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B. Sehgal ¹, G. B. Kunde ²

Affiliations
1 Dept. of Applied Chemistry, Maharaja Sayajirao University of Baroda, Vadodara-390001, Gujarat, IN
2 Dept. of Applied Chemistry, Datta Meghe College of Engineering, Navi-Mumbai, Maharashtra, IN

Abstract

Natural rubber (NR) is a very reactive rubber because of its structure. The modification of NR with other functional groups can be achieved by incorporation of monomer carrying the desired functional group in the polymerization process using ene reaction. Grafting of a second polymer on to the natural rubber backbone leading to the chemical modification of the polyisoprene occurs at allylic double bond system. This route following grafting gave good control over the extent of reaction as the reaction limits itself on individual olefinic sites present on rubber and does not employ a catalyst that gets poisoned by non rubbers. With the help of ene reaction not only the molecular wt of the polymer that underwent grafting can be accurately determined but the no of grafting sites can also be controlled. Azo compounds have been used as effective modifiers of NR as they have long-term stability and have fewer tendencies to decompose to free radicals.

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B. Sehgal ¹, G. B. Kunde ²

Affiliations
1 Dept. of Applied Chemistry, Maharaja Sayajirao University of Baroda, Vadodara-390001, Gujarat, IN
2 Dept. of Applied Chemistry, Datta Meghe College of Engineering, Navi-Mumbai, Maharashtra, IN

Abstract

The type of interactions that take place between a polymer and its degradation products and also the changes that occur on addition of a second polymer in the same environment as in the case of polymer blends or graft copolymers, has been examined in the present study. Some pair of polymers shows no evidence of interaction during the degradation of a blend whereas in some cases it has been found that the presence of degradation product from one polymer can highly influence the degradation behavior of the other polymer.

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B. Sehgal ¹, G. B. Kunde ²

Affiliations
1 Department of Applied Chemistry, Maharaja Sayajirao University of Baroda, Vadodara-390001, Gujarat, IN
2 Datta Meghe College of Engineering, Dept. of Applied Chemistry, Navi Mumbai, Maharashtra, IN

Abstract

A comparative study of oxidation stability of biodiesel prepared via transesterification and sonication routes was carried out. The polyphenols from tea extract, while acting as an antioxidant could prolong the onset of degradation by about two weeks. Difference in viscosity and peroxide value were used as an indicator of oxidation. Though the polyphenols could not prevent a viscosity increase that corresponds to the beginning of rapid polymerisation but the rate of the increase was quiet slow. Polyphenols from tea extract stabilizes the methyl ester by reducing the rate of peroxide formation and by stabilising the viscosity. A sudden rise of viscosity was attributed to onset of secondary oxidation marked by an increased release of free fatty acid. The onset of secondary oxidation showed a marked delay in ultrasonicated samples as compared to transesterification.

Keywords

Transesterification, Sonication, Peroxide Value, Antioxidant.

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B. Sehgal ¹, G. B. Kunde ²

Affiliations
1 Maharaja Sayajirao University of Baroda, Department of Applied Chemistry, Vadodara-390001, Gujarat, IN
2 Datta Meghe College of Engineering, Dept. of Applied Chemistry, Navi Mumbai, Maharashtra, IN

Abstract

The behavior of polymer blend depends on the properties of the individual components in the blend, the proportion in which they are present in blend and the structure and morphology of the blend. The structure of the dissolved molecules of the blend in the polymer-polymer mixture plays a major role in the molecular state of dispersion, the adhesion between the phases and consequently influences most of the properties and applications. In the present study we have made use of grafting of a polymer on to the natural rubber backbone leading to chemical modification of the poly-isoprene allylic double bond system. This type of modification leads to a change, not only in chemical properties but physical properties as well, like increased hardness, strength with decreased tackiness and the blend behaves like a thermoplastic rubber without making use of vulcanization. In order to optimize the processing conditions, the properties like miscibility characteristics, torque and melt viscosity were studied.

Keywords

PVC (Poly Vinyl Chloride), NR (Natural Rubber) ENR (Epoxidised Natural Rubber), PMMA (Polymethyl Methacrylate).

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