Emerald | Pigment & Resin Technology | Table of Contents

Microwave-assisted synthesis of diketopyrrolopyrrole pigments in ionic liquid

Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - In this study, a novel pathway for the synthesis of high performance diketopyrrolopyrrole pigments (DPPs) using diethyl succinate under microwave irradiation in the presence of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4]), as a novel medium has been investigated. Design/methodology/approach - Rapid synthesis of DPPs were achieved in [BMIM][BF4] as well as in dry medium under microwave irradiation based on succinate ester condensation with benzonitrile derivatives. The obtained results were compared with those of conventional method as well as Reformatsky route under microwave irradiation. The obtained pigments were characterized and their optical properties and the morphologies were investigated.Findings - This study provides a novel approach to the synthesis of DPP pigments in a flash time with comparatively good yields.Research limitations/implications - DPPs have been synthesized via succinate ester route in ionic liquid media. Besides, they can also be synthesized based on Reformatsky method in ionic liquid media. Practical implications - Practical implication- The developed method provides a simple and practical solution to improving the rapid synthesis of DPP pigments, with regarded to their traditional application in many different industries, such as paints, inks, and plastics, as well as in electronic devices, LEDs, and laser dyes Originality/value - The method for synthesis of DPP pigments via succinate ester route in ionic liquid under microwave irradiation in a flash time, was novel and could find applications in DPP pigments’ industries.

Effect of hollow glass microspheres and cenospheres on insulation properties of coatings

Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - To prepare heat insulating exterior emulsion coating and to study its heat insulating property along with mechanical, chemical and weathering resistance properties with varying amount of hollow glass microspheres and cenospheres.Design/methodology/approach - For heat insulating effect, various compositions were made by incorporating different proportions of hollow glass microshperes (HGM) and cenospheres (C). The mechanical, chemical, morphological and optical properties of the coating films were studied and compared.Findings - Addition of hollow glass microspheres and cenospheres enhanced heat insulating property of the coating, hardness, tensile strength and wet scrub resistance. It was evaluated that optimum loading for both cenospheres and hollow glass microsphere were 10 wt % and both the systems showed good mechanical, chemical resistance and weathering properties.Practical implications - Addition of hollow glass microspheres and cenospheres to acrylic emulsion coating is a simple and inexpensive method.Originality/value - The new heat insulating coating with good thermal insulation properties and improved weather resistance were prepared. These coatings could find applications in demanding fields such as exterior wall coatings and roof coatings.

"Thermally stable pigments based on mixed metal oxides"

literatinetwork@emeraldinsight.com (Hassan S. Emira, Fawzia Fahim Abdel-Mohsen) — Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - This work aims to prepare black mixed transition metal oxide pigments to be used as solar absorber in solar selective and other industrial paints.Design/methodology/approach - Mixed metal oxide CoCuMnOx spinel pigments were synthesized via a sol-gel route.. Three different mixed metal oxides were prepared with different molar ratios by annealing at 600, 800 and 900°C respectively: (I-Co0.50Cu0.25Mn0.25)Ox, (II-Co0.25Cu0.50Mn0.25)Ox and (III-Co0.25Cu0.25Mn0.50)Ox. The obtained samples were characterized by Differential Scanning Calorimetry analysis (DSC), X-ray diffraction (XRD), transmission electron microscope (TEM) and optical properties. Findings - The prepared pigments have a spinel structure with the composition CoCuMnOx. All synthesized pigments consisted of nano-particles ranged between 10-80 nm. The optical properties showed high absorption and moderately low reflectance in the solar wavelength range.Research limitations/implications - The prepared, samples, used in the present work were synthesized from cobalt sulphate, copper chloride and manganese chloride. The salts were dispersed in polyacrylamide as a precursor.Practical implications - The prepared samples produced were thermally stable and have good optical properties. Originality/value - These thermally stable mixed metal oxides could be used in the painting of solar collectors. Also, they were highly efficient for some industrial paints. The three mixed metal oxides could be used as absorber materials for heating collectors due to their high absorption and moderately low reflectance in the solar wavelength range.

Review of Chemo-Responsive Shape Change/Memory Polymers

literatinetwork@emeraldinsight.com (Yongtao Yao, haibao Lu, Wei Min Huang) — Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - To examine the underlying mechanism and physico-chemical requirements of chemo-responsive shape change/memory polymers and to explore the future trend of development and potential applications.Design/methodology/approach - Working mechanism in chemo-responsive shape change/memory polymers is firstly identified. And then the physico-chemical requirements for the representative polymers are characterized.Findings - The different working mechanisms, fundamentals, physico-chemical requirements and theoretical origins have been discussed. Current research and development on the fabrication strategies of chemo-responsive shape change/memory polymers have been summarised. The future trend and potential applications have been explored and estimated.Research limitations/implications - This review examines physico-chemical requirements and theoretical origins necessary to achieve chemo-responsiveness, and then discusses recent developments and future trends.Practical implications - Shape change/memory polymers can be used in the broad field of bio- and/or medicine.Originality/value - Breakthroughs and rapid development of chemo-responsive shape change/memory polymers will significantly improve the research and development of smart materials, structures and systems.

