A general method to improve 3D-printability and inter-layer adhesion in lignin-based composites

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Abstract

We report the utilization of a melt-stable lignin waste-stream from biorefineries as a renewable feedstock, with acrylonitrile-butadiene rubber and acrylonitrile-butadiene-styrene (ABS) polymer to synthesize a renewable matrix having excellent 3D-printability. While the initial low melt viscosity of the dispersed lignin phase induces local thermo-rheological relaxation facilitating the composite's melt flow, thermal crosslinking in both lignin and rubber phases as well as at the lignin-rubber interface decreases the molecular mobility. Consequently, interfacial diffusion and the resulting adhesion between deposited layers is decreased. However, addition of 10 wt.% of discontinuous carbon fibers (CFs) within the green composites not only significantly enhances the material performance but also lowers the degree of chemical crosslinking formed in the matrix during melt-phase synthesis. Furthermore, abundant functional groups including hydroxyl (from lignin) and nitrile (from rubber and ABS) allow combinations of hydrogen bonded structures where CFs play a critical bridging role between the deposited layers. As a result, a highly interfused printed structure with 100% improved inter-layer adhesion strength was obtained. This research offers a route toward utilizing lignin for replacement of petroleum-based thermoplastics used in additive manufacturing and methods to enhance printability of the materials with exceptional mechanical performance.

Original languageEnglish
Pages (from-to)138-152
Number of pages15
JournalApplied Materials Today
Volume12
DOIs
StatePublished - Sep 2018

Funding

This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy BioEnergy Technologies Office Program. C. C. B. acknowledges support from Wigner Fellowship Program as part of the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.

Keywords

  • 3D-printing
  • Carbon fibers
  • Inter-layer diffusion
  • Lignin composites
  • Weld energy

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