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Thin wall joints for elevated temperature (~550 °C) applications can be prepared by Laser Beam Welding (LBW), Gas Tungsten Arc Welding (GTAW) and High Temperature Brazing (HTB) methods. The joints have been made and tests such as helium leak test (HLT), micro hardness test and tensile test were carried out. A study has been performed on these joining techniques to recognize the suitable method for high temperature applications. No observable leak was identified during HLT. Microstructures shows dissimilarity in solidification morphology due to disparity in heat sources. It has been identified that the joint made by brazing process having higher micro hardness value. Further, it has been observed that LBW joints have better mechanical properties than GTAW joints and HTB joints. [ABSTRACT FROM AUTHOR]

Abstract: This review delineates on molecular interactions of N,N-dimethylformamide (DMF) with some solvents reported by various thermodynamic and thermophysical measurements. Several topics and examples of thermodynamic studies are depicted on the basis of the present author''s experience focusing on the structural behavior for binary and ternary mixtures of DMF with different non-electrolytes. Valuable information on the behavior and factors governing of the liquid structure of the strongly associated solvents are also reviewed. A discussion is presented and deviations are interpreted in terms of size, shape, the position of ketone group, the chain length of alkanol and hydrogen bond effects in the liquid mixtures to explain about chemical and thermophysical behavior. Our goal in this review is to provide the structural and thermophysical contribution of the literature related to DMF with other solvents. Eventually, we reviewed what has been learned about the excess volumes and ultrasonic studies of ternary mixtures containing DMF with other solvents from experimental studies and also summarized the important contributions of DMF in the molecular interactions with other solvents. [Copyright &y& Elsevier]

Abstract: Accurate excess molar volumes (V E), at ambient pressure and 303.15K, have been determined in the ternary liquid mixtures of N,N-dimethylformamide (DMF)+2-pentanone (PE)+1-alkan-1-ols (C3–C6) and in the binary mixtures of PE+alkan-1-ols (C3–C6) as a function of composition. The alkanols include 1-propanol, 1-butanol, 1-pentanol and 1-hexanol. The intermolecular interactions and structural effects were analyzed on the basis of the measured and derived properties. Excess molar volumes increase in magnitude with increase in chain length of alcohol. Valuable information on the behavior and governing factors of the liquid structure of the strongly associated solvents studied were inferred from the parameters deduced. The V E results were correlated and fitted by the Redlich–Kister equation for binary mixtures and by the Cibulka equation for ternary mixtures, as a function of mole fraction. Several predictive empirical relations were applied to predict the excess volumes of ternary mixtures from the binary mixing data. An analysis of the data indicates a good agreement between experimental results and predicted values in all ternary systems. A discussion is presented and deviations are interpreted in terms of size, shape, the position of ketone group, the chain length of alkanol and hydrogen bond effects in the liquid mixtures studied to explain chemical and thermophysical behavior. [Copyright &y& Elsevier]

Solid–liquid equilibria (SLE) of the n-alkanes (octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane and octacosane) in N,N-dimethylacetamide (DMA) are reported. The data has been measured by the dynamic method from 275 K to the melting temperatures of the n-alkane. The experimental results have been correlated by the Redlich–Kister equation with two and three parameters and the NRTL equation. [Copyright &y& Elsevier]

Abstract: Densities (ρ) and ultrasonic sound velocities (u) have been measured over the whole composition range for the binary mixtures of tetrahydrofuran (THF) with 1,2-dichlorobenzene (1,2-DCB), 1,3-dichlorobenzene (1,3-DCB), 1,2,4-trichlorobenzene (1,2,4-TCB), o-chlorotoluene (o-CT), m-chlorotoluene (m-CT), p-chlorotoluene (p-CT), o-nitrotoluene (o-NT) and m-nitrotoluene (m-NT) at 298.15K and atmospheric pressure. To gain some insight into the several aggregations of molecular interactions present in these mixed solvents, we determined the excess molar volume (V E) and the deviation in isentropic compressibilities (Δκ s) as a function of the concentration of THF from the measured ρ and u, respectively. The V E values have been correlated using Redlich–Kister and Hwang et al. equations. The V E data is completely positive over the entire mole fraction range in all the binary mixtures of THF with chlorobenzenes, chlorotoluenes and nitrotoluenes. The sound velocity data have been obtained in terms of free length theory (FLT) and collision factor theory (CFT). The Δκ s values have been correlated using Redlich–Kister equation. The values of Δκ s were negative over the entire composition range in all the binary mixtures under the same experimental conditions. The measured data were discussed on the basis of intermolecular interactions and structural effects between unlike molecules. Based on our V E data of THF+DCBs or TCB and THF+chlorotoluenes are compared with existing V E data of THF+chlorobenzene (CB) and THF+toluene (TE), respectively. [Copyright &y& Elsevier]

