Pigment & Resin Technology

Studies on the film characteristics of polyesteramide resins based on hydroxy ethyl fatty acid amide : Table of Contents

Sukhen Mistry, Devendra Agarwal — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to describe the synthesizing of polyesteramide (PEA) resins using an acid functional acrylic copolymer (ACR) and hydroxy ethyl fatty amide (HEFA) of dehydrated castor oil (DCO) and to study the effect of HEFA on the performance properties of the coating films of PEA resins. Design/methodology/approach – The PEA resins are synthesised by using ACR (synthesised by using butyl methacrylate (BMA) and maleic anhydride (MA)), and HEFA. Different formulations are developed by using ACR and HEFA. The coatings are made using xylene/acetone as a solvent. These coatings are applied on mild steel panels and are cured at 110°C. Various mechanical, optical and chemical properties of the coating films are evaluated. Findings – The study reveals that, HEFA of DCO is used successfully as a cross-linking agent for the ACR to form the PEA resins. Incorporation of long chain fatty acid (C18) moieties of the fatty amide in the PEA resins backbone is thought to serve as flexibliser, which lead to improved mechanical and chemical properties of the films. The optimum results are obtained from composition three of copolymer A having (3:1) (ACR:HEFA) molar ratio. Research limitations/implications – The PEA resins synthesised here are made up of ACR (synthesised by using BMA and MA), and HEFA of DCO. Besides, this ACRs can be synthesised from acrylic acid. In addition to this, one can also use HEFA synthesised from other oils. Practical implications – This method provides a simple solution for the synthesis of PEA resins and resulting to their improved mechanical properties. The developed product is also an environment friendly product. Originality/value – The method developed here for the synthesis of PEA resins form ACRs and HEFA is unique and can be used as an effective surface coating material. These studies will help to develop low volatile organic compounds product which could find numerous industrial applications in surface coatings for metal surfaces.

Dyeing of flax fabric with natural dye from chestnut shells : Table of Contents

Lijuan Wang, Jian Li, Hao Feng — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to develop an environmentally friendly dyeing process using brown pigment from chestnut shells (BPFCS). This material is obtained from foodstuff residues and can make a significant contribution to reusing a reproducible biomass resource, economizing petroleum, avoiding water pollution and protecting human health. Design/methodology/approach – The brown pigment is extracted from the raw material and purified with solvents containing 30 and 100 per cent EtOH. It is then used to dye flax fabric in aqueous solution with added NaCl as a dye accelerator. The effects of dyeing conditions and fastness are investigated. The pigment, and the pristine and dyed fabrics are analysed by Fourier-transform infrared spectroscopy (FT-IR) and the fabric samples are observed using a scanning electron microscope (SEM). Fastness to washing, rubbing and light are also measured. Findings – BPFCS show promising dyeability on cellulosic fibers. White flax fabric is successfully dyed with the pigment to a yellow-brown colour. The base dyeing conditions are as follows: pigment concentration 16?g/l, NaCl concentration 10?g/l, liquor ratio 10:1, temperature 95°C, dyeing time 40?min. The dyed fabrics have lower fastness to washing and higher fastness to rubbing and light. A total of 4 per cent Al3+ or Fe2+ treatment of dyed fabric can improve fastness to washing, but decrease fastness to rubbing. The yellowish-brown samples are transformed to brown or dark-green after Al3+ or Fe2+ treatment, respectively. The pigment is a mixture with abundant hydroxyl groups. Research limitations/implications – The studies of dyeing conditions and fastness are carried out in detail as BPFCS used as a dye. However, a qualitative analysis of the pigment could not be performed due to the difficulty of separating the mixture. The BPFCS used in this paper can dye cellulosic fiber and can also be used to dye other fibers such as silk, wool and PET. Dyeing conditions for these other fibers need to be investigated. Practical implications – BPFCS may play an important role in the dyeing industries because of its good dyeability, lack of toxicity and resistance to water, rubbing and light. The present work offers an environmentally friendly dye and a simple dyeing method. Originality/value – At present, no report exists in the literature of work on dyeing flax fabric with BPFCS. This paper represents a preliminary study to determine the relationships of dyeing conditions to fastness and the role of mordant. BPFCS appears to be a new and practically useful natural dye.

