Effect Dehydrants to Increasing Molecular Weight of Condensed Polylactic Acid

Abstract:

The polylactic acid (PLA) was prepared by direct melt polycondensation using lactic acid aqueous solution as raw material. Considering of the difficulty to rule out small molecules of water, magnesium or magnesium methoxide which could react with water were used as dehydrant and added in the PLA polycondensation, respectively. The determination of moisture, GPC and DSC results showed that both the magnesium and magnesium methoxide are effective in dehydration, the molecular weight of final products PLA is significantly improved and the latter is better. Both of them have a good promoting effect on polycondensation reaction to get a higher molecular weight polylactic acid products. For the time of adding magnesium and magnesium methoxide, it is better to add in the late stage of polycondensation reaction rather than early stage. Furthermore, magnesium has a smaller influence on crystallization of PLA, whereas the crystallinity of PLA is greatly reduced after adding magnesium methoxide.

• Periodical: Applied Mechanics and Materials (Volume 456)
• Pages: 525-528
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.456.525
• Online since: October 2013
• Authors: Meng Yan Yin, Rong Jie Yang*, Ding Hua Li
• Keywords: Dehydrant, Direct Melt Polycondensation, Magnesium, Magnesium Methoxide, Poly(lactic acid) (PLA)

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