Effects of molten poly(3-hydroxybutyrate) on crystalline morphology in stereocomplex of poly(L-lactic acid) with poly(D-lactic acid)

Ling Chang, E. M. Woo

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Effects of poly(3-hydroxybutyrate) (PHB) on crystalline morphology of stereocomplexing capacity of poly(L- and D-lactic acid) (PLLA and PDLA) were studied by differential scanning calorimetry (DSC), polarizing-light optical microscopy (POM), atomic-force microscopy (AFM) and wide-angle X-ray diffraction (WAXD). When crystallized at high Tc (130 °C or above), morphology transition of stereocomplexed PLA (sc-PLA) occurs from original well-rounded Maltese-cross spherulites to dendritic form in blends of high PHB contents (50 wt.% or higher), where PHB acts as an amorphous species. Microscopy characterizations show that morphology of sc-PLA in PHB/sc-PLA blends crystallized at Tc = 170 °C no longer retain original complexed Maltese-cross well-rounded spherulites; instead, the spherulites are disintegrated and restructured into two types of dendrites: (1) edge-on feather-like dendrites (early growth) and (2) flat-on wedge-like crystal plates (later growth) by growing along different directions and exhibiting different optical brightness. The concentration and/or distribution of amorphous PHB at the crystal growth front, corresponding to variation of the slopes of spherulitic growth rates, is a factor resulting in alteration and restructuring of the sc-PLA spherulites in the blends. Despite of spherulite disintegration, WAXD result shows that these two PHB-induced dendrites still retain the original unit cells of complexes, and thus these two new dendrites are sc-PLA.

Original languageEnglish
Pages (from-to)68-76
Number of pages9
Journalpolymer
Volume52
Issue number1
DOIs
Publication statusPublished - 2011 Jan 7

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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