Paluvai Nagarjuna Reddy | Hanyang University (original) (raw)

Papers by Paluvai Nagarjuna Reddy

In this present study, an efficient method has been proposed to develop a high hydrophobic zincat... more In this present study, an efficient method has been proposed to develop a high hydrophobic zincated coating on the eva-core aluminium (Al) alloy surface. The double zincating method (Z2) was utilized to develop the required roughness on the Al surface. To control the surface energy, lauric acid (LA) was coated on the surface using the liquid self-assembled monolayers (L-SAMs) method. Surface morphology, the chemical composition of the treated and untreated Al alloy has been studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), optical microscopy and X-ray diffraction (XRD), respectively. The hydrophobicity of the substrates has also been analysed using a contact angle measurement (CA). AFM micrographs show the surface roughness of the Al alloy has been drastically increased with chemical treatments from 0.071 to 0.32 μm. XRD shows the percentage crystallinity of the Al alloy is decreased with double zincating and LA coating from 56.8 to 22.7%. As a result, a high hydrophobicity of Al alloy was induced with a contact angle of 150° upon the double zincating method and L-SAMs coating.

The quick removal of condensed water generated during operation of an automobile air conditioner ... more The quick removal of condensed water generated during operation of an automobile air conditioner is essential to prevent the growth of bacteria and fungi, which may produce odors and cause illness. Modification of an evaporator core (evacore) surface to provide superhydrophobicity is one technique that can be used to remove the condensed water. However, if the evacore surface is superhydrophobic, small water droplets can flow towards the inside of the automobile engine along with the air flowing through the air conditioner. In the present investigation, we propose an approach to fabricate an evacore surface that can be switched from hydrophobic to hydrophilic by changing the temperature. In the initial stage of air conditioner operation, the surface is hydrophilic at ambient temperature, causing water to stay on the surface. After the operation of the air conditioner, the surface becomes hydrophobic at a higher temperature, and the water rolls off the surface. To fabricate this surface, aluminum (Al) substrate was used, and it was etched by immersion in 10 wt.% hydrochloric acid (HCl) for 8 min. The etched Al substrate was coated with a functionalized poly(NIPAM-co-MAA) polymer by immersing in a coating solution for 1 h at 120 °C. The resulting surface is a thermosensitive hydrophobic/hydrophilic switchable Al surface, which provides a hydrophilic state under the lower critical solution temperature (LCST), 35 °C, and a hydrophobic state above the LCST.

In this review, thermosetting polymers derived from natural resources are highlighted for future ... more In this review, thermosetting polymers derived from natural resources are highlighted for future generation with greater sustainability for different applications. Recently, agro-based polymer products are gained popularity since last two decades due to the depletion of fossil reserves and to protect the environment from carbon emissions. This review also designed to explain the various types of agro-based polymer products derived from cardanol, itaconic acid, tannin, sugar (isosorbide), and vegetable oils as important starting materials due to their abundant availability, low price, and unique reactive chemical structure.

