P. H. Parsania

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.

Preparation, Mechanical and Electrical Properties of Glass and Jute–Epoxy/Epoxy Polyurethane Composites

Glass and jute (treated and untreated) composites of epoxy resin of 1,1′-bis(3-methyl-4-hydroxy phenyl)cyclohexane(EMC) cured using 20% triethylamine as a hardener (G-EMCT-20 and J-EMCT-20) and EMC- polyurethane of toluene diisocyanate (J-EMCPU and TJ-EMCPU) have been prepared by a hand layup technique under 27.58 MPa pressure and at 150°C for 4 h. G-EMCT-20, J-EMCT-20, J-EMCPU and TJ-EMCPU showed 275, 96.5, 37.3 and 31.5 MPa tensile strength; 351, 84, 10 and 24 MPa flexural strength; 5837, 2758, 1277 and 1619 MPa elastic modulus; 24.6, 7.1, 1.9 and 1.6 kV/mm electric strength; and 1.4 × 1013, 1.1 × 1011, 7.7 × 1010 and 3.6 × 1010 ohm cm volume resistivity, respectively. Fairly good to excellent mechanical and electrical properties of the composites indicated their industrial applications in building and construction, electrical and electronic industries.

Synthesis and Thermal Study of Cured Epoxy-Acrylate-Maleate, Unsaturated Polyester and Their Interpenetrating Networks of Varying Compositions

Epoxy-acrylate-maleate of bisphenol-C (ECAM), unsaturated polyester resin of phthalic anhydride, maleic anhydride and propylene glycol (PMP) were synthesized. ECAM, PMP and their varying compositions (25–75 wt%) were cured using MEKP and cobalt naphthenate and characterized by IR, DSC and TGA techniques. Interpenetrating networks possess intermediate thermal stability of ECAM (300°C) and PMP (227°C) and followed single step degradation with fractional order kinetics (0.6–2.4) leaving 10–25% residue above 400°C. Low magnitudes of energy of activation and frequency factor of interpenetrating networks indicated improvement in flexibility due to toughening of PMP by ECAM of varying compositions.

Synthesis, Curing Behavior and Characterization of Epoxyacrylate and Triethylamine Cured Epoxy Resin of 1,1′-Bis(3-methyl-4-hydroxy phenyl) cyclohexane

Epoxy resin of 1,1′-bis(3-methyl-4-hydroxy phenyl) cyclohexane (EMC) and its acrylate (EMCA) have been synthesized and characterized. EMC has been cured by 5–25% triethyl amine at 100°C. The cured samples are characterized by solubility, IR, DSC and TGA at 10°C/min heating rate in nitrogen atmosphere. The associated kinetic parameters for EMCA, EMCT-5 and EMCT-20 have been determined according to Freeman-Anderson method and discussed. It is observed that EMCA and EMCT-20 have almost same thermal stability (300–308°C) but for EMCT-5 it is slightly lower (285°C). Cured samples followed fractional order degradation (0.63–1.44). In case of EMCT-5, all determined kinetic parameters are marginally lower than those of EMCA and EMCT-20.

Preparation, Mechanical and Electrical Properties and Water Absorption Study of Novel Bisphenol-C-Formaldehyde-Acrylate Treated and Untreated Jute Composites

Bisphenol-C-formaldehyde-acrylate (BCFA) resin was synthesized by reacting 1M bisphenol-C-formaldehyde resin and 4M acrylic acid using 1,4-dioxane as a solvent and phenothiazine as a catalyst at 80°C for 6 h. Hydrophilic character of the jute fibers has been reduced by malinization of alkali treated fibers with maleic anhydride. Bisphenol-C-formaldehyde-acrylate jute (treated and untreated) composites have been prepared by hand lay up technique at 150°C under 30.4 MPa pressure for 2 h. Tensile strength has been increased from 50 to 62 MPa (24%), while flexural strength has been decreased from 58 to 54 MPa (6.9%) on alkali treatment and malinization. Similarly electric strength has increased from 1.2–1.8 kV mm−1 (50%) and volume resistivity has increased from 0.62 × 10 13 to 3.93 × 10 13 Ωcm (533.9%). The edges of 5 × 5 cm 2 specimens were sealed with matrix material and subjected to distilled water and 10% each of HCl and NaCl at room temperature for water uptake study. The equilibrium water uptake is reduced drastically from 12.1–28.9% to 4.3–24.0% on malinization. Similarly diffusivity is also found to reduce from 3.76–25.3 × 10−12 to 0.72–8.30 × 10−12 m 2 sec−1. Drastic reduction in water uptake and diffusivity are due to replacement of hydrophobic ester groups. The reduction of water uptake is probably due to weak H-bond formation with ester and CH=CH groups and π-electrons of benzene rings.

Synthesis and Characterization of Cardo Bisbenzoxazines and their Thermal Polymerization

Bisbenzoxazines of bisphenol-C (BCO) and phenolphthalein (PHO) were synthesized by condensing 0.05 mol bisphenol-C/phenolphthalein, 0.2 mol formaldehyde, and 0.1 mol aniline. Both BCO and PHO were thermally polymerized via ring-opening polymerization. The resultant cross-linked polymers (PBCO and PPHO) were characterized by solubility, Infrared (IR), Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The bisoxazines and their polymers followed two-step degradation. Both BCO and PHO undergo selective ring-opening polymerization over the temperature range 100–150°C and are thermally stable up to about 250°C. The % residue at 550°C is substantially higher for PHO samples (56–67%) than BCO samples (20–25%), indicating the highly thermally stable nature of PHO. A ring transformation reaction is also supported by DSC. New thermosetting materials may be useful for specific applications to be exploited.

