Vithal S. Patel

Synthesis and Dyeing Performance of Some Novel Heterocyclic Azo Disperse Dyes

The synthesis of some novel heterocyclic azo disperse dyes derived from 5-acetyl-2-amino-4-methylthiazole (1) using various N-alkyl derivatives of aniline (2a-e) and their dyeing performance as disperse dyes have been assessed on polyester and nylon fabrics. The spectral properties of these dyes were measured. The dyed fabrics show moderate to good light fastness, very good rubbing, perspiration, washing fastness and excellent sublimation fastness. These dyes have been found to give bright orange-red colour hues with very good depth and levelness on fabrics. The dyebath exhaustion on fabrics has been found to be very good.

Investigation of kinetics of curing of triglycidyl-p-aminophenol with aromatic diamines by differential scanning calorimetry

The kinetics of curing of triglycidyl-p-aminophenol with four different diamines in stoichiometric amounts were investigated by means of differential scanning calorimetry. The results indicated that the curing reaction follows first-order Arrhenius kinetics with an activation energy in the range 40–70 kJ · mol−1. The effect of the structure of the curing agent on the curing characteristics is discussed on the basis of the curing characteristics and the kinetic parameters. An epoxy fortifier was observed to lower the curing temperature of an epoxy-amine system when incorporated prior to curing.ZusammenfassungMittels Differential-Scanning-Kalorimetrie wurde die Kinetik der Vernetzung von Triglycidyl-p-aminophenol mit stöchiometrischen Mengen vier verschiedener Amine untersucht. Laut den Ergebnissen verläuft die Vernetzungsreaktion mit einer Arrhenius-Kinetik erster Ordnung, wobei die Aktivierungsenergie im Bereich von 40–70 kJ/mol liegt. Auf Grundlage der Vernetzungscharakteristika und der kinetischen Parameter wird der Einfluss der Struktur des Vernetzungsreagenz auf die Vernetzungskenndaten beschrieben. Mit einem vor der Vernetzung eingebrachten Epoxyfortifyers konnte die Vernetzungstemperatur eines Epoxy-Amin-Systemes heruntergesetzt werden.РЕжУМЕМЕтОДОМ Дск ИсслЕДОВ АНА кИНЕтИкА ОтВЕРжД ЕНИь тРИглИцИДИл-п-АМИНОФ ЕНОлА с ЧЕтыРьМь РАжлИЧНыМИ ДИАМИНАМИ, Вжьтых В стЕхИОМЕтРИЧЕскИх к ОлИЧЕстВАх. РЕжУльтА ты пОкАжАлИ, ЧтО РЕАкцИь ОтВЕРжДЕНИь пОДЧИНь Етсь АРРЕНИУсОВскОИ кИНЕ тИкЕ пЕРВОгО пОРьДкА с ЁНЕРгИЕИ АктИВАцИИ В ИНтЕРВАлЕ 40–70 кДж·МОль−1. НА ОсНОВЕ кИНЕтИЧЕскИх пАРАМЕтРОВ ОБсУжДЕНО ВлИьНИЕ ст РУктУРы ВУлкАНИжИРУ УЩЕгО АгЕНтА НА хАРАктЕРИстИкИ РЕ АкцИИ ОтВЕРжДЕНИь. УстАНОВлЕНО, ЧтО ЁпОк сИжАкРЕпИтЕль, ВВЕДЕ ННыИ РАНьшЕ ВУлкАНИжИРУУЩЕгО Аг ЕНтА, пОНИжАЕт тЕМпЕРАтУР У ОтВЕРжДЕНИь.

Glass-reinforced Vinyl Ester Resin Composites:

The curing behaviour of vinyl ester resin, the condensation product of acrylic acid with diglycidyl ether of bisphenol-A, was studied by differential scanning calorimetry. The glass-fibre-reinforced composites of the vinyl ester resin were prepared and evaluated for their chemical, electrical and mechanical properties. The incorporation of styrene during the curing of the vinyl ester resin showed significant improvements in tensile strength and dielectric properties.

Synthesis, characterization and application of monomeric and polymeric dyes based on N-arylmaleimides

Novel monomeric dyes have been prepared by diazotization of 2,6-dibromo-4-nitroaniline and coupled with various N-arylmaleimides. The polymeric dyes were prepared by free radical polymerization of monomeric dyes. The resultant dyes were characterized by IR spectral studies, intrinsic viscosity, thermogravimetry analysis, elemental analysis and molecular weight was characterized by VPO. The monomeric dyes were also characterized by elemental analysis and IR spectra. The purity of all the dyes were checked by thin layer chromatography and they have also been applied on nylon and polyester fibres as a disperse dye. These dyes have been found to give various colour shades with good to very good depth and levelness on each fibre. The percentage dye bath exhaustion on different fibres have been found to be good to very good. The light, washing, rubbing, perspiration and sublimation fastness properties of the dyed fibres has been found to be very good to excellent.

