Application of lime kiln dust as a filler in the natural rubber industry

Abstract

Lime kiln dust (LKD) obtained from kraft chemical recovery systems by conversion of calcium carbonate (CaCO 3 ) back into calcium oxide (CaO) for reuse in the causticizing process, is mainly composed of CaCO 3 . A two-stage conventional mixing procedure was used to incorporate LKD into natural rubber (NR). For comparison purposes, four commercial fillers, stearic acid coated CaCO 3 , ground CaCO 3 , silica, and carbon black, were also used. The effect of these fillers on the curing characteristics and mechanical properties of NR materials at various loadings ranging from 0 to 60 phr were studied. The results indicate that the use of LKD filler resulted in a lower Mooney viscosity and shorter curing time in the NR materials. The incorporation of LKD into NR improved the Young's modulus and hardness but decreased the tensile strength and tear strength. However, LKD was better in processability than the commercial fillers. Scanning electron micrographs revealed that the morphology of the rubbers filled with reinforcing fillers, such as silica and carbon black, was finer and more homogeneous compared to the those of the rubbers filled with LKD and commercial CaCO 3 . The dispersion of LKD and commercial CaCO 3 fillers in the rubber matrix was discontinuous, which in turn, generated a weak structure compared with the reinforcing fillers. According to these observations, LKD could be used as a cheaper filler for NR materials where improved mechanical properties are not critical.

Dielectric behavior and structural characterization of polymeric double layer thin films

“…It is well known that polar aand nonpolar polymers form electrets with extremely long life and are less sensitive to temperature and environmental humidity. However, the greatest volume of work has been carried out with single layer polymers belonging to the polar and nonpolar class . Electronic transport in polymers has been investigated by many workers; both from scientific interest in large energy band gap systems and for engineering needs for electrical insulators .…”

Influences of the grafting percentage of natural rubber‐graft‐poly(2‐hydroxyethyl acrylate) on properties of its vulcanizates

“…This corresponds to the CRI increasing with the amount of grafting due to crosslinking reactions via the sulfidic linkages together with reactions of polar functional groups between PHEA molecules . The polar functional groups of the grafted side chains could form hydrogen bonds with each other, accelerating vulcanization and curing rate …”

“…Arayapranee and Rempel examined the grafting of the olefinic monomers acrylonitrile, MMA and styrene onto NR, to enhance the polarity of the NR backbone in order to improve the silica−rubber interactions. It was found that the grafted NR provided significant improvements in resistance of the composites to heat, oil and ozone, while maintaining the mechanical properties of the rubber . Klinpituksa et al .…”

Study on the effect of virgin and recycled chloroprene rubber (vCR and rCR) on the properties of natural rubber/chloroprene rubber (NR/CR) blends

“…[2] as per reports cited in many works [3][4][5][6][7][8][9][10]. A wide range of the applications of rubber products can be manufactured, because they have the potential to combine the attractive properties of both constituents in the blend, when compared to the economic and technical uncertainties that are associated with synthesizing new polymeric materials [11].…”