Thermogravemetric Analysis Research Articles

Adsorption of brilliant green dye by polyaniline/silver nanocomposite: Kinetic, equilibrium, and thermodynamic studies

Polyaniline/silver nanocomposite (PANI/AgNPs) was synthesized by the chemical oxidative polymerization of aniline with ammonium peroxydisulphate in acidic medium of sulfuric acid (1M). The surface of polyaniline is modified by silver nanoparticles. Samples were prepared at various molar ratios of silver nitrate to PANI ranging from 1 to 2.5. The emeraldine base was oxidized to pernigraniline, where the silver nitrate was reduced to metallic silver. The modified surface of PANI was confirmed by the scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), FT-IR and thermogravemetric analysis (TGA). The efficiency of polyaniline/silver nanoparticles for the adsorptive removal of brilliant green (BG) from aqueous solutions, has been evaluated with respect to several experimental conditions. These conditions are contact time, initial BG concentration, temperature and nanocomposite dosage. The experimental data were analyzed by the Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm fits the experimental data very well due to the homogeneous distribution of active sites onto PANI/AgNPs surface. The thermodynamic parameters such as Gibbs free energy, entropy and enthalpy changes of the ongoing adsorption process indicated the feasibility and endothermic nature of BG adsorption. The kinetics study revealed that adsorption of BG onto PANI/AgNPs follows the pseudo-second order kinetic model.

Development of PVC membranes with clove oil as plasticizer for blood bag applications

In the present study, Antimicrobial PVC films containing different amounts of clove oil as a plasticizer were prepared using traditional casting method. The physical and mechanical properties of the plasticized PVC membranes e.g. surface wettability were investigated. The increase of clove oil content demonstrated an increase in surface hydrophilicity and elongation to break the film. The thermogravemetric analysis revealed a decrease of polymer thermal stability by increasing clove oil concentration. The antibacterial activities against four different bacterial strains (two-gram positive: Staphylococcus aureus and Bacillus cereus & two-gram negative: Pseudomonas aeruginosa and Escherichia coli were promoted by addition of clove oil. Although the natural source of clove oil, the bio-evaluation of plasticized membranes showed an increase in hemolysis percent (%) and thrombus weight. It can be concluded that the addition of clove to PVC need to further studies for applying in blood bags.

Investigation of the nanocrytalline SnO2 Synthesized by Homogeneous Precipitation

Nanocrystalline tin dioxide synthesized by the homogeneous pre cipitation method using the reaction of tin tetrachloride pentahydrate and urea solutions has been investigated. The nanocrystalline powder has been traced at different calcination temperatures (300ºC-1050ºC), and then characterized by using Thermogravemetric analysis, differential thermal analysis and x-ray diffraction. The microstructure of the obtained nanoparticles has been examined by scanning and transmission electron microscopy. The average crystallite size, determined by x-ray diffraction, was found to be in the range of 3 –30 nm. The analysis exhibited a tetragonal phase. Optical properties were investigated by a UV–vis absorption spectrophotometer. The calculated optical band gap lies between 4.47–3.71 eV as a result of increasing the calcination temperatures and crystallite size. Surface area and porosity of SnO2 nanoparticles are measured. Specific surface area which is related to pore volume and decreases from 155 m2/g at 100ºC to 3.3 m2/g at 1050ºC.

Di-Sulfide Linked Polyethylenimine Coated Gold Nanoparticles as a Non-Viral Gene Delivery Agent in NIH-3T3 Mouse Embryonic Fibroblast.

Di-sulfide linked polyethylenimine coated gold nanoparticles (ssPEI-GNPs) of 20 nm size was prepared in order to deliver the genes to target site. DLS and TEM analysis demonstrated that the GNPs have average size of 13 nm in diameter. Upon coating the GNPs with ssPEI in the weight ratio of 1:3, the average hydrodynamic diameter of the ssPEI-GNPs was found to 19±1.14 nm and a zeta potential value 41±1.23 mV was observed. TEM analysis of ssPEI-GNPs demonstrated that the nanoparticles have spherical morphology. Thermogravemetric analysis of the prepared ssPEI-GNPs showed that the estimated composition of the ssPEI coated over the GNPs was approximately 5% (w/w). Gene expression capabilities of the nanoparticles were confirmed by fluorescent microscopy and luciferase assay, which demonstrated the transgene delivery capability of the ssPEI-GNPs. These results demonstrate that ssPEI-GNPs could be used as gene delivery agent.

