Epoxy is a large family of resins which represent some of the high-performance resins.106 It is a thermosetting polymer formed from the reaction of an epoxide resin with polyamine hardener.107 Epoxy is one of the best matrix materials for industrial application, due to its excellent properties such as good adhesion, mechanical prop­erties, chemical and heat resistance, low moisture content, little shrinkage, and pro­cessing ease.16107 The outstanding performance of epoxy in terms of adhesive and mechanical properties, and resistance to environmental degradation lead to its wide usage in the aircraft and boat building industry.106 Over the years, there were many studies conducted on SPF-epoxy composites.108114

9.4.5.1 EFFECT OF AGING ON SUGAR PALM FIBER REINFORCED EPOXY COMPOSITE

Tensile and impact tests were conducted by Ali et al.16 on original and aged SPF/ epoxy composite to compare their mechanical properties. An accelerated aged com­posite was obtained by using the standard material age acceleration under ASTM F1980 with 10% error. The parameters used in their investigation were; (a) time of real time aging in a natural environment (70 days), (b) ambient temperature (25 °C), (c) accelerated aging temperature (70 °C), and (d) accelerated aging factor (2.0). Equation 1 and 2 were used to determine the accelerated aging rate and accelerated aging time duration.

Where AAR was accelerated aging rate, AAT was accelerated aging tempera­ture, AT was ambient temperature, Q10 was accelerated aging factor, AATD was

accelerated aging time duration and DRTA was the desires real time aging.16 When the parameters were substituted into the equations, the accelerated aging time (AAT) was 74 hrs. and 10 mins which was equivalent to 70 days of aging in a natural en­vironment.

Aged SPF/epoxy composite manifested superior tensile strength compared to those of the original composite. The tensile strength of the aged composite increased by 50.4%, which indicates that the aging process rendered the composite matrix more compact, yielding a harder and denser composite material. This may happen due to slight increase in specific volume of the epoxy polymer chains and energy was stored within the chains during the heating process. The polymer chains even­tually release the stored energy during the cooling stage (after heating the compos­ite), causing a decrease in the composite specific volume. This phenomenon causes the epoxy polymer chains to become denser and further strengthen the composite bond.108 However, lower tensile modulus of the aged composite was obtained from the tensile test as compared to the original composite. It was evident from their findings that the aged SPF/epoxy composites had very low ductility properties. The resistance towards deformation decreased for the aged composite due to the dense epoxy matrix polymer chains. The impact strength of both composites explicitly shows that SPF/epoxy composites are brittle and that aging has a minimal effect on the impact properties of the composite.108