Gautam Sarkhel

Polyethersulfone Membranes: The Effect of Sulfonation on the Properties

Polyethersulfone (PES) was sulfonated using chlorosulfonic acid in order to improve proton conductivity. Incorporation of ‒SO3H groups into polymer main chain through sulfonation was confirmed using FTIR and 1H NMR. Ion exchange capacity of sulfonated membranes was determined via titration. Morphological studies (AFM, SEM) revealed the presence of hydrophilic proton transfer channels, which became continuous at higher degrees of sulfonation. Thermal stability was observed from thermogravimetric analysis (TGA). Storage modulus and tan δ also exhibited an increase with degree of sulfonation as determined from DMA. Conductivity measurements and fuel cell performance showed that sulfonated samples possessed higher conductivity than virgin PES.

Effect of Zn+2 Poly(ethylene-co-methacrylic acid) Ionomer on Mechanical Properties, Thermal Properties, Morphology and Process Rheology of Acrylonitrile Styrene Acrylate (ASA) Terpolymer

The present study deals with acrylonitrile–styrene–acrylic elastomer (ASA) terpolymer and an ionomer based blend to develop a weather resistant material with good heat sealability and excellent adhesion properties. The mechanical properties of ASA/ionomer blends were reduced with increase in ionomer content, whereas the thermal stability was improved. On addition of ionomer, the effects of shear rate and temperature on melt viscosity were also investigated. The mechanical modulli were also carried out to justify and correlate with ionomer content. The thermal stability, investigated by thermogravimetric analysis, showed that the thermal stability was increased with the incorporation of ionomer.

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.

Preparation, Characterization and Properties of Flexible Magnetic Nanocomposites of NiFe2O4-polybenzoxazine-LLDPE

A simple method for the preparation of magnetic nanocomposites consisting of NiFe2O4 nanoparticles, polybenzoxazine (PB), linear low-density polyethylene (LLDPE) and LLDPE-g- Maleic anhydride (LgM) is described. Composites were prepared by forming benzoxazine- NiFe2O4 nanocomposites followed by melt blending with LLDPE and thermal curing of benzoxazine. The composites were characterized by XRD, DSC and TGA, FT-IR, SEM, UTM and VSM. The saturation magnetization of the composites containing 33.25 wt% NiFe2O4 was 7.72 emu/g and it decreased with decreasing amount of NiFe2O4 in the composite. The composite films exhibited mechanical flexibility as well as magnetic properties.

Effect of Zirconium Phosphate on Structural, Thermal, and Electrical Properties of Polyether Sulfone (PES) Membrane

Fuel cell application in automobiles requires proton exchange membranes having low dependency on temperature and humidification. In view of this application, systematic and well-defined sulfonated polyether sulfone–zirconium phosphate composite membranes were prepared using zirconium phosphate as a proton-conducting filler by the sol-gel method. The thermal stability of the prepared composite membranes was analyzed by thermogravimetric analysis. Dynamic mechanical analysis was used to determine storage modulus and tanδ. The proton conductivity of the membranes was measured by impedance spectroscopy. Microscopy study was used to investigate the homogenous distributions of fillers in the composite membranes.

Study of Dynamic Rheological, Dynamic Mechanical and Creep Properties of Acrylonitrile Styrene Acrylate (ASA)/Zn+2poly(ethylene-co-methacrylic acid) Ionomer Blend

A new class of blend system comprising weather resistant acrylonitrile/styrene/acrylate (ASA) terpolymer and Zn-ionomer was developed. Based on Zn-ionomer content, the blend system either forms ‘mushroom’ or ‘brush’ type conformation which affected dynamic rheology, DSC, DMA and creep properties differently. Formation of ionic crosslinkings by Zn-ionomer in ‘brush regime’ as well as limited ionic crosslinkings in ‘mushroom regime’ resulted in different nature molecular chain relaxation response. The DSC endotherm peak and glass transition temperature were also influenced by the type of conformation and ion-dipole interaction between the blend components. The tan δ from DMA study also reflected the similar trend. The creep deformation behavior of the blend was found to be dependent on highly deformable Zn-ionomer content and with temperature. The Findley model analysis suggests the ionic crosslinkings may be the possible reason for controlled creep deformation of the blend.

