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Karawila (Momordica charantia), also known as bitter gourd, is widely used as a food and a medicine in Asian countries. Representative samples of the seeds of the most abundant cultivar (MC43) in Sri Lanka were collected. The kernel represented 60 ± 4.7% of the seed by dry weight basis. The oil content of the dry kernel was 40.45 ± 3.12%. The seed oil was rich in a-eleosteric acid (50.04 ± 4.80%) and three other geometrical isomers of 9,11,13-octadecatrienoic acid that constituted 6.55%. The acid value, the saponification value and the iodine value were 2.73 ± 0.876, 190.70 ± 1.82 mg/g and 115.96 ± 3.46 cg/g, respectively. The set-to-touch drying time of 3 h observed for the seed oil of MC43 was significantly less than that of linseed oil (13 h). The presence of a high amount of conjugated octadecatrienoic acids, low acid value, high saponification value, moderate iodine value and the low set-to-touch drying time are promising indicators of the potential of karawila seed oil as a good drying oil for the paint and coating industry.

Hybrid organic-inorganic composites were prepared by precipitating silica into hydroxypolybenzoxazole (HPBO) and sulfopolybenzobisthiazole (SPBT) polymers, with interfacial bonding between the phases improved by use of isocyanatopropyltriethoxy silane and N,N-diethylaminopropyltrimethoxy silane, respectively. The resulting materials were characterized with regard to their transparency, silica particle distribution, tensile modulus and tensile strength, thermal stability, and tendency to absorb water.

A mathematical model for the prediction of gel formation in the synthesis of alkyd resins is developed. The probability of developing linear polymer molecules is related to the average functionality, F av . A statistical factor φ is introduced to represent the probability of having free OH groups in the backbone of a linear alkyd molecule. Factor φ increases from 0 to a maximum of φ max when the acid value decreases from AV initial to AV max during the polymerization. Branch generation in alkyd molecules becomes significant only after the acid value is reached, AV max , and it continues until a gel is formed. At φ max , the average functionality (F av(max) ) and the acid value (AV max ) are calculated in terms of the number of moles of OH groups, number of moles of COOH groups, and total number of molecules per unit mass at the beginning of polymerization. The acid value at the gel point, AV gel , is then calculated using the values of F av(max) and AV max . The predicted acid values using the new model are in good agreement with the actual data reported for polyesterification in the synthesis of alkyd resins.

Use of reclaimed rubber as a component of a blend with virgin rubber or as a replacement for the virgin material in most rubber applications, especially in tyre components, has increased in the recent past. This is due to the increase in prices of natural and synthetic rubbers and growing concern about environmental issues. This research is aimed at evaluating the properties of rubber compounds produced by blending virgin natural rubber (NR) with ground rubber tyre (GRT), which was modified using a readily available, environmentally friendly, low-cost amino compound. Initially, reclaiming of 40 mesh GRT in the presence of rubber processing oil was studied at four different concentrations of the amino compound and two milling time periods. Mechanochemical reclaiming/devulcanisation was performed at a temperature of 30-70°C, using a laboratory two-roll mill. Properties such as initial plasticity, swelling ratio, crosslink density, and molecular weight between two crosslinks (M c) of the reclaimed rubber samples were evaluated. Rubber compounds were prepared in the second stage by blending the reclaimed GRT samples with virgin NR in a ratio of 15:85. Mooney viscosity, initial plasticity, cure characteristics, and dynamic properties of the above blend compounds were evaluated and compared with those of the control compounds. This study shows that the amino compound acts as a devulcanising/reclaiming agent for GRT. Rubber compounds prepared by blending virgin NR with novel reclaimed rubber exhibit higher stock viscosity, lower scorch resistance, and lower hysteresis in comparison with the control compounds.