The present study highlights the structure and property relationships of epoxidized castor oil (E... more The present study highlights the structure and property relationships of epoxidized castor oil (ECO) toughened Diglycidyl Ether of Bisphenol A (DGEBA) epoxy nanocomposites. Toughened epoxy systems have been prepared by an addition of 10–40 wt% ECO to the DGEBA epoxy resin. Nanocomposites were prepared by mixing small amounts of Cloisite 30B (C30B) clay and 3-aminopropyltriethoxysilane to the DGEBA/ECO blends. The chemical structure of toughened systems was confirmed using proton nuclear magnetic resonance and fourier transform infrared spectroscopy. The triethylenetetraamine-cured DGEBA/ECO/C30B (8:2:0.1) nanocomposites exhibited tensile strength (50 MPa), tensile modulus (1.7 GPa), flexural strength (120 MPa), flexural modulus (3.02 GPa), and elongation (19%). The fracture toughness (critical intensity factor, KIC) and fracture energy (critical energy release rate, GIC) of DGEBA/ECO/C30B (8:2:0.1) system found to be higher than the other systems (2.5 MPa.m1/2 and 1.8 kJ/m2 for KIC and GIC, respectively). The thermal stability and heat of reaction of DGEBA/ECO blends increase with the addition of C30B clays that were analyzed using thermogravimetric analysis and differential scanning calorimetry. Rheological characterizations of uncured samples revealed a pronounced effect of the C30B clay on the DGEBA/ECO blend systems that exhibited a shear-thickening behavior. On the other hand, the dynamic mechanical properties also revealed that the addition of C30B clays to the DGEBA/ECO blend a significant enhancements in viscoelastic and cross linking density behavior. Scanning electron microscope analysis was used to study the fractured morphology of DGEBA, DGEBA/ECO, and its nanocomposite systems. Copyright © 2015 John Wiley & Sons, Ltd.

Unsaturated polyester (UP) toughened epoxy nanocomposites were prepared, and their effective mech... more Unsaturated polyester (UP) toughened epoxy nanocomposites were prepared, and their effective mechanical and thermal properties were studied. Two types of organo-modified montmorillonite (OMMT) clays were used to prepare the nanocomposites. X- ray diffraction (XRD) and Transmission electron microscope (TEM) analysis showed the formation of exfoliated silicate layers in the UP-toughened epoxy matrix. Mechanical tests revealed that nanocomposites (containing 1 wt% OMMT clay) showed an increase in tensile strength to 13.8%, flexural strength to 10% and impact strength to 4% compared with an UP-toughened epoxy blend. The effect of different heating rates on the curing behavior of UP toughened epoxy nanocomposites was investigated using non-isothermal differential scanning calorimetry. The data were interpreted using the Kissinger and Flynn-Wall-Ozawa models to find the curing reaction parameter. The water uptake behavior for nanocomposites increased with the addition of OMMTs. Scanning electron microscopy (SEM) micrographs indicated morphological changes in the impact fractured samples of UP-toughened epoxy nanocomposites.

In the present study, the mechanical and thermal properties of sisal fiber-reinforced unsaturated... more In the present study, the mechanical and thermal properties of sisal fiber-reinforced unsaturated polyester (UP)-toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier-transform infrared spectroscopy. The UP-toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber-reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP-toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP-toughened epoxy system. The results showed that the tensile and flexural strength of (alkali-silane)-treated fiber (30 wt%) -reinforced composites increased by 83% and 55%, respectively, as compared with that of UP-toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali-silane)-treated fiber and its composite exhibited higher thermal stability than the untreated and alkali-treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP-toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali-silane-treated fiber-reinforced composites is found to be less as compared with the untreated fiber-reinforced composite. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers

Castor oil-based epoxy monomer was prepared using a two-step approach: epoxidation of castor oil,... more Castor oil-based epoxy monomer was prepared using a two-step approach: epoxidation of castor oil, followed by acrylation of epoxidized castor oil. A bio-based diglycidyl ether of bisphenol A (DGEBA) epoxy nanocomposites was prepared by the incorporation of organo-modified montmorillonite (OMMT) clay to the DGEBA/AECO system. The cured bio-based DGEBA epoxy nanocomposites at 0.80:0.2:0.001 g/g exhibited higher tensile strength (56 MPa), tensile modulus (1933 MPa), flexural strength (132 MPa), flexural modulus (2518 MPa), elongation (23.1 %), and impact strength (34 KJ/m2). The nanocomposites at 0.6:0.4:0.001 g/g can easily bend up to 360° without any damage; similarly, the 0.8:0.2:0.001 g/g system can bend up to 180°. Thermal behaviour of the bio-based epoxy systems was characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The obtained nanocomposites displayed a higher char yield (8.9 %) at 700 °C and glass transition temperature (108 °C) than the DGEBA/AECO systems. Further SEM analysis was used to study the morphological changes in the fractured surfaces of bio-based epoxy systems, which reveals that crack propagation decreases with addition of AECO to the DGEBA epoxy system.

