Rubber Science

POLYPHOSPHORAMIDO SULPHIDES : A NEW CLASS OF FLAME RETARDANT FOR HTPBResearch Articles
Pages 75 - 79
P. Kannan & K. Kishore
- Abstract
- Keywords
Polyphosphoramido sulphides were synthesized from aryl phosphoramidic dichlorides and aryl thiophosphoramidic dichlorides with sodium polysulphide in aqueous acetone medium at room temperature. These polymers were characterized by elemental analysis and IR spectroscopy. Their thermal and flammability characteristics were evaluated by thermogravimetry and limiting oxygen index data respectively. These polymers were used as flame retardnt for hydroxyl terminated polybutadiene rubber. The flammability and mechanical properties were studied for the cured HTPB rubbers. Higher sulphur content in the structure enhances the LOI and thus the flame retardancy. Polynaphthylthiophosphoramido sulphide emerges as a promising flame retardant amongst four such polymers.

Polyphosphoramido sulphides, Flame retardant, HTPB, Limiting oxygen index

AN INDEX TO ASSESS AREAS HYDROTHERMALLY SUITABLE FOR RUBBER CULTIVATIONResearch Articles
Pages 80 - 91
P. Sanjeeva Rao, K. Jayarathnam & M. R. Sethuraj
- Abstract
- Keywords
A simple climatic index (CI) was developed, incorporating temperature and rainfall distribution, with respect to the climatic requirements of Hevea brasiliensis. The climatic resources for rainfed rubber cultivation have been categorised into six zones : (1) highly suitable, (2) suitable, (3) moderate, (4) marginal, (5) conditional and (6) not favourable. Comparison of CI with already established commercial natural rubber growing regions elsewhere indicates that most of the locations in India, where commercial cultivation of rubber is being undertaken, fall under zones 2 and 3. Temperature conditions along West Coast, parts of East Coast and a few locations in North-East India are more favourable for rubber cultivation than rainfall. Areas marginally or conditionally suitable for rubber cultivation in different parts of India, with irrigation and soil conservation, are reported.

Hevea brasiliensis, Climatic requirement, Rainfed cultivation, Drought, Climatic suitability, Marginal area, India

CROWN BUDDING: PROSPECTS AND EARLY RESULTS IN VIETNAMResearch Articles
Pages 92 - 96
Lai Van Lam & Tran Trung Hai
- Abstract
- Keywords
Seven crown budding trials conducted at Rubber Research Institute of Vietnam have shown that crown could exert influence on the trunk clone : both positive and negative. Important trunk characters modified by crown clones are vigour, yield, diseases and latex characteristics. A proposal is made to adopt crown diversified three-part-plants for commercial planting so as to make use of the beneficial effects of crown on trunk.

Hevea, Crown budding, Vietnam

AGEING CHARACTERISTICS OF NATURAL RUBBER CONTAINING PHOSPHORYLATED CASHEW NUT SHELL LIQUIDResearch Articles
Pages 97 - 100
Jasmine Maret, A. R. R. Menon, C. K. S. Pillai & D. Joseph Francis
- Abstract
- Keywords
The effect of phosphorylated cashew nut shell liquid prepolymer, (PCNSL) on the ageing characteristics of natural rubber vulcanizates was studied in comparison with styrenated phenol. It was found that at low concentrations PCNSL improved ageing characteristics of natural rubber and the improvement was more than that by styrenated phenol. PCNSL showed antiozonant property also.

Natural rubber, Cashew nut shell liquid, Phosphorylation, Flame retardancy, Ageing resistance

ENERGY CONSIDERATION DURING MIXING OF CARBON BLACK WITH NR AND SBRResearch Articles
Pages 101 - 104
D. Khastgir, A. K. Bhattacharya & P. P. De
- Abstract
- Keywords
Different aspects of energy consumption in the process of HAF black mixing with natural rubber (NR) and styrene-butadiene rubber (SBR) in a Brabender Plasticorder and the effect of different processing parameters like mixing temperature, rotor speed and fill factor on the rate and efficiency of mixing, energy consumption and the temperature rise are reported. It is found that energy consumption is higher for SBR-black mixing as compared to NR-black mixing and the former process is more exothermic in nature. The rate of dispersive mixing increases with increase in temperature, rotor speed and fill factor. Relatively smoother energy profiles are observed, for NR-black mixing as compared to SBR-black mixing.

Natural rubber, Styrene-butadiene rubber, Mixing, Carbon black. Energy consumption

EFFECT OF ASPECT ON SOIL TEMPERATURE AND GROWTH OF HEVEA ON HILLS OF NORTH EAST INDIAResearch Articles
Pages 105 - 110
S. A. Saseendran, D. Mandai, R. R. Sinha, K. R. Vijayakumar, S. N. Potty & M. R. Sethuraj
- Abstract
- Keywords
Effect of aspect on soil temperature and growth of Hevea trees on a gently undulating terrain (slope about 25°) of North East India was studied. Soil temperatures under Hevea at depths 5, 10 and 20 cm on a south facing slope was found to be significantly higher than that on a north facing slope during the winter months. The difference in temperature was not found to exist during the summer months. Slope orientations were also found to influence the growth of Hevea trees. Girth of the trees on the south facing slope was observed to be significantly higher than on the north facing slope. At the end of 6th year of planting, a mean difference of 9 cm in girth of the trees on these aspects was observed.

Hevea brasiliensis, Soil temperature, Aspect, North East India