Effect of modifier and filler concentration on properties of epoxy-red mud waste composite : Table of Contents

Bidhan Samanta, Tithi Maity — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to evaluate the concentration effect of liquid amine terminated poly (ethylene glycol) benzoate (ATPEGB) modifiers and red mud waste filler on mechanical and thermal properties of cured epoxy along with the optimum result of modified epoxy. Design/methodology/approach – For effective toughening, different compositions are made by adding various concentration of ATPEGB to epoxy. The concentration of 2, 5 and 10 parts per 100 parts of epoxy resin of aluminium silicate-based pristine red mud waste is incorporated into each modified epoxy matrix. These filled modified matrixes are cured with ambient temperature curing agent triethylene tetramine and are evaluated with respect to their impact, tensile and flexural strengths. The morphology is analysed by scanning electron microscopy and dynamic mechanical analysis. The thermal stability by thermogravimetric analysis is also reported. Findings – The modification of epoxy resin using ATPEGB and filler shows significant enhancement of mechanical strength over unmodified epoxy. The increase depends on concentration of the modifier and filler. The reason behind this is that in the initial stage of curing the ATPEGB are miscible with the epoxy and form a homogeneous solution. This good mixing promotes the chemical reaction and network formation. During the curing process, as the molecular weight increases, the component separates within the reaction medium to form a second dispersed phase. Research limitations/implications – This paper discusses only ATPEGB synthesised by using poly (ethylene glycol) (PEG) of 200, 400 and 600 and only one filler red mud waste. Besides these, by changing the molecular weight of PEG, other ATPEGB could be synthesised and the efficiency of modification of epoxy resin using these modifiers and other filler besides red mud waste could also be studied. Originality/value – This paper regarding concentration effect of modifier and filler is novel and ATPEGB modified filled epoxy could be used in the fields of coating, casting, adhesives, potting and encapsulation of semiconductor devices.

Synthesis and application of novel disazo pyrazolo[1,2-a]pyrazole reactive dyes : Table of Contents

Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to evaluate the efficiency of modifying reactive azo dyes using pyrazolo[1,2-a]pyrazole fused systems as the chromophoric moiety which could satisfy many and varied criteria drawn from economic, synthetic, physicochemical and fastness properties. Design/methodology/approach – Six novel heterocyclic disazo reactive dyes were prepared, containing monofunctional sulphatoethylsulphone (SES) and hetero-bifunctional monochlorotriazine (MCT)/SES reactive groups. Dyes intermediates based on 4-arylazo-1,5-dioxopyrazolo[1,2-a]pyrazole chromophoric moieties are initially synthesised and coupled with two different diazonium salts having the aforementioned reactive groups, thus yielding the new target reactive dyes. The synthesised dyes are applied to cotton, wool and silk fabrics under the typical exhaust dyeing conditions and their dyeing properties were investigated. Findings – The results assessed for dyeing indicate high-quality dyeing properties. However, the heterobifunctional MCT/SES dyes showed higher exhaustion and fixation values, colour yields and fastness properties than those of the monofunctional SES dyes. Research limitations/implications – The method developed provided a simple and practical procedure for producing fused pyrazolo[1,2-a]pyrazole disazo chromophoric systems that afford valuable reactive dyes. In addition, the dyes intermediates based on 4-arylazo-1,5-dioxopyrazolo[1,2-a]pyrazole as well as their disazo counterparts could be applied as acid dyes to wool and silk. Originality/value – The method for producing novel disazo reactive dyes could find numerous applications for affording a variety of reactive dyes with different binding linkages and structural reactivity. These could be valuable as reactive dyes with different colour shades.

