Preparation and Characterization of Poly(lactic acid) with Different Molecular Weights by Thermal Hydrolysis

Abstract

A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligomers with different controlled molecular weight from PLA is presented in this paper. The thermal hydrolytic reaction was carried out by immerging PLA resin pellets in boiling distilled water for a certain period of time. Ester groups in PLA chains are hydrolytically degraded in the presence of water and thermal, so PLA oligomers with different molecular weight were prepared. The structures and properties of PLA oligomers were characterized by FT-IR, GPC, DSC, etc. The results showed that thermal hydrolytic reaction could effectively reduce the molecular weight of PLA, which declines with the increase of the thermal hydrolytic reaction time. Meanwhile, the content of terminal hydroxyl group, glass transition temperature, melting point of PLA oligomers prepared from thermal hydrolytic reactions exhibit gradual changes with the extension of the thermal hydrolytic time.

A journey across the solid state polymerization to assess the role of critical factors influencing the molecular weight of polylactic acid

“…The glass transition temperature of prepolymers decreased from 63°C for PLA to lower temperatures and finally disappeared in the case of H7 specimen. The glass transition temperature is strongly dependent on the degree of chain entanglement that is expected to be decreased by diffusing the water molecules playing the role of plasticizer into PLA chains .…”

Development of Online Spectroscopic pH Monitoring for Nuclear Fuel Reprocessing Plants: Weak Acid Schemes

“…The commercial lactic acid/lactate stock was diluted with water to approximately 3 M and boiled for 24 h to eliminate esterification/polymerization effects . The lactic acid concentration was measured by titration using a Metrohm 800 Dosino Automatic Titration device equipped with Tiamo 1.2 software.…”

“…The commercial lactic acid/ lactate stock was diluted with water to approximately 3 M and boiled for 24 h to eliminate esterification/polymerization effects. 20 The lactic acid concentration was measured by titration using a Metrohm 800 Dosino Automatic Titration device equipped with Tiamo 1.2 software. The pH was adjusted as needed by addition of NaOH and pH was measured using an ORION 3 STAR meter along with the ORION 8103BNUWP ROSS Probe.…”