Browsing by Author "SelvaKumar, S."

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Chitosan-based nanocomposites for medical applications
(John Wiley and Sons Inc, 2021) SelvaKumar, S.; Scheibel, T.
Chitosan as a biobased polymer is gaining increasing attention due to its extraordinary physico-chemical characteristics and properties. While a primary use of chitosan has been in horticultural and agricultural applications for plant defense and to increase crop yield, recent research reports display various new utilizations in the field of advanced biomedical devices, targeted drug delivery, and as bioimaging sensors. Chitosan possesses multiple characteristics such as antimicrobial properties, stimuli-responsiveness, tunable mechanical strength, biocompatibility, biodegradability, and water-solubility. Further, chitosan can be processed into nanoparticles, nano-vehicles, nanocapsules, scaffolds, fiber meshes, and 3D printed scaffolds for a variety of applications. In recent times, nanoparticles incorporated in chitosan matrices have been identified to show superior biological activity, as cells tend to proliferate/differentiate faster when they interact with nanocomposites rather than bulk or micron size substrates/scaffolds. The present article intents to cover chitosan-based nanocomposites used for regenerative medicine, wound dressings, drug delivery, and biosensing applications. © 2021 The Authors. Journal of Polymer Science published by Wiley Periodicals LLC.
Evaluation of piezoelectric behavior and biocompatibility of poly(vinylidene fluoride) ultrafine fibers with incorporated talc nanosheets
(John Wiley and Sons Inc, 2022) Shetty, S.; SelvaKumar, S.; Salehi, S.; Pellert, A.; Scheibel, M.; Scheibel, T.; Anandhan, S.
Herein, we fabricated biocompatible ultrafine fibers based on talc nanosheets (TNS)/PVDF composites that can exhibit robust electromechanical responses. Piezoresponse force microscopy (PFM) was extensively used to decode various characteristics, including ferroelectric and piezoelectric coefficients. The 0.5 wt% TNS dispersed ultrafine fibers exhibited well-defined ferroelectric characteristics with an enhanced piezoelectric coefficient (d33) of ≈43.3 pm/V compared to 10 pm/V measured for the pristine PVDF ultrafine fibers. It was observed that the piezoelectric coefficient values strongly depended on the morphology and electroactive phase fraction of the ensuing composite ultrafine fiber. The advantage of a high aspect ratio and surface charges offered by TNS alongside electrospinning augmented the composite ultrafine fiber's piezoelectric response. Further, in-vitro cytotoxicity of the TNS/PVDF composite ultrafine fibers was examined using BALB/3T3 fibroblasts based on ISO Standard 10993-5. Importantly, the new composite fibers showed no cytotoxic response and the exposed fibroblasts showed excellent viability. Thus, these fabricated TNS/PVDF piezoelectric ultrafine fibers are well suited for applications in bioelectronics, especially as flexible wearable electronic devices, including sensors. © 2022 Wiley Periodicals LLC.
Fly ash-reinforced poly(vinyl alcohol) composites
(Elsevier, 2021) Anandhan, S.; SelvaKumar, S.; Patil, A.G.
Fly ash (FA) is a waste residue and huge amounts of it have been produced from coal-fired power plants. As a result, it has become a serious issue and there is an urgent need to reduce its accretion as well as improve the safe disposal of FA as it has many toxic constituents including lead, arsenic, and chromium. In an effort to utilize FA, it has been widely used as filler for fabricating polymer composites to improve their performance. Recently, FA-incorporated polymers have received the attention of researchers and industries due to their remarkable properties, such as improved mechanical strength without sacrificing their elasticity, thermal, flame resistance, wettability, resistance to hydrolysis, and possessing excellent dynamic mechanical properties even at low temperatures. In comparison with conventional FA-based polymer composites, those based on surface-modified FA and nanostructured FA (NFA) exhibit superior mechanical and technical properties. The present article reviews various aspects of poly(vinyl alcohol)/FA-based composites. It also focuses on the effect of particle size reduction of FA on the physicochemical properties of poly(vinyl alcohol)/NFA composites. © 2022 Elsevier Inc. All rights reserved.
Graphene-based elastomer nanocomposites: A fascinating material for flexible sensors in health monitoring
(CRC Press, 2022) Khalifa, M.; SelvaKumar, S.; Anandhan, S.
