Curing Characteristics And Properties Of Epoxidized Natural Rubber ( Enr )

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dc.contributor.authorMD. SADEQUL AMIN
dc.date.accessioned2023-01-06T03:26:05Z
dc.date.available2023-01-06T03:26:05Z
dc.date.issued1997-07
dc.description.abstractThe cure characteristics of accelerated sulphur vulcanization of epoxidized natural rubber containing 25 mol % of epoxidation ( ENR 25 ) was studied while one grade of unmodified natural rubber - standard Malaysian rubber light ( SMR L ) was used as a control. The influences of different accelerator types - zinc dimethyldithiocarbamate ( ZDMC ), tetramethylthiuram disulphide (TMTD), diphenylguanidine ( DPG ), N-t-butylbenzothiazole-2-sulphenamide (TBBS ), and 2-mercaptobenzothiazole ( MBT ) at various temperatures were investigated. Three vUlcanization systems - conventional high-sulphur vulcanization ( CV ), semi-efficient vulcanization ( semi-EV ) and efficient vUlcanization ( EV ) were also investigated. Mooney Shearing Disk Viscometer ( MV 2000 ) and Moving Die Rheometer ( MDR 2000 ) were used to determine the Mooney scorch time and cure time respectively in the temperature range of 100 to 180 DC. The results obtained indicate that Mooney scorch time and cure time decreases exponentially with increasing temperature for the two type of rubbers studied. At fixed curing temperature, ENR 25 shows shorter scorch time and cure time compared to that of SMR L. These differences in scorch behaviour and cure time is attributed to the activation of the double bond by the adjacent epoxide group in ENR 25. The investigation involving different accelerators show that mooney scorch time decreases in the order, TBBS > TMTD > DPG > MBT > ZDMC. Studies of the effect of varying amounts of MBT at a fixed sulphur concentration show that scorch and cure time decrease as the accelerator concentration increases. From this study it has been fOLJnd that the cure index of SMR L is higher than that of ENR 25, especially at lower temperatures of study, i.e., 120 DC and below. This is attributed to the activation of double bonds by the adjacent epoxide group in the ENR compound. ENR 25 shows higher torque maximum than SMR L. This observation can be related to the oxirane group which is bulky and this accounts for increased glass transition temperature with increase in the level of epoxidation. ENR 25 contains epoxide groups that activate the adjacent double bonds, thus a faster cure is observed. In all the vulcanization systems, CV shows the highest torque maximum followed by semi-EV and than EV. This differences are attributed to the amount of active sulphurating agent which increases with increasing accelerator concentration. ENR 25 shows lower activation energy than SMR L for all the three different vulcanization systems and the accelerators studied. This is obviously due to the presence of epoxide groups that activate the adjacent double bonds, thus lowering the activation energy of vulcanization. However, some differences in the magnitude of cure time, cure index, torque maximum and activation energy in the temperature and accelerator studies are observed between ENR 25 and SMR L.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/17083
dc.subjectCuring Characteristics And Propertiesen_US
dc.subjectOf Epoxidized Natural Rubber ( Enr )en_US
dc.titleCuring Characteristics And Properties Of Epoxidized Natural Rubber ( Enr )en_US
dc.typeThesisen_US
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