Jignesh P. Patel

The Preparation and PhysicoChemical Study of Glass, Jute and Hybrid Glass-Jute Bisphenol-C-Based Epoxy Resin Composites

Glass-PA (EC-G-PA), Jute-PA (EC-J-PA), Glass-Jute-Glass (EC-GJG-PA), Jute-Glass-Jute (EC-JGJ-PA) composites of epoxy resin of bisphenol-C (EBC) have been prepared using a hand lay-up technique at 150°C under 27.58 MPa pressure for 6 h by using phthalic anhydride as a curing agent. EC-G-PA, EC-J-PA EC-GJG-PA and EC-JGJ-PA Possess 34, 41, 27 and 21 MPa tensile strength; 34, 27, 19 and 22 MPa flexural strength; 1.9, 1.0, 1.6 and 1.3 kV/mm electric strength and 4.2 × 1013, 1.2 × 109, 8.7 × 1011 and 4.0 × 1011 ohm.cm volume resistivity. Hydrolytic stability of the composites was tested against water, 10% aq. HCl and NaCl solutions at 35°C and also in boiling water. The percent water uptake, equilibrium time and diffusivity of the composites have been determined and discussed their possible applications.

Curing, Spectral and Thermal Study of Epoxy Resin of Bisphenol-C and Its Polyester Polyols Based Polyurethanes

Epoxy resin of bisphenol-C (EBC), its ricinoleate- and linoleate-based polyols have been cured using 5–25 wt% triethylamine and toluene-2,4-di-isocyanate at 100° and 140°C, respectively. Cured resins are insoluble in common solvents and characterized by IR, DSC and TGA. Amine-cured resin was thermally stable up to about 309–318°C and followed 1.5-order degradation kinetics. Ricinoleate-based polyurethane was thermally stable up to about 215°C and followed 0.43-, 0.75-, and 1.12-order degradation kinetics. Linoleate-based polyurethane was thermally stable up to about 260°C and followed, respectively, 1.9- and 0.93-order degradation kinetics. Kinetic parameters are interpreted in light of resin structure and nature of hardeners used. Amine-cured epoxy resin possesses better thermal properties than those of its polyols-based polyurethanes.

Spectral and thermal study of cured tetrafunctional epoxy-ester-amide polymeric framework

Tetrafunctional epoxy resin of bisphenol-C (EBCF) has been cured by various bisamic acids of anhydrides (tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, and tertrabromophthalic anhydride) and diamines (4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylether, and 4,4′-diaminodiphenyl methane) at 120 °C. Cured resins are found insoluble in common solvents. IR spectral data of cured resins revealed expected groups in polymeric network. Differential scanning calorimetric transitions revealed melting of traces of uncured or branched EBCF and also decomposition reaction. The use of nonstoichiometric amounts of hardeners resulted in about 15–29% sol content and 71–85% gel content except EBCF-TCPADDM for which sol content is considerably high and gel content is low. Cured resins are thermally stable up to about 150–200 °C and followed multistep fractional and integral degradation reactions with 21–48% residue at 700 °C. Halogenated resins displayed somewhat better thermal stability and a large amount of residue. The structure of bisamic acids affected thermal behavior of EBCF. Various kinetic parameters are determined and discussed in light of structure of the bisamic acids.

Preparation and Physico-Chemical Study of Sandwich Glass-Jute-Bisphenol-C-Formaldehyde Resin Composites

Glass-Jute-bisphenol-C-formaldehyde (Glass-Jute-BCF) sandwich composites were prepared by hand lay-up technique at 150°C under 30.4 MPa pressure for 2 h. The resin, glass and jute fiber content in the sandwich composite were 33.3, 10.4 and 56.3 wt%, respectively. 10 prepregs containing 8 inner prepregs of jute mats sandwiched between 2 outer prepregs of glass mats. Glass-Jute-BCF sandwich composite has 23 MPa tensile strength, 119 MPa flexural strength, 1.72 kV/mm electric strength and 1.25 × 1012 ohm cm volume resistivity. Tensile strength and volume resistivity both decreased, while flexural strength and electrical strength both improved upon hybridization. Sandwich composite showed high diffusivity in water, 10% NaCl and 10% HCl solutions as compared to Glass-BCF composite. Equilibrium water absorption time is found to be 72 h in all 3 environments. Comparatively low diffusivity is observed due to silane treated glass fibers. No effect of boiling water is observed on stability of composite. Saturation time in boiling water reduced 18 times without any damage to the composite. Glass-Jute-BCF sandwich composite may be useful for low load bearing applications in construction, electrical and electronic industries as well as in harsh acidic and saline environments.

Characterization, testing, and reinforcing materials of biodegradable composites

Natural fibers are biomass, which is mainly used as a feedstock for the chemical industries, biomaterials, and bioenergy and also in making high-performance biocomposites for various applications. The importance and origin of natural fibers, their classification, properties, advantages over conventional fibers, fiber extraction techniques, and fiber cleaning are summarized in brief. Sixteen fiber yielding plants or trees are selected along with their physicochemical properties and applications. Ten different fiber modification techniques and their spectroscopic techniques (infrared, scanning electron microscopy, and X-ray diffraction) and thermal, mechanical, and water absorption characterization techniques are discussed.

