Mechanical Properties of Carbon Nanofiber Reinforced Polylactic Acid

Abstract

Carbon nanofiller reinforced PLA was fabricated, and the mechanical properties and heat resistivity were measured. Vapor grown carbon fiber (VGCF) produced by Showa Denko K.K. was used for reinforcement, which has 150 nm in diameter and 10 μm in length. No surface treatment of VGCF was conducted. VGCF and PLA were compounded by using a twin screw extrusion machine and then pelletized. The weight fraction of VGCF ranged from 1wt% to 10wt%. Three point bending specimens were fabricated by using injection molding. At first, three point bending tests were carried out at room temperature. The bending stiffness increased from 3GPa to as high as 5GPa, but the bending strength slightly decreased. SEM observation of the fracture surfaces indicated pull-out of VGCFs over the fracture surfaces. These results imply that adhesion between VGCF and matrix was imperfect. Then, the heat deflection temperatures and glass transition temperatures of the specimens were measured. The addition of VGCF did not increase the glass transition temperature but slightly increased the heat deflection temperature.