Surface free energy and dielectric properties of vinyltriethoxysilane functionalized SBA-15-reinforced unsaturated polyester nanocomposites

In this work, organic–inorganic hybrid nanocomposites based on vinylsilane-functionalized SBA-15 reinforced unsaturated polyester resin were developed and characterized. SBA-15 was synthesized and functionalized with vinyltriethoxysilane. The surface functionalized SBA-15 (VSBA-15) with varying weight percentages (1, 3, 5, and 7 wt%) was incorporated into the unsaturated polyester resin. The resulting VSBA-15-reinforced epoxy composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermogravemetric analysis and impedance analyzer. Among the composite samples with varying loadings, the dielectric behavior of 7 wt% VSBA-15 loaded composite sample possesses the lowest value of dielectric constant, that is, 2.4 at 1 MHz frequency when compared with that of other samples. Further, the thermal stability was also enhanced to an appreciable extent, when compared with that of the samples with lower V-SBA-15 loadings. POLYM. COMPOS., 37:3433–3441, 2016. © 2015 The Authors Polymer Composites published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers

Investigation of optical properties of pristine and functionalized single-walled carbon nanotubes

Single-walled carbon nanotubes have been synthesized by chemical vapor deposition technique followed by hydroxyl addent functionalization. Crystallographic, topographic and morphological analyses of pristine and functionalized single walled carbon nanotubes (SWCNTs) have been studied via powder X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscope and atomic force microscope respectively. UV–Vis absorption, Raman spectroscopy, thermogravemetric analysis, X-ray photo electron spectroscopy and Fourier transform infra-red spectroscopic studies have been carried out for confirmation of functionalization. Optical, quantitative and qualitative analysis of the pristine and functionalized SWCNTs have been completed via energy resolved and time resolved photoluminescence and energy dispersive X-ray spectroscopic studies respectively. Spectroscopic studies confirm the formation of good quality pristine and functionalized SWCNTs with hydroxyl addent. Recorded electron micrographs reveal the formation of fragmented functionalized SWCNTs with high aspect ratio whereas recorded diffraction patterns show the good crystallinity of synthesized nanostructures. Structural analyses of pristine and functionalized SWCNTs have been studied using Brunauer–Emmett–Teller surface area analysis, Barrett–Joyner–Halenda pore size and volume analysis technique. Improved CVD method used in present studies is an eco-friendly method, which gives good yield of high quality SWCNTs.

Optical and thermal properties of azo derivatives of salicylic acid thin films

N-acryloyl-4-aminosalicylic acid (4-AMSA), monomer (HL) and 5-(4′-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are synthesized and characterized with various physico-chemical techniques. Thin films of 5-(4′-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are prepared by spin coating technique. The X-ray diffraction (XRD) patterns of 4-aminosalicylic acid (4-ASA) and its derivatives are investigated in powder and thin film forms. Thermal properties of the compounds are investigated by thermogravemetric analysis (TGA). The optical energy gap and the type of optical transition are investigated in the wavelength range (200–2500nm) for 4-ASA, HL and HLn. The values of fundamental energy gap (Eg) are in the range 3.60–3.69eV for all compounds and the type of optical transition is found to be indirect allowed. The onset energy gap Eg∗ appeared only for azodye compounds is found to be in the range 0.95–1.55eV depending on the substituent function groups. The refractive index, n, shows a normal dispersion in the wavelength range 650–2500nm, while shows anomalous dispersion in the wavelength rang 200–650nm. The dispersion parameters ε∞, εL, Ed, Eo and N/m∗ are calculated. The photoluminescence phenomena (PL) appear for thin films of 4-ASA and its derivatives show three main emission transitions.

Synthesis and biodegradation studies of gamma irradiated electrically conductive hydrogels

Abstract Poly(acrylamide-aniline)-grafted gum ghatti [Gg-cl-poly(AAm)] conducting hydrogel was prepared via 60 Co γ-irradiation using N, N′-methylene-bis-acrylamide as a cross linker. The effects of the reaction conditions (viz. gamma dose, monomer, solvent and cross linker concentration) were investigated on the degree of swelling of Gg-cl-poly(AAm). Results showed that optimum reaction conditions for maximum percentage swelling were 10 ml of solvent, 1.08 mol/L of monomer concentration, 0.324 × 10 −1 mol L −1 of crosslinker concentration and 1.5 kGy of total dose. The semi-interpenetrating network (Semi-IPN) was converted into an IPN through the impregnation of poly(aniline) chains followed by doping with HCl. The influence of dopant concentration on the conductivity of synthesized hydrogel was investigated. Different physical properties of the synthesized hydrogel were also studied. The candidate polymers were characterized using different techniques such as X-ray diffraction and thermogravemetric analysis techniques. The mechanism of graft copolymerization via 60 Co irradiation was discussed. Biodegradation studies of the synthesized hydrogels were carried out using a soil burial test. IPN showed better degradation efficiency than semi-IPN. Weight loss of semi-IPN and IPN was 68% and 78%, respectively, in 60 days. Different degradation stages were studied using FTIR and SEM techniques.

