PRECIPITATED NANO ZINC HYDROXIDE ON THE SILICA SURFACE AS AN ALTERNATIVE CURE ACTIVATOR IN THE VULCANIZATION OF NATURAL RUBBER

ABSTRACT We synthesized precipitated zinc hydroxide on the surface of precipitated silica via a conventional precipitation method. The zinc hydroxide is characterized by Fourier transform infrared spectroscope, X-ray diffraction, and field-emission scanning electron microscope measurements. The synthesized zinc hydroxide is a platelike structure with an average nano dimension of 40 nm in crystalline depth. The aim of the present study is to reduce the cure activator level of conventional environment pollutant zinc oxide in the vulcanization of natural rubber. To study the effects of the synthesized zinc hydroxide on the vulcanization of natural rubber curing, mechanical and thermal properties were determined and compared with the vulcanized properties of conventional 5 phr (per hundred grams of rubber) zinc oxide cured rubber vulcanizate. A strong enhancement in the cross-link density and mechanical properties (namely, modulus, tensile strength, and hardness) with only 2 phr of synthesized zinc hydroxide cured rubber system compared with 5 phr of conventional zinc oxide cured rubber system was found. A slightly higher thermal stability of 2 phr zinc hydroxide cured vulcanizate was observed because of better cross-link density than conventional 5 phr zinc oxide cured rubber vulcanizate. Thus, by this novel method, a greater than 60% reduction of the conventional cure activator level can be possible with improved physical properties in the vulcanization of natural rubber.