Computer simulation method for calculating concentration profiles in polyurethane/polystyrene interpenetrating polymer network membranes

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and polystyrene (PS; 90/10 and 75/25) were synthesized by the condensation reaction of castor oil with methylene diisocyanate and styrene, with benzoyl peroxide as an initiator. The IPN membranes were characterized for physicomechanical, optical, and X‐ray diffraction properties. Computer‐simulated concentration profiles of aqueous salt solutions through PU/PS IPN membranes were generated with Fick's second‐order differential equation, and the results were examined in terms of diffusion anomalies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 122–128, 2003     

Physicomechanical,optical, barrier,and wide angle X‐ray scattering studies of filled low density polyethylene films

Series of low density polyethylene (LDPE) films filled with different fillers such as silica, mica, soya protein isolate, potassium permanganate, and alumina were processed using a single screw extruder. The filled LDPE films were characterized for physicomechanical properties like tensile strength, percentage elongation at break, and tear strength, optical properties like percent transmission and haze. The barrier properties such as water vapor transmission rate and oxygen transmission rate of the filled LDPE films have also been reported. Microcrystalline parameters such as crystal size (〈N〉) and lattice distortion (g) of the filled LDPE films obtained using wide angle X‐Ray scattering method have been reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2781–2789, 2006     

Thermal and mechanical properties of poly(methyl methacrylate) and ethylene vinyl acetate copolymer blends

A series of poly(methyl methacrylate) (PMMA) blends have been prepared with different compositions viz., 5, 10, 15, and 20 wt % ethylene vinyl acetate (EVA) copolymer by melt blending method in Haake Rheocord. The effect of different compositions of EVA on the physico‐mechanical and thermal properties of PMMA and EVA copolymer blends have been studied. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) has been employed to investigate the phase behavior of PMMA/EVA blends from the point of view of component specific interactions, molecular motions and morphology. The resulting morphologies of the various blends also studied by optical microscope. The DSC analysis indicates the phase separation between the PMMA matrix and EVA domains. The impact strength analysis revealed a substantial increase in impact strength from 19 to 32 J/m. The TGA analysis reveals the reduction in onset of thermal degradation temperature of PMMA with increase in EVA component of the blend. The optical microscope photographs have demonstrated the PMMA/EVA system had a microphase separated structure consisting of dispersed EVA domains within a continuous PMMA matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Studies on miscibility of blends of poly (ethylene acrylic acid) and ethylene‐co‐vinyl acetate by melt rheology

Rheological behavior of blends of poly (ethylene‐acrylic acid) (EAA) and ethylene vinyl acetate (EVA) copolymer have been carried out at various temperatures, namely, 100, 110, and 120°C, and different shear rates from 61.33 to 613.30 s^?1 using a Monsanto Processability Tester. The melt viscosity of the blends shows synergism during processing. The activation energy of the blends is in the range 20.7–44.6 kJ/mol. Highest activation energy was observed for the blends containing 40–60% of EVA by weight. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1947–1954, 2005     

Preparation of polyaniline nanostructures using sodium dodecylsulphate

Polyaniline (PANI) nanostructures with an average diameter of 30-35 nm and a conductivity of 2.13-1.15 × 10^− 1 S/cm were prepared using sodium dodecylsulfate (SDS) emulsion in the absence of any added acid. Fiber like nanostructures was observed after 1 and 2 h, whereas an aggregated particulate morphology was observed for 4 and 24 h. The effect of the reaction time on the PANI morphology was monitored using field-emission scanning electron microscopy (FESEM). Furthermore, the effects of the reaction time on the chemical structure, conductivity and crystallinity of PANI are reported.     

Novel PAAm/Laponite clay nanocomposite hydrogels with improved cationic dye adsorption behavior

A nanocomposite (NC) hydrogel was prepared by incorporating the nanoclay (Laponite (Lap) XLS) into a poly(acrylamide) (PAAm) hydrogel by the in situ polymerization method without any organic cross-linker. The parameters pertaining to the swelling (Q) and diffusion (D) of water for the PAAm/Lap NC hydrogels were estimated. The crystal violet (CV) dye adsorption properties of the PAAm/Lap NC hydrogels were investigated. The adsorption of CV dye by the hydrogel increases as the concentration of the dye increases. The cationic dye adsorption ability of the NC hydrogel increased with increasing clay content in the NC hydrogel. The NC hydrogels containing CV dye were characterized by FT-IR. A sigmoidal type of adsorption isotherm was observed for the CV-NC hydrogels. The effects of heat treatment on the dye adsorption behavior of the NC hydrogels were studied.     