Investigations of Water Barrier and Thermal Stability Properties of Glass Fiber Reinforced Epoxy Polymer Nanocomposites

This paper deals with the water uptake and thermal stability properties epoxy matrix /glass fiber composites reinforced with HNT (EP/GF/HNT nanocomposites). HNT at 2wt%, 4 wt%, 8wt% and 10 wt.% were filled in glass fibre reinforced epoxy polymer and placed in a water medium at room temperature. The result shows a dramatic decrease in water mass uptake of HNT filled composites. Hence the role of HNT on reducing water uptake is studied and results are compared with unfilled glass fiber reinforced epoxy composites. Thermal degradation behaviour were also studied by thermogravemetric analysis (TGA) and it was found that the thermal stability of the nanocomposite increases with increasing the HNT content.

Effect of Thermal Conditioning on Combustion and Pollutant Emissions Characteristics of Sewage Sludge

Thermal conditioning (TC) can improve sludge mechanical dewaterability and drying performance, and produce solid fuel from sewage sludge with low-cost and harmlessness. This study investigates the influence of the TC on sludge combustion with thermogravemetric analysis of sewage sludge with/without TC. The experiments were carried out at a 150 mL/min air ambient with a heating rate of 10, 20, 30, 40, 50 °C/min. Tow integration approximation methods (Coats-Redfern and Flynn,-Wall-Ozawa) and a differential method (Kissinger method) were applied to study the kinetics. The Coats-Redfern method requires assuming the reaction’s kinetic mechanism. The calculated activation energy was lower than that from the Flynn-Wall-Ozawa and Kissinger, which were very close to each other. Among these methods, the Flynn-Wall-Ozawa can predict the energy required at every combustion stage, which therefore would be the best one to explore the combustion mechanism. The results show that the organic matters within sewage sludge are much more homogeneous after TC. The combustion of the thermal conditioning sludge (TCS) is much more stable with a 10% reduction in burnout time and a 9.94% reduction in combustion temperature range. The ignition temperature of the raw sludge keeps increasing from 188 to 224 °C with the heating rate, while that of the TCS is almost constant at 222-240 °C. The TC can improve the activation energy, which is about 144.52 and123.00 kJ/mol for the raw sludge (RS) and TCS. Considering the gaseous pollutant emissions, the TC can dramatically reduce NO emissions, which is decreased from 14.22 to 6.59 mg/g by the TC, representing a reduction of 50.7%. Therefore, the TC can promote the hydrolysis of macromolecular organics, which would improve the sludge combustion performance, and reduce the gaseous pollutant emissions from combustion.

Sol-gel synthesis and morphology, thermal and optical properties of epoxidized natural rubber/zirconia hybrid films

Sol-gel technique was employed to synthesize epoxidized natural rubber/zirconia hybrid films by varying the addition of zirconium(IV)-n-propoxide in the range from 10 to 50wt.% during the synthesis process. The prepared films were characterized using Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), field emission scanning electron microscopy (FESEM), thermogravemetric analysis (TGA), differential scanning calorimetry (DSC) and refractive index measurements. The possible interaction between zirconia and epoxidized natural rubber (ENR-50) was revealed by both FTIR and UV–vis measurements. The prepared hybrid samples exhibited very good optical transparency. Hybrid films obtained with 30wt.% zirconium(IV)-n-propoxide addition revealed that the zirconia nanoparticles are uniformly and homogeneously distributed to the ENR-50 matrix with the particle size in the range from 50 to 70nm. The thermal stability and glass transition temperature (Tg) of the hybrid materials could be increased by the addition of zirconia. The refractive indices of the hybrid materials significantly improved with an increase of zirconia addition.

