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Title: Fire retardant behavior of Kenaf fibre reinforced Floreon composite
Author: Lee, Ching Hao
ISNI:       0000 0004 7233 8246
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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According to the report, more than 41% of fatalities in flight were to find to be caused by fire. In recent years, composites used in aircrafts are carbon fibre/ glass fibre reinforced epoxy, due to light weights and high strength properties. However, these composites are known as highly flammable. Serious fire incident will be created in a short time after a spark of fire. Furthermore, ingredients for fibre and epoxies are, toxic and resulting in the release of toxic gases during fire, and cutting off fresh air to survivors and hindering their escape. In the meantime, biopolymers have attracted considerable attention due to their environmentally friendly and sustainable nature, Kenaf Fibre (KF) is one of the most famous natural fibre used as a reinforcement in Polymer Matrix Composites (PMC). Kenaf is also known as Hibiscus Cannabimus L., and is an herbaceous annual plant that is grown in a wide range of weather conditions, growing more than 3 meters within 3 months. However, the inherent drawbacks associated with Floreon (FLO) based composites include brittleness, lower strength and high moisture sensitivity, which in turn limit their application in the aircraft industry. In order to overcome such drawbacks, two modification techniques were employed in this study: (1) incorporated kenaf fibre into polypropylene polymer with magnesium hydroxide flame retardant and (2) reinforces kenaf fibre and magnesium hydroxide by different combination of volume. Consequently, KF reinforced FLO or polypropylene (PP) composites with magnesium hydroxide (MH) flame retardant specimens were successfully developed using extrusion followed by hot pressing. The increment of KF contents in PP composites had shown higher tensile modulus and decomposed mass loss at onset temperature, but lower values in tensile strength, elongation, flexural strength and onset temperature. In the meantime, 25 wt% KF contented PP composite shown a slightly higher flexural strength, while the higher volume of MH filler in composites caused lower strength, tensile modulus, elongation, but with higher onset temperature and the 2nd peak temperature in thermogravimetric analysis (TGA) testing. Furthermore, increasing the KF contents in PP matrix has found lower mass residue. However, increasing of KF contents in MH contented composite had increased the mass residue at the end of the testing. On the other hand, the increment of the melt flow properties (MVR and MFR) was found for the KF or MH insertion, due to the hydrolytic degradation of the polylactic acid (PLA) in FLO. The deterioration of the entanglement density at high temperature, shear thinning and wall slip velocity were the possible causes for the higher melt flow properties. In the meantime, increasing the KF loadings caused the higher melt flow properties while the FLO composites with higher MH contents created stronger bonding for higher macromolecular chain flow resistance, hence, recorded lower melt flow properties. However, the complicated melt flow behavior of the KF reinforced FLO/MH biocomposites was found in this study. The high probability of KF-KF and KF-MH collisions was expected and there were more collisions for higher fibre and filler loading, causing lower melt flow properties. Besides that, insufficient resin for fibre wetting, hydrolytic degradation on the biopolymer and poor interfacial bonding were attributed to low strength profile. Yet, further addition of KF increased the tensile strength and flexural. Nevertheless, inserting KF and MH filler have shown positive outcome on flexural modulus. Insertion of KF and MH showed the deterioration of impact strength, while the addition of KF increased the impact strength. Meanwhile, FLO is a hydrophobic biopolymer which showed only a little of total water absorption. In this regard, for the first 24 hours, the water absorption rates were high for all bio-composites. Hence, it is worth mentioning that the high contents of KF in bio-composites shown higher saturation period and higher total amount of water absorption while MH caused shorter saturation period but lower total amount of water absorption. However, interface bonding incompatibility has increased the water absorption of KF/FLO/MH composites. Moreover, some synergistic effect was located in char formation, Tg reduction and a lower tan δ peak shown in the three-phase system (KF/FLO/MH). The MH filler was found to be more significant in enhancing mass residual. The Tg were show deterioration for all samples compared to pure FLO biopolymer. The melting temperature has found no meaningful change for either insertion of KF or MH or both. The values of co-coefficient, C recorded decreasing as increasing the fibre loading. This showing the fibres transfer the loading effectively. As conclusion, although 10KF5MH specimen does not have the best performance in mechanical properties, a higher flame retardancy shall provide KF reinforced FLO composite with MH filler for more applications in advanced sector especially, in hazardous environment.
Supervisor: Sapuan, S. M. ; Hassan, M. R. ; James, Meredith Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available