Anisotropic nucleation and Janus-faced crystals of poly(l -lactic acid) interacting with an amorphous diluent

Eamor Woo, Hikmatun Ni'Mah, Yu Hsiang Wang

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Atomic-force microscopic and X-ray techniques were applied to reveal and analyze uniquely three types of distinctly different crystals, including a Janus-face composite type of spherulites in LMw-PLLA induced by mixing with aPMMA (20 wt %). One type (Type-1) is completely packed by fibrous lamellae, while the second type (Type-2) is completely packed by flat-on platelet crystals; and the third type, a dual-faced (i.e., Janus-faced - Type-3) spherulite with two distinguished patterns filling the composite spherulite's perpendicular quadrants that is originated from sheaf-like directional growth from nuclei to pack into fibrous lamellae, while the perpendicular growth was diffusion-drained leading to thinner flat-on platelets. The Janus-face spherulite type (half-and-half fibrous lamellae and flat-on platelets) became more significant only when the 80/20 mixtures were melt-crystallized at T c = 110-115 °C. That is, existence of Type-3 Janus-faced spherulite is composition- and temperature-selective for favorable nucleation and growth. Mechanisms leading to such diversified patterns and Janus-face spherulites in the LMw-PLLA/aPMMA blend were probed.

Original languageEnglish
Pages (from-to)9772-9780
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Volume53
Issue number23
DOIs
Publication statusPublished - 2014 Jun 11

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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