S. Ananda Kumar

Bio-composites: Development and mechanical characterization of banana/sisal fibre reinforced poly lactic acid (PLA) hybrid composites

The work focuses on the influencing effect of fiber surface treatment by BP towards mechanical properties of BSF reinforced PLA composites. BSF were treated by BP to improve the adhesion between fibres and matrix. BSF (30 wt %) reinforced PLA (70 wt %) hybrid composites were fabricated by means of twin screw extrusion followed by injection molding process. Tensile strength, flexural strength and modulus were tested by means of UTM. The morphological analysis of the untreated and treated BSF reinforced PLA composites in comparison with virgin PLA was carried out by SEM to examine the existence of interfacial adhesion between BSF and PLA. The resultant data reveals that treated BSF restricts the motion of the PLA matrix due to better wettability and bonding. Consequently, mechanical properties like tensile and flexural moduli of BSF reinforced PLA composites were enhanced in comparison to virgin PLA and untreated BSF reinforced PLA composites. The results are discussed in detail.

Development of silane grafted ZnO core shell nanoparticles loaded diglycidyl epoxy nanocomposites film for antimicrobial applications

In this article a series of epoxy nanocomposites film were developed using amine functionalized (ZnO-APTES) core shell nanoparticles as the dispersed phase and a commercially available epoxy resin as the matrix phase. The functional group of the samples was characterized using FT-IR spectra. The most prominent peaks of epoxy resin were found in bare epoxy and in all the functionalized ZnO dispersed epoxy nanocomposites (ZnO-APTES-DGEBA). The XRD analysis of all the samples exhibits considerable shift in 2θ, intensity and d-spacing values but the best and optimum concentration is found to be 3% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposites supported by FT-IR results. From TGA measurements, 100wt% residue is obtained in bare ZnO nanoparticles whereas in ZnO core shell nanoparticles grafted DGEBA residue percentages are 37, 41, 45, 46 and 52% for 0, 1, 3, 5 and 7% ZnO-APTES-DGEBA respectively, which is confirmed with ICP-OES analysis. From antimicrobial activity test, it was notable that antimicrobial activity of 7% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposite film has best inhibition zone effect against all pathogens under study.

Studies on corrosion-resistant behavior of siliconized epoxy interpenetrating coatings over mild steel surface by electrochemical methods

Solvent-free siloxane-modified epoxy coatings were developed by the interpenetrating technique using epoxy resin as base (DGEBA, GY 250, Ciba-Geigy) and hydroxyl-terminated polydimethylsiloxane as modifier (commercially known as silicone) with γ-aminopropyltriethoxysilane as cross-linker, dibutyltindilaurate as catalyst, and 25% zinc powder as additive. Hexamethylenediamine (Aldrich) and polyamidoamine (HY 840, Ciba-Geigy) were used as curatives for the siliconized epoxy coatings containing 25% zinc powder. The corrosion-resistant behavior of these coating systems is assessed by electrochemical methods such as electrochemical potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopic methods. Based on the results obtained from the electrochemical potential measurements for epoxy and siliconized epoxy coating systems, few samples, namely AX4 and BX4, have been found to be the best corrosion-resistant coating systems, and they are used for potentiodynamic polarization measurements, electrochemical impedance, and salt-spray tests. The experimental results reveal that the siloxane (10%) modified epoxy coating system (AX4) with 25% zinc powder cured by hexamethylenediamine offers the maximum corrosion protection to the steel surface rather than the polyamidoamine-cured system (BX4). The better protective action offered by the coating system (AX4) is mainly imparted by the reaction of aliphatic amine hydrogens with oxirane groups of the epoxy resin, which gives coating films with a high cross-link density. The observation is further supported by a capacitive behavior in the Nyquist plot and no spreading of visible corrosion product in the salt-spray test.

Studies on mechanical, thermal and dynamic mechanical properties of functionalized nanoalumina reinforced sulphone ether linked tetraglycidyl epoxy nanocomposites

The objective of the present work is to synthesize 1,4′-bis (4-amine-phenoxy) sulphone benzene epoxy resin (TGBAPSB) via 1,4′-bis (4-amine-phenoxy) sulphone benzene (BAPSB) and epichlorohydrin in order to obtain tetra functional epoxy with improved properties. The molecular structure of TGBAPSB epoxy resin was confirmed from FTIR and NMR spectral data and molecular weight was determined by GPC and epoxy equivalent weight (EEW) by titration method. The amino functionalized nanoalumina (F-nAl) was synthesized via the sol–gel method using 3-aminopropyltriethoxysilane and has been confirmed by FT-IR. TGBAPSB epoxy resin was further reinforced with varying weight percentages (1–5 wt%) of F-nAl and cured with diaminodiphenylmethane (DDM). The thermal and thermo-mechanical behaviour of TGBAPSB epoxy matrix and nanocomposites were analysed by TGA, DMA and DSC. The surface morphology of the epoxy nanocomposites was examined using XRD, TEM, SEM and AFM studies. Data obtained from mechanical, thermal and thermo-mechanical, dielectric and water absorption studies indicate a significant improvement in properties of the resultant epoxy nanocomposites, which appear to be ideal material for advanced high performance applications when compared to those of neat epoxy matrices.

