2013年8月9日星期五

PLA synthesis methods using direct polymerization


PLA synthesis methods using direct polymerization, ring-opening polymerization, copolymerization and the polymerization of a chain extender. Is currently used more ring-opening polymerization, the method can be obtained relatively large molecular weight, high mechanical strength polymer. Sodium lactate is an isotactic polymer, wherein the main chain of the stereochemistry of the polymerization process in the PLA by adjusting the D-and L-lactic acid monomer to form a random or block ratio of stereoregular polymer, and the relative molecular mass directly by adding a compound containing a hydroxyl group (such as lactic acid, water, alcohol, etc.) to control. Further, by controlling the stereochemistry of PLA, can accurately control the zinc lactate,  the crystallization rate, mechanical properties and processing temperature, can be indirectly controlled polymer degradation rate. Large molecular weight PLA is colorless, has a high strength and modulus properties similar to polystyrene.

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