Durability of Natural Fibre-Reinforced Polymer Composites
Bibliographic record
Abstract
Fibre-reinforced polymers (FRP) are a composite system which may be able to meet the demands of both new and existing infrastructures. Due to its constituents’ environmental impact, natural alternatives are becoming increasingly popular; however, their longevity still needs to be assessed prior to its use in civil infrastructure. In this thesis, the long-term performance and durability of natural fibres (flax) and resins (epoxidized pine oil (EPO) and furfuryl alcohol (FA)) were investigated, using 729 tension coupons and 36 structural insulated panels (SIP). Four phenomena were studied: wet-dry cycling, freeze-thaw cycling, cold temperature testing and mechanical fatigue testing. Flax-FRP (FFRP) exposed to 12 wet-dry cycles experienced maximum reductions of 12% and 19% in tensile strength and modulus, respectively, due to delamination at the fibre-resin interface. FFRP exposed to 300 freeze-thaw cycles experienced maximum reductions of 8% and 10% in tensile strength and modulus, respectively, due to delamination at the fibre-resin interface and damage within the fibres. In both cases, conventional epoxy and EPO underwent hydrolysis, and exhibited a decreased and increased glass transition temperature, respectively. To mitigate damage, flax was treated to reduce moisture absorption and improve fibre-resin bond, although similar deterioration was observed post-conditioning. Conversely, conventional glass-FRP showed no deterioration. Furthermore, FFRP tested at cold temperatures resulted in a 20% increase in stiffness, specifically the slope of the second linear phase of its bi-linear stress-strain response. FFRP-skinned SIPs tested at cold temperatures showed a 28% increase in capacity under flexural load; however, there was no impact on the load-deflection response within serviceability limits. Finally, FA-based carbon-FRP (CFRP) was tested in tension-tension fatigue. Based on a 2,000,000 fatigue life, the ASTM model predicted an allowable stress amplitude of 59% and the Whitworth model predicted a modulus retention of 65%. Conventional epoxy-CFRP had a predicted modulus retention of 80%. Through this study, it is clear that FFRP with a higher FVF will be more resilient against cyclic environmental exposure than those with fibre treatment; and, its performance will improve in cold climates. Furthermore, FA-CFRP’s fatigue performance is worst than epoxy-CFRP; however, this trade-off may be beneficial for its chemical resistance.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".