Sadhan Kumar De

Electrical properties of natural rubber nanocomposites: effect of 1-octadecanol functionalization of carbon nanotubes

This article reports the results of studies on the effect of 1-octadecanol (abbreviated as C18) functionalization of carbon nanotubes (CNT) on electrical properties of natural rubber (NR) composites. Dispersion of CNT in NR matrix was studied by transmission electron microscopy (TEM) and electrical resistivity measurements. Fourier transform infra red spectrometry (FTIR) indicates characteristic peaks for ether and hydrocarbon in the case of C18 functionalized CNT. Dielectric constant increases with respect to the filler loading for both unmodified and functionalized CNTs, the effect being less pronounced in the case of functionalized CNT due to its better dispersion in the matrix. Stress–strain plots suggest that the mechanical integrity of the NR/CNT composites, measured in terms of tensile strength, increases on C18 functionalization of the nanofiller. TEM reveals that the functionalization causes improvement in dispersion of CNT in NR matrix, which is corroborated by the increase in electrical resistivity in the case of the functionalized CNT/NR composites.

Reinforcement of starch/polyvinyl alcohol blend using nano‐titanium dioxide

The article reports the results of the studies on the effect of nano‐titanium dioxide (TiO2) on the morphology, thermal, and mechanical properties of 1:1 starch/polyvinyl alcohol (PVA) composites. Degree of crystallinity of the starch/PVA blends increases with increase in the amount of nano‐TiO2 as determined by differential scanning calorimeter and X‐ray diffraction studies. Results of stress–strain studies indicate an increase in the tensile properties and a decrease in the percentage of elongation and energy at break particularly at higher amount of nano‐TiO2. Increase in peak width in the differential thermogram plot for the maximum decomposition temperature is indicative of increased blend heterogeneity in the presence of nanofillers. The degree of swelling in water decreases with increase in filler loading due to filler–matrix bonding.

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 5.00u2009wt%) 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 (>1.0u2009wt%). 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 (>0.1u2009wt%).

Easy one-pot method to control the morphology of polyethylene/carbon nanotube nanocomposites using metallocene catalysts

AbstractAn easy one pot method is demonstrated for the controlled periodical surface coating of polyethylene over multiwalled carbon nanotubes (MWCNT) by insitu polymerization of ethylene using highly active metallocene catalysts (Cp2ZrCl2 and Cp2TiCl2) in combination with methylalumoxane. The crystallinity of the nanocomposite was increased and its morphology could be tuned from “sausage” like to “shish-kebab” in the presence of CNT depending on the experimental condition and choice of metal atom.n FigureA convenient one-pot method is illustrated to control the morphology of polymer nanocomposite by simple mixing of metallocene catalyst (Cp2ZrCl2 or Cp2TiCl2) and MWCNT in toluene at normal conditions followed by the activation with MAO. The crystallinity of the nanocomposite is increased and the polymer morphology could be tuned from “sausage” like to “shish-kebab”, depending on the experimental conditions.

Natural weather ageing of starch/polyvinyl alcohol blend: effect of glycerol content

Abstract Starch plasticized with glycerol and blended with polyvinyl alcohol (PVA) is recommended for use as a biodegradable material. The present article reports the results of studies of the natural weather ageing of starch/PVA blends having various amounts of glycerol in natural weather conditions of Saudi Arabia, with special reference to morphology and thermal behavior. Neat PVA has been used as a control to understand its behavior in its blend with starch. Differential scanning calorimeter studies indicated that an increase in the exposure time of samples to natural environment increases the crystallinity of PVA due to the breakage of intermolecular hydrogen bonding, thus facilitating the removal of the amorphous portion of the polymers in the blend. Thermogravimetric analysis revealed that an increase in glycerol content enhanced the degradation of the polymer, which is corroborated with the findings from the surface morphology using scanning electron microscopy and Fourier transfer infrared spectroscopy analyses.

Effect of Modified and Nonmodified Carbon Nanotubes on the Rheological Behavior of High Density Polyethylene Nanocomposite

This paper reports the results of studies on the rheological behavior of nanocomposites of high density polyethylene (HDPE) with pristine multiwall carbon nanotubes (CNT) as well as phenol and 1-octadecanol (C18) functionalized CNT at 1, 2, 3, 4, 5, and 7u2009wt% loading. The viscosity reduction at 1u2009wt% CNT follows the order, pristine CNT < phenol functionalized CNT < C18 functionalized CNT. As the filler loading increases from 1 to 2, 3, and 4u2009wt%, neat HDPE and filled HDPE systems show similar moduli and viscosity, particularly in the low frequency region. As the filler loading increases further to 5 and 7u2009wt%, the viscosity and moduli become greater than the neat HDPE. The storage modulus, tan, and the Cole-Cole plots show that CNT network formation occurs at higher CNT loading. The critical CNT loading or the rheological percolation threshold, where network formation occurs is found to be strongly dependant on the functionalization of CNT. For pristine CNT, the rheological percolation threshold is around 4u2009wt%, but for functionalized CNT it is around 7u2009wt%. The surface morphologies of CNT and functionalized CNT at 1u2009wt% loading showed good dispersion while at 7u2009wt% loading, dispersion was also achieved, but there are few regions with agglomeration of CNT.

Thermal effect of ceramic nanofiller aluminium nitride on polyethylene properties

Ethylene polymerization was done to form polyethylene nano-composite with nanoaluminum nitride using zirconocene catalysts. Results show that the catalytic activity is maximum at a filler loading of 15 mg nanoaluminum nitride. Differential scanning calorimeter (DSC) and X-ray diffraction (XRD) results show that percentage crystallinity was also marginally higher at this amount of filler. Thermal behavior of polyethylene nanocomposites (0, 15, 30, and 45) mg was studied by DSC and thermal gravimetric analyzer (TGA). Morphology of the component with 15 mg aluminium nitride is more fibrous as compared to 0mg aluminium nitride and higher filler loading as shown by SEM images. In order to understand combustibility behavior, tests were performed on microcalorimeter. Its results showed decrease in combustibility in polyethylene nanocomposites as the filler loading increases.