Arup Choudhury

Preparation and characterization of nanocomposites of poly-p-phenylene benzobisthiazole with graphene nanosheets

Poly-p-phenylene benzobisthiazole (PBT)/graphene nanocomposite films were fabricated using a simple method with methanesulfonic acid (MSA) as the processing solvent. In this approach, graphene nanosheets were exfoliated in the MSA solution of PBT using ultrasonication and mechanical stirring, and then processed into thin films. The structure and composition of as-prepared graphene oxide (GO) and reduced graphene oxides (rGO) were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrical conductivity of pristine PBT was enhanced by 10 orders of magnitude upon incorporation of 5 wt% rGO nanosheets. The enhanced conductivity of the nanocomposites was interpreted by the percolation model. The thermo-oxidative stability of PBT was improved with the incorporation of both GO and rGOs, while rGOs showed more pronounced effect. On addition of only 5 wt% GO, the tensile strength and Youngs modulus of PBT increased by ∼4-fold and ∼7-fold, respectively, whereas relatively inferior tensile properties were observed for the PBT/rGO nanocomposites. The enhanced mechanical properties could be attributed to the molecular-level dispersion of the exfoliated GO nanosheets in PBT matrix, as evidenced by the results from morphological studies. A modified Halpin–Tsai model has been used to evaluate the reinforcement or orientation effects of GO/rGO on the Youngs modulus of the nanocomposites.

Effect of Polyvinylpyrrolidone on Separation Performance of Cellulose Acetate-Polysulfone Blend Membranes

Blend membranes comprising cellulose acetate and polysulfone (CA/PSf) were prepared through a solution casting method using a different concentration of polyvinylpyrrolidone (PVP) as the pore former. Fourier transform infrared spectroscopy (ATR-FTIR) was used to investigate structural properties of membranes. Membranes morphology and its thermal properties were characterized by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The strength of membranes was studied by mechanical stability. The effect of PVP concentration on separation performance of the prepared membranes was studied. The separation performance of prepared membranes was tested by using an aqueous solution of cadmium metal complexed with humic acid. The results showed that an increase in the PVP concentration in the cast film from 0 to 3 wt% increased the thermal stability, water content (%), pure water flux, and solute rejection. SEM results showed that the pore size decreased but the number of pores increased on an increase in the PVP concentration.

Recycling of polyethylene/poly(ethylene terephthalate) post- consumer oil pouches using compatibiliser

The recyclability of LDPE/LLDPE/PET based post-consumer laminated oil pouches, and the scope for improvement of the properties of the recycled polymer by the addition of reactive compatibilisers are evaluated. Two efficient reactive compatibilisers, viz., a zinc salt of ethylene methacrylic acid copolymer (Surlyn ionomer) and polyethylene graft maleic anhydride (Fusabond) were used. The effectiveness of the compatibiliser in the recycling of laminated oil pouches was evaluated by infrared spectroscopy, melt flow index, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, rheological and mechanical properties. The melt viscosity, thermal stability and mechanical properties of the recycled material were improved to a satisfactory level by the addition of 5 wt% of compatibiliser. The Surlyn ionomer gave better thermal and mechanical properties. The overall performance of the compatibilised recycled oil pouch materials indicates their suitability for several demanding applications.

Recycling of Edible Oil Pouches: Composition and Thermal Stability

Recycled polyethylene containing very small amounts of nylon-6 or PET, which is the source of flexible oil pouches, may find applications as raw materials for other polymer products after the recycled polymer is properly identified and characterized before reprocessing. Proper identification and characterization of the polymer components present in the waste has considerable importance for obtaining value-added products. In this investigation, post-use oil pouch films, collected from municipal garbage, were first subjected to sorting, washing and drying. Then the dried films were fractionated by dissolving in solvents. The isolated component polymers were characterized and identified by solvent fractionation, FTIR, DSC-TGA and WAXD analysis.

