Poly(lactic acid)/pulp fiber composites: The effect of fiber surface modification and hydrothermal aging on viscoelastic and strength properties

Sara Paunonen (Corresponding Author), Fredrik Berthold, Kirsi Immonen

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Abstract

Poly(lactic acid) (PLA)/kraft pulp fiber (30 wt%) composites were prepared with and without a coupling agent (epoxidized linseed oil, ELO, 1.5 wt%) by injection molding. The non‐annealed composite samples, along with lean PLA, were exposed to two hydro‐thermal conditions: cyclic 50% RH/90% RH at 23 and 50°C, both up to 42 days. The aging effects were observed by size exclusion chromatography, differential scanning calorimetry, dynamic and tensile mechanical analysis, and fracture surface imaging. ELO temporarily accelerated the material's internal transition from viscous to an increasingly elastic response during the aging at 50°C. ELO also slowed down the tensile strength reduction of the composites at 50°C. These observations were explained with the hydrophobic ELO molecules' coupling and plasticizing effects at fiber/matrix interfaces. No effects were observed at 23°C.
Original languageEnglish
Article number49617
JournalJournal of Applied Polymer Science
Volume137
Issue number42
Early online date27 Jun 2020
DOIs
Publication statusPublished - 10 Nov 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • aging
  • biopolymers and renewable polymers
  • cellulose and other wood products
  • composites

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