S. Arungalai Vendan

Biodegradable polymer based ternary blends for removal of trace metals from simulated industrial wastewater

The ternary blends consisting of Chitosan (CS), Nylon 6 (Ny 6) and Montmorillonite clay (MM clay) were prepared by the solution blending method with glutaraldehyde. The prepared ternary blends were characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermo gravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bondings were established between chitosan, nylon 6 and montmorillonite clay. TGA showed the thermal stability of the blend is enhanced by glutaraldehyde as Crosslink agent. Results of XRD indicated that the relative crystalline of the pure chitosan film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend was rough and heterogenous. Further, it confirms the interaction between the functional groups of the blend components. The extent of removal of the trace metals was found to be almost the same. The removal of these metals at different pH was also done and the maximum removal of the metals was observed at pH 4.5 for both trace metals. Adsorption studies and kinetic analysis have also been made. Moreover, the protonation of amine groups is induced an electrostatic repulsion of cations. When the pH of the solution was more than 5.5, the sorption rate began to decrease. Besides, the quantity of adsorbate on absorbent was fitted as a function in Langmuir and Freundlich isotherm. The sorption kinetics was tested for pseudo first order and pseudo second order reaction. The kinetic experimental data correlated with the second order kinetic model and rate constants of sorption for kinetic models were calculated and accordingly, the correlation coefficients were obtained.

Experimental Studies on Thermo-Mechanical Behavior of Ultrasonically Welded PC/ABS Polymer Blends

This research paper attempts to investigate the performance of blended PC/ABS joints using the ultrasonic material joining process. The key focus is on examining the thermal aspects during the joining of PC/ABS blends using ultrasonic welding and the subsequent mechanical testing to determine the strength of the weldments. Thermal behavior of the blends during welding may govern or alter the mechanical properties and integrity of the joints. Hence, investigations on thermal characteristics involved in PC/ABS blends when subjected to high vibrational heat generated during the ultrasonic welding process is imperative. DSC is used to measure the glass transient temperature (Tg) after subjecting it to welding. Mass loss is calculated with TGA. TGA and DSC results indicate change in Tg which are attributed to the molecular alignment occurring when the specimens are subjected to ultrasonic vibrations. Initially, two step mass losses occur that is contributed by ABS in which long single chains are associated and alters PC. SEM images reveal the absence in intermolecular compounds or impurities that tend to weaken weld joints. The diffusion of these molecules is uniform in the welded region. The amorphous nature enhances the integrity of weld joints. Molded part illustrates the higher strain rate in comparison with the welded specimens. The RSM model proposed is sufficient and has limited possibility for violating the independence or the assumption of constant variance.

Experimental investigations on the polypropylene behavior during ultrasonic welding

ABSTRACT The polypropylene material meets the needs and requirements in automotive industry due to its features such as wide range of physical properties, ease of processing, and low cost. This research has focused on the investigation of the behavior of polypropylene during ultrasonic welding process. The lap welded samples were examined by modern methods such as Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). Also, the morphology of the non-welded and welded regions of the polypropylene samples was analyzed by Scanning Electronic Microscopy (SEM) method. TGA and DSC results showed a negligible difference between the mass loss of the molded and the welded propylene materials. Furthermore, the SEM images revealed the formation of voids in close correlation with vibration amplitude. The weld strength and bond integrity appears to be higher for higher vibrations, emphasizing that the lap joint interface strength is higher when the tendency of voids formation is decreasing. The stress-strain curve of the material, plotted for three ultrasonic welding variants, illustrated that increasing the main process parameters (pressure, time, and vibration amplitude) makes the weld strength higher, but a decrease in plasticity was noticed in the welded polypropylene samples.

Thermal and structural analysis of ultrasonic-welded PC/ABS blend for automobile applications

PC/ABS thermoplastic blends are widely employed in manufacturing sectors, as it yields good mechanical behavior when subjected to dynamic loading conditions. While investigating the fundamental nature of PC/ABS blends, ultrasonic welding process appears to suit their joining as compared to other conventional techniques. This paper focuses on PC/ABS welding using ultrasonic and the subsequent investigation from the insight of thermal science. It is imperative for the materials to retain key properties after subjecting it to welding. Examinations to evaluate these properties through DSC reveal a lower onset temperature change and a small variation of glass transition temperature, respectively, for parts which indicate minimal changes in thermal properties in welded and non-welded specimens. Apparent activation energies determined from TG data are practically independent of heating rates, which suggests that the most important process in the degradation of these materials corresponds to ABS. Those mixtures with high PC content show a clear increase in apparent activation energies with heating rate, suggesting that the thermal degradation mechanism of these samples is composed of several complex processes, each predominant during different stages of the overall process. SEM is used to investigate the structural morphology of the welded parts.

Insight into Arc Welding Power Source Terminologies

Welding arc is an electric current flowing between two electrodes through an ionized gas column. Arc stability is a critical problem which influences the metal transfer during welding. When the arc is stable, metal transfer is uniform with minimum spatter (Shklovski and Janson in Development of constant-power source for arc welding, pp. 255–258, 2012 [37]). The terminologies of major concerns during the joining process are presented below.

Welding an Overview

This book categorically presents the mechanical, metallurgical and electrical terminologies and the associated science for welding power sources. Key focus is laid on arc welding processes owing to its growing demand in versatile applications. Figure 1.1 illustrates the types of welding processes.

Power Sources and Challenges for Different Arc Welding Processes

The choice of power source is based on the working principle of joining technique and the material type to be welded. Power sources for various arc welding process are discussed in the following sections.

Sensors for Welding Data Acquisition

Sensors in arc welding process can obtain information about the geometry and position of the workpiece, electrical parameters like voltage, current, wire feed rate, in addition to providing suitable form of control over the welding process parameters. The weld quality mainly depends on weld parameters like current, voltage, wire speed and wire feed rate. The welding torch also influences the flow of the material. The input heat for melting the component and constant heat flow is directly related with the welding torch control and it further influences the weld quality. This chapter presents the fundamental knowledge on data acquisition in arc welding process with real-time case study illustrations.

Optimization in Arc Welding Process

Optimization is a valuable tool in making decisions and in analysing physical systems. In mathematical terms, optimization is the process of determining the best solution achievable close to desired value among the set of all feasible solutions.

Codes and Safety Standards During Welding

Arc welding becomes a safe procedure when adequate safety precautions are considered and followed to protect the workers from harmful hazards. When such safety measures are neglected, the workers come across potential hazards such as exposure to gases and fumes, arc radiation, electric shock and fire accidents, which could be serious and fatal.