Abstract: In this article, we present densities (ρ), ultrasonic sound velocities (u) and viscosities (η) for the binary systems of the highly polar compound dimethylsulfoxide (DMSO) with ionic liquids (ILs) over the whole composition range at temperature ranging from 298.15 to 328.15K under atmospheric pressure. The ILs investigated in the present study included diethyl ammonium hydrogen sulfate ([Et2NH][HSO4], DEAS) is an ammonium salt (protic IL) and 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) is an imidazolium salt (aprotic IL). Further, to gain some insight into the several aggregations of molecular interactions present in these mixed solvents, we predicted the excess molar volume (V E), the deviation in isentropic compressibilities (ΔK s ) and deviation in viscosity (Δη) as a function of the concentration of IL using the measured properties of ρ, u and η, respectively. Redlich–Kister polynomial was used to correlate the results. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. A qualitative analysis of the results is discussed in terms of the ion–dipole, ion-pair interactions, and hydrogen bonding between ILs and DMSO molecules and their structural factors. Comparison of these properties of DMSO with ILs explicitly elucidates the influence of ions and also the temperature effects on the thermophysical properties. [Copyright &y& Elsevier]

Abstract: Excess molar enthalpies (H E) at 298.15K have been measured by a Paar 1451 solution calorimeter as a function of composition for the binary liquid mixtures of dimethylsulfoxide (DMSO) with substituted benzenes. The substituted benzenes include toluene, ethylbenzene, chlorobenzene, bromobenzene and nitrobenzene. The H E values for the above mixtures are all positive over the entire composition range. The experimental results have been correlated using the Redlich–Kister (R–K) polynomials. The results are interpreted on the basis of possible hydrogen bonding between unlike molecules and changes in molecular association equilibria as well as structural effects for these systems. The excess enthalpy data have also been correlated with the Peng–Robinson (PR) as well as the Patel–Teja (PT) equations of state (EOS) and also the activity coefficient models of the Wilson and the NRTL. [Copyright &y& Elsevier]

• LCST of PNIPAM was assessed by introducing biomass derived FCHs. • An alternative form of biomass was used to monitor LCST of PNIPAM. • The LCST of PNIPAM was found to decrease by introducing FCHs. • DSC was used to study the heat changes of PNIPAM in various concentrations of FCHs. • TEM was assessed to study the information about morphological changes. Functional carbon helices (FCHs) containing various oxygenated functionalities derived directly from lignocellulosic biomass is proved to be a potential eco friendly candidate for biomolecules. No study reports the effect of biomass derived platform molecules on the thermoresponsive behavior of polymers, which have been proved potential candidates in carrying various drug delivery applications, gels, and tissue engineering in this vast area of research. Poly(N -isopropylacrylamide) (PNIPAM) is a thermoresponsive polymer that has been found to be a prevailing tool in carrying various aforesaid applications. This study reports a powerful impact on the thermoresponsive behavior of PNIPAM by a non-hazardous alternative form of a herbecious plant Parthenium hysterophorus. Fluorescence spectroscopy was deployed to study the microenvironment provided by carbon helices around the polymer structure. The results obtained are directly correlating with the increased polarity with higher concentration of FCHs and further confirmed a decrease in fluorescence intensity. Moreover, for better understanding of interactions between PNIPAM and FCHs, Fourier transform infrared spectroscopy (FTIR) was employed. The analysis of hydrodynamic diameter (d H) was carried out by dynamic light scattering (DLS) and the aggregate size of PNIPAM was found to increase in higher concentration of FCHs. A decrease from 34.7 °C to 29.0 °C in the lower critical solution temperature (LCST) of PNIPAM in FCHs was further confirmed by differential scanning calorimetry (DSC). Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) were also taken into account to understand the morphological changes of PNIPAM in presence of biomass derived carbon helices. The micrographs of PNIPAM-biomass are representing a perturbed morphology of PNIPAM during interaction with FCHs. In this study, high degree of oxygenated functionalities on the carbon helices has a meaningful impact on the conformational phase behavior of PNIPAM. The tendril like functional carbon helices (TLFCHs) are uniquely causing a decrease in the lower critical solution temperature (LCST) of PNIPAM. Our combined study indicates that biomass derived carbon helices significantly decrease the LCST of PNIPAM by 5 °C. Ultimately, the polymer achieves compact globule conformational and complete aggregated state. [ABSTRACT FROM AUTHOR]