C-CVD grown MWCNTs: disclosure of defects by influence of drying condition on carboxyl functionalized structure

C-CVD grown Multi-Walled Carbon Nano-tubes (MWCNTs) as reinforcement have shown excellent mechanical, thermal properties as long as homogeneously dispersed in the matrix (polymer, epoxy and etc.). Modification of carbon nano-tubes is the base steps to prepare the surface microstructure to strong bonding with matrix thereby decouple bundled nano-tubes due to Vander Waals interactions. The main purpose of this research work is modification of MWCNTs in order to obtain less damaged and strong bondable nano-tubes and comparing to two vacuum-drying methods to find most effective one. In this research, we carried out by sulfuric and nitric acid treatment (H2SO4:HNO3) as 3:1 v/v to modify the side-wall surface. Two types of condition of dehydration have been performed during 24 hrs: heating (120°C) at 750 mmHg and freezing (-80°C) at 1900 mmHg to obtain qualitative MWCNTs with low viscosity and higher aspect ratio. It is believed that the most important factor is low viscosity within higher loading of MWCNTs. Quality of well-dried functionalized multi-walled carbon nano-tubes (F-VFD MWCNTs) can be estimated as well in creating well-oriented nano composite. A quantitative characterization of presence carboxyl (-COOH) group on the external wall observed by Fourier Transmission Infrared Spectroscopy (FTIR). Disclosure of defects and disruption on the graphitic structure of F-VFD MWCNTs was analyzed by Raman Spectroscopy. In order to enhance dispensability, it is necessary to quantify the F-VFD MWCNTs dispersion quality after applied chemical modification. Although, purity of F-VFD MWCNTs was analyzed by Energy-Dispersive X-ray spectroscopy (EDX) to predict in-organic and metal impurities after performing functionalization. Observation by Scanning Electron Microscope gave us clear view of structure surface of MWCNTs. According to the results, we found out that effect of drying temperature is one of the critical factors to obtain less damaged and strong bondable nano-tubes regardless of matrix thereby to improve mechanical and thermal properties of nano-composites in advance. The results showed the effective influence of functionalization (unlocking) on the interfacial interaction between MWCNTs and isophthalic polyester resin which obtained after performing vacuum-freezing dry method.