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Article
Publication date: 1 March 1991

D.N. Goswami and Shravan Kumar

Insulating varnishes are widely used for coating of armatures/coils of electric motors, transformers and also for finishing electrical components. Natural resin shellac finds…

66

Abstract

Insulating varnishes are widely used for coating of armatures/coils of electric motors, transformers and also for finishing electrical components. Natural resin shellac finds considerable use in the manufacture of insulating varnishes. Improved dielectric properties have been obtained for varnishes prepared from shellac modified with synthetic resins, drying oils etc. The present article provides information about the researchers so far carried out on both the air‐drying and baking type of insulating varnishes based on shellac.

Details

Pigment & Resin Technology, vol. 20 no. 3
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 4 April 2016

Dipanjan Goswami, Sakun Boon-Itt, Neera Jain and D.R. Agarwal

The quality and reliability of medical communication for branded drug adoption is extremely critical, not only for safeguarding patient interests but also for ensuring successful…

415

Abstract

Purpose

The quality and reliability of medical communication for branded drug adoption is extremely critical, not only for safeguarding patient interests but also for ensuring successful investments by multinational pharmaceutical firms. This paper predicts doctors’ prescribing intentions based on communication relationship among factors for late entrant branded drugs, compared with pioneering brand choice, for treating chronic diseases such as hypertension.

Design/methodology/approach

The constructs were validated with structural equation model for a sample set of 151 doctors from private hospitals in the National Capital Region of India.

Findings

This research reveals communication drivers and draws on theory to suggest that the doctor’s behavioural prescription intentions, subject to social influence from their colleagues, leads to lower adoption responses.

Research limitations/implications

Given that limitations on sample size are often unavoidable, this study reveals that, due to the availability of substituting brands, alternate therapeutic routes and lack of availability of a practical guide for prescription, a communication model needs to be developed and validated.

Practical implications

Furthermore, managers of pharmaceutical firms should differentiate between the effects of direct and indirect communication–integration efforts for minimizing uncertainty in drug adoption in the context of the fragmented and unpredictable Indian market.

Originality/value

A late entrant may lose its dominant market share to alternate brands from other suppliers due to communication gaps in an unstructured market, leading to low adoption intentions. The study provides business theorists, drug marketers and health-care professionals with unique insights into specific communication drivers of prescribing decisions, aimed at ensuring reliable and appropriate drug adoption in Indian markets.

Details

International Journal of Pharmaceutical and Healthcare Marketing, vol. 10 no. 1
Type: Research Article
ISSN: 1750-6123

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Article
Publication date: 1 April 2003

D.N. Goswami, P.C. Jha and K. Mahato

The melt‐viscosity of shellac at various temperatures, the solution viscosity of shellac and the solution viscosity of several shellac‐based varnishes were investigated using a…

427

Abstract

The melt‐viscosity of shellac at various temperatures, the solution viscosity of shellac and the solution viscosity of several shellac‐based varnishes were investigated using a cone and plate rheometer. The study revealed information regarding yield stress (minimum force required for initiating flow) and thixotropic properties of shellac and shellac‐based materials. Such information will be useful for developing shellac‐based moulded articles and shellac‐based varnish compositions.

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Pigment & Resin Technology, vol. 32 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 February 1988

D.N. Goswami and Shravan Kumar

The curing of shellac with epoxy resin by fusion was studied in detail by Tripathi et al. An improvement in the film properties was noticed for the varnishes prepared from the…

56

Abstract

The curing of shellac with epoxy resin by fusion was studied in detail by Tripathi et al. An improvement in the film properties was noticed for the varnishes prepared from the cured products of 70 parts of shellac with 30 parts of epoxy resin. Similar study was made on the modification of shellac with phenolic resin by Kumar and Sankaranarayanan and Kumar. The films obtained from the modified varnishes showed improved heat and water resistance.

Details

Pigment & Resin Technology, vol. 17 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 6 August 2019

Rawya Ben Jaballah, Mohamed Bechir Ben Hamida, Jehad Saleh and Mohammed A. Almeshaal

The purpose of this paper is to investigate the enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled NH3/H2O absorption system to reduce their size…

153

Abstract

Purpose

The purpose of this paper is to investigate the enhancement of the performance of bubble absorber using hybrid nanofluid as a cooled NH3/H2O absorption system to reduce their size and to find the best fitting model. A numerical model for ammonia-water bubble absorber was developed to show the influence of operating conditions and design parameters on the absorber performance.

Design/methodology/approach

A finite difference numerical method is used to solve the numerical model. The model is subjected to the inlet conditions of liquid, vapor and coolant flow regimes. The absorber modeling was divided into small elements along the absorber length.

Findings

The model proposed is validated with previously published works. Then agreement between the both is considered as good.