Microstructural behaviors of polyaniline/CB Composites by SAXS

Polyaniline doped with dodecylbenzene sulfonic acid and conductive carbon black (PAn.DBSA/CB) hybrid materials have been prepared by in situ polymerization. The electrical resistivity of the PAn/CB was measured as a function of CB. The minimum resistivity was noticed for the composites with 25 wt % of CB as compared to other systems. Small angle x‐ray diffraction data was used to characterize the molecular arrangements of these composites. The refinement parameters such as periodicity (L), phase lengths (<Y> and <Z>), phase ratio (<Y>/<Z>), and probability distribution of phases [γ_Z (crystalline), γ_Y (amorphous)] for PAn, CB, and PAn/CB composites have been measured by SAXS data. It was observed that there is decrease in the crystallinity with increase in CB content in the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of zeolite particulate filler on the properties of polyurethane composites

Polymer-Zeolites composites have been prepared, using castor oil based polyurethane (PU) as a host and AlPO₄-5 as particulate filler. The prepared PU/zeolite composites have been characterized for mechanical properties such as tensile strength and tensile modulus. These PU composites exhibited an improved mechanical performance compared to the unfilled PU. Thermo gravimetric analyzer (TGA) curve shows that all the chain-extended PUs are stable up to 250 °C and maximum weight loss occurs at 490 °C. The thermal stability of composites increases with increase in zeolite content. Microcrystalline parameters and micro voids of composites have been measured by using wide-angle X-ray scattering (WAXS) and Positron Annihilation Lifetime (PALS) methods respectively. The microcrystalline parameters and micro-voids from PALS indicate the interaction of the filler with the matrix is stronger beyond 5% of the filler which reflect the mechanical performance as well. Surface morphology of composites has been studied using Scanning Electron Microscopy (SEM). The photomicrograph of SEM indicates a uniform distribution of zeolite filler in the PU matrix.     

Tensile behavior of composite patched cracked metallic structures

Composite patches of epoxy-based unidirectional carbon and woven glass prepregs were adhesively bonded on uncracked and center cracked standard specimens of aluminum sheet, and patched specimens were evaluated by tensile testing. The effect of various surface treatments, patch length, and number of plies on the tensile strength was studied. Surface preparation of the specimens by sandblasting had a pronounced effect on strength improvement compared to other physical or chemical treatments. The strength of the cracked specimens increased up to 79% for unidirectional carbon patched specimens and 75% for woven glass patched specimens. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2063–2068, 1998     

Interaction of crosslinked ethylene–propylene–diene terpolymer blends with chlorinated organic penetrants

The sorption and diffusion of halogenated hydrocarbon penetrants through different ethylene–propylene–diene terpolymer (EPDM) blends, such as EPDM/natural rubber, EPDM/bromobutyl rubber, and EPDM/styrene butadiene rubber (50/50 w/w), were studied. The diffusion coefficient of halogenated penetrants fell in the range 1.5–14.52 × 10^?7 cm²/s in the temperature range of 25–60°C. Transport data were affected by the nature of the interacting solvent molecule rather than its size and also by the structural variations of the EPDM blends. 1,2‐Dichloroethane showed a lower mass uptake compared to other penetrants. The temperature dependence of the transport coefficient was used to estimate the activation parameters, such as the activation energy of diffusion (E_D) and the activation energy of permeation (E_p) from Arrhenius plots. The activation parameters for E_D of aliphatic chlorinated organic penetrants was in the range 7.27–15.58 kJ/mol. These values fell in the expected range for rubbery polymers, well above their glass‐transition temperature. Also, the thermodynamic parameters, such as enthalpy and entropy, were calculated and fell in the range 2–15 kJ/mol and 3–54 J/mol/K, respectively. Both first‐ and second‐order transport kinetics models were used to investigate the transport kinetics, and first‐order kinetics were followed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1366–1375, 2003