Abstract
The aim of the present work is to study the effect of different sterilization methods on the biodegradation of biomedical polypropylene (PP) under the same biotic conditions. Three different sterilization techniques; γ-irradiation, steam sterilization and UV-irradiation were used to compare the effect of different sterilization methods on the biodegradability of PP. Neat and sterilized samples were incubated in compost and fungal culture environments. The changes in functional groups, mechanical properties, surface morphology and intrinsic viscosity in polymer were characterized by FT-IR spectroscopy, Instron, SEM and viscometric measurements, respectively. It was observed that the biodegradation of γ-sterilized samples in composting and microbial culture environments was higher than UVirradiated samples, while UV-irradiated more than steam-sterilized and neat samples. The results showed that the radio and photo-oxidative pretreatment directly enhanced the biodegradability of PP as the increase in fungal growth rate and weight loss during composting was found. The biodegradation rate of PP at the same biotic conditions mainly depends on the rate of degradation that initially occurred during sterilization. Overall, this study demonstrated that the biodegradation of sterilized PP in biotic conditions significantly depends on the nature of sterilization method.
Highlights
The unique properties of polyolefins such as durability, transparency, mechanical properties, low cost, resistance to weathering and photo-degradation as well as biological attack and hydrophobicity, have contributed to their skyrocketing utility in different applications
The formation of oxidation products in γ-sterilized samples (G-PP) was higher than UVirradiated samples (U-PP), while steam-sterilized samples (S-PP) showed lower oxidation products. This indicates that the oxidative degradation occurred due to γ-sterilization is higher than other sterilization methods
The increasing order in the rate of biodegradation was found to be similar to the increasing order in the rate of degradation after sterilization (G-PP > U-PP > S-PP). This indicates that the biodegradation rate at the same biotic conditions mainly depends on the rate of degradation that initially occurred during sterilization
Summary
The unique properties of polyolefins such as durability, transparency, mechanical properties, low cost, resistance to weathering and photo-degradation as well as biological attack and hydrophobicity, have contributed to their skyrocketing utility in different applications. Any change of the polymer properties relative to the initial desirable properties is called “degradation”. In this sense, degradation is a generic term for any number of reactions that are possible in a polymer. The degradation of polymers involves several physical and/ or chemical processes accompanied by structural changes which lead to significant deterioration of the quality of the polymeric materials (i.e., worsening of its mechanical) and to the loosening of its functionality. A number of factors are responsible for the deterioration of the polymer properties, such as oxidative and thermal degradation, photo irradiation, highenergy irradiation, biological, chemical and climate factors, etc.; all these factors limit their service life. The degradation process of the polymer has specific mechanism and depends on the type of degrading agent and the nature of macromolecular chain and structure
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