-0217-9}, author = {Alariqi, Sameh A. S. and Singh, R. P.} }