In this study, the bio-based epoxy nanocomposites were prepared from acrylated epoxidized castor ... more In this study, the bio-based epoxy nanocomposites were prepared from acrylated epoxidized castor oil toughened diglycidyl ether of bisphenol A epoxy network filled with sisal fibers and cloisite 30B clay. The chemical structure of acrylated epoxidized castor oil resin was confirmed by Fourier transform infrared and Proton nuclear magnetic resonance (1HNMR) spectroscope techniques. Mechanical and thermal properties of the sisal fiber reinforced acrylated epoxidized castor oil toughened diglycidyl ether of bisphenol A epoxy composites and nanocomposites were investigated. Mechanical tests revealed that bio-based epoxy nanocomposites (containing 80% diglycidyl ether of bisphenol A/20% acrylated epoxidized castor oil / 30% treated sisal fiber/ 1% cloisite 30B weight ratio) were found to be higher in tensile strentgh to 78%, flexural strentgh to 44% and impact strength to 20% than the 80% diglycidyl ether of bisphenol A/20% acrylated epoxidized castor oil matrix. Thermogravimetric analysis results showed that the thermal stability of diglycidyl ether of bisphenol A /acrylated epoxidized castor oil matrix increased with the incorporation of alkali-silane-treated sisal fiber and cloisite 30B nanoclay. The apparent activation energy was increased from 236 to 273 KJ/mol with the addition of 1% cloisite 30B clay and 30% alkali-silane-treated sisal fiber to the 80% diglycidyl ether of bisphenol A /20% acrylated epoxidized castor oil matrix. Scanning electron microscopy was performed to investigate the fracture behaviour at the fiber-matrix interface.

This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polye... more This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polyester (UP) toughened epoxy nanocomposites. The chemical structures changes in Epoxy, UP and UP toughened epoxy (Epoxy/UP) systems were characterized by Proton Nuclear magnetic resonance (1HNMR) spectroscopy. The morphological alterations of the nanocomposites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The untreated, chemically treated fibers, nanoclays, and the fiber reinforced Epoxy/UP nanocomposites were confirmed by FTIR spectrometer. The obtained mechanical results showed that alkali-silane treated fibers improve the tensile strength (96%) and flexural strength (60%) of the Epoxy/UP nanocomposite than that of Epoxy/UP blend due to the strong interfacial bonding between the sisal fiber and matrix. The fracture toughness (KIC) and fracture energy (GIC) of treated sisal fiber reinforced DGEBA/UP/C30B nanocomposites found to be higher than that of untreated sisal fiber nanocomposites. The dynamic mechanical analysis (DMA) reveals that the fiber reinforced Epoxy/UP nanocomposites contains 30 wt% treated fiber and 1 wt% nanoclays, exhibits the highest storage modulus and better glass transition temperature (Tg) among the other kind of systems. The surface morphology of the fibers, fractured surface of the resins and composites were confirmed by scanning electron microscope (SEM). POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

International Journal of Polymer Analysis and Characterization, Mar 11, 2015

Renewable resource based epoxidized castor oil (ECO) is synthesized and used as a prime material ... more Renewable resource based epoxidized castor oil (ECO) is synthesized and used as a prime material to develop the acrylated epoxidized castor oil (AECO) networks. AECO nanocomposites prepared via sol-gel method from OMMT clay and silane. It is found that AECO/1 wt.% OMMT system increases in tensile strength from 28 to 37 MPa and flexural strength from 54 to 63 MPa as compared with the AECO system, respectively. The non-isothermal cure kinetics of bio-based systems has been studied using differential scanning calorimetry (DSC). The activation energy of AECO/OMMT system obtained from Kissinger and Flynn-Wall-Ozawa models is lower than that of AECO system