Photochromic properties of 7',8'-dichloro-1,3,3-trimethylspiro[indoline-2,3'-[3H]benzo[b][1,4]oxazine] doped in PMMA and epoxy resin thin films : Table of Contents

A.A. Bahajaj, A.M. Asiri, A.M. Alsoliemy, A.G. Al-Sehemi — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to evaluate the photochromic performance of photochromic compounds in polymer matrices. Design/methodology/approach – The poly(methyl methacrylate) PMMA and epoxy resin doped with photochromic spirooxazine (SO) are prepared and the effects of ultraviolet (UV) irradiation are studied using spectrophotometer. The reversible reaction is effected using white light. Photochemical fatigue resistance of these films is also studied. Findings – Irradiation of colourless 7',8'-dichloro-1,3,3-trimethylspiro[indoline-2,3'-[3H]benzo[b][1,4]oxazine] (SO) doped in PMMA and epoxy resin with UV light (366?nm) results in the formation of an intense purple-red coloured zwitterionic photomerocyanine (PMC). The reverse reaction is photochemically induced by irradiation with white light. Photocolouration and photobleaching reactions follow a first-order rate equation. It is found that photocoloration rate constant of (SO) in both matrices is almost the same, which is unexpected. On the other hand, the rate of photobleaching reaction of (PMC) in PMMA is twice slower than that in the epoxy resin. It seems that the presence of the two chlorine atoms at positions 7' and 8' of the benzooxazine moiety destabilise the PMC in epoxy resin film and results in speeding up the fading process compared to that in PMMA. SO doped in epoxy resin shows much better fatigue resistance than that doped in PMMA. Research limitations/implications – The PMMA and epoxy resin polymers doped photochromic spirobenzooxazine described in this paper were prepared and studied. The principle of study established can be applied to any type of polymer or to any type of photochromic compounds. Practical implications – The photochromic materials developed can be used for different applications, such as coatings and holography. Originality/value – The method developed may be used to enhance the performance of photochromic materials.

Electronic and optical properties of silole-based derivatives : Table of Contents

C.B. Li, G.X. Yang, Z.H. Huang, Y. Xin, C. Wang, J.H. Yuan — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to focus on the development of highly efficient emission materials for light-emitting diodes (LEDs). Design/methodology/approach – The equilibrium geometries of silole-based derivatives are optimised by means of DFT/B3LYP method with the 6-31G(d) basis set in this paper. The geometries of single-excitation are optimised using the ab initio configuration interaction with single excitations/6-31G(d), the first singlet excited states and optical properties are calculated by using time-dependent density-functional theory based on the 6-31G(d) basis set. Findings – The highest occupied molecular orbital and lowest unoccupied molecular orbital suffer larger effects from the variation of the substituent groups of methyls and phenyls. The absorption wavelengths of all the cases are similar, but the emission wavelengths are significantly different. Research limitations/implications – Solid-state stacking effect is not included in this paper. Originality/value – In view of the application of silole-based derivatives systems, the control of photophysical properties and electronic structures by structural modification is relevant to further molecular design.

Inhibitive effect of methyl green dye on the corrosion of low carbon steel in acidic media : Table of Contents

Emeka Oguzie, Chris Akalezi, Conrad Enenebeaku — Sat Nov 07 08:00:18 GMT 2009

Abstract:
Purpose – The purpose of this paper is to study methyl green dye (MG) as a corrosion inhibitor for low carbon steel (LCS) in hydrochloric acid (1?M) and sulphuric acid (0.5?M) and to assess the effect of temperature variation and halide additives on the inhibition efficiency. Design/methodology/approach – Corrosion rates are monitored using the gravimetric technique. Inhibition efficiency is determined by comparing the corrosion rates in the absence and presence of additives. Attempts are also made to elucidate the inhibition mechanism from the trend of inhibition efficiency with change in temperature and type of acid anion. Findings – MG reduces the corrosion rate of the LCS specimens in both acid media within the investigated temperature range by adsorption at the metal/solution interface. Inhibition efficiency increases with MG concentration but decreases with rise in temperature. Maximum values of 67 and 73 per cent are obtained in 1?M HCl and 0.5?M H2SO4, respectively, at [MG]=0.001?mol?dm-3. Halide additives increase the inhibition efficiency mainly in the sulphuric acid medium. Research limitations/implications – The inhibiting effect of MG is studied within a fixed concentration range, which can be expanded for further studies. The same applies to the effect of halide additives. Also, the dye structure can be modified by introducing different functional groups, and the effect on inhibition efficiency is investigated. Practical implications – The research findings can find practical application for corrosion control in aqueous acidic environments. Originality/value – This paper provides new information on the application of MG for corrosion inhibiting purposes. The experimental results form part of an extensive database on the corrosion inhibiting characteristics of organic dyes.