High-Strength Polylactic Acid (PLA) Biocomposites Reinforced by Epoxy-Modified Pine Fibers

Xianhui Zhao, Kai Li, Yu Wang, Halil Tekinalp, Gregory Larsen, Daniel Rasmussen, Ryan S. Ginder, Lu Wang, Douglas J. Gardner, Mehdi Tajvidi, Erin Webb, Soydan Ozcan

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

The stiffness and tensile strength of biopolymers (e.g., polylactic acid (PLA)) are less than desirable for load-bearing applications in their neat form. The use of natural fibers as reinforcements for composites (for large-scale three-dimensional (3D) printing) has expanded rapidly, attributable to their low weight, low cost, high stiffness, and renewable nature. Silane and acid/alkali are typically used to modify the surface of natural fibers to improve the fiber/polymer interfacial adhesion. In this study, a simple method of impregnation was developed to modify pine fibers (loblolly, mesh size of 90-180 μm, 30 wt %) with a solvent-borne epoxy to reinforce PLA. As a benefit of the epoxy modification (0.5-10 wt %), the tensile strengths and Young's moduli of the epoxy-modified pine/PLA composites increased by up to 20 and 82%, respectively, as compared to that of neat PLA. The epoxy-modified pine/PLA composites, with an optimum epoxy modification (1.0 wt %), had fewer voids on the fracture surface as compared with pine/PLA composites without the modification of pine fibers via epoxy. Results confirmed that epoxy partially penetrated the pore/hollow inner structures of pine fibers and improved the fiber/matrix interfacial adhesion. Epoxy modification is found to be a simple and effective technique to improve the properties of biocomposites.

Original languageEnglish
Pages (from-to)13236-13247
Number of pages12
JournalACS Sustainable Chemistry and Engineering
Volume8
Issue number35
DOIs
StatePublished - Sep 8 2020

Funding

The authors would like to acknowledge financial support from the U.S. Department of Energy (DOE), FY 2019 BETO Project, under Contract 2.5.6.105 with UT-Battelle LLC. The authors thank the members of the Carbon and Composites Group and Manufacturing Science Group of Oak Ridge National Laboratory for their kind help during the research. Scanning electron microscopy studies were completed at the Center for Nanophase Materials Sciences (CNMS), a DOE Office of Science User Facility. This manuscript was authored in part by UT-Battelle LLC under contract DE-AC05-00OR22725 with DOE. The U.S. government retains, and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Keywords

  • biocomposite
  • epoxy
  • impregnation
  • natural fiber
  • pine
  • polylactic acid

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