This research paper describes the synthesis of nano-and micro-structures of high purity precipitated calcium carbonate (PCC) on poly(ethylene glycol)(PEG) templates for broadrange industrial applications, using readily available and cheap impure dolomitic marbles. In the method, calcium components of impure dolomitic marbles are extracted as calcium sucrate which is then bubbled with carbon dioxide gas using a carbonation column in the presence of PEG. The effects of concentration of PEG, pH of calcium sucrate solution and temperature on the final yield, morphology and polymorphism of PCC have been studied. Vaterite and calcite are the crystalline forms of calcium carbonate found in final PCC products. The vaterite is observed as hollow spheres with particle diameter of 1.5-2 μm which is formed by aggregation of vaterite nanoparticles with particle size of 20 nm on PEG templates. Optimum conditions for the highest PCC yield of 79.94% are 0.4 mol dm −3 of PEG, pH of 6.5 and temperature of 80°C. The purity of PCC products is about 99%. Therefore, the synthesized PCC products are of required purity and quality for industrial applications.
An attempt was made to replace conventional ZnO with nanoZnO in low ammonia, tetramethylthiuramdisulphide (TMTD)/Zinc oxide (ZnO) natural rubber latex preservative system (LATZ). Different percentages of TMTD and nanoZnO dispersions containing equal portions were prepared and used to preserve the latex. Centrifuged natural rubber latex (CNRL) thus prepared were tested for VFA (volatile fatty acid) number and MST (mechanical stability time) periodically over a period of 75 days. Mechanical properties of vulcanized latex thin films made out of CNRL preserved were measured. Development of VFA number in CNRL samples preserved with nanoZnO was lower than the sample prepared with the conventional ZnO (control). Both the VFA number results and surface plots of the matured CNRL samples showed that preservative action of the modified preservative system was mainly governed by the amount of nanoZnO in the system. MST values of CNRL preserved with nanoZnO substituted systems were significantly high when compared to the control. Tensile and tear properties of the vulcanized films prepared using CNRL preserved with nanoZnO were almost comparable with those of the vulcanized films prepared using control system. The statistical analysis indicated that CNRL preserved with modified preservative system of 10% and 15% of TMTD/nanoZnO could be stored up to 55 and 75 days respectively, without exceeding VFA value above 0.02.
A comparative study on processed mica waste (PMW) filled natural rubber latex foams (NRLF) made out of centrifuged latex and creamed latex was conducted. The morphological, mechanical, and degradability properties of the composites were studied. The PMW was incorporated at 0, 2, 4, 6, 8, and 10 phr loading. Morphological studies revealed that both types of composites possess open‐cell structures. However, creamed latex based foam rubber composites showed foam structures with much larger cell sizes. PMW loading showed similar influences on the properties of the foam composites, irrespective of the latex type used. Increasing filler loading increases tensile strength, modulus at 100% elongation, tear strength, compression set, shrinkage, biodegradability, and antibacterial properties and reduces elongation at break and extractable protein content while offering a slightly dark color to the composites. It was also found that the creamed latex based foam rubber exhibits lesser extractable protein content and slightly inferior properties in tensile strength, shrinkage properties and color compared to centrifuged latex based foam rubber. However, it was shown that type of latex does not influence biodegradability, antibacterial properties, and color retention. Thermogravimetric analysis results confirmed the thermal resistance and reinforcing ability of mica in both NRLF composites.
Incorporation of finely powdered mica waste into natural rubber latex processed into foam rubber, consuming a minimum amount of energy could contribute to progress towards a greener environment. In this study, mica waste generated in the mining industry was finely powdered and incorporated into creamed natural rubber latex which is an alternative form of concentrated latex manufactured using a green process known as the creaming process. Finely powdered processed mica waste (PMW) was added as a filler into latex varying the loading from 0 to 10 pphr at 2 pphr intervals. The latex foam was then converted into a vulcanized natural rubber latex foam (NRLF). Effects of mica loading on certain properties of the foam rubber produced from creamed natural rubber latex were studied. It was found that the density and hardness of the mica powder incorporated foam rubber increased with increasing filler loading. Fourier transformed infrared spectroscopy (FTIR) studies confirmed that no structural changes occurred in natural rubber due to the addition of PMW. The overall results of the study showed the potential of utilization of mica waste and creamed natural rubber latex to manufacture greener natural rubber foam composites in cottage-level foam manufacturing industries.
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