Gyanaranjan Prusty

Dispersion of expanded graphite as nanoplatelets in a copolymer matrix and its effect on thermal stability, electrical conductivity and permeability

Expanded graphite/polyacrylonitrile-co-poly (methyl methacrylate) (EG/PAN-co-PMMA) composites were prepared by the incorporation of EG at various concentrations (1%, 2%, 3%, and 4%, w/w) into PAN-co-PMMA by an in situ emulsifier-free emulsion polymerization method. As-synthesized composites were characterized by UV/VIS and FT-IR, XRD, SEM, TEM and TGA. The thermal stability of the copolymer was significantly improved by the addition of EG. The oxygen permeabilities of the composites were substantially reduced and the electrical conductivities of the composites were significantly increased by increasing the EG content.

SYNTHESIS OF PAN/CLAY NANOCOMPOSITES: STUDY OF GAS PERMEATION PROPERTIES

Polymer based composites have received high interest due to their unusual combination of stiffness and toughness that are difficult to attain from individual components. For this reason, they have been widely used in areas of transportation, construction, electronics and consumer products. Nanocomposites exhibiting a change in composition and structure over a nanometer length scale have been shown over the last few years to afford remarkable property enhancements relative to conventional composites. Organically modified clays can be effective reinforcing agents in manufactured polymer–clay nanocomposites. Polyacrylonitrile (PAN)/clay nanocomposites were prepared by the emulsifier free emulsion polymerization with variable power and frequency of ultrasound. The ultrasound waves of powers of 80 watt and 120 watt at frequencies of 60 KHz and 80 KHz were applied to assist the dispersion of organically modified clay with polymer matrix. The structure and morphology of nanocomposites were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The oxygen permeability of the samples was measured by gas permeameter. A substantial reduction in oxygen permeability was observed by increasing clay loading and through sonication.

Conductive, Gas Barrier, and Thermal Resistant Behavior of Poly (methyl methacrylate) Composite by Dispersion of ZrO2 Nanoparticles

Poly (methyl methacrylate)/zirconium dioxide (PMMA/ZrO2) nanocomposites were prepared by the incorporation of ZrO2 nanoparticles in various proportions (2, 4, 6, 8, and 10%) with PMMA matrix by in situ emulsifier-free emulsion polymerization technique. The structural property of PMMA/ZrO2 nanocomposites was studied by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The thermal stability of PMMA/ZrO2 nanocomposites was improved with increasing concentration of ZrO2. The electrical conductivity of composites was measured as function of ZrO2 concentration. The oxygen barrier properties of PMMA/ZrO2 nanocomposites were measured by using gas permeameter.

Expanded graphite as a filler for epoxy matrix composites to improve their thermal, mechanical and electrical properties

Abstract Expanded graphite (EG)-reinforced epoxy composites were prepared by a solution mixing method. The structure and morphology of the EG/epoxy composites were investigated by XRD, FE-SEM and HR-TEM. The EG prepared by acid oxidation and thermal expansion shows good compatibility with the epoxy resin that enters the EG layers to decrease their thickness to 60–70 nm, owing to its abundant oxygen-containing functional groups. With the addition of 9 wt% EG, the thermal decomposition temperature of the composite increases from 340 to 480 °C, the electrical conductivity from 10−15 to 10−5 S/cm and the tensile stress is increased by more than 30%. These improvements are attributed to the good dispersion of EG sheets in the epoxy matrix.

Dispersion of nanoplatelets of graphite on PMMA matrix by in situ polymerisation technique

Poly(methyl methacrylate)/expanded graphite (PMMA/EG) composites were prepared by the incorporation of EG in various proportions (1%, 2%, 3%, 4% and 5%) with PMMA by in situ polymerisation technique. The polymer composites were characterised by ultraviolet–visible (UV–vis) and Fourier transform infra-red spectroscopies. The structural property of PMMA/EG nanocomposites was studied by X-ray diffraction. The scanning electron microscopy and transmission electron microscopy of synthesised composites were taken in order to study their morphological properties. The conductivity of composites was measured as function of EG concentration. It was found that conductivity of composites gradually increased with the increase in EG loading. Oxygen permeability of PMMA/EG nanocomposites was calculated and it was found that the property was reduced substantially with rise of EG proportion. The thermal stability of PMMA/EG nanocomposites was improved by dispersion of EG with PMMA matrix.

Carbon quantum dot tailored calcium alginate hydrogel for pH responsive controlled delivery of vancomycin

&NA; Herein, we demonstrate the preparation of highly luminescent carbon quantum dots (CQDs) from Aloe vera leaf gel; in just 2 h at 250 °C through carbonization pathway. The prepared CQDs are structurally characterized with high resolution transmission electron microscopy (HRTEM), hydrodynamic diameter, surface polarity, Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), Raman, UV–visible absorption spectrophotometry and fluorescence spectroscopy. The functional carbon nanoparticles are observed as non‐cytotoxic materials. The biocompatibility, less cytotoxicity and high aqueous dispersibility of as‐synthesized CQDs are motivated to design carbon quantum dot (CQD) tailored calcium alginate (CA) hydrogel films with an aim to controlled delivery of glycopeptides antibiotic vancomycin in the gastrointestinal tract (GI). With CQD, the drug loading capacity of CA/CQD film is increased to 89% from 38% (CA film), whereas; with &bgr;‐cyclodextrin (&bgr;‐CD) the vancomycin uptake capacity is increased more, 96%. The release of vancomycin through CA/CQD film is more pronounced at pH 1.5, close to the pH of the stomach and it is found that in pH 1.5 with &bgr;‐CD, the release rate of vancomycin is lowered, 56% in 120 h. The high drug uptake capacity (96%) and lower release rate (56% in 120 h) of CA/CQD hydrogel film in pH 1.5 with &bgr;‐CD can be used for its applicability as drug delivery vehicle for controlled release of vancomycin into the stomach region and therefore it can offer a potential option for oral administration of vancomycin. Graphical abstract Figure. No caption available.

Sonochemical Compatibility of Polyvinyl Alcohol/Polyacrylic Acid Blend in Aqueous Solution

Ultrasonic velocities, viscosities, and densities of polyvinyl alcohol (PVA), polyacrylic acid (PA), and their mixtures (1:1 and 1:2) in aqueous solutions were measured. Various acoustic parameters were calculated as a function of concentrations of PVA, PA, and PVA-PA mixtures in water with the resonance method at ultrasound frequencies of 2, 3, 5, and 10 MHz at 30°C. From the comparative results, the mode of interactions of the two polymers was shown to be due to hydrogen bonding. The bonding among the hydroxide groups of both macromolecules were verified by infrared spectroscopy. The explanations of the acoustic results were confirmed by the intrinsic viscosities of the ternary system. Significant interactions and compatibility of PVA/PA may lead to the development of pharmaceutically active molecules.

Characterization of Polyacrylonitrile Nanocomposites by Reinforcement of Functionalized Single-Walled Carbon Nanotubes

Polyacrylonitrile/functionalized single-walled carbon nanotubes (PAN/f-SWCNTs) nanocomposites were synthesized by an emulsifier-free in situ polymerization process. Interaction of polyacrylonitrile with functionalized single-walled carbon nanotubes was evidenced by ultraviolet-visible and Fourier transforms infrared spectroscopy. The structure and morphology of nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. Electrical conductivity was found to be increased by addition of f-SWCNTs. Thermogravimetric analysis study of PAN/f-SWCNT nanocomposites show more thermal resistance compared to the virgin PAN. The oxygen barrier property of PAN/f-SWCNT nanocomposites was reduced by eight times with increasing f-SWCNTs proportions.