The Effects of Phosphate Adsorption on the Surface Characteristics of Mn Oxides

Mn-oxide was characterized using X-ray diffractometry, scanning electron, transmission electron microscopy, and thermogravemetric and differential thermal analysis. The surface charge density and zero point if charge (pHzpc) of the solid surface were determined by potentiometic titration. Mn-oxide was subjected to different phosphate concentrations in the pH range 3 to 7 at 303 K to investigate the effect of phosphate complexation on the surface properties of solid. The surface compositions before and after phosphate sorption were studied with X-ray photoelectron spectroscopy. The O/OH groups at the surface of Mn-oxide differed with acidity and below pH 6, a drastic change was observed in the O1 s peaks in X-ray photoelectron spectrum, due to the dissolution of Mn-oxide. The surface charges arise as a result of H/OH bond breaking and phosphate anions complexation with solid surface. These charges are compensated by counter ions (K+ and NO3-) of the background electrolyte at solid-liquid interface. The phosphate sorption increased with increased phosphate concentration but decreased with pH increasing of the aqueous solution, a process which is the characteristics of metal oxides surfaces. Thus, it was concluded from the present investigation that phosphate anion sorption on Mn oxide have greatly affected the overall surface characteristics of the solid.

Development of flax/carbon fibre hybrid composites for enhanced properties

Uni-directional (UD) and cross-ply (CP) cellulosic flax fibre epoxy composites were produced by hybridising UD carbon fibre prepreg onto flax system. A compression moulding technique was used to produce both flax and carbon/flax hybridised laminates. The effect of carbon fibre hybridisation on the water absorption behaviour, thermal and mechanical properties of both UD and CP flax specimens were investigated by means of water absorption, tensile, thermogravemetric analysis and flexural testing. The results showed that water absorption behaviour of hybrid samples are markedly improved compared to those without hybridisation. Similarly, the thermal stability, tensile and flexural properties of the hybrid composites are significantly improved in comparison with UD and CP flax composites without hybridisation. The experimental results suggest that cellulosic flax fibre reinforcement contributed to improve the toughness properties by promoting crack propagation whereas the carbon fibre contributed in improving thermal stability, water absorption behaviour and the overall strength and the stiffness of the hybrid composites.

Effect of NiLaxFe2−xO4 nanoparticles on the thermal and coating properties of epoxy resin composites

Epoxy resin has been modified with Ni–La–Fe–O nanoparticles in the form of NiLaxFe2−xO4/epoxy nanocomposites to improve their coating properties. The new composites of different x composition (x=0.00, 0.50, 1.00, 1.50 and 2.00) were synthesized in situ while epoxy resin was prepared by using a simple solution method with ultrasonic assistance. The new nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravemetric analysis (TGA) and scanning electron microscopy (SEM). The thermal degradation showed a more complicated behavior in the presence of Ni–Fe–La–O as shown by the presence of two maxima in the 300–475°C temperature range. Reinforced composites with nanoparticles showed enhanced compressive coating properties. Ni–Fe formulations showed great promise to improve epoxy coating due to their higher barrier properties and ionic charge transfer resistance.

Melt functionalization of LDPE with thio ester, amino ester, and hydroxy ester by thermolysis method—An FTIR study

AbstractLow density poly(ethylene) (LDPE) was melt functionalized with three different esters namely, thio ester, amino ester, and hydroxy ester under inert atmosphere at 160°C with different experimental conditions. During the functionalization reaction, crosslinking (C.L) and CC formation are the simultaneous competitive reactions. FTIR‐RI analysis method was used to determine the % functionalization onto LDPE backbone and the order of functionalization reaction. Thermogravemetric analysis (TGA) and Differential scanning calorimetry (DSC) were used to assess the thermal properties of the functionalized LDPE. Suitable reaction scheme was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Molecular-scale design of a high performance organic–inorganic hybrid with the help of gamma radiation

In the age of green chemistry, gamma-radiation-assisted grafting of polar groups onto polymers in aqueous solution is becoming attractive as it is a rapid, scalable, clean physical process with much less chance of contamination. In this case, a methacrylic acid (MAA) polar group was grafted onto LDPE (low density polyethylene) by gamma radiation to increase the compatibility of LDPE with organically modified clay by reducing the hydrophobicity of LDPE. The clay, cloisite 20A was melt-mixed with g-LDPE (grafted LDPE) to synthesize a nanohybrid and the mixes were subsequently compression-molded to make a sheet, which was used for characterization. Many of the drawbacks of polyolefin based nanohybrid synthesis were overcome by this technique. Wide angle X-ray diffraction (WAXS), transmission electron microscopy (TEM), thermogravemetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing were conducted to characterize the nanohybrids. The interlayer distance (d values) change in WAXS confirmed nanohybrid formation, which was later directly seen by TEM. TGA revealed that nanohybrids were more thermally stable than pure polymer and this went on increasing with clay loading. From DSC it was noticed that melting temperatures (Tms) remained unchanged, but the crystallinity of the polymer was increased by more than 5% at higher clay loading (8 wt%), which was useful for barrier properties as well as mechanical property improvement. Young's modulus of nanohybrid was increased considerably by a small mount of clay incorporation (by 50% and 85% for 2 and 8 wt% clay). Uniquely, with increase in modulus toughness was also found to increase by more than 20%, keeping the elongation-at-break unchanged. Thus by this rapid, clean, user friendly and well controlled technique, pure and high-performance nanohybrids were developed successfully.

