Coordination crosslinks of epoxidized natural rubber with reactive zinc chloride

Coordination crosslinks of epoxidized natural rubber with reactive zinc chloride

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque...

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Bibliographic Details
Main Authors: Kamonthip Rittimas, Skulrat Pichaiyut, Charoen Nakason
Format: Article
Language:English
Published: Budapest University of Technology and Economics 2024-11-01
Series:eXPRESS Polymer Letters
Subjects:
crosslinking
crosslinking agent
natural rubber
thermal degradation
vulcanization
Online Access:http://www.expresspolymlett.com/letolt.php?file=EPL-0013037&mi=cd
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Summary:Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.
ISSN:1788-618X

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