Wiley, Feb 25, 2015

Unsaturated polyester (UP) toughened nanocomposites were prepared using both sisal fibers and mon... more Unsaturated polyester (UP) toughened nanocomposites were prepared using both sisal fibers and montmorillonite clays. The effect of fibers and Cloisite 30B (C30B) nanoclays on the mechanical properties, thermal stability, flame retardant, and morphological behavior of the UP toughened epoxy (Epoxy/UP) were systematically studied. The chemical structures of Epoxy, UP, and Epoxy/UP systems were characterized using Proton Nuclear magnetic resonance (1HNMR) and Fourier transform infrared (FTIR) spectra. The homogeneous dispersion of nanoclay within the polymer matrix was analyzed using transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. Incorporation of sisal fibers and C30B nanoclays within Epoxy/UP system resulted in an increase in the mechanical, thermal, and flame retardance properties. Thermogravimetric analysis (TGA) has been employed to evaluate the thermal degradation kinetic parameters of the composites using Kissinger and Flynn-Wall-Ozawa methods. Cone calorimeter, UL-94, and LOI tests revealed a reduction in the burning rate of the matrix with the addition of fibers and nanoclays. The results showed that the treated fiber reinforced nanocomposites had higher thermal stability and better flame retardant properties than the treated fiber reinforced composites. VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42068.

SAGE, Jan 7, 2015

Bio-based epoxy monomer was synthesized by acrylation of epoxidized castor oil (ECO). Subsequentl... more Bio-based epoxy monomer was synthesized by acrylation of epoxidized castor oil (ECO). Subsequently, acrylated epoxidized castor oil (AECO)-toughened DGEBA nanocomposites were prepared via sol-gel process with the addition of organically treated montmorillonite (OMMT) nanoclays. In the current study, the curing kinetics of anhydride cured DGEBA/AECO monomer with and without clays was studied by non-isothermal differential scanning calorimetry (DSC) analysis. The apparent activation energy obtained by Flynn-Wall-Ozawa method was reduced from 63 to 59 kJ/mol and 69 to 61 kJ/mol, respectively, with the addition of 1 wt.% clay to the DGEBA/10 wt.% AECO and DGEBA/20 wt.% AECO systems, respectively. The two-parameter Šesták–Berggren autocatalytic model was used to obtain the reaction orders m and n, respectively. The curves obtained by the Málek method show good agreement with the experimental data for bio-based epoxy systems.

This article is designed to review the developments in synthesis, modifications, and properties o... more This article is designed to review the developments in synthesis, modifications, and properties of epoxy monomers derived from both petroleum and renewable resources. It begins with the enhancement in epoxy monomer properties such as mechanical, thermal, adhesive, barrier, etc. by addition of flexible polymer and elastomers. It also explains the role of organic/inorganic fillers on epoxy monomers to achieve the desired properties for outdoor applications. The effects of chemical/physical treatments on fiber are reviewed and their improvements with epoxy monomers are also observed. The authors also suggest for further improvement of epoxy monomers to obtain various eco-friendly high-performance applications.

The present study investigated the mechanical-thermal properties of “natural composites” obtained... more The present study investigated the mechanical-thermal properties of “natural composites” obtained from sisal fiber and epoxy unsaturated polyester blends. The partial removal of wax, hemicelluloses, and lignin is confirmed from the FTIR spectroscopy. The Epoxy/Unsaturated polyester blends were prepared. The mechanical and thermal properties such as tensile, flexural, impact strength, heat deflection temperature (HDT), Dynamic mechanical analysis and thermogravimetric analysis were examined. The optimum properties of the natural composites were achieved by 30% wt% fiber loading. The SEM was applied to study and evaluate the surface changes of treated and untreated fibers and also to discuss the results originated from the evaluation of mechanical properties. Hand lay-up technique was used for making the composites and tests are carried out by using ASTM methods.

