Browsing by Author "Srinivasan, A."

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Advances in Polymer Materials and Technology
(CRC Press, 2016) Srinivasan, A.; Bandyopadhyay, S.
This book covers recent advancements in the field of polymer science and technology. Frontiers areas, such as polymers based on bio-sources, polymer based ferroelectrics, polymer nanocomposites for capacitors, food packaging and electronic packaging, piezoelectric sensors, polymers from renewable resources, superhydrophobic materials and electrospinning are topics of discussion. The contributors to this book are expert researchers from various academic institutes and industries from around the world. Â© 2017 by Taylor and Francis Group, LLC.
Electrospinning: From Fundamentals to Applications
(CRC Press, 2016) Senthil, T.; George, G.; Srinivasan, A.
Electrospinning is not only a unique and fascinating process for the production of polymeric nanobers with diameters ranging from 3 nm to 20 µm, but also the simplest and inexpensive technique to fabricate ultrane continuous polymeric bers. Electrospinning is also known as electrostatic spinning and electrospraying. In the last few years, electrospinning has become popular among academic researchers and industries as it overcomes the various processing diculties in the other nanober-forming techniques. Some of the other techniques for the production of polymer nanobers are drawing, template synthesis, phase separation, and self-assembly (Table 5.1). While electrospinning can produce nanobers, its conventional counterparts, such as melt spinning, dry spinning, gel spinning, and wet spinning, can only produce microbers (Figure 5.2) (Gibson et al. 2001). Almost all the straight chain homopolymeric materials have been actively investigated for developing nanobers by electrospinning. Meanwhile, various FIGURE 5.1 Electrospun nanobers have high surface area. (Reprinted from Colloids Surf., A, 187-188, Gibson, P., Gibson, H.S., and Rivin, D., Transport Properties of Porous Membranes Based on Electrospun Nanobers, 469-481. Copyright 2001, with permission from Elsevier.) semicrystalline and amorphous polymers, natural and synthetic biopolymers, polymer blends, and block copolymers can also be converted into nanobers via the electrospinning technique. © 2017 by Taylor and Francis Group, LLC.
Fly Ash-Based Polymer Matrix Composites
(CRC Press, 2016) Patil, A.G.; Srinivasan, A.; Bandyopadhyay, S.
One can consider plastics as nonrenewable materials, as many of the widely used ones are derived from petroleum and hold up to 95% of the market share. e ecacy of plastic consumption can be reduced in many cases by adding inexpensive llers, which contribute to the volume of the nal product, at the same time providing the adequate strength to the product for intended use. Another way of reducing the usage of plastics to a large extent is by adding nano/microsized reinforcements (sometimes referred to as llers) to the polymer matrix through which the several properties of the matrix can be controlled meticulously. By doing so, these materials can outperform the conventional pristine plastics with a lower consumption rate. For instance, addition of layered llers to polyethylene terephthalate (PET) improves the gas barrier properties and strength; therefore, the thickness of the PET bottles can be reduced to meet the barrier properties of the current requirements compared with the pure PET. © 2017 by Taylor and Francis Group, LLC.
Hemocompatibility of Sulfuric Acid-Treated Metallocene Polyethylene and its Application in Reducing the Quantity of Medical Plastic Waste
(2017) Jaganathan, S.K.; Balaji, A.; Mohandas, H.; Sivakumar, G.; Kasi, P.; Selvakumar, M.; Kadiman, S.B.; Srinivasan, A.; Mohd, Faudzi, A.A.B.; Supriyanto, E.; Mandal, M.
The hazards of dumping medical plastics have created a huge demand to reduce the quantity of plastic usage without compromising its quality. The metallocene synthesized polyethylene is one such advent, however, its clinical usage is limited by the problem of hemocompatibility. This study investigates the effect of sulfuric acid-induced changes in metallocene polyethylene. Fourier transform infrared spectroscopy analysis illustrated the addition of OH and sulfonic acid group, which subsequently increased the wettability. An improvement in micro as well as nanosurface roughness was observed. Ultimately, the treated surfaces depicted delayed clotting time, adsorption of specific plasma proteins, reduced hemolysis, and resistance against platelet adhesion. 2017 Taylor & Francis.
Laser surface modification of Mg-Zn-Gd alloy: Microstructural, wettability and in vitro degradation aspects
(2018) Rakesh, K.R.; Bontha, S.; Ramesh, M.R.; Arya, S.B.; Das, M.; Balla, V.K.; Srinivasan, A.
Mg-Zn-Gd have great potential for biomedical applications owing to excellent bioactivity and non-toxicity properties. In the present study, laser surface melting (LSM) was carried out on newly developed Mg-1Zn -2Gd (wt%) alloy. Effects of laser energy on microstructural evolution, corrosion properties, surface energy, and hardness have been investigated. The surface modified sample processed at different energy densities showed fine grain structure in the melt zone compared to the untreated substrate. Grain refinement in the laser melted region improved the hardness by 60%. The surface roughness was found to be increased with increasing laser energy density. At higher energy density, removal of materials from the surface is enhanced, resulting in deeper grooves and higher surface roughness. The wettability studies indicated that the variations in surface geometry, grain size and surface roughness of LSM samples strongly influence the surface energy and hydrophilicity. Improved wetting of LSM sample was achieved owing to grain refinement and low surface roughness. The corrosion resistance determined by immersion and electrochemical methods of laser melted sample in Hank's balanced salt solution improved considerably due to grain refinement, meltpool depth and uniform distribution of secondary phases. 2018 IOP Publishing Ltd.
