Reinforcement of Epoxy Thermoset Composite Using Cellulose Microfibers from Napier Grass [Cenchrus purpureus (Schumach.) Morrone]

Author : Ronquillo, Mariel Gonzales
Major Adviser : Sanchez, Denise Ester S.
Major Co-Adviser : Manalo, Ronniel D.
Committee Members : Guerrero, Gino Apollo M.; Migo, Veronica P.
Year : 2019
Month : June
Type : Thesis
Degree: BS
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Microfiber as polymer reinforcement is gaining attention for the past years due to its biodegradability and high strength; and to utilize wastes, agricultural wastes, like grasses, are being studied as microfiber source. In this study, the effects of pre-curing time and fiber loading on the flexural strength and water absorption of microfiber-reinforced epoxy composites were investigated. Microfibers were first extracted from Napier grass, an abundant wild grass in the Philippines, using Kraft pulping, bleaching, and alpha cellulose extraction with NaOH; and was then treated with acetone to increase its surface roughness. SEM images showed that the diameter and length of the produced microfibers are 6.34 μm and 474.77 μm, respectively; and the surface roughness of fibers were not improved. The variations in fiber loading and curing time used were 1 vol%, 3 vol%, and 5 vol%; 0.5 hour, 1 hour, and 1.5 hours respectively. It was observed that increasing the fiber loading decreases the flexural strength and water absorption of the composites; while increasing curing time increases water absorption and flexural strength (to some value, then decreases afterwards). The highest reinforcement on flexural strength (28.0938% increase) was obtained by 1 vol% reinforced composites cured for 1 hour, while the lowest water absorption observed (17.4174% decrease) was obtained by 5 vol% reinforced composites cured for 0.5 hour. However, the reinforced composites generally exhibited lower flexural strength and higher water absorption compared to neat epoxy due to weak fiber-matrix interphase that affected the curing process, load transfer at the interphase, and void formation.

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