Synthesis and Application of Disperse Dyes Based on 2-Aminothiazole Derivatives

A series of novel monoazo disperse dyes based on 2-amino-5-nitro-4-(p-nitrophenyl)thiazole were prepared using various N,N-dialkylaniline derivatives as the coupling components. The spectral properties in the IR and visible range of the dyes were investigated. The dyeing performance of these dyes was assessed on nylon fabric. These dyes were found to give a wide range of color shades from reddish brown to indigo with excellent brightness, levelness, and depth on nylon fabric. The dyed fabric showed fairly good light fastness, good to excellent fastness to wash and perspiration, and excellent fastness to sublimation. The dyebath exhaustion and fixation of the dyes on nylon were found to be very good and acceptable.

Thiazole based disperse dyes for nylon and polyester fibers

Nine disperse dyes have been synthesized by diazotization of 2-amino-4-(p-nitrophenyl)-5-nitrothiazole and coupled to substituted N-alkylanilines. Spectral properties in the IR and visible range of the dyes obtained were investigated. The dyeing performance of these dyes was assessed on nylon and polyester fibers. These dyes were found to give reddish brown to bluish violet shades on dyeing with very good depth, brightness and levelness on nylon and polyester fibers. The dyed fibers showed fairly good light fastness, very good to excellent fastness to wash, rubbing, perspiration and excellent fastness to sublimation. The dyebath exhaustion and fixation on the fiber were found to be very good.

Synthesis of novel azo dyes containing the thiophene moiety

A series of disperse dyes have been synthesized by diazotation of 2-aminothiophene derivative and coupling with various N-arylmaleimides. The dyes were characterized by IR spectral studies, visible absorption spectra, and elemental analysis. The dyeing performance of these dyes was assessed on nylon fabric. These dyes were found to give yellowish brown to reddish violet shades on dyeing with very good depth, levelness, and brightness on fabric. The percentage dyebath exhaustion and fixation on fabric was found to be very good. The dyed fabric showed poor light fastness and good to excellent fastness to washing, rubbing, perspiration, and sublimation.

Kinetics of thermal degradation of cured epoxy resins based on triglycidyl-p-aminophenol

Abstract Epoxy resin prepared from p -aminophenol was cured with six different curing agents, viz. diaminodiphenyl sulfone, diaminodiphenyl methane, diaminodiphenyl ether, benzidine, m -phenylene diamine and diethylenetriamine. Kinetics of thermal degradation of the cured epoxy resins were studied by thermogravimetry in a static air atmosphere at a heating rate of 10°C min −1 . The effect of the structure of the curing agent on the thermal stability of the cured epoxy resins was investigated on the basis of temperature characteristics such as initial decomposition temperature, temperature of half volatilization and the integral procedural decomposition temperature, as well as the kinetic parameters. The thermal degradation reactions were found to proceed in a single step having an activation energy in the range 90–122 kJ mol −1 . They were first-order reactions.

Polymeric dyes based on thiadiazole derivatives

A series of polymeric dyes were synthesized by free radical addition polymerization of monomeric dyes. The 2-amino-5-mercapto-1,3,4-thiadiazole was diazotized and coupled with various N-arylmaleimides to give monomeric dyes. All the polymeric dyes were characterized by elemental analysis, infrared spectroscopy, visible absorption spectroscopy, viscometry, and thermogravimetric analysis. Color and dyeing properties of the polymeric dyes were discussed by comparing them with those of the corresponding monomeric dyes. The dyeing performance of these dyes was assessed on nylon fiber. These dyes were found to give various color shades with good to very good depth and levelness on the fiber. The dyeing of the monomeric dyes showed moderate fastness to light and good to excellent fastness to washing, perspiration and sublimation and their corresponding polymeric dyes showed excellent fastness properties. The dyebath exhaustion and fixation on nylon fiber has been found to be good.

Kinetic study of thermal degradation of guar gum esters

Abstract The guar gum esters were synthesized by reacting guar gum with various anhydrides. The degree of substitution of guar gum esters was estimated. The thermal degradation of guar gum and its esters in the presence of air was examined by thermogravimetry to ascertain their relative thermal stabilities on the basis of various temperature parameters. The experiments were carried out at a heating rate of 10 °C min −1 in the range 25–550 °C.