A Study On Thermal And Mechanical Properties Of Icelandic Horse Hair Fiber Reinforced Poly (Lactic Acid) Green Composites

In this work, fully biodegradable, green composite laminates were fabricated with Icelandic horse hair fibers and poly (lactic acid) resin using a hot press forming process. Composites were manufactured by hand lay-up method with fibers in both random orientation and approximately unidirectional orientation. Fiber volume fraction was varied across1,5,10,15, and20of fiber. The composites were evaluated for thermal and mechanical properties.Icelandic horse hair fiber has a hollow core which is elaborately subdivided as characterized by SEM observations. These pores retain a significant volume of air in the fibers which are expected to provide the composite with good thermal insulation. Thermal conductivity of composites were measured through Thermolab KESF-TL2C system, the results showed that the addition of Icelandic horse hair fiber significantly lowered the conductivity of the composite compared to neat PLA resin. Moreover, the thermal conductivity decreased from0.071W/m K to0.043W/m K by increasing fiber volume fraction from1%to20%. The results obtained from testing were compared to theoretical predictions based on some composite transverse conductivity models.Icelandic horse hair fibers consist of keratin which is mostly hydrophobic in the amino acid sequence and thus were able to be compatible with the same hydrophobic PLA resin to some degree. The scale cells on the fiber surface were also believed to improve the interfacial bonding between fiber and resin. The tensile stress and modulus of approximate unidirectional fiber composites were significantly larger than those of neat PLA resins as well as randomly oriented fiber composites. Randomly oriented fiber composites were found to have lower tensile stress and higher modulus compared with PLA resins, but they did not differ from each other significantly by varying fiber content in terms of these two properties. This might be explained by the fact that hand lay-up method resulted in a small part of fibers aligned in the tensile test direction. It might result from the relative long fiber length and void content existing in the randomly oriented fiber composites as well. The void content in these composites also contributed to the thermal insulation as well as reducing the tensile properties of composites. The SEM micrographs of tensile fracture surface revealed that the IHHF/PLA interactions were good but not maximized.