Chemically Modified Carbon Black Filled Ethylene-Propylene-Diene Rubber Composites : Mechanical and Dynamic Mechanical Study

A surface-modified carbon black (N330) has been prepared by treating it with pentaerythitol, combination of pentaerythitol and pyrogallol and a combination of pentaerythitol and resorcinol in aqueous solution at different molar concentrations. The adsorption of modifier and formation of new functional groups could be identified from the FTIR peaks. This modified carbon black has been used as one of the compounding ingredients in EPDM rubber. It was found that carbon black modified with pentaerythitol and resorcinol showed more pronounced effect than the other two. In all cases the properties like hardness, tensile strength, and modulus are found to be increasing as the concentration of modifier was increased. All these values are higher as compared to rubber compound with unmodified carbon black. While the properties like abrasion loss, compression set, elongation at break, tan delta were found to be decreasing with increase in modifier concentration. All these results points towards an improved interaction between the filler and rubber. The surface functional groups on the modified carbon black would attach to the rubber chains and will act as secondary cross linker. Calculated values of crosslink density were found to be increasing with the modifier concentrations, clearly defines the formation of secondary crosslinking.

Flexible and freestanding supercapacitor based on nanostructured poly(m-aminophenol)/carbon nanofiber hybrid mats with high energy and power densities

Nanostructured poly(m-aminophenol) (PmAP) coated freestanding carbon nanofiber (CNF) mats were fabricated through simple in situ rapid-mixing polymerization of m-aminophenol in the presence of a CNF mat for flexible solid-state supercapacitors. The surface compositions, morphology and pore structure of the hybrid mats were characterized by using various techniques, e.g., FTIR, Raman, XRD, FE-SEM, TEM, and N2 absorption. The results show that the PmAP nanoparticles were homogeneously deposited on CNF surfaces and formed a thin flexible hybrid mat, which were directly used to made electrodes for electrochemical analysis without using any binders or conductive additives. The electrochemical performances of the hybrid mats were easily tailored by varying the PmAP loading on a hybrid electrode. The PmAP/CNF-10 hybrid electrode with a relatively low PmAP loading (> 42 wt%) showed a high specific capacitance of 325.8 F g-1 and a volumetric capacitance of 273.6 F cm-3 at a current density of 0.5 A g-1, together with a specific capacitance retention of 196.2 F g-1 at 20 A g-1. The PmAP/CNF-10 hybrid electrode showed good cycling stability with 88.2% capacitance retention after 5000 cycles. A maximum energy density of 45.2 Wh kg-1 and power density of 20.4 kW kg-1 were achieved for the PmAP/CNF-10 hybrid electrode. This facile and cost-effective synthesis of a flexible binder-free PmAP/CNF hybrid mat with excellent capacitive performances encourages its possible commercial exploitation.

Effect of Tetraethyl Orthosilicate on the Structural, Thermal, and Morphological Properties of a Cellulose Acetate Membrane

The present investigation deals with the preparation of a new organic–inorganic hybrid membrane based on cellulose acetate (CA)/tetraethyl orthosilicate (TEOS) by the sol–gel and phase-inversion process. This paper also investigates the effect of TEOS content on the mechanical, thermal, and ultrafiltration (UF) performance of the newly prepared membranes. These newly prepared membranes were characterised by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). The ultrafiltration performance of the membranes was examined by water content (%), compaction, and pure water flux. Results showed that the addition of TEOS increased the thermal and mechanical properties. SEM results showed that the pore size decreased but the number of pores increased on the addition of TEOS. Moreover, the hydrophilicity and permeability increased with increase in TEOS content from 0 to 2 wt%. Thus, it can be concluded that these hybrid membranes may be suitable for use in the UF separation process.

Mixtures of recycled milk pouches with a virgin LDPE-LLDPE blend

The present investigation deals with the viability of the use of recycled milk pouch material, which is a 50:50 mixture of LDPE and LLDPE, and the scope for improvement of its properties by combining it with virgin LDPE-LLDPE (50/50). Melt flow index (MFI), rheological properties, thermal and mechanical properties of the pure materials and their formulated blends containing recycled milk pouches were studied. The properties of the recycled materials were not as satisfactory as those of the corresponding virgin materials. But a significant improvement in viscosity, crystallinity, tensile strength and elongation at break of the recycled LDPE-LLDPE material was achieved by blending it with the corresponding virgin LDPE-LLDPE blend.