Development and characterization of new phosphorus based flame retardant tetraglycidyl epoxy nanocomposites for aerospace application

A study was made in the present investigation on the development and characterization of triphenyl phosphine oxide based phosphorus tetraglycidyl epoxy nanocomposites denoted as ‘C’ and to find out its suitability for use in high performance applications. The synthesized resin was characterized by Fourier transform infrared spectra (FT–IR) and 1H, 13C nuclear magnetic resonance (NMR) spectra. Nanoclay and POSS-amine nano-reinforcements denoted as N1 and N2 were incorporated into the synthesized epoxy resin. Curing was done with diaminodiphenylmethane (DDM) and bis(3-aminophenyl) phenylphosphine oxide (BAPPO) curing agents denoted as X and Y, respectively. Mechanical, thermal, flame retardant, water absorption behaviour and electrical properties of the epoxy nanocomposites were studied and the results are discussed.

Assessment of corrosion-resistance of siliconised epoxy coatings by potentiodynamic polarisation method

SummariesEpoxy and siliconised epoxy coating systems are developed and their corrosion resistant behaviour is assessed by potentiodynamic polarisation method. Solvent-free coatings are used increasingly for a number of applications, due to lower cost per unit film thickness, better performance and freedom from fire and pollution hazard. In the present work solvent-free epoxy and siliconised epoxy coating systems are developed using epoxy resin, hydroxyl terminated polydimethylsiloxane, γ-aminopropyltriethoxysilane as the cross-linking agent, and dibutyltindilaurate as the catalyst. Hexamethylenediamine and polyamidoamine are used as curing agents for epoxy and siliconised epoxy coating systems and zinc dust (25%) is used as an additive. The corrosion resistance of these coating systems has been studied already by the authors by electrochemical potential measurements. Based on the results obtained from electrochemical measurements for epoxy and siliconised epoxy coating systems, two samples, namely AX4 and BX4 are selected for potentiodynamic polarisation measurements. From the potentiodynamic polarisation measurements, it is ascertained that the siliconised epoxy coating system (AX4) cured by hexamethylenediamine offers better corrosion resistance than the siliconised epoxy coating system (BX4) cured by polyamidoamine. Furthermore, incorporation of zinc in both the epoxy and the siliconised epoxy coating systems enhances corrosion resistance of both coating systems.RésuméOn met au point des systèmes de revêtements d’époxy et d’époxy siliconisée et on a évalué leur résistance à corrosion au moyen d’une méthode de polarisation potentiodynamique. Revêtements sans solvant sont de plus en plus utilisés pour une gamme d’applications à cause de leurs prix plus interessants en termes de l’unité d’épaisseur de feuil, de meilleur rendement et de l’absence des hazards tels que l’incendie et de la pollution. Dans les travaux actuels, on a developpé des systèmes de revêtements sans solvant d’époxy et d’époxy siliconisée en utilisant une résine époxy, hydroxylterminé polydiméthylsiloxane γ-aminopropyltriéthoxysilane comme l’agent de reticulation et la dilaurate de dibutyltin comme le catalysateur. Hexaméthylèndiamine et polyamidoamine sont utilisés comme agents réticulation pour durcir de revêtements d’époxy et d’époxy siliconisée avec (25%) de poudre de zinc en tant d’adjuvant. Les auteurs ont étudié au préalable la résistance à corrosion de ces systèmes de revêtements en servant des mesures du potentiel électrochimique. Fondé sur les résultats à partir des mesures électrochimique sur des systèmes de revêtements et d’époxy et d’époxy siliconisée, deux échantillons AX4 et BX4 sont choisis pour les mesures de polarisation potentiodynamiques. A partir de ces mesures on a trouvé que le système AX4 durci par hexaméthylènediamine donne de meilleure protecti contre corrosion que le système BX4 durci par polyamidoamine. En plus l’augmentation de la teneur en zinc augmente la résistance à corrosion de tours les deux systèmes.ZusammenfassungEpoxid — und Silikonepoxidbeschichtungssysteme werden entwickelt und deren Korrosionsbeständigkeitsverfahren durch eine potentiodynamische Polarisations methode bewertet. Lösemittelfreie Beschichtungsstoffe werden bei Einer Reihe Anwendungen wegen die niedrig niedrigeren Kosten pro Einheitfilmdicke, bessere Leistung und Freiheit von Feuer — und Umweltverschmutzungsgefahren zunehmend benutzt. In dem aktuslen Werk werden lösemittel-freie Epoxid — und Silikonepoxidbeschichtungssysteme mittels Epoxidharz, hydroxylbeendete Polydimethylsiloxan oder γ-aminopropyltriethoxysilan als Härter und Dibutyltindilaurat al Katalysator entwickelt. Hexamethyldiamin und Polyamidoamin werden als Härter für Epoxid — und Silikonepoxidbeschichtungsstoffessysteme mit Zinkstaub (25%) als ein Additiv benutzt. Der Korrosionswiderstand dieser Beschichtungsstoffessysteme wurden von den Autoren, mitte Elektrochemischpotentialmessungen studiert. Auf der Basis der Resultaten aus diesen Messungen zur Epoxidund Silikonepoxidbeschichtungsstoffessystemen, werden ein Paar Muster, bzw. AX4 und BX4 zur Elektrochemischpotentialmessungen ausgewählt. Aus diesen Messungen wird es festgestellt, daß der Silikonepoxidbeschichtungsstoffessystem (AX4) vernetzt von Hexamethylendiamin liefert besser Korrosionswiderstand als das Silikonepoxidbeschichtungsstoffessystem (BX4) vernetzt von Polyamidoamin. Überdies die Einfügung des Zinks in beiden Epoxid- und Silikonepoxidbeschichtungsstoffessysteme verbessert den Korrosionswiderstand der beiden Beschichtungssysteme.

