Rubber Science

DIAGNOSIS AND RECOMMENDATION INTEGRATED SYSTEM 1. FORMULATION OF DRIS NORMS FOR HEVEA BRASILIENSISResearch Articles
Pages 111 - 116
Mercykutty Joseph, M. Mathew, M. R. Sethuraj & C. R. Ranganathan
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The Diagnosis and Recommendation Integrated System (DRIS) involves the use of nutrient concentration ratios to determine the relative sufficiency of nutrients within the plant tissue. A data bank comprising yield, leaf nutrient concentration for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) and soil fertility status from 1200 individual fields from 15 estates representing the major rubber growing regions of South India was built. DRIS norms for the nutrients N, P, K, Ca and Mg were developed from a regrouped data set having uniformity in age and system of tapping. The variance ratio (low yield/high yield) was highly significant for the nutrient combinations involving Mg indicating the direct role of Mg on latex yield. The mean values and the corresponding cv from the high yielding population for the ratio N/P, K/N, KIP, Ca/N, Ca/P, Ca/K, Ca/Mg, N/Mg, P/Mg and K/Mg were selected as the standard norms.

Hevea brasiliensis, DRIS, Foliar diagnosis, Data bank, India

HIGH TEMPERATURE VULCANIZATION OF NATURAL RUBBER BY SULPHUR DONORS AND TRIACCELERATOR SYSTEMResearch Articles
Pages 117 - 122
C. K. Das, M.S. Banerjee & W. Millns
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High temperature vulcanization of natural rubber using sulphur donors and sulphur accelerated with triaccelarator systems was studied with the help of a rheometer. Thiocarbonyl type of accelerator acts as booster for both MBTS and TMTD, with more pronounced effect on TMTD, through a sulphurating complex at stoichiometric ratio. Sulphuration by MBT, DPG and TMTD together, can be varied depending on their molar ratios and there appears to be an interaction between DPG and TMTD.

Natural rubber, Vulcanization, High temperature, Sulphur donors, Triaccelerator system

EVALUATION OF ISOCYANATE AND BLOCKED ISOCYANATE BONDING SYSTEMS IN SELECTIVE FIBRE/ELASTOMER COMPOSITESResearch Articles
Pages 123 - 130
A. Guha, A. K. Ghosh & R. N. Ghosh
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This paper investigates the use of a commercially available caprolactam blocked methylenebis (4-phenylisocyanate) along with RFL as a bonding agent for cord/fabrics made with nylon-66, polyester and aramid under different conditions, with special reference to the influence of heat and steam ageing on adhesion. An attempt has also been made to compare the present bonding agent with the conventional dipping techniques. All the dipping systems studied showed good adhesion with NR and SBR compounds. In most of the dipping systems the SBR compound had better adhesion compared to the NR compound. The blocked isocyanate/ RFL adhesive system showed an appreciable drop in H-pullout adhesion compared to unblocked isocyanate and RFL system. However, peel adhesion was remarkably better for the former with both compounds in the case of nylon fabrics. No significant change in adhesion was observed by the incorporation of epoxy compounds in blocked isocyanate/RFL adhesive system. Excellent adhesion retention was observed after ageing of fibres treated with blocked isocyanate/RFL system compared to unblocked isocyanate/RFL system in both the rubber compounds.

Natural rubber, Styrene-butadiene rubber, Cord/ fabric-rubber bonding, Composites, Adhesion strength

PHYSICAL AND MECHANICAL PROPERTIES OF RUBBER WOOD FROM KARNATAKAResearch Articles
Pages 131 - 136
B. S. Kamala & P. V. Krishna Rao
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Strength properties in green and air dry conditions based on tests conducted on small clear specimens obtained from eight logs of Hevea brasiliensis (rubber) wood from Sullia region of Karnataka have been reported. The comparative suitability indices and safe working stresses have also been evaluated and reported. The results obtained have been compared with rubber wood from Kerala and Malaysia. The strength properties of rubber wood from Karnataka were slightly higher than those of Kerala rubber wood and less than those of Malaysian rubber wood. Rubber wood from spent Hevea brasiliensis trees could be efficiently used for a variety of uses such as furniture, door and window shutters, manufacture of packing cases, tool handles, etc.

Hevea brasiliensis, Rubber wood, Mechanical properties, Safe working stress, Suitability coefficient, India

SOME SOILS OF NORTHERN BENDEL STATE OF NIGERIA AND THEIR POTENTIAL FOR GROWING RUBBERShort Scientific Reports
Pages 137 - 142
D.O.K. Asawalam & I.K. Ugwa
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CLONAL VARIATION IN LIPID COMPOSITION IN THE LATEX OF HEVEA BRASILIENSIS AND ITS IMPLICATION IN LATEX PRODUCTIONShort Scientific Reports
Pages 143 - 145
N. Usha Nair, Molly Thomas, S. Sreelatha, Sheela P. Siomon, K.R. Vijayakumar & P.J. George
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