Chain extended vinyl aniline modified cyclohexanone formaldehyde resin

literatinetwork@emeraldinsight.com (Nilgun Kizilcan, Esin Ates) — Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - The in situ chemical oxidation(ICO) of vinyl aniline modified cyclohexanone formaldehyde resin (CFVAnR) in the presence of potassium persulphate salt (K2S2O8) was accomplished in dimethyl sulphoxide (DMSO) solutions at 35°C and 70°C. The chemical composition and structure of the oxidized CFVAnR were characterised by nuclear magnetic resonance (1H-NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, DSC, TGA and SEM. Design/methodology/approach - The reactive vinyl and amine groups of the cyclohexanone formaldehyde resin were reacted in the presence of potassium persulphate. CFVAn resin was dissolved in DMSO inside a round bottom flask immersed in a water bath thermostated at reaction temperature of 35°C and 70°C, respectively. Solution of K2S2O8 was prepared in DMSO and this was added into the resin solution. Findings - It was shown that the vinyl groups in the resin were reacted easily with persulphate salt to obtain chain extended CFVAnR (CECFVAnR). The oxidised 4-vinyl aniline modified cyclohexanone-formaldehyde resin has solublity in organic solvents. Research limitations/implications - The reaction mixture must be stirred continuously. Temperature should be controlled to prevent the thermal polymerisation of vinyl group and higher branching of amino groups. The persulphate ion (S2O82_) has a standard oxidation potential, but when activated by heat (40–60 °C). Furthermore, sulphate radical can react with water or hydroxide to produce hydroxyl radical(.OH). When persulphate is used for in situ chemical oxidation (ISCO) application at relatively low temperatures (e.g., <20 °C), the oxidation reactions are usually less aggressive due to a slow generation rate of SO4-.Practical implications - This study provides technical information for the synthesis of chain extended resins. The modified resins contain vinyl groups. The chemical radical system has been used to polymerise these vinyl groups and resins with much higher molecular weight might be produced. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating. Originality/value - Chain extended CFVAnR(CECFVAnR) was synthesised by one step reduction-oxidation reaction, at 35°C (CECFVAnR1) and 70°C (CECFVAnR2) in the presence of potassium persulphate salt. These soluble resins may overcome difficulties in the applications of polymers and open new application areas. Therefore, the chain extended vinyl aniline modified resin may find a number of new application areas as well as existing uv curable resin and polymer applications.

Changes in the properties of shellac on blending with rosin, effect on storage

Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - To study the effect on the properties of shellac on blending with rosin (another natural resin) and study their changes during storageDesign/methodology/approach - Blending of rosin was done at seedlac (semi-pure lac) stage. Shellac was then prepared by bhatta (Indian country) process, in the form of button lac. Physico-chemical properties of the blends were studied at regular time interval following standard procedures.Findings - Improvement in the physicochemical properties of shellac was noticed by blending with rosin to a great extent; less degradation in the properties of blends was observed with storage compared to those of parent shellac.Research limitations/implications - Rosin possesses very high flow and life under heat. Flow and life of shellac-rosin blends (50:50 and 40:60) and rosin control could be determined upto a certain limit to derive conclusions.Practical implications - The results of the study will give an idea to entrepreneurs, processors, industrialists to how much rosin is to be blended with shellac to bring improvements in its fluidity and life under heat for commercial exploitation especially, for inferior quality of shellac.Originality/value - Systematic study was carried out for the first time; as no quantitative data was available on the changes in the different properties of shellac take place on blending with rosin.

Synthesis and applications of new bifunctional dyes Bis(monochlorotriazine) based on tetrahydrobenzo[b]thiophene moiety

literatinetwork@emeraldinsight.com (Fatma Ali Mohamed, Rafaat Melaad Mohareb) — Fri, 28 Jun 2013 00:00:00 +0100

Abstract

Purpose - Purpose – The purpose of this paper is to synthesise, characterise and find out properties of some new bifunctional dyes Bis (monochlorotriazine) using tetrahydrobenzo[b]thiophene systems as the chromophoric moiety, bearing good color strength, lightfastness, and other favorable properties.Design/methodology/approach - Design/methodology/approach – The novel reactive dyes were prepared, containing bis monochlorotriazine as reactive groups. The dye is synthesised by diazotization and coupling reactions, firstly we synthesised the ethyl 2-amino 4,5,6,7-tetrahydrobenzo[b]thiophen-3-carboxylate chromophoric moiety then diazotized and coupled with 1-amino-8-naphthol-3,6-disulphonic acid ( H- acid) and 2-amino-8- naphthol-6-sulphonic (? acid) to give the monoazo dye intermediates. Such, products reacted with 2,4,6-trichloro-1,3,5-triazine in 1:1 molar ratio afforded via nucleophilic displacement, which reacted with 1,4-phenylenediamine in 2:1 molar ratio to give bisazo bifunctional bismonochlorotriazine reactive dyes thus yielding the new target reactive. The synthesised dyes were applied cotton fabric under the typical exhaust dyeing conditions and their dyeing properties were investigated.Findings - Findings – The results assessed for dyeing indicate high quality dyeing properties. However, the homobifunctional (bis MCT) dyes showed higher exhaustion and Fixation values, colour yield and fastness properties. Research limitations/implications - Research limitations/practical implications – The described method showed the synthesis of bismonochlorotriazines derived from the tetrahydrobenzo[b]thiophene derivative 3 followed by their application towards cotton fabric. Practical implications - Developed method provided a simple and practical procedure for producing Tetrahydrobenzo [b]thiophene bisazo chromophoric systems that afford valuable reactiv dyes could be applied on cotton fabrics to increase the substantivety of dyes on fabric. Originality/value - Originality/value– In this work, the novel reactive dyes derived from the tetrahydrobenzo[b]thiophene derivative 3 were synthesized and their structures were based on the analytical and spectral data. Such group of compounds are considered to be excellent reactive dyes with different colour shades.

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