Abstract
The aim of this study was to evaluate the moisture absorption behaviour and its influence on the mechanical properties of newly developed sandwich biocomposites with flax fibre-reinforced poly-lactic acid (PLA) face sheets and soft cork as the core material. Three different types of sandwich biocomposite laminates comprised of different layup configurations, namely, non-woven flax/PLA (Sample A), non-woven flax/PLA and cork as core (Sample B) and non-woven flax/paper backing/PLA, cork as core (Sample C), were fabricated. In order to evaluate the influence of moisture ingress on the mechanical properties, the biocomposites were immersed in seawater for a period of 1200 h. The biocomposites (both dry and water immersed) were then subjected to tensile, flexural and low-velocity falling weight impact tests. It was observed from the experimental results that the moisture uptake significantly influenced the mechanical properties of the biocomposites. The presence of the cork and paper in sample C made it more susceptible to water absorption, reaching a value of 34.33%. The presence of cork in the core also has a considerable effect on the mechanical, as well as energy dissipation, behaviours. The results of sample A exhibited improved mechanical performance in both dry and wet conditions compared to samples B and C. Sample A exhibits 32.6% more tensile strength and 81.4% more flexural strength in dry conditions than that in sample C. The scanning electron microscopy (SEM) and X-ray micro-CT images revealed that the failure modes observed are a combination of matrix cracking, core crushing and face core debonding. The results from this study suggest that flax/PLA sandwich biocomposites can be used in various lightweight applications with improved environmental benefits.
Highlights
Introduction iationsThe advancement of high-performance carbon and glass fibre-reinforced polymer composites has changed our society in many ways
3 depicts the percentage of the sandwich weight gain vs. a function the square roota of the fractured surfaces of the impacted composites wereofacquired using of time for the three different biocomposites immersed in seawater at room temperature
Gain vs. a function the square rootbe of time for the three different biocomposites immersed in seawater at room temperature before the mechanical testing
Summary
The advancement of high-performance carbon and glass fibre-reinforced polymer composites has changed our society in many ways. These materials have excellent performance and have been immensely successful over the last few decades in terms of providing lightweight composite materials in various critical applications in comparison to their metallic counterparts. These reinforcements are fossil fuel based; their adverse effects, such as resource depletion, global warming and an overall negative impact on the environment, are major concerns. Extensive research works have been conducted in the past, focusing on the Licensee MDPI, Basel, Switzerland
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