118 resultados para Raw natural rubber


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Futures trading in Commodities has three specific economic functions viz. price discovery, hedging and reduction in volatility. Natural rubber possesses all the specifications required for futures trading. Commodity futures trading in India attained momentum after the starting of national level commodity exchanges in 2003. The success of futures trading depends upon effective price risk management, price discovery and reduced volatility which in turn depends upon the volume of trading. In the case of rubber futures market, the volume of trading depends upon the extent of participation by market players like growers, dealers, manufacturers, rubber marketing co-operative societies and Rubber Producer’s Societies (RPS). The extent of participation by market players has a direct bearing on their awareness level and their perception about futures trading. In the light of the above facts and the review of literature available on rubber futures market, it is felt that a study on rubber futures market is necessary to fill the research gap, with specific focus on (1) the awareness and perception of rubber futures market participants viz. (i) rubber growers, (ii) dealers, (iii) rubber product manufacturers, (iv) rubber marketing co-operative societies and Rubber Producer’s Societies (RPS) about futures trading and (2) whether the rubber futures market is fulfilling the economic functions of futures market viz. hedging, reduction in volatility and price discovery or not. The study is confined to growers, dealers, rubber goods manufacturers, rubber marketing co-operative societies and RPS in Kerala. In order to achieve the stated objectives, the study utilized secondary data for the period from 2003 to 2013 from different published sources like bulletins, newsletters, circulars from NMCE, Reserve Bank of India (RBI), Warehousing Corporation and traders. The primary data required for this study were collected from rubber growers, rubber dealers, RPS & Rubber Marketing Co-operative Societies and rubber goods manufacturers in Kerala. Data pertaining to the awareness and perception of futures trading, participation in the futures trading, use of spot and futures prices and source of price information by dealers, farmers, manufacturers and cooperative societies also were collected. Statistical tools used for analysis include percentage, standard deviation, Chi-square test, Mann – Whitney U test, Kruskal Wallis test, Augmented Dickey – Fuller test statistic, t- statistic, Granger causality test, F- statistic, Johansen co – integration test, Trace statistic and Max –Eigen statistic. The study found that 71.5 per cent of the total hedges are effective and 28.5 per cent are ineffective for the period under study. It implies that futures market in rubber reduced the impact of price risks by approximately 71.5 per cent. Further, it is observed that, on 54.4 per cent occasions, the futures market exercised a stabilizing effect on the spot market, and on 45.6 per cent occasions futures trading exercised a destabilizing effect on the spot market. It implies that elasticity of expectation of futures market in rubber has a predominant stabilizing effect on spot prices. The market, as a whole, exhibits a bias in favour of long hedges. Spot price volatility of rubber during futures suspension period is more than that of the pre suspension period and post suspension period. There is a bi-directional association-ship or bi-directional causality or pair- wise causality between spot price and futures price of rubber. From the results of the hedging efficiency, spot price volatility, and price discovery, it can be concluded that rubber futures market fulfils all the economic functions expected from a commodity futures market. Thus in India, the future of rubber futures is Bright…!!!

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Zinc butyl xanthate [Zn(bxt)2] was prepared in the laboratory . The effect of this xanthate with zinc diethyl dithiocarbamate (ZDC) on the vulcanization of natural rubber ( NR), polybutadiene rubber (BR), and NR/BR blend has been studied at different temperatures. The amounts of Zn (bxt)2 and ZDC in the compounds were optimized by varying the amount of ZDC from 0 . 75 to 1.5 phr and Zn (bxt)2 from 0 . 75 to 1 .5 phr. The cure characteristics were also studied . HAF filled NR, BR, and NR / BR blend compounds were cured at different temperatures from 60 to 150 C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density and elongation at break, compression set, abrasion resistance, etc. were evaluated. The results show that the mechanical properties of 80NR/20BR blends are closer to that of NR vulcanizates, properties of 60NR/40BR blends are closer to BR vulcanizates, while the 70NR/30BR blends show an intermediate property.

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Zinc salts of ethyl, isopropyl and butyl xanthates were prepared in the laboratory. The effect of these xanthates with zinc diethyldithiocarbamate (ZDC) on the vulcanization of HAF filled NR compound has been studied at different temperatures. The rubber compounds with the three xanthate accelerators and ZDC were cured at various temperatures from 60°C to 150°C. The sheets were moulded and properties such as tensile strength , tear strength , cross-link density, elongation -at-break, compression set, heat build up, abrasion resistance, flex resistance , etc. were evaluated . The properties showed that zinc xanthate/ZDC accelerator combination has a positive synergistic effect on the mechanical properties of NR compounds. The curing of HAF filled NR compound containing zinc xanthate /ZDC is slightly slower than the curing of the corresponding gum compounds . It is observed that, by gradually increasing the amount of the accelerator, the cure time of black filled NR compound can be made equal to that of the gum compou