In this present study, an efficient method has been proposed to develop a high hydrophobic zincat... more In this present study, an efficient method has been proposed to develop a high hydrophobic zincated coating on the eva-core aluminium (Al) alloy surface. The double zincating method (Z2) was utilized to develop the required roughness on the Al surface. To control the surface energy, lauric acid (LA) was coated on the surface using the liquid self-assembled monolayers (L-SAMs) method. Surface morphology, the chemical composition of the treated and untreated Al alloy has been studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), optical microscopy and X-ray diffraction (XRD), respectively. The hydrophobicity of the substrates has also been analysed using a contact angle measurement (CA). AFM micrographs show the surface roughness of the Al alloy has been drastically increased with chemical treatments from 0.071 to 0.32 μm. XRD shows the percentage crystallinity of the Al alloy is decreased with double zincating and LA coating from 56.8 to 22.7%. As a result, a high hydrophobicity of Al alloy was induced with a contact angle of 150° upon the double zincating method and L-SAMs coating.

The quick removal of condensed water generated during operation of an automobile air conditioner ... more The quick removal of condensed water generated during operation of an automobile air conditioner is essential to prevent the growth of bacteria and fungi, which may produce odors and cause illness. Modification of an evaporator core (evacore) surface to provide superhydrophobicity is one technique that can be used to remove the condensed water. However, if the evacore surface is superhydrophobic, small water droplets can flow towards the inside of the automobile engine along with the air flowing through the air conditioner. In the present investigation, we propose an approach to fabricate an evacore surface that can be switched from hydrophobic to hydrophilic by changing the temperature. In the initial stage of air conditioner operation, the surface is hydrophilic at ambient temperature, causing water to stay on the surface. After the operation of the air conditioner, the surface becomes hydrophobic at a higher temperature, and the water rolls off the surface. To fabricate this surface, aluminum (Al) substrate was used, and it was etched by immersion in 10 wt.% hydrochloric acid (HCl) for 8 min. The etched Al substrate was coated with a functionalized poly(NIPAM-co-MAA) polymer by immersing in a coating solution for 1 h at 120 °C. The resulting surface is a thermosensitive hydrophobic/hydrophilic switchable Al surface, which provides a hydrophilic state under the lower critical solution temperature (LCST), 35 °C, and a hydrophobic state above the LCST.

In this review, thermosetting polymers derived from natural resources are highlighted for future ... more In this review, thermosetting polymers derived from natural resources are highlighted for future generation with greater sustainability for different applications. Recently, agro-based polymer products are gained popularity since last two decades due to the depletion of fossil reserves and to protect the environment from carbon emissions. This review also designed to explain the various types of agro-based polymer products derived from cardanol, itaconic acid, tannin, sugar (isosorbide), and vegetable oils as important starting materials due to their abundant availability, low price, and unique reactive chemical structure.

The present study highlights the structure and property relationships of epoxidized castor oil (E... more The present study highlights the structure and property relationships of epoxidized castor oil (ECO) toughened Diglycidyl Ether of Bisphenol A (DGEBA) epoxy nanocomposites. Toughened epoxy systems have been prepared by an addition of 10–40 wt% ECO to the DGEBA epoxy resin. Nanocomposites were prepared by mixing small amounts of Cloisite 30B (C30B) clay and 3-aminopropyltriethoxysilane to the DGEBA/ECO blends. The chemical structure of toughened systems was confirmed using proton nuclear magnetic resonance and fourier transform infrared spectroscopy. The triethylenetetraamine-cured DGEBA/ECO/C30B (8:2:0.1) nanocomposites exhibited tensile strength (50 MPa), tensile modulus (1.7 GPa), flexural strength (120 MPa), flexural modulus (3.02 GPa), and elongation (19%). The fracture toughness (critical intensity factor, KIC) and fracture energy (critical energy release rate, GIC) of DGEBA/ECO/C30B (8:2:0.1) system found to be higher than the other systems (2.5 MPa.m1/2 and 1.8 kJ/m2 for KIC and GIC, respectively). The thermal stability and heat of reaction of DGEBA/ECO blends increase with the addition of C30B clays that were analyzed using thermogravimetric analysis and differential scanning calorimetry. Rheological characterizations of uncured samples revealed a pronounced effect of the C30B clay on the DGEBA/ECO blend systems that exhibited a shear-thickening behavior. On the other hand, the dynamic mechanical properties also revealed that the addition of C30B clays to the DGEBA/ECO blend a significant enhancements in viscoelastic and cross linking density behavior. Scanning electron microscope analysis was used to study the fractured morphology of DGEBA, DGEBA/ECO, and its nanocomposite systems. Copyright © 2015 John Wiley & Sons, Ltd.

