25/02/2015 · Polylactic acid plastic ..
Solvent evaporation, Indomethacin, Polylactic acid, Microspheres, Stirring speed, Particle size
Poly(lactic acid) Synthesis in Solution Polymerization ..
The annual production of L-lysine is about 1 million tonnes, with China producing 35%. It is an essential amino acid, meaning that most vertebrates cannot synthesise it. It is often deficient in livestock diets so the major use of L-lysine is in animal feed.
There have been studies to obtain high molar mass polymer by manipulating the equilibrium between lactic acid, water and polylactic acid in an organic solvent or a multifunctional branching agent was used to give star-shaped polymers.
From Lactic Acid to Polylactic Acid
With the exception of aminoethanoic acid (glycine), the industrially produced amino acids are chiral and the two isomers (D and L) have different properties in biologically induced reactions. However, chemical synthesis produces equimolar quantities of D- and L- forms and additional expensive steps are required to produce a pure stereoisomer. However, biotechnological routes have the great advantage of producing pure optically active amino acids.
The synthesis of polylactic acid through polycondensation of the lactic acid monomer gave weight average molecular weights lower than 1.6 x 10 4, whereas ring opening polymerisation of lactides gave average molecular weights ranging from 2 x 10 4 to 6.8 x 10 5.
for the polymerization of polylactic acid
Petrochemicals are a finite resource which will become more expensive as oil becomes scarce, and their use is associated with the release of greenhouse gases that lead to global warming. Producing more chemicals using biotechnology could reduce our dependence on natural gas and oil and reduce the environmental impact of the chemical industry. Some chemicals, such as 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), have for many years been routinely produced on the million-tonne scale using biotechnology, as the chemical synthetic routes are complex and expensive. Other notable examples are described in this unit but there are many other processes still in the developmental stage, with chemicals being produced in small reactors on the scale of a few tonnes. A huge amount of research is being done by chemists, biotechnologists and engineers to make these reactions more efficient and cost-effective.
ABSTRACT: In order to evaluate the effects of different processing parameters on drug-loaded microspheres, the solvent evaporation technique was chosen as the formulation method. Indomethacin-loaded Polylactic acid microspheres were prepared by varying drug masses, then by changing the stirring speed. They were analyzed for their drug content, physical morphology, size, polymer-drug physicochemical compatibility, and in vitro drug release. Microspheres revealed a spherical profile along with a porous structure. The effect of changing the drug mass was noted on drug encapsulation and loading efficiencies. Indomethacin had better encapsulation when introduced in small amounts. On the other hand, the effect of changing the stirring speed was remarkable on the size of obtained microspheres and drug release profile. The particle size decreased as the speed of mixing increased. In addition, a faster drug release was observed for larger microspheres.
Polylactic acid (PLA) synthesis …
Based on the fact that the polylactic acid ..
Technological and economical potential of polylactic acid and lactic acid derivatives.
Polylactic acid - Howling Pixel
Polylactic acid - Wikipedia
Polylactic acid This page was last ..
Polylactic acid ..
Synthesis and Hydrophilic Performance of Poly(Lactic Acid) ..
Biotechnology is defined as the application of the life sciences to chemical synthesis. This unit discusses its increasingly important role in the direct production of speciality chemicals via fermentation, such as citric acid, lactic acid, propane-1,3-diol and some amino acids.
There have been two processes in the synthesis of polylactic acid, ..
The disposal problem due to non-degradable petroleum-based plastics has raised the demand for biodegradable polymers. Poly(lactide) (PLA) is a biodegradable aliphatic polyester derived from 100% renewable resources, such as corn and sugar beets. Moreover, it has unique physical properties that make it useful in diverse applications including paper coating, fibers, films, and packaging. In this work, the results of the synthesis of high molar weight poly(L(+) lactic acid) (PLA) which is able to thermally crystallize have been described. The synthesis of poly(L(+) lactic acid) was carried out in a solution of p-xylene. Tin(II) chloride was used as catalysts in a quantity of 1.0 wt% calculated on the monomer. Polycondensation was carried out over a period from ten to over 20 h. The resulting poly(L(+) lactic acids) were characterized by FT-IR, DSC and the GPC. The molecular weight of PLLA reached as high as 26000. FTIR spectra of PLLA were analyzed to determine the configuration of the PLLA. The main byproduct of condensation polymerization is cyclo-polyester. The glass transition temperature of PLA after is 46.25°C. PLA after the recrystallization does not show glass transmission temperature because the crystallinity is more than 40%.
polylactic acid by ring-opening polymerization of a lactide ..
Polylactic acid (PLA) belongs to the family of polyesters. It has several characteristics that make it very important in biomedicine, such as good mechanical properties, non-toxicity, biodegradability and biocompatibility 10. PLA can be used into rods, bone screws, sutures, tissue engineering scaffolds, and microspheres for the delivery of a variety of drugs as anti-fungal, anti-inflammatory, or steroids 11-14.
Polylactic Acid (PLA) is the first ..
Polylactic acid or polylactide (PLA) is a thermoplastic aliphatic polyester derived from renewable resources, such as corn starch (in the United States), tapioca roots, chips or starch (mostly in Asia), or sugarcane (in the rest of the world).
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