Water Absorption and Performance Degradation of Natural Fiber Reinforced Thermoplastic Composites

• Water Absorption and Performance Degradation of Natural Fiber Reinforced Polyethylene Composites

• Author / Creator

  Robertson, Nicole Lee M.

• Natural fiber reinforced polyethylene biocomposites are an environmentally friendly alternative to non-biodegradable thermoplastic materials. The addition of natural fibers to polyethylene improves mechanical properties such as tensile modulus and tensile strength. Unlike thermoplastics, biocomposites are water absorbant due to the presence of natural fibers. Biocomposites mechanical properties degrade when exposed to water. Immersion in water shortens the product life of biocomposites and limits their use in many applications. However, a shorter product life is advantageous for some applications because early degradation reduces the material's environmental impact. The work herein explores long-term water immersion (6000+ hours) of injection molded hemp and wood pulp fiber reinforced polyethylene. Both low density polyethylene (LDPE) and high density polyethylene(HDPE) were tested, each with three fiber fill fractions. The comprehensive dataset collected for this project allowed for conclusions to be drawn about the effect of fiber type, content and distribution as a function of immersion time to predict water absorption. The extent of mechanical degradation was proven to be dependent on the quantity of water absorbed. A model was developed to predict the percentage of water absorbed over a long time scale that accounts for fiber degradation to enable the prediction of changes to the mechanical properties. The prediction of the rate and magnitude of water absorption by natural fiber thermoplastic composites will allow designers to understand, and account for, the degradation of the material's mechanical properties over time.

• Subjects / Keywords

  • Water absorption
  • Mechanical properties
  • Degradation
  • Polyethylene
  • Natural fiber

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3XD0RB7B

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.