Unsaturated polyester (UP) toughened epoxy nanocomposites were prepared, and their effective mech... more Unsaturated polyester (UP) toughened epoxy nanocomposites were prepared, and their effective mechanical and thermal properties were studied. Two types of organo-modified montmorillonite (OMMT) clays were used to prepare the nanocomposites. X- ray diffraction (XRD) and Transmission electron microscope (TEM) analysis showed the formation of exfoliated silicate layers in the UP-toughened epoxy matrix. Mechanical tests revealed that nanocomposites (containing 1 wt% OMMT clay) showed an increase in tensile strength to 13.8%, flexural strength to 10% and impact strength to 4% compared with an UP-toughened epoxy blend. The effect of different heating rates on the curing behavior of UP toughened epoxy nanocomposites was investigated using non-isothermal differential scanning calorimetry. The data were interpreted using the Kissinger and Flynn-Wall-Ozawa models to find the curing reaction parameter. The water uptake behavior for nanocomposites increased with the addition of OMMTs. Scanning electron microscopy (SEM) micrographs indicated morphological changes in the impact fractured samples of UP-toughened epoxy nanocomposites.

In the present study, the mechanical and thermal properties of sisal fiber-reinforced unsaturated... more In the present study, the mechanical and thermal properties of sisal fiber-reinforced unsaturated polyester (UP)-toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier-transform infrared spectroscopy. The UP-toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber-reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP-toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP-toughened epoxy system. The results showed that the tensile and flexural strength of (alkali-silane)-treated fiber (30 wt%) -reinforced composites increased by 83% and 55%, respectively, as compared with that of UP-toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali-silane)-treated fiber and its composite exhibited higher thermal stability than the untreated and alkali-treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP-toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali-silane-treated fiber-reinforced composites is found to be less as compared with the untreated fiber-reinforced composite. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers

Castor oil-based epoxy monomer was prepared using a two-step approach: epoxidation of castor oil,... more Castor oil-based epoxy monomer was prepared using a two-step approach: epoxidation of castor oil, followed by acrylation of epoxidized castor oil. A bio-based diglycidyl ether of bisphenol A (DGEBA) epoxy nanocomposites was prepared by the incorporation of organo-modified montmorillonite (OMMT) clay to the DGEBA/AECO system. The cured bio-based DGEBA epoxy nanocomposites at 0.80:0.2:0.001 g/g exhibited higher tensile strength (56 MPa), tensile modulus (1933 MPa), flexural strength (132 MPa), flexural modulus (2518 MPa), elongation (23.1 %), and impact strength (34 KJ/m2). The nanocomposites at 0.6:0.4:0.001 g/g can easily bend up to 360° without any damage; similarly, the 0.8:0.2:0.001 g/g system can bend up to 180°. Thermal behaviour of the bio-based epoxy systems was characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The obtained nanocomposites displayed a higher char yield (8.9 %) at 700 °C and glass transition temperature (108 °C) than the DGEBA/AECO systems. Further SEM analysis was used to study the morphological changes in the fractured surfaces of bio-based epoxy systems, which reveals that crack propagation decreases with addition of AECO to the DGEBA epoxy system.

