Development of a Direct Polycondensation Process for Poly (L-lactic acid)
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T. Fukushima
Abstract
Poly(L-lactic acid) (PLLA) is quite promising for use as biodegradable and non-petroleum derived plastics. In this study we developed an innovative two-step polycondensation process so as to produce economically PLLA with high molecular weight. The process is composed of both melt polycondensation under the lactide-re ux and solid-phase polycondensation. First we studied a direct polycondensation of L-lactic acid with a small amount of solvent, using a mixture of L-lactic acid as raw material, diphenyl ether as solvent, Tin (II) chloride dihydrate as catalyst, and p-toluene sulfonic acid as a discoloration prevention agent. After the dehydrative oligomerization of L-lactic acid, the polycondensation of the oligocondensates and solid-phase post-polycondensation, PLLA of Mw = 266,000 could be obtained. Then, we carried out direct bulk polycondensation tests from L-lactic acid without any solvent added. After optimization of the reaction conditions, PLLA with Mw = 134,000 was successfully produced by the melt-poly-condensation of L-lactic acid accompanied by solid-phase post-poly-condensation. In both systems, the lactide-re ux was indispensable for promoting dehydration/water removal. The re uent lactide was taken into the polymer-chain by trans-esterification reaction during the melt-poly-condesation. Furthermore, the catalyst was allowed to deactivate and stabilize during the solid-phase polymerization to cause the Mw growth.
© 2000, Carl Hanser Verlag, Munich
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Articles in the same Issue
- Editorial
- Seventh of a Series: Pioneer of Carbonaceous Pitch Processing Sugio Otani
- Invited Paper
- Injection Blow Molding Technology for Polyethylene Terephthalate
- Screw Extrusion/Mixing
- A New Polymer Processing Technology for Polymer Blends with Unmatched Viscosity: Solid-State Shear Pulverization (S3P)
- In-Line Density Monitoring of Rigid PVC Foam during Extrusion Process
- In-Process R eometry Studies of LDPE Compounds
- In-Process R eometry Studies of LDPE Compounds
- Rheological and Morphological Properties of Immiscible Blends and Microfiber Preparation from the Blends
- Reactive Extrusion
- Development of a Direct Polycondensation Process for Poly (L-lactic acid)
- Fiber and Film
- Radially Dependent Stress and Modeling of Solidi cation in ilament Melt Spinning
- Structure Development in Melt Spinning Syndiotactic Polypropylene and Comparison to Isotactic Polypropylene
- Fibers and Films
- Investigation of Structure and Properties in Biaxially Stretched Poly(butylene terephthalate) Films
- Molding
- Filling and Postfilling Analysis of Injection/Compression Molding