Synthesis and Comparative Physico-chemical Study of Polyester Polyols Based Polyurethanes of Bisphenol-A and Bisphenol-C Epoxy Resins

Polyester polyols of epoxy resins of bisphenol-A and bisphenol-C were synthesized by reacting corresponding 0.02 mol epoxy resin, and 0.04 mol ricinoleic acid by using 1,4-dioxane (30 ml) as a solvent and 0.5 g triethyl amine as a catalyst at reflux temperature for 4–5 hr. Polyurethanes have been synthesized by reacting 0.0029 mol of polyester polyols with 0.004 mol toluene diisocyanate at room temperature and their films were cast from solutions. The formation of polyester polyols and their polyurethanes are supported by IR spectral data (1732.9–1730.0 cm−1 ester and urethane and 3440.8–3419.6 cm−1 OH and NH str). The densities of polyurethane of bisphenol-A (PU-A) and polyurethane of bisphenol-C (PU-C) were determined by a floatation method. The observed densities of PU-A and PU-C are 1.2190 and 1.2308 g/cm3, respectively. Slightly high density of PU-C is due to structural dissimilarity of two bisphenols. The tensile strength, electric strength, and volume resistivity of PU-A and PU-C are 34.7, 18.7 MPa; 80.7, 44.4 kv/mm; and 1.7 × 1015, 2.2 × 1015 ohm cm, respectively. PU-A and PU-C are thermally stable up to about 182–187°C and followed three step degradation. Incorporation of cyclohexyl cardo group in polyurethane chain did not impart any change in thermal properties but it caused drastic reduction in tensile and electric strength due to rigid nature of PU-C chains. PU-C has excellent chemical resistance over PU-A. Both polyurethanes possess good resistance against water, 10% each of aqueous acids (HCl, HNO3, and H2SO4), alkalis (NaOH and KOH) and NaCl. Good thermo-mechanical, excellent electrical properties, and good chemical resistance of polyurethanes signify their usefulness in coating and adhesive, electrical and electronic industries.

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.

Preparation and Physicochemical Study of Hybrid Glass-Jute (Treated and Untreated) Bisphenol-C-Based Mixed Epoxy Phenolic Resin Composites

Glass-jute (treated and untreated) composites of mixed matrix materials [epoxy resin of bisphenol-C (EBC) and bisphenol-C-formaldehyde (BCF) of 50 wt.% of glass-jute fibers] have been prepared by hand layup technique at 150°C under 7.6 MPa pressure for 2 h. The hydrophilic character of the jute fibers has been reduced by acrylation of alkali-treated fibers with acrylic acid. Tensile strength increased from 87 MPa to 112 MPa (28.73%) and flexural strength increased from 66 MPa to 89 MPa (34.84%) on alkali treatment and acrylation. Similarly, electric strength increased from 2.71 to 3.89 kV/mm (43.54%) and volume resistivity increased from 1.23 × 1012 to 1.77 × 1012 Ω cm (143.90%). The edges of the 5 cm × 5 cm specimens were sealed with matrix material and subjected to distilled water and 10% each of aq. HCl and aq. NaCl solutions at room temperature for a water uptake study. The equilibrium water uptake was reduced drastically from 12.07–7.69% to 6.17–3.39% on acrylation. Similarly, diffusivity was also found to be reduced from 1.99–0.99% to 0.96–0.45%. Drastic reductions in water uptake and diffusivity are due to the replacement of hydrophobic ester groups. The reduction of water uptake is probably due to weak H-bond formation with ester and CH=CH groups, and π-electrons of benzene rings. No effect of boiling water is observed on the stability of the composite. Saturation time in boiling water was reduced twenty-eight/twenty-one times without any damage to the untreated/treated jute-glass composites, respectively.

Mechanical, Electrical and Water Absorption Study of Jute/Glass/Jute-bamboo/Glass-bamboo-bisphenol-C-formaldehyde-acrylate a Value Added Composites

Bisphenol-C-formaldehyde-acrylate (BCFA) resin was synthesized by reacting 0.1 mol bisphenol-C-formaldehyde resin, 0.4 mol acrylic acid in 25 ml 1,4-dioxane and 1.5 g phenothiazine catalyst at 80°C for 6 h. Jute, glass, jute-bamboo, and glass-bamboo composites were prepared by compression molding technique at 150°C for 2 h under 30.4 MPa pressure. Jute-BCFA, Glass-BCFA, Jute-bamboo-BCFA, Glass-Bamboo-BCFA possess 50, 114, 49, and 65 MPa tensile strength; 58, 185, 69, and 70 MPa flexural strength; 1.2, 3.3, 1.3, and 1.9 kV/mm electric strength and 6.2 × 1012, 2.5 × 1013, 6.6 × 1012, and 1.5 × 1013 ohm cm volume resistivity. The data are interpreted in terms of nature of fibers and resin and fiber loading and orientation. Water absorption behavior of composites is tested in pure water, 10% NaCl and 10% Hcl solutions at room temperature as well as in boiling water. Observed diffusivity order for each of composite is H2O < NaCl < HCl. Sandwich composites shown high water absorption in all media due to high bamboo fiber loading and fiber agglomeration. The presence of HCl and NaCl affected the water structure and hence diffusivity. Jute-bamboo-BCFA and Glass-Bamboo-BCFA delaminated in boiling water within half an hour. Mechanical and electrical properties and water absorption behavior are affected by the nature of fibers and matrix, fiber loading and fiber arrangement. Fairly good mechanical and electrical properties of Jute-BCFA and Glass-BCFA and their low water absorption behavior signify their usefulness as low load bearing applications. Composites signify their use for low load bearing applications in construction, electrical and marine industries.