In this study, the bio-based epoxy nanocomposites were prepared from acrylated epoxidized castor ... more In this study, the bio-based epoxy nanocomposites were prepared from acrylated epoxidized castor oil toughened diglycidyl ether of bisphenol A epoxy network filled with sisal fibers and cloisite 30B clay. The chemical structure of acrylated epoxidized castor oil resin was confirmed by Fourier transform infrared and Proton nuclear magnetic resonance (1HNMR) spectroscope techniques. Mechanical and thermal properties of the sisal fiber reinforced acrylated epoxidized castor oil toughened diglycidyl ether of bisphenol A epoxy composites and nanocomposites were investigated. Mechanical tests revealed that bio-based epoxy nanocomposites (containing 80% diglycidyl ether of bisphenol A/20% acrylated epoxidized castor oil / 30% treated sisal fiber/ 1% cloisite 30B weight ratio) were found to be higher in tensile strentgh to 78%, flexural strentgh to 44% and impact strength to 20% than the 80% diglycidyl ether of bisphenol A/20% acrylated epoxidized castor oil matrix. Thermogravimetric analysis results showed that the thermal stability of diglycidyl ether of bisphenol A /acrylated epoxidized castor oil matrix increased with the incorporation of alkali-silane-treated sisal fiber and cloisite 30B nanoclay. The apparent activation energy was increased from 236 to 273 KJ/mol with the addition of 1% cloisite 30B clay and 30% alkali-silane-treated sisal fiber to the 80% diglycidyl ether of bisphenol A /20% acrylated epoxidized castor oil matrix. Scanning electron microscopy was performed to investigate the fracture behaviour at the fiber-matrix interface.

This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polye... more This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polyester (UP) toughened epoxy nanocomposites. The chemical structures changes in Epoxy, UP and UP toughened epoxy (Epoxy/UP) systems were characterized by Proton Nuclear magnetic resonance (1HNMR) spectroscopy. The morphological alterations of the nanocomposites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The untreated, chemically treated fibers, nanoclays, and the fiber reinforced Epoxy/UP nanocomposites were confirmed by FTIR spectrometer. The obtained mechanical results showed that alkali-silane treated fibers improve the tensile strength (96%) and flexural strength (60%) of the Epoxy/UP nanocomposite than that of Epoxy/UP blend due to the strong interfacial bonding between the sisal fiber and matrix. The fracture toughness (KIC) and fracture energy (GIC) of treated sisal fiber reinforced DGEBA/UP/C30B nanocomposites found to be higher than that of untreated sisal fiber nanocomposites. The dynamic mechanical analysis (DMA) reveals that the fiber reinforced Epoxy/UP nanocomposites contains 30 wt% treated fiber and 1 wt% nanoclays, exhibits the highest storage modulus and better glass transition temperature (Tg) among the other kind of systems. The surface morphology of the fibers, fractured surface of the resins and composites were confirmed by scanning electron microscope (SEM). POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

International Journal of Polymer Analysis and Characterization, Mar 11, 2015

Renewable resource based epoxidized castor oil (ECO) is synthesized and used as a prime material ... more Renewable resource based epoxidized castor oil (ECO) is synthesized and used as a prime material to develop the acrylated epoxidized castor oil (AECO) networks. AECO nanocomposites prepared via sol-gel method from OMMT clay and silane. It is found that AECO/1 wt.% OMMT system increases in tensile strength from 28 to 37 MPa and flexural strength from 54 to 63 MPa as compared with the AECO system, respectively. The non-isothermal cure kinetics of bio-based systems has been studied using differential scanning calorimetry (DSC). The activation energy of AECO/OMMT system obtained from Kissinger and Flynn-Wall-Ozawa models is lower than that of AECO system

