Epoxy and unsaturated polyester resins are the most used thermosetting polymers. They are commonly used in electronics, construction, marine, automotive and aircraft industries. Moreover, reinforcing both epoxy and unsaturated polyester resins with carbon or glass fibre in a fabric form has enabled them to be used in high-performance applications. However, their organic nature as any other polymeric materials made them highly flammable materials. Enhancing the flame retardancy performance of thermosetting polymers and their composites can be improved by the addition of flame-retardant materials, but this comes at the expense of their mechanical properties. In this regard, a comprehensive review on the recent research articles that studied the flame retardancy of epoxy resin, unsaturated polyester resin and their composites were covered. Flame retardancy performance of different flame retardant/polymer systems was evaluated in terms of Flame Retardancy index (FRI) that was calculated based on the data extracted from the cone calorimeter test. Furthermore, flame retardant selection charts that relate between the flame retardancy level with mechanical properties in the aspects of tensile and flexural strength were presented. This review paper is also dedicated to providing the reader with a brief overview on the combustion mechanism of polymeric materials, their flammability behaviour and the commonly used flammability testing techniques and the mechanism of action of flame retardants.

Natural fibre-reinforced polymer composites are standing in the limelight of investigations due to their light weight and availability from natural and renewable resources. Improved mechanical and physical behaviour is targeted through hybridisation with other reinforcing elements. This study investigates the potential of adding silicon carbide particles at volume contents ranging between 2 and 8% to jute fabric-reinforced epoxy composite to produce such hybrid composites. In contrast to the commonly applied processing technique of hand layup used to produce natural fibre-reinforced laminates, the vacuum-assisted resin infusion method was applied in this study to produce high quality laminates. Samples were tested for their mechanical behaviour through tensile, flexural and impact tests. Scanning electron microscopy was further performed to analyse the modes of failure of the composites. Finally, erosion tests were conducted, by directly sanding the hybrid composite samples to evaluate their erosion wear resistance. Results indicated that the addition of particles had a significant effect on the tensile, flexural, impact and erosion wear behaviour of the composites under investigation. Hybrid composites reinforced with 4 vol.% SiC exhibited acceptable mechanical properties. The behaviour was found to deteriorate at SiC contents beyond 4 vol.%.

This research investigates the development of a mathematical model to predict the influence of flame retardants (FR) on the mechanical and flame retardancy performance of natural fibre reinforced thermosetting composites. The study focuses on two types of FRs: Diammonium Phosphate (DAP) and silica fumes that were added to Jute reinforced epoxy composites (JRECs). Two mathematical models were established based on three variables and two measured responses. The variables include FRs type, FR content, and FR method of preparation, while the measured responses are Limiting oxygen index (LOI) and Flexural strength (FS). The models were developed using a statistical approach based on multiple linear regression fitting and validated using analysis of variance (ANOVA) technique. The developed models were verified using experimental result data from literature and the analysis of these models showed that the maximum discrepancy between the observed and predicted values for relative LOI and relative FS was within the range of ± 6% and ± 5%, respectively. This research contributes to the understanding of the impact of FRs on the mechanical and flame retardancy performance of natural fibre reinforced thermosetting composites, which can aid in the design and development of safer and more efficient composite materials.