Optimization of bio based glass polyfurfuryl alcohol prepreg for composite applications

Global sustainability and emissions concerns in the manufacture and application of fibre composites have recently fueled research and development of bio-based alternatives to mitigate these challenges. One such material that has been developed and recently explored for composites applications is bio-based polyfurfuryl alcohol resin. It has demonstrated impressive mechanical and thermal properties in fibre applications. However, this comes with a major disadvantage of the long processing time, which for its manufacture is synonymous with manufacturing processes such as oven or autoclave curing, which limits its application for high volume production. To this end, this project aims to optimize the curing cycle of the glass / PFA prepreg for rapid manufacturing. Model-free and model-based kinetic studies were performed to understand the curing mechanism that occurs during the curing reaction. The Friedman and Ozawa-Flynn wall models were used to investigate the conversion-dependent activation energy. Both methods found that the average activation energy for the curing process was 88.9 ± 4.9 kJ/mol and further revealed a curing mechanism with a multi-step curing reaction consisting of parallel and competing reactions taking place simultaneously during the reaction. This was found to be relatively consistent with that obtained by the Kamal-Sourour fitted model. The excellent correlation between the Friedman model and the experimental data made it suitable for predicting the evolution of the reaction time under isothermal conditions, leading to an optimization of the total process cycle time from the manufacturer's recommended cycle of 113 minutes to 30 minutes when held isothermally at 160℃. Thus, suggestively making it suitable for rapid manufacturing processes such as the compression moulding process. Mechanical and thermal characterization was performed on Glass/PFA laminate manufactured by a hot press using the optimized cycle from the kinetic study at two different pressure (5 and 10bars) and this was benchmarked against laminates manufactured by the vacuum bagging - oven curing method using the manufacturer’s recommended cycle. The experimental results reveal that the cured glass/PFA laminate manufactured using the optimized cycle at 5 bar pressure was found to exhibit the best result showing an increase in the glass transition temperature (Tg) from 175℃ to 201℃. The impact of the optimized cure parameters on the mechanical properties of the glass/PFA composite was significant. It resulted in a notable 10.25% improvement in tensile strength, a substantial 13.04% increase in flexural strength, and a commendable 10.34% enhancement in apparent shear strength compared to the reference oven-cured glass/PFA sample. This successful study has effectively established the ideal cure parameters for the glass/PFA prepreg, enabling rapid and efficient composite fabrication

A review of advancements in synthesis, manufacturing and properties of environment friendly biobased Polyfurfuryl Alcohol Resin and its Composites

The quest for environmentally friendly and sustainable materials in the production of fibre reinforced composite materials has led to the use of biobased materials, which are easily accessible and renewable. Biomass-derived chemicals, their derivatives, and their applications have become increasingly prevalent in various industries and processes, greatly contributing to the goal of ecological sustainability. The biobased Polyfurfuryl Alcohol (PFA) resin is one of such polymeric materials that is gaining attention for composite applications due to its endearing Fire Smoke and Toxicity properties. Derived from agricultural by products such as sugar cane bagasse, it has been known for applications within the foundry, coating, and wood industries. However, there has been a growing interest in its use for fibre reinforced composite applications. For this reason, this work intends to provide a comprehensive review of the PFA resin in relationship to fibre reinforced composites applications. The work provides an in-depth discussion on the synthesis, curing process, manufacturing, and properties of the PFA resin as well as its composites

Capacitive Sensors based on Recycled Carbon Fibre (rCF) Composites

Recycled carbon fibre (rCF) composites are increasingly being explored for applications such as strain sensing, manufacturing of automobile parts, assistive technologies, and structural health monitoring, due to their properties, economic and environmental benefits. The high conductivity of carbon and its wide application for sensing, makes rCF very attractive for integrating sensing into passive structures. In this paper, capacitive sensors have been fabricated using rCF compo-sites of varying compositions. First, we investigated the suitability of recycled carbon fibre pol-ymer composites for different sensing applications. As a proof of concept, we fabricated five touch/proximity sensors and three soil moisture sensors, using recycled carbon fibre composites and their performances compared. The soil moisture sensors were realized using rCF as elec-trodes. This makes them corrosion-resistant and more environmental-friendly compared to conventional soil moisture sensors realized using metallic electrodes. The results of the touch/proximity sensing show an average change in capacitance (ΔC/C~34) for 20mm and (ΔC/C~5) for 100mm, distances of a hand, from the active sensing region. The results of the soil moisture sensors show a stable and repeatable response, with a high sensitivity of ~116pF/ml of water in the linear region. These results demonstrate their respective potential for touch/proximity sensing, as well as smart and sustainable agriculture

Maize defence mechanisms against the European corn borer, Ostrinia nubilalis Hubner (Lepidoptera: Crambidae)

Maize is arguably the most widely grown crop in the world, but it is often associated with one of its major insect pests, the European corn borer (ECB). The damage caused by this species to maize production is generally variable, but in many cases it is economically significant. This review paper provides an overview of the research findings on the natural plant defence mechanisms against ECB larvae published till now. What is resistance and how it is achieved, what is the chemical response of maize plants to insect feeding and how tolerance can be increased. A short introduction in breeding for resistance and a discussion if the mentioned traits can be used in conventional breeding in order to create maize hybrids less affected by ECB are given