Wiley, Feb 25, 2015

Unsaturated polyester (UP) toughened nanocomposites were prepared using both sisal fibers and mon... more Unsaturated polyester (UP) toughened nanocomposites were prepared using both sisal fibers and montmorillonite clays. The effect of fibers and Cloisite 30B (C30B) nanoclays on the mechanical properties, thermal stability, flame retardant, and morphological behavior of the UP toughened epoxy (Epoxy/UP) were systematically studied. The chemical structures of Epoxy, UP, and Epoxy/UP systems were characterized using Proton Nuclear magnetic resonance (1HNMR) and Fourier transform infrared (FTIR) spectra. The homogeneous dispersion of nanoclay within the polymer matrix was analyzed using transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. Incorporation of sisal fibers and C30B nanoclays within Epoxy/UP system resulted in an increase in the mechanical, thermal, and flame retardance properties. Thermogravimetric analysis (TGA) has been employed to evaluate the thermal degradation kinetic parameters of the composites using Kissinger and Flynn-Wall-Ozawa methods. Cone calorimeter, UL-94, and LOI tests revealed a reduction in the burning rate of the matrix with the addition of fibers and nanoclays. The results showed that the treated fiber reinforced nanocomposites had higher thermal stability and better flame retardant properties than the treated fiber reinforced composites. VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42068.

SAGE, Jan 7, 2015

Bio-based epoxy monomer was synthesized by acrylation of epoxidized castor oil (ECO). Subsequentl... more Bio-based epoxy monomer was synthesized by acrylation of epoxidized castor oil (ECO). Subsequently, acrylated epoxidized castor oil (AECO)-toughened DGEBA nanocomposites were prepared via sol-gel process with the addition of organically treated montmorillonite (OMMT) nanoclays. In the current study, the curing kinetics of anhydride cured DGEBA/AECO monomer with and without clays was studied by non-isothermal differential scanning calorimetry (DSC) analysis. The apparent activation energy obtained by Flynn-Wall-Ozawa method was reduced from 63 to 59 kJ/mol and 69 to 61 kJ/mol, respectively, with the addition of 1 wt.% clay to the DGEBA/10 wt.% AECO and DGEBA/20 wt.% AECO systems, respectively. The two-parameter Šesták–Berggren autocatalytic model was used to obtain the reaction orders m and n, respectively. The curves obtained by the Málek method show good agreement with the experimental data for bio-based epoxy systems.

This article is designed to review the developments in synthesis, modifications, and properties o... more This article is designed to review the developments in synthesis, modifications, and properties of epoxy monomers derived from both petroleum and renewable resources. It begins with the enhancement in epoxy monomer properties such as mechanical, thermal, adhesive, barrier, etc. by addition of flexible polymer and elastomers. It also explains the role of organic/inorganic fillers on epoxy monomers to achieve the desired properties for outdoor applications. The effects of chemical/physical treatments on fiber are reviewed and their improvements with epoxy monomers are also observed. The authors also suggest for further improvement of epoxy monomers to obtain various eco-friendly high-performance applications.

The present study investigated the mechanical-thermal properties of “natural composites” obtained... more The present study investigated the mechanical-thermal properties of “natural composites” obtained from sisal fiber and epoxy unsaturated polyester blends. The partial removal of wax, hemicelluloses, and lignin is confirmed from the FTIR spectroscopy. The Epoxy/Unsaturated polyester blends were prepared. The mechanical and thermal properties such as tensile, flexural, impact strength, heat deflection temperature (HDT), Dynamic mechanical analysis and thermogravimetric analysis were examined. The optimum properties of the natural composites were achieved by 30% wt% fiber loading. The SEM was applied to study and evaluate the surface changes of treated and untreated fibers and also to discuss the results originated from the evaluation of mechanical properties. Hand lay-up technique was used for making the composites and tests are carried out by using ASTM methods.