Laser surface modification of Mg-Zn-Gd alloy: Microstructural, wettability and in vitro degradation aspects
(Institute of Physics Publishing helen.craven@iop.org, 2018) Rakesh, K.R.; Bontha, S.; Ramesh, M.R.; Arya, S.; Das, M.; Balla, V.K.; Srinivasan, A.
Mg-Zn-Gd have great potential for biomedical applications owing to excellent bioactivity and non-toxicity properties. In the present study, laser surface melting (LSM) was carried out on newly developed Mg-1Zn -2Gd (wt%) alloy. Effects of laser energy on microstructural evolution, corrosion properties, surface energy, and hardness have been investigated. The surface modified sample processed at different energy densities showed fine grain structure in the melt zone compared to the untreated substrate. Grain refinement in the laser melted region improved the hardness by 60%. The surface roughness was found to be increased with increasing laser energy density. At higher energy density, removal of materials from the surface is enhanced, resulting in deeper grooves and higher surface roughness. The wettability studies indicated that the variations in surface geometry, grain size and surface roughness of LSM samples strongly influence the surface energy and hydrophilicity. Improved wetting of LSM sample was achieved owing to grain refinement and low surface roughness. The corrosion resistance determined by immersion and electrochemical methods of laser melted sample in Hank's balanced salt solution improved considerably due to grain refinement, meltpool depth and uniform distribution of secondary phases. © 2018 IOP Publishing Ltd.
Microstructural Evolution of Mg-Zn-Gd Alloy Using Equal Channel Angular Pressing to Enhance Mechanical and Corrosion Properties
(Springer, 2025) Rokkala, U.; Patil, A.; Bontha, S.; Ramesh, M.R.; Balla, V.K.; Srinivasan, A.
Equal channel angular pressing (ECAP) was used on the Mg-Zn-Gd alloy in this study to improve its corrosion and mechanical properties. Microstructural and phase analysis reveal that, after ECAP, a substantial grain refinement occurred, and secondary phases were observed. The grain size of the as-cast (AC) sample is reduced from 20 ± 1 to 0.88 ± 0.6 µm, attributed to dynamic recrystallization. The mechanical properties of the ECAP sample were significantly improved when compared to the AC sample. An improvement in the microhardness (43%), ultimate tensile strength (73%), yield strength (76%), and ductility (50%) were observed for the ECAP sample. A decrease in the corrosion rate was observed for ECAP sample (9 ± 1 mm/year) compared to the AC (16 ± 2 mm/year) sample. The grain refinement and crystallographic orientation of the ECAP samples contributed to the enhancement of corrosion resistance. © ASM International 2025.
Polymer Nanocomposites for Food Packaging Applications
(CRC Press, 2016) George, G.; Kumar, B.; Srinivasan, A.
Polymers are widely used in packaging of food, chemicals, medicines, industrial components, agriculture, and household items as listed in Table 26.1. Polymer consumption has an average growth rate of 5% and it will touch a gure of 227 million metric tons in 2015. Criteria for selection of a particular polymer for packaging is its biodegradability, migration of hazardous compounds, barrier properties, processability, strength, and inertness. Polymers are made to order in a variety of fashions using additives, functionalization, crosslinking, and so on for a particular application. A successful packaging material should be able to maintain the quality of the packed commodities to meet the customers’ expectation as it moves from manufacturer to customer. © 2017 by Taylor and Francis Group, LLC.
Tailoring surface characteristics of bioabsorbable Mg-Zn-Dy alloy using friction stir processing for improved wettability and degradation behavior
(Elsevier Editora Ltda, 2021) Rokkala, U.; Bontha, S.; Ramesh, M.R.; Balla, V.K.; Srinivasan, A.; Kailas, S.V.
Magnesium (Mg) and its alloys are currently under consideration for use as temporary implants. However, early degradation and maintaining mechanical integrity is a significant concern. Surface modification techniques are used to improve mechanical and corrosion properties of Mg based alloys. In the present study, friction stir processing (FSP) was used to tailor the surface characteristics of Mg-1Zn-2Dy (wt.%) alloy for temporary implant applications. The FSPed alloy was characterized using EBSD to understand the influence of FSP on crystallographic texture, grain size and grain boundaries and thereby their effect on corrosion, wettability and hardness. Results showed that the grain size of stir zone (SZ) was refined to less than 3 ?m, as a result of dynamic recrystallization (DRX) during FSP and the FSPed alloy exhibited better wettability than as-cast alloy. An increase in the hardness (11.7%) and elastic modulus (6.84%) of FSPed alloy were also observed. Electrochemical corrosion and weight loss methods were conducted in Dulbecco's Modified Eagle's Medium (DMEM) with, 10% Fetal Bovine Serum (FBS) physiological solution. The lower degradation rate (0.72 mm/yr) of FSPed alloy has been attributed to the fine grains and evenly distributed secondary phase particles. Further, the influence of grain boundary characteristics and crystallographic texture on the corrosion behavior have been investigated. © 2021 The Author(s).