Thermal Study of Anhydrides Cured Tetrafunctional Cardo Epoxy Resin

Tetrafunctional cardo epoxy resin (EBCF) was cured by using 10 wt% maleic anhydride (MA), pyromellitic dianhydride (PMDA), phthalic anhydride (PA), tetrahydrophthalic anhydride (THPA), tetrabromophthalic anhydride (TBPA), and tetrachlorophthalic anhydride (TCPA) as hardeners at 120°C for 40–105 min (gel time) and then postcured 1 h at 130°C. Gel time is found to depend on the structure of the anhydrides used. Cured samples were found insoluble in common solvents. Cured and uncured EBCF were characterized by FTIR, DSC, and TGA techniques. Cured and uncured resins followed multistep degradation reactions. Kinetic parameters, namely, order of degradation, energy of activation, frequency factor, and entropy change, were determined according to the Anderson-Freeman method and interpreted in light of the nature of hardeners used for curing purpose. The resins followed integral or fractional order degradation kinetics. Complex degradation reactions are due to different types of linkages in cured resins. Both nature and structure of resin and hardeners affected the curing behavior and the resultant thermal properties of the cured resins.

Physicochemical Study of CPOL-701–Glass/Jute Composites

Glass and jute composites (CPOL-701-G and CPOL-701-J) have been fabricated by hand lay-up technique at 50°C under 27.6 MPa pressure for 3–4 h using MEKP and cobalt naphthenate. Both composites possess excellent tensile, flexural and dielectric strengths, volume resistivity and dielectric constant as well as hydrolytic stability against water, 10% aq. HCl and 10% aq. NaCl at 35°C. Cured CPOL-701 appears to be having good thermal stability (206°C) and high values of kinetic parameters. Excellent physicochemical properties of the composites signify their industrial importance.

Synthesis and characterization of epoxy resin of 9,9′-bis-(3,5-dibromo-4-hydroxyphenyl) anthrone-10 and its jute composite

Abstract Epoxy resin of 9,9′-bis-(3,5-dibromo-4-hydroxyphenyl) anthrone-10 (EANBr, EEW 490) was synthesized and was characterized by IR and 1HNMR . EANBr and EPK3251 cured resin (EANBrC) were characterized by DSC and TGA at 10°Cmin−1 under nitrogen atmosphere. Broad DSC endothermic transitions of EANBr (265.3 °C) and EANBrC (291.4 °C) are due to some physical change and further confirmed by no weight loss in their TG thermograms. EANBr and EANBrC are thermally stable up to 340 °C and 310 °C, respectively. EANBr has followed single step degradation kinetics, while EANBrC has followed two step degradation kinetics. EANBr followed apparently zero order kinetics, while EANBrC followed apparently second order (1.80) and first order (0.89) degradation kinetics, respectively. Ea and A values of EANBrC (299.7 kJmol−1 and 6.32 × 1020 s−1) were found higher than that of EANBr (201 kJmol−1 and 2.45 × 1013 s−1) due to more rigid nature of EANBrC. The ΔS* value of the first step degradation of EANBrC (146.3 JK−1 mol−1) was found much more than that of EANBr (4.6 JK−1 mol−1). Jute – EANBr composite (J-EANBr) was prepared by compression molding technique at 120 °C for 5 h and under 20 Bar pressure. The observed tensile strength, flexural strength, electric strength and volume resistivity of J-EANBr are 24.7 MPa, 19.0 MPa, 1.8 kVmm−1 and 3.5 × 1012 ohm cm, respectively. Water absorption in J-EANBr was carried out at 30 ± 2 °C against distilled water, 10% NaCl, 10% HCl, 10% HNO3, 10% H2SO4, 10% NaOH, and 10% KOH and also in boiling water. The equilibrium time and equilibrium water content for J-EANBr in different environments are 384–432 h; 12.7–15.2%, respectively. The observed equilibrium water content and diffusivity trends of J-EANBr are KOH>H2SO4>HCl>NaOH>H2O>NaCl and H2O>NaCl>NaOH>H2SO4>HCl>KOH, respectively. Good thermo-mechanical, electrical properties and excellent hydrolytic stability of J-EANBr may be useful for high temperature applications in diverse fields.

Ultrasonic Speed and Related Acoustical Parameters of 1,1ʼ-Binaphthalene-2,2ʼ-diyl Diacetate Solutions at 308.15 K

The density (ρ), viscosity (η) and ultrasonic speed (U) (2 MHz) of chloroform, THF, ethyl alcohol, ethyl acetate, 1,4-dioxane and 1,1ʼ-binaphthalene-2,2ʼ-diyl diacetate (DBNA) solutions have been determined at 308.15 K. Various acoustical parameters namely specific acoustical impedance (Z), adiabatic compressibility (κa), Van der Waals constant (b), intermolecular path length (Lf), internal pressure (π), Raoʼs molar sound function (R), relaxation time (τ), classical absorption coefficient (α/f2)cl and solvation number (Sn) have been derived from ρ, η and U data and correlated with concentration (C). A fairly good to excellent correlation has been observed between a particular parameter and C. Linear increase of Z, R, b, (α/f2)cl and τ (except EA) (R2 = 0.90 – 0.999) and linear decrease of κs, π and Lf (R2 = 0.947 – 0.995) with C supported existence of powerful molecular interactions in the solutions and further supported by nonlinear increase of Sn with C. A fairly constant Gibbs free energy of activation has been observed in all the solvent systems studied.