lunes, 19 de abril de 2010

Quimica - Chemistry: Biopolymers plastics from renewable sources


The need to reduce the high degree of dependence on fossil compounds, suggesting the incorporation within the oil chain of renewable raw materials, which affect not only energy production but also the products of the petrochemical industry such as plastics. This possibility is given inter alia by the production of biodegradable polymers from residual carbon sources as feedstock.

For the production of common plastic materials are used non-renewable fossil reserves, contributing to the depletion of natural energy that the planet has, contributing to increased greenhouse gases (GHGs). These conventional materials, by their nature, are stable from the chemical viewpoint, which means that they remain unchanged for long periods in the environment. Biopolymers Biopolymers renovableLos origin plastics plastics are renewable source molecular structures composed of chains of monomers, which together have a structure and properties similar to plastics of fossil origin. UsanBiopolímeros plastic renovabledo feedstock source for bacterial fermentation of carbon sources from renewable sources, such as sugars from energy crops or waste generated in different industries (biodiesel, sewage, biomass ...) are available these biopolymers, with the fundamental property that are biodegradable and completely safe at the time of decomposition.

For use as raw material, waste from the biodiesel industry (crude glycerin), biopolymers are more projection from PLA (polylactic acid) and PHA (polihidroxialcanatos), obtained by bacterial fermentation and with properties similar to thermoplastics. Biopolymers plastics from renewable sources and characteristics of properties that these polymers possess biodegradability, make them very versatile for a wide range of functions, such as use in the packaging (containers), profit biomedical (sutures, temporary sccalfolds, release capsules controlled and facial surgery) mainly. Biopolymers from renewable sources plastic polylactic acid (PLA) Polylactic acid or PLA is a polymer of lactic acid polymers can replace non-renewable resource based. The advantages are its biodegradability and its possible origin from renewable raw materials. The main route now followed for the commercial production of lactic acid is based on the use of sugar or starch substrate (usually of plant origin) by fermentative bacteria. Among the different plastic biodegradable polylactic acid (PLA) is has the greatest potential as a substitute for conventional plastic because, besides their excellent mechanical and physical properties, can be processed by existing machinery. The PLA is also a very versatile material that can be processed with several formulations to meet most specifications of different products. Polihidroxialcanato (PHA) The polyhydroxyalkanoates (PHAs) are polymers produced as reserve materials by various groups of bacteria that are of wide application in biotechnology and the pharmaceutical industry. Are synthesized when the culture medium has an excess carbon source and a defect of another type of nutrient, usually nitrogen or phosphorus. Are deposited in bacteria as inclusion bodies, occupying more than 90% by weight, to be used as carbon and energy source under conditions of nutritional shortage. The most known and used polihidroxialcanato is poly-3-hydroxybutyric acid (PHB). The properties of the polymer that forms are similar to those of propylene, as defined as a thermoplastic. The main difference has to petroleum polymers is their biodegradability by microorganisms (bacteria, fungi and algae) that transform the PHAs into harmless substances such as CO2 and water.

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