Abstract: This work presents the preparation of thermoset poly(lactic acid) (PLA) through polycondensation and cross-linking reactions. Firstly, four-armed star-shaped poly(lactic acid) (4sPLA) with short chains was synthesized by polycondensation using L-lactic acid as monomer and pentaerythritol as initiator, and was hydroxyl-terminated using methacrylic anhydride to obtain the unsaturated-group-terminated star-shaped oligomer precursor (M4sPLA) capable of cross-linking and solidification. Then, the thermoset PLA samples were obtained by a free-radical-initiated cross-linking reaction, and the effects of polycondensation duration on mechanical properties and thermal stability of the thermoset PLA product were studied. The results showed that the reaction initiation efficiency can be obviously enhanced by increasing the polycondensation duration, which lead to low inpurity content, high molecular weight and low polydispersity of 4sPLA. Moreover, the prolonged polycondensation duration is conducive to higher cross-linking density of the thermally cured PLA product. The most satisfactory mechanical properties, thermal stability and microstructure of the thermoset PLA could be achieved when the polycondensation reaction duration was 20 h.
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2019, Vol. 33 
