Multi-walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first effort to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbonnanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubess can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied. Mechanical test results show an increase in the initial modulus for up to 12 times in relation to pure NR. In addition to mechanical testing, the dispersion state of the MWNTs into NR was studied by transmission electron microscopy (TEM) in order to understand the morphology of the resulting system. According to the present study, application of the physical and mechanical properties of carbon nanotubes to NR can result in rubber products which have improved mechanical, physical and chemical properties, compared with existing rubber products reinforced with carbon black or silicone.
Purification of NRL protein was accompanied by extraction of waste proteins using salting out and multiple centrifugation methods. Both methods contributes to varying degree of yield and purified protein characteristics. However both methods produces protein that can bind metal efficiently. Conventionally, salting out method was used and it is uncommon to use multiple centrifuge to extract protein. The key aspects discussed here, were on how the pH condition exposed to the NRL waste leads to variation in hevea protein extracted amount and how metal binding featured in FTIR spectroscopy. The purified protein were reacted with metal solution of different strength to study the binding characteristics. Molecular weight cut-off (MWCO) size of dialyzing tube shows greater effect on the final protein extracted amount by about 50% when smaller size were used. Acidic condition favors part of proteins from waste in purification while some favors basic condition. Standard salting out method shows consistent profile in extracting metal compared to multiple centrifugation method from 30 to 80%.
Hevea protein isolated from skim serum, a by-product of centrifugation process, contains useful proteins in extracting metal. It can be used directly from the source or purified before reacting with metal solutions. Those proteins bind with metal at varying degrees. Upon exposure from as low as 2 ppm concentration to up to 20 ppm metal solution concentration, different binding characteristics were seen. The reasons of such inconsistency in the characteristics might be due to the existence of some of the metal itself in the NRL serum. Mg++ and Zn++ are common metal found in NRL products and those metals would show the slightest in binding with hevea protein. Other metals which were covered in this scope of study shows a good binding characteristics disregard of the group of metals belongs. Selectivity was measured from the final concentration of metal in percentage. In most cases, lead, copper and cadmium show good interaction with hevea proteins.
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