Effect of Carbon Fiber Loading in Mechanical Properties and Electrical Conductivity of Polyvinyl Alcohol Based Composites Ismadi,* 1,2 Akhmad Herman Yuwono, 1 Sotya Astutiningsih, 1 Subyakto 2 Summary: Polyvinyl alcohol (PVA) needs to be reinforced with other material to increase its mechanical strength and electrical conductivity to get wider applications. In this research effect of addition of carbon fiber on the mechanical properties and electrical conductivity of PVA based composites was observed. Concentrations of carbon fiber applied were 0, 2, 4 and 6% w/w based on PVA dry weight. PVA film was synthesized by dilute solid PVA in water at temperature of 80  C for 6 hours with 8% w/w of water, and continued with chilling for 12 h. Carbon fiber was added and stirred by ultra-turrax for 40 seconds, and the solution was film- casted. Characterization the composites include morphology analysis (optical microscope and SEM), crystallite size (X-ray diffraction), mechanical test and electrical conductivity measurement. The result showed that tensile strength increase with increased of carbon fiber added. The optimal value of tensile strength (34.08 MPa) was obtained from 2% w/w of carbon fibers. Addition of 6% w/w of carbon fiber increased electrical conductivity up to 1.33  10 3 S/cm, this was significantly enhanced from that net PVA of 2.3  10 8 S/cm. Generally, addition of carbon fiber increase tensile strength and electrical conductivity of PVA based composites. Keywords: carbon fiber; composites; electrical conductivity; polyvinyl alcohol; strength Introduction One of the materials that have been applied in biomedical is Polyvinyl Alcohol (PVA). PVA is representative water soluble poly- mer. PVA possess a good compatibility to human body, non-toxic and easy to be synthesized. PVA aqueous solution can form both chemical and physical gels depending on the preparation condition. [1] However, its low mechanical strength and conductivity lead to a limitation for appli- cations. [2] Thus, addition of reinforcement materials is necessary. The most conductive materials that used to reinforce other materials is carbon fiber. Carbon fibers are light, an-isometric, and conducting materials. This combination of properties make them as ideal filler to achieve light and conductive polymer composites which can be useful for shielding devices, anti- static plastics, packaging, and others. [3] Addition of plasticizer and dispersal of organic or inorganic fillers in the pristine polymer electrolytes have resulted in sig- nificant improvement in amorphous phase and the conductivity. [4] Therefore, addition of carbon fiber could improve mechanical characteristic and electrical conductivity of composite materials. Increases of electrical conductivity of PVA composites lead to wider applications. [5–8] The aim of this study was to investigate the addition of carbon fiber to enhance 1 Department of Metallurgy and Material Engineering, Faculty of Engineering, University of Indonesia, Indonesia Fax: þ62 – 21 – 87914511; E-mail: ismadi@biomaterial.lipi.go.id; my_ismadi@yahoo.com 2 Research Center for Biomaterial, Indonesian Insti- tute of Sciences, Bogor, Indonesia Macromol. Symp. 2015, 353, 102–107 DOI: 10.1002/masy.201550313 102 | © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com