Green solvents, plastics and biocomposites for sustainable development
Green chemistry is the design of chemical products and processes that are more environmentally benign. Among others, it advocates atom economy, waste reduction, use of safe solvents, avoidance of hazardous chemicals, energy efficiency and use of renewable feedstock. In this presentation, the role of alternative solvents, green plastics and biocomposites is highlighted. Solvents that are currently used in industry and research are largely volatile organic compounds (major environmental concern), hazardous and flammable. Hence the need for solvents that are stable, inexpensive, and with an acceptable environment impact. They include supercritical fluids [SCF] and ionic liquids. Key advantages with SCF include improved heat and mass transfer (due to high diffusion rates and low viscosities), large operating window in supercritical region and easy solvent removal and recycle.
An ionic liquid generally consists of a large nitrogen-containing organic cation and a smaller, inorganic anion. The asymmetry reduces the lattice energy of the crystalline structure and results in a low-melting-point salt. They exhibit near-zero vapour pressure, are nonflammable and non-oxidizing. Ionic liquids represent new media for synthesis and modification of polymers and are also investigated as designer additive of the polymer materials, as novel electrolytes in batteries, plasticizers, etc. Green plastics are often obtained from renewable sources and may be cellulose based, starch based, polyhydroxy alkanoates, polylactic acid. Biocomposites are polymer matrix composites reinforced with natural fibres such as sisal, pineapple leaf fibre [PALF], jute, coir, etc. The fibres are renewable, abundant, cheap and eco-friendly. They are evaluated as environmentally friendly and low-cost alternatives for glass fibres in engineering composites. The mechanical properties, processing behavior and applications of the ‘green composites’ are discussed.
Department of Chemical Engineering and Materials Science
Amrita Vishwa Vidyapeetham University, Coimbatore 641112 India
Phone : +91(422) 2685551 Fax : +91(422)2656274
