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M. Zaborski, L. Ślusarski, A. Vidal


The effect of structure of elastomer matrix on the activity of fillers. Part II. Modification of silica and its interaction with components of the rubber mix

Polimery 1993, No 3, 114


DOI: dx.doi.org/10.14314/polimery.1993.114

Summary

After having proved in Part I of the paper that filler activity depends on the type of elastomer forming the dispersive matrix, we are presenting now the results, for on the example of ethylene-propylene-diene (EPDM) terpolymer, attesting the importance of adsorption of vulcanization accelerators by silica and of interactions of silanol group present on its surface. Adsorption of accelerators [diphenylguanidine and di(2-benzothiazole)disulphide] on the surface of Zeosil 175 MP silica is equal to 1.84 and 0.18 molecules per nm2, respectively. Modification of silica with alcohols or amines results in shifting of the absorption band of -OH groups in IR spectrum of silica in the direction of smaller wavenumbers. Amines alter surface properties of silicas by decreasing of ispersive component of surface tension. The electrokinetic potential (t;) of silica changes its sign from negative to positive. Moreover, modification with amines results in a decrease of viscosity of silica dispersions in mineral oil because of decreasing the ability of silica to form its own structure in this medium, being a model of EPDM rubber. The effect of silica modification on mechanical properties of EPDM ulcanizates was also characterized and discussed.


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