Application of micromechanical models to tensile properties of wood–plastic composites

Abstract

Wood–plastic composites (WPC) were produced with white birch pulp fibers of different aspect ratios (length-to-diameter), high-density polyethylene, and using two common processes: extrusion or injection molding. Three additive levels were also used: no additive, compatibility agent, and process lubricant. Fiber size was measured with an optical fiber quality analyzer. Tensile properties of WPC were measured and modeled as a function of fiber aspect ratio. Models were fitted to experimental values using the minimum sum of squared error method. A shift from the oriented fiber case (injection molding) to the randomly oriented fiber case (extrusion) was achieved using a fiber orientation factor. Fiber/matrix stress transfer increased with increasing fiber aspect ratio. Stress transfer was reduced with the use of process lubricant. Unexpectedly, the compatibility agent had the same effect. Fiber strength and stiffness contributions to the composite were lower than those of intrinsic fiber properties.

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Acknowledgments

The authors are grateful to the Canada Research Chair Program, the Ministère du développement économique et de l’innovation et de l’Exportation (MDEIE) du Québec, NSERC, Caisse Populaire Desjardins, Tembec, and the UQAT Foundation for financial support. The authors wish to thank Professor Michael Wolcott and Dr. Karl Englund from Washington State University for granting access to the Wood Engineering Material Laboratory and for their collaboration on this project.

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Correspondence to Ahmed Koubaa.

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Migneault, S., Koubaa, A., Erchiqui, F. et al. Application of micromechanical models to tensile properties of wood–plastic composites. Wood Sci Technol 45, 521–532 (2011). https://doi.org/10.1007/s00226-010-0351-5

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Keywords

  • Injection Molding
  • Fiber Orientation
  • HDPE
  • Tensile Modulus
  • Interfacial Shear Stress