[No abstract available]
Influence of multiwalled carbon nanotubes on the structure and properties of poly(ethylene-co-vinyl acetate-co-carbon monoxide) nanocomposites
(John Wiley and Sons Inc, 2021) George, G.; Mahendran, A.R.; SelvaKumar, S.; Anandhan, S.
In this work, composites of poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO)/surface-modified multiwalled carbon nanotubes (m-MWCNTs) were prepared using a solution casting technique. Acid treatment was employed for the surface modification of MWCNTs to improve the compatibility between polar EVACO and MWCNTs. The influences of m-MWCNTs on the crystalline, mechanical, thermal, and electrical properties of EVACO at very low filler loading were systematically evaluated. The presence of m-MWCNTs in the EVACO matrix influenced the crystallinity, and the respective changes were determined and quantified using dynamic scanning calorimetry and X-ray diffraction. The mechanical properties of the composites were improved remarkably by the addition of a minute quantity (0.05, 0.1, 0.15, 0.2, and 0.25 wt%) of m-MWCNTs. Additionally, m-MWCNTs in the EVACO matrix improved the thermal stability and electrical properties of EVACO. However, the filler loading is below the threshold loading of the fillers, and there was no drastic improvement in the electrical conductivity of the composite. © 2021 Society of Plastics Engineers.
Insights into mechanical, thermal, and electrical properties of peroxide-cured chlorinated polyethylene/ethylene methacrylate copolymer blend vulcanizates
(American Chemical Society, 2021) Bhagabati, P.; SelvaKumar, S.
This work unveils the effect of chemical modification of compatible elastomer blends based on the chlorinated polyethylene (CPE) and ethylene methacrylate copolymer (EMA) (60:40 ratio) using dicumyl peroxide (DCP). CPE/EMA blend vulcanizates were prepared by varying the DCP concentration from 0.5 to 3.0 wt %. All blend vulcanizates showed significant enhancement in physiomechanical properties and thermal stability upon increasing the DCP concentration. DCP incorporation also enhanced the compatibility between CPE and EMA rubbers, which was revealed from FTIR data and other technical properties. Specifically, the vulcanizates with 1.5 wt % DCP showed an enormous improvement in mechanical properties and glass transition temperature (Tg) due to various reasons such as cure characteristics, cross-linking densities, co-cross-linking systems, and morphological features. Uniform distribution of DCP in both the elastomeric phases across their interphases caused co-cross-linking, which increased interphase adhesion in the blend vulcanizates. High interphase adhesion of the blend vulcanizates of 1.5 wt % DCP was directly reflected in its improved mechanical, thermal, flame retardation properties and enhanced oil resistance and volume resistivity in comparison to pristine CPE/EMA blend vulcanizates. Also, the volume resistivity and oil resistance properties of blend vulcanizates were found to be marginally improved upon increasing the concentration of DCP. © 2021 The Authors. Published by American Chemical Society.
Sustainable and safer nanoclay composites for multifaceted applications
(Royal Society of Chemistry, 2022) Padil, V.V.T.; Akshay Kumar, K.P.; SelvaKumar, S.; Torres–Mendieta, R.; Wacławek, S.; Cheong, J.Y.; Černík, M.; Varma, R.S.
Nanoclays, 2D layered mineral silicates, have been used for centuries and have retained a prominent role in advancing materials science and technology. This class of materials has gained importance over other layered nanomaterials, owing to their abundance, low cost, diverse morphologies, and multiple chemical compositions, imparting them with exceptional physical and chemical properties. Polymer-clay nanocomposites possess exceptional attributes relative to neat polymers or their composite forms. Incorporating an adequate amount of clay content enhances crucial properties, such as tensile strength, modulus, thermal stability, elasticity, and heat deflection temperature, thereby extending their varied appliances. This review outlines the recent advancements in the performance of polymer-reinforced nanoclay composites, including their structures, chemical compositions, and emergent roles in various fields. The deployment and application of nanoclays in food packaging, water treatment, biomedical applications (tissue engineering, regenerative medicines, and therapeutic antibodies), catalysis, energy storage and conversions, and environmental remediation, among others, are critically appraised, including the emerging and latest applications of nanoclays in 3D printing. Finally, the latest advancements of nanoclay composites in terms of the present challenges and future possibilities for innovative applications are outlined. © The Royal Society of Chemistry 2022.