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It is observed that reclamation of natural rubber latex based rubber using 2,2'-dibenzamidodiphenvldisulphide as reclaiming agent is an optional methodology for recycling of waste latex rubber (WLR). For progressive replacement of virgin natural rubber by the reclaim, two alternatives curing system were investigated: adjustment or reduction of the curing system with increasing reclaim content, to compensate for the extra amount of curatives brought along by the reclaim. For fixed curing system, as if the reclaim were equivalent to virgin NR. The cure behavior, final crosslink density and distribution, mechanical properties, and dynamic viscoelastic properties of the blends with reclaimed WLR are measured and compared with the virgin compound. The morphology of the blends, sulfur migration, and final distribution are analyzed.The mechanical and dynamic viscoelastic properties deteriorate for both curing systems, but to a lesser extent for fixed curing system compared to adjusted curing system. With the fixed cure system, many properties like tensile strength and compression set do still deteriorate, but tan 6 and Mrrr„/Murxr, representative for the rolling resistance of tires are improved. On the other hand, with the adjusted cure system both mechanical and dynamic properties still deteriorate.

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Ethylene-propylene-diene rubber (EPDM) and isobutylene-isoprene rubber (IIR) were compounded, precured to a low degree, and then were blended with natural rubber (NR). The compounding ingredients for NR were then added and the final curing was done. NR/ EPDM and NR/IIR blends, prepared using this method, were found to possess much improved mechanical properties as compared to their conventional counterparts. The optimum precuring crosslink density that has to be given to the EPDM and IIR phases has been determined.

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Butyl (IIR) tube reclaim (RR) was mixed with carbon black filled natural rubber (NR) compounds at various percentages. The blend containing a low percentage of RR was found to show improved ageing resistance and improved processability with out much reduction in the mechanical properties.

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Polymer-solvent interaction parameters for the blends of natural rubber (NR) with styrene-butadiene rubber (SBR) and polybutadiene rubber ( BR) are calculated using the Flory-Rehner equation by equating the network density of the vulcanizates in two solvents.

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Blends of natural rubber (NR) with styrene-butadiene rubber (SBR), polybutadiene rubber (BR), ethylene-propylene terpolymer (EPDM) and acrylonitrile-butadiene rubber (NBR) were vulcanised using an efficient vulcanisation (EV) system and a semi-EV system. Compatible blends show a definite pattern of curing whereas the incompatible blends show no such pattern.

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Blends of 50/50 natural rubber (NR) and styrene-butadiene rubber (SBR) are vulcanized using several conventional and semi-EV systems. The cure characteristics and vulcanizate properties are compared. The quantity and quality of crosslinks in each case are deciphered by chemical probes to correlate them with the vulcanizate properties.

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A carbon black filled 50/50 Natural Rubber (NR)/Polybutadiene Rubber (BR) blend is vulcanized using several conventional systems designed by varying the amounts of sulphur and accelerator . The cure characteristics and the vulcanizate properties are compared. The quality and quantity of crosslinks in each case are deciphered by chemical probes to correlate them with the vulcanizate properties.

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Compounding of styrene-butadiene copolymer/polybutadiene , natural rubber/ ethylene-propylene-diene terpolymer and natural rubber/butadiene-acrylonitrile copolymer blends was done in three different ways and their curing behaviour and the tensile properties of the es are compared.

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In natural rubber/high styrene resin microcellular sheets, part of natural rubber was replaced by latex reclaim prepared from waste latex products. The mechanical properties and cell structure of the products were evaluated. It was found that latex reclaim can replace about 30% of natural rubber without affecting the technical properties of the microcellular sheets.

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Paraphenylenediamine and diphenylamine were chemically attached to natural rubber during mastication . The rubber bound antioxidants were characterized by TLC, 'H-NMR, IR and TGA. The efficiency and permenance of these bound antioxidants were compared with a conventional amine type antioxidant in filled natural rubber vulcanizates . The rubber bound antioxidants were found to be less volatile and less extractable as compared to conventional antioxidants. The vulcanizates showed improved ageing resistance as compared to vulcanizates containing conventional antioxidants. This semisolid rubber bound antioxidant can reduce the amount of plasticizer required for compounding.

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ABSTRACT: The dipping characteristics of radiation-vulcanized natural rubber latex and natural rubber latex compounds were investigated with a lab-model semiautomatic dipping machine. The effect of the variation of the speed of immersion and withdrawal, dwell time, compound viscosity, and concentration of coagulant on the thickness of the latex deposit was investigated. The results of the study show that the deposit thickness depends on the withdrawal speed of the former, the concentration of the coagulant, dwell times, and the viscosity of the latex compounds

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Carbon Black is incorporated In natural rubber latex in , the presence of polyethylene glycol. The dispersion of carbon blade in the vulcanizatea is analyzed using polaroid M.4 land camera The mechanical properties of the carbon black meeterbatched NR/SBR blend Is compared with that of conventional NR/SBR blend before and after ageing , The resilience, flex resistance and hardness are found to be superior for N-LCMISBR compounds. The compression set and abrasion resistance are comparable for both types of blends . The processebiity and die swell of these blends at different shear rates are also compared.