Advisor(s)
Haibin Ning
Committee Member(s)
Selvum Pillay
Shane Aaron Catledge
Tianjiao Lei
Vinoy Thomas
School
School of Engineering
Document Type
Dissertation
Department (new version)
Materials Engineering
Date of Award
1-6-2025
Abstract
Natural fiber reinforced composites have garnered significant interest as potential substitutes for conventional materials because of their eco-friendly attributes and favorable physical and mechanical properties. Typically, natural fibers undergo chemical treatments to enhance their compatibility with the polymer matrix prior to composite production. However, these treatments primarily affect the surface of the fiber bundles and have a limited impact on the inner elementary fibers within the bundle. This research work introduced a mechanical treatment method for hemp fiber by using an elevated temperature aqueous condition and mechanical force, which broke down the technical fiber bundles into elementary fibers and created a fourfold increase in fiber surface area for further chemical treatment and fiber-matrix bonding surface area. First, the impacts of this elevated temperature aqueous debundling method on the variation of hemp fibers dimensional features and the specific fiber surface area were investigated. The reinforcement effects of debundling treated fibers with different debundling times on their mechanical properties were studied and compared with composites reinforced by alkaline treated fibers. The results presented that the low density polyethylene (LDPE) reinforced by hemp fibers using the debundling treatment method had improved tensile, flexural, and impact properties over the LDPE reinforced with alkaline treated fibers. Second, the debundling treatment was successfully combined with the alkaline treatment to further improve the bonding suitability for the matrix. The untreated and treated fiber reinforced epoxy composite panels were manufactured via compression molding. The influence of the specific fiber surface area on the mechanical performance of composite samples was analyzed, including tensile, flexural, and impact properties. The experimental results indicated that the combination of debundling treatment and alkaline treatment provided better interfacial bonding between the debundled fiber and epoxy matrix. The apparent enhancement of the mechanical behaviors proved that the specific fiber surface area played a vital role in the resultant composite material properties. Third, representative volume element (RVE) models were constructed based on the exact microstructural attributes of composites such as fiber dimension, spatial distribution, and fiber volume fraction. These RVEs were generated based on three different combinations of fiber length and diameter in order to study the influence of the specific fiber surface area on the effective properties of composites. Analytical results were obtained from the RVEs in combination with finite element analysis, which were in accordance with experimental results. The predicted properties of numerical models exhibited a strong correlation between effective elastic properties and the specific fiber surface area.
ProQuest ID
Recommended Citation
Sun, Shuo, "Processing, Testing, Failure Analysis, And Modeling Of Elementary Natural Fiber-Reinforced Composites" (2025). All ETDs from UAB. 7321.
https://digitalcommons.library.uab.edu/etd-collection/7321