Research limitations/implications

Numerical results/The use of hybrid nanofluids.

Originality/value

The results showed that the hybrid nanofluid is the best cooling medium. Very high heat transfer rates are obtained because of the high thermal conductivity and specific heat of hybrid nanofluid, and consequently, the absorber size decreases. It was also found that the absorber thermal load and the mass absorption flux increase with increasing of solid volume fraction. Also, the existence of an optimal absorber length was revealed, required for complete absorption when using hybrid nanofluid as a cooling medium. It is recommended that using hybrid nanofluid to remove the heat from the absorber is the best candidate for NH3/H2O absorption performance enhancement.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 10
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 July 2006

M.F. Ansari and D.N. Goswami

To explore compatibility of natural resin shellac with acrylic resin in order to make a more eco‐friendly coating composition and also to open a new avenue for consumption of…

569

Abstract

Purpose

To explore compatibility of natural resin shellac with acrylic resin in order to make a more eco‐friendly coating composition and also to open a new avenue for consumption of shellac.

Design/methodology/approach

Different compositions of paint were prepared by varying the contents of shellac and acrylic resin. Selection was made for the composition yielding the best combination of properties like water resistance, alkali resistance, washability, etc.

Findings

Modification of shellac with acrylic resin showed improved film performance. The modified product showed good adhesion, finish; the films were smooth, flexible and no flaking/detachment was observed from the surfaces. This resulted in from esterification linkages between shellac and acrylic resin.

Research limitations/implications

The concentration of shellac in the composition was limited to a certain extent. Increase in shellac content impairs the film performance of the composition, especially with regard to alkali resistance.

Practical implications

Shellac was found to be very compatible with acrylic resin at all concentrations, this may be adopted in developing other shellac‐acrylic based products.

Originality/value

The modification of shellac with acrylic resin has been done, for the first time, to open a new vista for the consumption of shellac in surface coating.

Details

Pigment & Resin Technology, vol. 35 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 30 August 2013

Mohammad Fahim Ansari, Gautam Sarkhel, Dipendra Nath Goswami and Bangali Baboo

The purpose of this paper is to improve the properties of shellac by blending with novolac and to study the thermal behaviour of the blends with an ultimate aim to use as surface…

217

Abstract

Purpose

The purpose of this paper is to improve the properties of shellac by blending with novolac and to study the thermal behaviour of the blends with an ultimate aim to use as surface coating material.

Design/methodology/approach

Novolac was synthesized by reaction of phenol with formaldehyde in a molar ratio of 1:0.8, in acidic condition. Blending of shellac with novolac was done in solution and films of the blends, prepared on glass slides and tin panels, were baked at 150°C for 15 minutes. Properties of the films were studied as per standard procedures.

Findings

Films of shellac‐novolac blends showed improvement in gloss and impact resistance compared to those of shellac alone. Gloss of blends increased with the increase in concentration of novolac and further increased on baking the films. Scratch hardness of shellac decreased on blending with novolac. Baked films of the blends showed resistance to heat and water. Films of shellac‐novolac blends were found to be more resistant to polar solvents compared to non‐polar solvents.

Research limitations/implications

Shellac, prepared from kusmi seedlac, was used in the study. Besides shellac, dewaxed decolorized lac (DDL), dewaxed lac (DL) and bleached lac (BL) could also be used for study on blending with novolac.

Practical implications

Blending of shellac with novolac improved the film properties of shellac. The study suggests that the compositions can be utilised in developing formulations of coating material with improved properties for metal surfaces.

Originality/value

The formulations based on modification of shellac with novolac and study of the film properties utilising various instruments are novel. The formulations based on shellac and novolac can find applications in the field of surface coating with desired purposes.

Details

Pigment & Resin Technology, vol. 42 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 6 March 2017

Mohammad Fahim Ansari and Gautam Sarkhel

The purpose of this study is to improve the coating properties of shellac–epoxidised novolac blends by treatment with melamine formaldehyde resin (MF) at ambient temperature for…

148

Abstract

Purpose

The purpose of this study is to improve the coating properties of shellac–epoxidised novolac blends by treatment with melamine formaldehyde resin (MF) at ambient temperature for its use as a coating material.

Design/methodology/approach

Epoxidised-novolac resin was synthesised by epoxidation of novolac resin with epichlorohydrin. Novolac resin was synthesised by reaction of phenol with formaldehyde in acidic medium. Shellac was blended with the epoxidised-novolac resin in solution in varying ratios and treated the blends with MF resin in fixed ratio. Coating properties of the treated compositions were studied using a standard procedure. The compositions were characterised with Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) spectroscopy.

