| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 831292 | Materials & Design (1980-2015) | 2011 | 9 Pages |
Zinc stearate was synthesized by precipitation method through two steps; neutralization of stearic acid by sodium hydroxide then double decomposition using zinc sulphate to precipitate zinc stearate. Mass balances of the two steps were calculated and the physical properties of the prepared zinc stearate were measured and compared to standard. It was characterized and incorporated it into natural rubber in the absence and presence of some filler through mixing process of rubber. The vulcanization process was carried out at 142 °C. The rheological properties of natural rubber mixes were measured using oscillating disc rheometer. The plysico-mechanical properties of the vulcanizates were determined using tensile testing machine. It was found that, partial and complete replacement of synthesized zinc stearate instead of the conventional zinc oxide and stearic acid; enhanced the physico-mechanical properties of natural rubber. The measured reinforcing parameter value αf can be arranged according to the type of filler as follows:HAF>Hisil>CaCO3>Ca3(PO4)2>BaSO4>TalcHAF>Hisil>CaCO3>Ca3(PO4)2>BaSO4>TalcThe highest value of αf represents the strength of filler and consequently the reinforcing effect of carbon black (HAF) filler while the lowest value of αf was observed for Talc which show moderate reinforcing effect of Talc. The scanning electron microscope study showed high surface homogenity and good dispersion of zinc stearate through natural rubber chains in case of the vulcanizate containing 9 phr zinc stearate without filler. The investigated natural rubber vulcanizates tolerated thermal oxidative aging at 90 °C for 7 days.
Research highlights► The mechanical properties of NR were enhanced through partial and complete replacement of zinc stearate. ► The effect of adding different concentrations of zinc stearate on the physic-mechanical and SEM properties has been investigated. ► Zinc stearate was found to play dual role, it reinforces the matrix blow its melting point and higher temperature it plasticizers the system. ► Zinc stearate can be used as activator for sulfur vulcanization process of rubber instead of ZnO and stearic acid; in absence and presence of fillers.