Effect of calcination temperature on the structural and electrical properties of cobalt ferrite synthesized by combustion method

In this paper, the structural and electrical properties of cobalt ferrite synthesized by combustion route with hexamine as a fuel are reported for the first time. Thermogravemetric analysis (TGA) confirm the stable phase formation of the phase above 700 °C. Structural characterizations of all the samples were carried out by X-ray diffraction (XRD) technique. It reveals an increase in the particle size with the calcination temperature (i.e. 700, 800 and 900 °C). Infrared (IR) spectroscopy confirms the presence of tetrahedral and octahedral group complexes within the spinel lattice. DC resistivity as function of temperature indicates that all the samples obey the semiconducting behavior and it decreases with calcination temperature. The variation of dielectric constant ( ɛ r ) and ac conductivity ( σ ac ), for all the samples have been studied as a function of applied frequency in the range from 20 Hz to 1 MHz. The dielectric constant increases with the calcination temperature and all the samples exhibit usual dielectric dispersion which is due to the Maxwell–Wagner-type interfacial polarization. The ac conductivity measurement suggests that the conduction is due to small polaron hopping.

Studies on Methylolated Cyclohexanone-Formaldehyde Resin–Epoxy Resin Condensation Products

Methylolated cyclohexanone-formaldehyde resins having different hydroxyl values were reacted respectively with commercial epoxy resins, i.e., diglicidyle ether of bisphenol A and brominated DGEBA. The resultant polyether products were designated as I(a-f) and II(a-f), respectively. All the polyether samples were characterized by elemental analysis, FTIR spectral studies, thermogravemetric analysis and average molecular weight, estimated by vapor pressure osmommetry. The polyether samples were then mixed with appropriate amount of DGEBA epoxy resin, monitored for differential scanning calorimetry, and based on this, the glass fiber-reinforced composites were prepared. All the resultant laminates were characterized by physical and mechanical properties.

Influence of calcinations temperature on physical properties of the nanocomposites containing spinel and CuO phases

Nanocomposites containing spinel and CuO phases have been synthesized by sol–gel method using Cu(II), Ni(II) and Fe(III) in a basic medium. The effect of calcinations temperature on the physical properties of the nanocomposites has been investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), micro-Raman spectroscopy (RS), differential scanning calorimetery (DSC)/thermogravemetric analysis (TGA), diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and vibrating sample magnetometer (VSM). The XRD pattern of nanocomposites synthesized at different calcinations temperature reveals spinel and CuO phases. The particle size of the nanocomposites is increasing with increasing the calcinations temperature. The band gap of synthesized nanocomposites has been calculated using DRS method. The prepared nanocomposites exhibit semiconducting nature with band gap values, 1.9–2.24 eV. The magnetic properties of nanocomposites are also measured at room temperature and the values of saturation magnetization (Ms), remanent magnetization (Mr) and coercivity are found enhanced with the calcinations temperature.

Glycolic acid assisted one-step synthesis of Cu–Ni–Fe metal oxide nanocomposites by sol–gel-combustion method: Structural, spectroscopic and magnetic studies

The present article reports the synthesis of copper, nickel and iron-based metal oxide nanocomposites by sol–gel method using disproportion of Cu(II) and Fe(III) in basic media. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy (RS), differential scanning calorimetery (DSC)/thermogravemetric analysis (TGA), field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HR-TEM) and vibrating sample magnetometer (VSM). The XRD patterns of nanocomposites confirm the presence of spinel, CuO and FeO phases. The particle size of the nanocomposite has been calculated using HR-TEM micrographs and found to be in the range of 10–120 nm. The magnetic properties of nanocomposites were measured at room temperature. The values of saturation magnetization (Ms) and remanent magnetization (Mr) were increasing with increase of iron concentration.