Selvin P. Thomas

Effect of –COOH Functionalized Carbon Nanotubes on Mechanical, Dynamic Mechanical and Thermal Properties of Polypropylene Nanocomposites

Multi-walled carbon nanotubes (CNTs) were functionalized on treatment with nitric acid and the surface-modified CNT was characterized using Fourier transform infrared spectroscopy (FTIR). Isotactic polypropylene (iPP)/CNT composites at different CNT loadings (i.e., 0.1, 0.25, 1.00, and 5.00 wt%) were prepared by melt blending in a mini blender. The differential scanning calorimetric (DSC) studies showed the nucleating effect of CNTs on the crystallization behavior of iPP. Results of X-ray diffraction studies are in conformity with the results of DSC studies. Results of stress–strain measurements reveal that Youngs modulus increases, while elongation at break decreases with increase in CNT loading and the ductility of the composites is adversely affected at high loading of CNTs (>1.0 wt%). Functionalization of CNTs causes an improvement in Youngs modulus, at all loadings studied, but elongation at break increases only up to 0.25%. At higher loading, the elongation at break drops down. Storage modulus increases with increase in CNT loading and the effect is greater in the case of functionalized CNTs. Tan δ shows a decrease with increase in CNT loading, but the effect is less pronounced at high CNT loading (>0.1 wt%).

Preparation and Characterization of Organoclay Filled Polysulfone Nanocomposites

Organo-modified fluorohectorite (OFH) clay filled polysulfone (PSf) nanocomposite films were prepared by solution casting method. The morphology of the nanocomposites was investigated using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The surface properties assessed by contact angle measurements showed significant increase in hydrophobicity of the nanocomposites relative to the virgin polymer. The relationship between contact angle, surface roughness, and surface chemistry was discussed. From the measured contact angle values, various surface parameters such as total surface free energy, interfacial free energy, work of adhesion, spreading coefficient, and Girifalco-Goods interaction parameter were calculated. The mechanical properties like tensile strength and elongation at break were increased considerably upon increasing the organoclay content to 3 wt%. But further increase in the clay content decreased the properties to some extent. The dielectric investigation carried out in room temperature indicated that dielectric constant of PSf/OFH clay nanocomposite films decreases with the increase of the clay content. This work describes the preparation of PSf nanocomposite with desired hydrophobic, dielectric, and mechanical properties for water repellent and electronic applications.

Impact of aspect ratio and CNT loading on the dynamic mechanical and flammability properties of polyethylene nanocomposites

Abstract In this study, the effects of aspect ratio and loading of multiwalled carbon nanotubes (MWCNTs) on the dynamic mechanical, thermal, and flammability properties of low-density polyethylene (LDPE)/MWCNT nanocomposites prepared by the melt blending technique were investigated. At low CNT loading, CNT with low aspect ratio acted as a plasticizer in LDPE. The storage modulus of the nanocomposites increased with the increase in aspect ratio and CNT loading. The increase in scan rate for the composites results in the decrease in total crystallinity, crystallization peak temperature, and a late onset of crystallization. The flammability properties like heat release capacity, peak heat release rate, and total heat release decrease with the increase in both aspect ratio and loading of CNTs in the composites.

Mechanical, Rheological and Thermal Properties of Polystyrene/1-Octadecanol Modified Carbon Nanotubes Nanocomposites

The results of the studies on the functionalization of multi-walled carbon nanotubes (MWCNT) with 1-octadecanol and its usage as reinforcing filler in the bulk polymerization of styrene are reported in this article. Both unmodified and modified CNTs were utilized in different loadings, however, without any initiator. The resulting composites were characterized by using mechanical testing, differential scanning calorimetry, thermogravimetric analysis and melt rheology. The tensile tests show the addition of 0.5wt% of CNT-C18 results in 19.5% increment of Youngs modulus. The DSC study shows a decrease in Tg values of prepared PS/CNT nanocomposite. The rheological study was conducted at 190°C and shows that addition of pure CNT increased the viscoelastic behavior of the PS matrices, while the CNT-C18 act as plasticizer. Thermogravimetric analysis shows that the incorporation of CNT into PS enhanced the thermal properties significantly.