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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.

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.

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.

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.

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.

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.

The purpose of this paper is to study the effect of various stoichiometric ratios for synthesised epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties.

In the present study, EPN (EPN-1, EPN-2, EPN-3, EPN-4 and EPN-5) resins were synthesised by varying five types of different stoichiometric ratios for phenol/formaldehyde along with the corresponding molar ratios for novolac/epichlorohydrin. Their different physicochemical properties of interest, thermomechanical properties as well as morphological properties were studied by means of cured samples with the variation of its stoichiometric ratios.

The average functionality and reactivity of EPN resin can be controlled by controlling epoxy equivalence as well as cross-linking density upon its curing as all of these factors are internally correlated with each other.

Epoxy resins are characterised by a three-membered ring known as the epoxy or oxirane group. The capability of the epoxy ring to react with a variety of substrates imparts versatility to the resin. However, these resins have a major drawback of low toughness, and they are also very brittle, which limits their application in products that require high impact and fracture strength.

Epoxy resins have been widely used as high-performance adhesives and matrix resins for composites because of their outstanding mechanical and thermal properties. Because of their highly cross-linked structure, the epoxy resin disables segmental movement, making them hard, and it is also notch sensitive, having very low fracture energy.

Epoxy resin is widely used in industry as protective coatings and for structural applications, such as laminates and composites, tooling, moulding, casting, bonding and adhesives.

Systematic study has been done for the first time, as no exact quantitative stoichiometric data for the synthesis of EPN resin were available on the changes of its different properties. Thus, an optimised stoichiometric composition for the synthesis of the EPN resin was found.

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.

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.

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.

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.

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.

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.

The purpose of this paper is to see the effect in the properties of shellac on blending with rosin (another natural resin) and study their changes during storage.

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 intervals following standard procedures.

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.

Because rosin possesses very high fluidity and life under heat, exact value of flow and life under heat of rosin and its blends with shellac having high rosin content could not be determined.

The results give an idea to entrepreneurs, processors and industrialists of 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.

Systematic study has been done for the first time, as no quantitative data was available on the changes in the different properties of shellac which take place on blending with rosin.

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.

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.

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.

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.

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.

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.

In Nepal, crop insurance is at initial phase. However, since its implementation seven years ago, the adoption rate has been fairly low even with the government's lucrative subsidy on premium. There have been very limited studies on specifics of insurance for different crops, and farmer's acceptability on insurance. This study examines WTP for tree-based insurance, a potential insurance scheme on fruit crops in hilly areas of Nepal.

The authors used a contingent valuation method to estimate farmer's willingness to pay (WTP) premium for insurance. They used a double-bounded dichotomous choice (DBDC) framework to elicit WTP and an interval regression method to estimate the WTP model.

The authors found that the farmers revealed WTP for tree-based insurance is three times higher than the premium they would pay under government's current subsidy plans of insurance. The authors’ result from interval regression also suggests that the factors such as farm size, farmer's adverse experience about invasive pest and weather, awareness of crop insurance, farming experience, and family involvement in agriculture significantly influence farmers' WTP.

A distinct modality of insurance, like tree-based insurance for fruit crops in mid and high hill areas, may enhance the adoption rate rather than a broad area-based plan generalized for all crops.

Only a few studies have examined specifics of insurance in fruit crop insurance in developing countries. The authors’ estimated WTP factors influencing WTP on citrus fruit-crop insurance in Nepal indicates that there is a scope for extending this insurance program. However, the authors also found that there is a gap in understanding of crop insurance and have limited awareness on the government's subsidy programs among farmers.