Scratch Resistance of Flexible Carbon Fiber‐Reinforced Polymer Composites Improved by Atmospheric Pressure Plasma Polymerized‐Organosilicon Oxide Films

An improvement on the scratch resistance of flexible carbon fiber‐reinforced polymer composites (FCFRPCs) has been undertaken by deposition of organosilicon oxide (SiO_xC_y) films. The SiO_xC_y films are synthesized using a low temperature‐atmospheric pressure‐plasma polymerization method with an atmospheric pressure plasma jet (APPJ) at various substrate distances. SiO_xC_y thin films are rapidly deposited onto FCFRPCs at a short exposed‐duration of 150 s with an APPJ. The precursor tetramethyldisiloxan (TMDSO) vapors are mixed with air gases, injected into the air plasma jet of APPJ, and sprayed onto FCFRPCs at room temperature (~23°C) at atmospheric pressure. The scratch resistance of FCFRPCs is meaningfully improved from an overpowering occurrence of scratching (100%) on as‐received FCFRPC to an overall absence of scratching (0%) on SiO_xC_y film deposited FCFRPC against the steel wool for up to 62 cycles at a 100 g loading. The enhanced scratch resistance of FCFRPCs by APPJ‐synthesized SiO_xC_y films is strongly dependent on the increased nanoindentation hardness (of up to 1.60 GPa), the increased surface hardness (of up to 7H), and the decreased surface roughness (of up to 6.5 nm for the roughness of the standard deviation from the height mean R_ms and 2.5 nm for the roughness of the mean deviation from the height mean R_a), respectively. How the critical films characteristics affect the increased surface hardness and the decreased surface roughness for APPJ‐synthesized SiO_xC_y films are discussed. POLYM. COMPOS., 40:E1893–E1902, 2019. © 2018 Society of Plastics Engineers