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Polymer biodegradation: mechanisms and estimation techniques.

Recent trends in biodegradable polymers indicate significant developments in terms of novel design strategies and engineering to provide advanced polymers with comparably good performance. However, there are several inadequacies in terms of either technology or cost of production especially in the case of applications in environmental pollution. So, there is a need to have a fresh perspective on the design, properties and functions of these polymers with a view to developing strategies for future developments. The paper reviews the present state-of-art on biodegradable polymers and discusses the salient features of the design and properties of biodegradable polymers. Special emphasis is given to the problems and prospects of (1) approaches adopted to make non-biodegradable synthetic polymers such as polyethylene biodegradable and (2) biodegradable polymers and copolymers made from renewable resources especially poly(lactic acid) based polymers and copolymers which are emerging as the candidate biodegradable materials for the future.

Biodegradable Polymers- A Review on Recent Trends and Emerging Perspectives

1 A Practical Introduction to Differential Scanning Calorimetry. 2 Fast Scanning DSC. 3 ThermoGravimetric Analysis. 4 Principles and applications of mechanical thermal analysis. 5 Applications of thermal analysis in electrical cable manufacture. 6 Application to Thermoplastics and Rubbers. 7 Thermal Analysis of Biomaterials. 8 Pharmaceuticals. 9 Thermal methods in the study of foods and food ingredients. 10 Thermal analysis of inorganic compound glasses and glass-ceramics

Principles and applications of thermal analysis

Due to the depleting fossil fuel sources such as crude oil, natural gas, and coal, the present rate of economic growth is unsustainable. Therefore, many sources of renewable energy have been exploited, but the potentials of some other sources such as plastics waste are yet to be fully developed as full scale economic activity. Development and modernization have brought about a huge increase in the production of all kinds of plastic commodities, which directly or indirectly generate waste due to their wide range of applications coupled with their versatility of types and relatively low cost. The current scenario of the plastic recycling technology is reviewed in this paper. The aim is to provide the reader with an in-depth analysis with respect to the pyrolysis of plastic waste as obtained in the current recycling technology. As the calorific value of the plastics is comparable to that of hydrocarbon fuel, production of fuel from plastic waste would provide a good opportunity to utilize the waste as a better alternative to dumpsites. Different techniques of converting plastics waste into fuel including thermal and catalytic pyrolysis, microwave-assisted pyrolysis and fluid catalytic cracking are discussed in detail. The co-pyrolysis of plastics waste with biomass is also highlighted. Thus, an attempt was made to address the problem of plastic waste disposal as a partial replacement of the depleting fossil fuel with the hope of promoting a sustainable environment.

Current state and future prospects of plastic waste as source of fuel: A review

Radiochemical oxidation of ethylene–propylene elastomers in the presence of some phenolic antioxidants

The effect of metals on thermal degradation of polyethylenes

Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

Novel procedure to enhance PLA surface properties by chitosan irreversible immobilization

Composite materials containing in different ratios poly(vinyl alcohol) (PVA), bacterial cellulose (BC) and glycerol (G) as plasticizer were obtained and exposed to different γ radiation doses using an irradiator GAMMATOR provided with 137Cs source. These films successively received up to 50 kGy absorbed doses at a dose rate of 0.4 kGy/h at room temperature. In order to study the chemical and structural changes during γ irradiation, Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and UV–Vis spectroscopy were used. Water vapour permeability (WVP), Hunter colour parameters and hardness were also measured for the irradiated samples. Investigation revealed that WVP was not significantly affected by the irradiation. Colour measurements indicated a slight decrease of pure PVA films transparency and it made clear that all samples became more reddish and yellowish after irradiation. The samples hardness was not affected by the irradiation doses used. However, the results showed no drastic structural or chemical changes of the irradiated samples, which prove, in consequence, a good durability. These composite materials could be used as packaging materials for γ irradiated products.

Traian Zaharescu

Papers

Radiochemical oxidation of ethylene–propylene elastomers in the presence of some phenolic antioxidants

The effect of metals on thermal degradation of polyethylenes

Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

Novel procedure to enhance PLA surface properties by chitosan irreversible immobilization

Effect of gamma irradiation on biopolymer composite films of poly(vinyl alcohol) and bacterial cellulose