Palm fiber composites for aircraft interiors

Khalili, Pooria (2018) Palm fiber composites for aircraft interiors. PhD thesis, University of Nottingham.

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Over the last decades, aircraft manufacturers have produced synthetic fiber thermoset composites to be used for interior components of aircraft. However, the ever increasing dependence on synthetic fibers and thermosetting resin has set the aerospace industry under considerable pressure to reduce its carbon footprint and enhance its sustainable credentials. The unrelenting passion of sustainability has led to an expanding search for eco-friendly fiber reinforced composite from renewable sources. However, there remains a significant challenge to produce palm fiber composite fit for aircraft interiors owing to its ease of combustibility.

Various flame retardants and expandable graphite (EG) at different concentrations were introduced into the epoxy composites reinforced with approximately 18 to 20% fiber (mass fraction). Amongst the flame retardant filled composites fabricated by resin infusion technique, two formulations with incorporation of (i) 10% ammonium phosphate (APP) and 5% alumina trihydrate (ATH) hybrid and (ii) 10% ammonium phosphate (APP) and 5% zinc borate (ZB) hybrid into EFB fiber reinforced epoxy composites demonstrated promising capability to meet the vertical Bunsen burner requirements for aircraft interiors, where zero molten drip time and zero flame time were observed, along with the lowest recorded gross heat of combustion being less than 27.4 MJ/kg from bomb calorimeter instrument. It was found that the lab-scale mechanical performances enhanced with inclusion of alkaline treated fibre compared with those of untreated fibre composites.

For expandable graphite filled composites fabricated by compression molding technique, all the composites containing EG was observed to possess the capability to meet the vertical Bunsen burner test requirements of aircraft interior parts. Palm fibre composites with inclusion of 5 %wt and 7 %wt EG fillers showed zero flame time, drip flame time and negligible burned length. From Bomb calorimetry and TGA tests, formulation with 7% EG filler (CEG7) recorded a gross heat of combustion of 27.91 MJ/kg and mass residue of 28.31 wt% at 700 °C. In a separate approach where 3 wt% and 5 wt% EG were coated onto the exterior surface of neat EFB fiber reinforced epoxy composite without any additional fillers, it was observed that composite coated with 5 wt% EG met the requirements of vertical Bunsen burner test. With regards to mechanical properties, the incorporation of EG fillers into EFB fiber composite dropped the mechanical behaviors. The mechanical performances of EG filled composite was found to improve with the alkali treatment of EFB fibers. Lab scale measured mechanical behaviors were observed to be in the acceptable range for the required application.

Finally, an aerospace grade Nomex honeycomb was used to fabricate laminate with the natural fibre composite skins, which could be a structure of an aircraft interior component for a sidewall, ceiling or partition. Two different types of composite face sheets were used, one with the optimum formulation from flame retardant filled composite (hybrid 10 wt% APP with 5 wt% ATH) and the other with 7 wt% expandable graphite. The requirements of 12 s vertical Bunsen burner testing were fully met for the panels. Three of the optimum formulations (APP/ATH hybrid, APP/ZB hybrid and EG7) were tested against 60 s vertical Bunsen burner experiment and found capable of meeting the test specifications of flame time, drip flame time and burn length.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Tshai, Albert
Kong, Ing
Mike, Clifford
Keywords: natural fibre, flammability,epoxy, flame retardants
Subjects: T Technology > TL Motor vehicles. Aeronautics. Astronautics
Faculties/Schools: University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Item ID: 45555
Depositing User: KHALILI, POORIA
Date Deposited: 15 Apr 2020 15:15
Last Modified: 15 Apr 2020 15:15

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