Improving Processing, Crystallization, and Performance of Poly-L-lactide with an Amide-Based Organic Compound as Both Plasticizer and Nucleating Agent

Nils Leone, Manta Roy, Sarah Saidi, Gijs de Kort, Daniel Hermida-Merino, Carolus H. R. M. Wilsens*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

In this work, we report on a novel hydrogen-bonding compound, N,N'-bis(2-hydroxyethyl)-terephthalamide (BHET), and its potential as additive in poly-L-lactide (PLA). Although the hydroxyl groups of BHET can participate in transesterification with the PLA matrix, we demonstrate through gel permeation chromatography that extrusion at 200 degrees C does not result in a drastic decrease in molecular weight. When dissolved in the PLA matrix, BHET facilitates a plasticizing effect, indicated by a suppression in both melt viscosity and glass-transition temperature. Additionally, BHET can crystallize from the PLA melt during cooling, where the generated BHET crystals facilitate heterogeneous nucleation of the PLA matrix. In general, BHET crystallization is favored at high undercooling/superstaturation, as this yields BHET crystals with a high surface area-to-volume ratio. However, rapid cooling to temperatures below the glass-transition temperature prevents the crystallization of the BHET, effectively yielding samples where only the plasticizing effect of BHET is evident. A suppression in yield point is observed during mechanical analysis of samples with increasing BHET concentration, a characteristic feature for samples with decreasing glass-transition temperatures. In contrast, when allowed to crystallize during processing, BHET can be used to generate PLA crystals oriented along the flow direction, effectively enhancing the tensile modulus. Overall, the combined plasticizing and nucleating effect of BHET makes it a verstaile additive for controlled processing and performance of PLA.

Original languageEnglish
Pages (from-to)10376-10387
Number of pages12
JournalAcs omega
Volume4
Issue number6
DOIs
Publication statusPublished - Jun 2019

Keywords

  • POLY(LACTIC ACID)
  • ISOTACTIC-POLYPROPYLENE
  • MECHANICAL-PROPERTIES
  • POLY(L-LACTIC ACID)
  • OXALAMIDE COMPOUNDS
  • HYDRAZIDE COMPOUND
  • BEHAVIOR
  • TRANSITION
  • MELT
  • ORIENTATION

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