Development and characterization of novel organic–inorganic hybrid sol–gel films

Organic–inorganic hybrid films were fabricated by reacting 3-glycidoxypropyltrimethoxysilane with 4,4′-diaminodiphenylether by hydrolysis and condensation reaction with acid catalysis. The chemical bonding between the organic and inorganic phases provides reinforcement to the films, and tetraethoxysilane was added in such a way that silica contents varied from 1 wt% to 3 wt% in the films. Structural characterization of the hybrid films was performed using Fourier transform infrared and nuclear magnetic resonance spectroscopic techniques. The thermal properties studied using thermogravimetric analysis, indicate an improved thermal stability for the films according to the percentage concentration of silica present in them. The water absorption was also found to be reduced for the films with increased silica content. The surface morphology was investigated by means of x-ray diffraction and scanning electron microscopic techniques. The films transparency and homogeneity seem to have been affected severely when the silica content kept on increasing and ultimately led to opaqueness in film.

Twin Applications of Tetra-Functional Epoxy Monomers for Anticorrosion and Antifouling Studies

This paper reports the development and characterization of nano-hybrid coatings using tetraglycidyl 2,2-bis(4-(4-amine phenoxy)phenyl)propane (TGBAPPP) and 3-aminopropyltriethoxysilane (APTES) functionalized ZnO as nano-reinforcement. The nano-hybrid coatings were cured by aromatic and aliphatic curing agents. The effect of the ZnO-APTES and curing agents on the corrosion and fouling resistant properties of these coatings was studied by electrochemical impedance, antifouling tests and toxicity test. It shows the tetraglycidyl epoxy nano-hybrid coatings have a better set of coating properties when compared to di-functional epoxy nano-hybrid coatings. The best results were obtained for ZnO-APTES loaded TGBAPPP with curing agent Aradur 140. These observations clearly indicate the synergistic effect of curing agent and nano-reinforcing effect of ZnO-APTES towards corrosion resistance.

Development of Environmentally Acceptable Nano-Hybrid Coatings for Bio-Fouling Protection

Alternative coatings should be as effective as conventional paints but with lower toxicity. In the present study, a commercially available epoxy resin modified with non functionalized nanozinc oxide (nZnO) was examined to get information on its antifouling and anti-corrosive properties. Epoxy nanohybrid coating was synthesized using nZnO (in the amount of 0wt%, 1wt%, 3wt%, 5wt%, 7wt% and 10wt%) and diglycidyl ether of bisphenol A (DGEBA) type of epoxy resin. The curing behavior of these materials was ascertained from FT-IR spectral studies. The anti-corrosive properties of the nanohybrid were investigated using salt spray and electro chemical polarization studies. The surface morphology images were taken by SEM analysis. This study indicates that nZnO particles were dispersed homogenously through the polymer matrix. The nZnO incorporated coating was found to exhibit enhanced anticorrosive performance. Approximately 50% reduction in fouling attachment was achieved with coatings containing 3wt% of nZnO.

Development and characterization of tetraglycidyl epoxy reinforced inorganic hybrid nanomaterials for high performance applications

In the present work, tetraglycidyl 1,4′-bis (4-amine-phenoxy) benzene (TGBAPB) epoxy resin has been developed using 1,4′-bis (4-amine-phenoxy) benzene and epichlorohydrin. The amine-functionalized nanoalumina (F-nAl) was prepared using 3-aminopropyltriethoxysilane. TGBAPB epoxy resin was further reinforced with different weight percentages (1–5 wt%) of F-nAl and were cured with 4,4′-diaminodiphenylmethane. Thermal and thermomechanical behavior of TGBAPB epoxy matrix and nanocomposites were studied using thermogravimetric and differential scanning calorimetric analyses. The surface morphology of epoxy nanocomposites was examined using transmission electron microscopic, scanning electron microscopic, and atomic force microscopic studies respectively. Data obtained from mechanical and thermal studies/analysis indicate that these nanocomposites could be used as high-performance materials for varied advanced industrial and engineering applications.