PENGARUH PENAMBAHAN JENIS PARTIKEL TERHADAP SIFAT MEKANIS DAN FISIS KOMPOSIT KENAF/EPOXY
Abstract
Kenaf (Hibiscus cannabius) is one of the filler materials that has been developed by the automotive industry, because of its advantages of high mechanical properties, environmentally friendly and easy to obtain. Use of matrix as binders for kenaf and particle powder as the reinforcement has been investigated but has not achieved the maximum results. Therefore, this research studied the composites of kenaf/epoxy fibers with the addition of different particle types (silica, bentonite, CaCO3) as the reinforcement aimed at knowing the mechanical and physical properties of the hybrid composite.
In this study, the fiber alkalized by soaking a 6% NaOH for 36 hours and neutralized with acetic acid for an hour. Then the fibers were chopped into about 5 mm length. The hybrid composites with 30% fillers consisting of kenaf fiber and the various particulates (silica, bentonite, CaCO3) were manufactured by hand lay-up method using hot press machine at 100ºC for 20-50 min. Impact and bending tests of the composite specimens were conducted by following ASTM D6110 and ASTM D790, respectively. Water absorption test, according to ASTM D570 was carried out for 216 h, and the measurement of weight gain and thickness swelling were done each 2 h. The morphology of impact fracture surface was characterized by scanning electron microscopy (SEM) and an optical microscope.
The results indicated that the impact (7.49 kJ/m2) and bending (61.09 MPa) strength were obtained from the hybrid composite of kenaf/Silica/epoxy with 2% volume fraction of Silica particles. While the lowest impact (5.36 kJ/m2) and bending (42.71 MPa) strength were shown in the composite with 2% CaCO3 and bentonite. Water absorption test results showed the smallest weight gain and thickness swelling reached by the composite kenaf/CaCO3/epoxy. Decrease of the mechanical properties is caused by the presence of voids formed in all composites as confirmed by SEM. The agglomerated micro-particles can inhibit transfer stress from the matrix to the fiber, increasing the presence of debonding and fiber pull-out.