Abstract:
Composite materials result into lightweight structures with high stiffness and tailored
properties for specific applications. Interest in agricultural materials for bio-composites has
grown rapidly due to their renewability, biodegradability and eco-friendliness hence an
alternative to non-renewable and non-biodegradable synthetic materials. Over 30 million
tons of banana peels are thrown away annually worldwide, hence disposed of by burning
that is environmentally unfriendly. Banana peels have a potential of development into eco-
friendly resins for bio-composite production. Banana pseudo-stems are used for banana
fibres though some are thrown away without further value addition. There is also a
declining trend of sisal production worldwide due to competition from polypropylene
synthetic fibres used in sack making, hence a decline in agricultural employment
opportunities. Bio-composites from renewable resources therefore, will reduce waste
disposal, promote agricultural value addition and create more employment opportunities.
The objectives of this study were to develop, characterize and optimize bio-resin
development from raw banana peels. Then surface-treat and characterize pseudo-stem
banana and sisal fibres, followed by development, characterization and optimization of the
design of bio-composites from banana peels bio-resin, pseudo-stem and sisal fibres. Pureed
raw banana peels paste was mixed with various ratios of water and Glycerine at different
temperatures and time and the bio-resin characterized for viscosity and density. Pseudo-
stem banana and sisal fibres were treated with 4% sodium hydroxide, boiled at 100 0 C for 1
hour, dried under the sun and characterized. The fibres were chopped to a critical length of
15mm and bio-composites produced using the hand layup technique and characterized.
Using surface response experimental design and regression analysis, effect of fibre volume
fraction, bio-resin mass and Glycerine mass on the mechanical properties of the developed
bio-composites were studied. The viscosity model exhibited an R 2 value of 0.95 and an
optimum viscosity of 242 mPa.s. Percentage contributions of factors affecting viscosity of
the bio-resin were water amount at 20% and Glycerine amount (18.6%) among others.
Regression analysis for bio-resin density yielded an R 2 of 0.83 with an optimized density
of 0.95g/cm 3 . Viscosity and density values were in close range with other commercial
resins. Treated pseudo-stem banana fibres yielded a linear density of 12.52tex, elongation
(0.49%), tenacity (189.5MPa) and Young’s modulus (3Gpa). Treated sisal fibres yielded a
linear density of 23.84tex, elongation (1.03%), tenacity (217.13MPa) and Young’s modulus
(5.6Gpa). There was significant improvement in the mechanical properties of treated
pseudo-stem banana and sisal fibres than untreated fibres. Treated pseudo-stem banana and
sisal fibres were used for bio-composite development using the optimized bio-resin. Sisal
and banana bio-composites yielded tensile strengths of 5.2MPa and 4.2MPa respectively,
with an R 2 value of 0.93 and fibre volume fraction contributing the highest percentage of
38.11% to the model. The sisal and banana bio-composites also exhibited compressive
strengths of 2.9MPa and 2.1MPa respectively with an R 2 value of 0.92 and fibre volume
fraction contributing the highest percentage of 42.8% to the model. The optimized bio-
composites were comparable to the available commercial composite boards. The
developed bio-resin can be used in development of bio-composites for interior applications
including partition, ceiling and notice boards as an alternative to non-renewable and non-
biodegradable petroleum based materials and solid wood products.