Optimization of Tensile Strength and Young’s Modulus of CNT–CF/Epoxy Composites Using Response Surface Methodology (RSM)

Abstract

Composites such as carbon fiber are used extensively by automotive, aerospace, marine, and energy industries due to their strong mechanical properties. However, there are still many areas it is lacking in testing, especially related to its electrophoretic deposition. In this research work, the tensile strength and Young’s modulus of CNT–CF/epoxy composites were measured using the tensile test by varying the electrophoretic deposition (EPD) process parameters. Response surface methodology (RSM) was used to optimize the three main parameters in this EPD process: the volume ratio (water as the basis), deposition voltage, and time to obtain the maximum tensile properties of the composites. There were four volume ratios (0%, 20%, 80% and 100%) used in this design of experiment (DoE) with ratios’ pairs of 0%, 100%, and 20%, 80%. For this study, water and methanol were used as the suspension medium. This design’s deposition voltage and time were 10 to 20 V and 5 to 15 min. ANOVA further verified the responses’ adequacy. The optimum conditions for the first Design of Experiment (DoE) (0% and 100%) were identified as a volume ratio of 99.99% water, deposition voltage of 10 V, and 12.14 min. These conditions provided the maximum strength of these composites with a tensile strength of 7.41 N/mm2 and Young’s modulus of 279.9 N/mm2. Subsequently, for the second DoE (20% and 80%), tensile strength of 7.28 N/mm2 and Young’s modulus of 274.1 N/mm2 were achieved with the ideal conditions: volume ratio of 44.80% water, deposition voltage of 10.04 V, and time of 6.89 min. It can be concluded that the ideal interaction between these three EPD parameters was necessary to achieve composites with good tensile properties.

Keywords

• electrophoretic deposition (EPD)
• volume ratio
• deposition voltage
• deposition time
• CNT–CF/epoxy composite
• response surface methodology