Findings

Treatment of shellac–epoxidised-novolac blends with MF resin improved water and alkali resistance of the blends, besides enhancing gloss. Gloss in all the blends was uniformly increased on treatment with MF resin. Water resistance of the blends tremendously improved after treatment with MF resin. Contact angle of the blends against water increased while decreased against ethylene glycol and dioxane. The compositions were more resistant to polar solvent than non-polar ones, suggesting that the compositions shifted to hydrophobic (lipophilic) nature on treatment with the MF resin.

Research limitations/implications

A specified concentration of MF resin was used in the study. Different concentrations of the MF resin can also be tried for treatment of shellac–epoxidised-novolac blends to see the effect of the resin on the blends.

Practical implications

Treatment of shellac–epoxidised-novolac blend with MF resin improved the coating properties of the blends. The formulation SeNB-64 is the best with high gloss, good impact, scratch hardness and water resistance, and hence can be used as coating material for metal surfaces.

Originality/value

Blending of shellac with epoxidised-novolac resin and treatment of the blends with the MF resin was done for the first time. The formulation SeNB-64 can be used as coating material for metal surfaces.

Details

Pigment & Resin Technology, vol. 46 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 26 August 2014

Mohammad Fahim Ansari, Gautam Sarkhel, Dipendra Nath Goswami and Bangali Baboo

– The purpose of this paper is to improve the properties of shellac by blending with epoxidised novolac resin for its use as coating material for metal surfaces.

175

Abstract

Purpose

The purpose of this paper is to improve the properties of shellac by blending with epoxidised novolac resin for its use as coating material for metal surfaces.

Design/methodology/approach

Epoxidised-novolac resin was synthesised by epoxidation of novolac resin, which in turn was synthesised by reaction of phenol with formaldehyde. The epoxidised-novolac resin was blended with different weight ratios of shellac ranging 10-50 weight per cent with an interval of 10 weight per cent. Films of the blends were studied for different coating properties using standard procedure.

Findings

Significant improvement in coating properties of shellac such as gloss, scratch hardness and impact resistance was observed on blending with epoxidised novolac resin. Resistance towards water and alkali increased, while acid resistance decreased, with the increase in concentration of epoxidised novolac resin in the blends. Contact angle measurement revealed that blends showed more resistance towards polar solvent than non-polar ones.

Research limitations/implications

Epoxidised-novolac resin used in the study was synthesised of epoxy equivalent of 187. Epoxidised-novolac resin of different epoxy equivalent can also be synthesised and used for blending and studying the properties.

Practical implications

Blending of shellac with epoxidised-novolac resin improved the coating properties of shellac, which was further enhanced with the treatment of butylated melamine formaldehyde resin. The formulation can be used as coating material for metal surfaces.

Originality/value

Blending of shellac with epoxidised-novolac resin was done for the first time. The formulation can be utilised for developing coating material for metal surfaces.

Details

Pigment & Resin Technology, vol. 43 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 July 2006

D. Bhatia, P.C. Sarkar and M. Alam

To investigate changes at molecular level in lac‐resole blends, occurring due to the effect of thermal stress at higher temperatures and different intervals of baking time.

242

Abstract

Purpose

To investigate changes at molecular level in lac‐resole blends, occurring due to the effect of thermal stress at higher temperatures and different intervals of baking time.

Design/methodology/approach

Films of lac‐resole blends were applied on tin‐panels and baked at 200°C for different time intervals. The baked films were examined by specular reflectance spectroscopy, as they were otherwise difficult to examine through conventional IR techniques, using KBr pellet method. The results obtained were compared and reported.

Findings

When lac‐resole blends are baked at 200°C, in addition to possible chromic ring structures, esters linkages are formed between lac and resole molecules through cross linkages among different reactive sites of lac and PF resin. Blend of 70 per cent lac: 30 per cent resole, baked at 200°C for 20 min was found to be the best in terms of different physico‐chemical properties.

Research limitations/implications

Lac‐synthetic resin blends are structurally complex in nature. Chemical researches on such blends have been typically limited due to lack of modern tools. The present method, to determine molecular level changes in lac‐resole blends due to heating effects, using state‐of‐the‐art instrumentation and computational techniques, opens a new field for research and industry.

Practical implications

Lac and its blends retain their significance in the surface coatings and food applications, in the formulation of lacquers, varnishes and in the finishing industry. This study could have significant implication for such industries from application point of view.

Originality/value

As of now, there is no report of specular reflectance data on lac‐synthetic resin blends. This paper represents the first attempt to obtain and correlate reflectance data on such blends. It also highlights the convenience of the method and the scope of sophisticated data analysis, including derivative spectrometry.

Details

Pigment & Resin Technology, vol. 35 no. 4
Type: Research Article
ISSN: 0369-9420

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