High-Density Polyethylene-Ethylene Propylene Rubber-Based Thermoplastic Elastomer: A Mechanical Modeling, Thermal and Rheological Study

The present investigation deals with the mechanical, thermal and rheological properties of binary HDPE/EPR blends at various dispersed phase (EPR) concentrations. The effects of EPR concentration on tensile, impact properties of the pure HDPE and HDPE/EPR blends were studied. Analysis of the tensile data in terms of various theoretical models revealed the variation of stress concentration effect with blend composition. Rheological study was carried out to investigate the change in viscosity with shear rate. DSC results show decrease in percent crystallinity of HDPE upon incorporation of EPR except at 20 wt% rubber concentrations wherein the percent crystallinity has shown marginal increment.

Preparation and characterization of flexible polybenzoxazine–LLDPE composites

Polybenzoxazine-based flexible composites have been prepared by blending benzoxazine with linear low density polyethylene (LLDPE) in presence of a compatibilizer (maleic anhydride grafted linear low density polyethylene [LLDPE-g-MA]) using a melt blending method. It has been observed that the thermal stability of the composites increased with increasing amount of polybenzoxazine in the composition. Mechanical properties of the composites have been investigated by using tensile and flexural tests. Presence of 5 wt% compatibilizer in the composition showed very good mechanical properties. Pure polybenzoxazine possessed high tensile strength and less elongation at break whereas LLDPE showed low tensile strength and significantly more elongation at break. Composites consist of LLDPE and polybenzoxazine with additional LLDPE-g-MA, exhibited higher tensile strength than pure LLDPE and more elongation at break than pure polybenzoxazine. Prepared composites possess very good mechanical flexibility, which makes them good candidates to prepare of complex structures and coating.

Effect of stoichiometric ratios for synthesized epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties

Purpose The purpose of this paper is to study the effect of various stoichiometric ratios for synthesised epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties. Design/methodology/approach In the present study, EPN (EPN-1, EPN-2, EPN-3, EPN-4 and EPN-5) resins were synthesised by varying five types of different stoichiometric ratios for phenol/formaldehyde along with the corresponding molar ratios for novolac/epichlorohydrin. Their different physicochemical properties of interest, thermomechanical properties as well as morphological properties were studied by means of cured samples with the variation of its stoichiometric ratios. Findings The average functionality and reactivity of EPN resin can be controlled by controlling epoxy equivalence as well as cross-linking density upon its curing as all of these factors are internally correlated with each other. Research limitations/implications Epoxy resins are characterised by a three-membered ring known as the epoxy or oxirane group. The capability of the epoxy ring to react with a variety of substrates imparts versatility to the resin. However, these resins have a major drawback of low toughness, and they are also very brittle, which limits their application in products that require high impact and fracture strength. Practical implications Epoxy resins have been widely used as high-performance adhesives and matrix resins for composites because of their outstanding mechanical and thermal properties. Because of their highly cross-linked structure, the epoxy resin disables segmental movement, making them hard, and it is also notch sensitive, having very low fracture energy. Social implications Epoxy resin is widely used in industry as protective coatings and for structural applications, such as laminates and composites, tooling, moulding, casting, bonding and adhesives. Originality/value Systematic study has been done for the first time, as no exact quantitative stoichiometric data for the synthesis of EPN resin were available on the changes of its different properties. Thus, an optimised stoichiometric composition for the synthesis of the EPN resin was found.

Changes in the properties of shellac on blending with rosin, effect on storage

Purpose – The purpose of this paper is to see the effect in the properties of shellac on blending with rosin (another natural resin) and study their changes during storage.Design/methodology/approach – Blending of rosin was done at seedlac (semi‐pure lac) stage. Shellac was then prepared by bhatta (Indian country) process, in the form of button lac. Physico‐chemical properties of the blends were studied at regular time intervals following standard procedures.Findings – Improvement in the physicochemical properties of shellac was noticed by blending with rosin to a great extent; less degradation in the properties of blends was observed with storage compared to those of parent shellac.Research limitations/implications – Because rosin possesses very high fluidity and life under heat, exact value of flow and life under heat of rosin and its blends with shellac having high rosin content could not be determined.Practical implications – The results give an idea to entrepreneurs, processors and industrialists of ...