Rubber Science

STUDIES ON BLENDS OF NATURAL RUBBER AND 1, 2-POLYBUTADIENEResearch Articles
Pages 1 - 8
Baby Kuriakose, C. K. Premalatha & N. M. Mathew
- Abstract
- Keywords
Blends having different proportions of natural rubber and thermoplastic 1, 2-polybutadiene were prepared and evaluated for processing characteristics, technological properties, ageing and ozone resistance. The results indicated that the cure rate index of the blends decreased as the proportion of 1 ,2-polybutadiene in the blend increased. Better technological properties were obtained for the blends which contained a higher proportion of natural rubber. However ageing and ozone resistance were better for the blends which contained a higher proportion of 1,2-polybutadiene. The reinforcing effect of silica in these blends was similar to its effect in normal rubber compounds.

Natural rubber, Blends, 1, 2-polybutadiene, Cure rate index, Ageing resistance, Ozone resistance, Silica

MOISTURE RETENTION CHARACTERISTICS OF SOILS UNDER HEVEA IN INDIAResearch Articles
Pages 9 - 21
A. K. Krishnakumar, B. Datta & S. N. Potty
- Abstract
- Keywords
A study on the moisture retention characteristics of soils under Hevea in India had been carried out. The soils belong to the orders Alfisol and Ultisol. Profiles representing the major rubber growing regions in the traditional rubber growing tract in the South Western coast of India were collected and analysed for the moisture retentive capacity.
The moisture retentive capacity of the soils had been found to vary. The moisture retention at -0.033 MPa ranged from 19.50 per cent in the profile from Calicut to 37.80 per cent in the profile from Goa, in the surface layers. Nevertheless, the available water storage capacity (AWSC) did not show much variation as a result of the concomitant increase in the moisture retained at -1. 5 MPa. The moisture retention at the above two tension ranges were found to be influenced by clay, sesquioxides, silt and organic matter, in consortium. The moisture retained at -1.5 MPa was more than 0.4 times clay, suggesting that clay is either not well dispersed or some water is held by gels. Silt has been found to play an active role in conjunction with clay in the moisture retention at -1.5 MPa suggesting colloidally active nature of silt in tropical soils. The study on the moisture retention points that the soils in general have high retention potential and this is of high practical significance in a rainfed crop like rubber. The data reveal that 36 per cent of the available moisture is desorbed at -0.1 MPa and 75 per cent at -0. 5 MPa indicating that the tension ranges could be of relevance to the water availability to Hevea.

Hevea brasiliensis, Alfisol, Ultisol, Available water storage capacity, Moisture tension range, Soil analysis

SKIM LATEX AS A POTENTIAL SOIL CONDITIONER IN A SANDY LOAM SOILResearch Articles
Pages 22 - 28
K. K. Sen & B. Datta
- Abstract
- Keywords
Skim latex- a waste material of rubber latex processing industry- was tested for the modification of physical properties of a sandy loam soil. Treatments, at 0.05, 0.10 and 0. 20 per cent concentrations, were found to enhance water stable aggregates by 6, 29 and 56 per cent, modulus of rupture by 15, 31 and 91 per cent, and saturated hydraulic conductivity by 15, 23 and 28 per cent, respectively. The treatments increased the pore sizes corresponding to 30 and 60 cm H₂O suction and decreased the available water content. Soil water diffusivity at the lower side of the moisture content was reduced and evaporation from the soil surface suppressed by the treatments.

Natural rubber, Skim latex, Rubber treatment, Water stable aggregates, Modulus of rupture, Saturated hydraulic conductivity, Moisture retention, Soil conditioner

DISTRIBUTION OF POTASSIUM IN THE MAJOR RUBBER GROWING SOILS OF SOUTH INDIAResearch Articles
Pages 29 - 34
Mercykutty Joseph, M. Karthikakutty Amma & M. Mathew
- Abstract
- Keywords
Profile studies of the major rubber growing soils of South India were undertaken to evaluate the distribution of potassium and its forms. The study revealed that the available K fractions were higher on the surface soils of all the regions. The total K content was higher in the lower depth of Kinalur, Mundakayam and Pudukad soils compared to Kulasekharam where the total K was higher in the surface soil. The major portion of the total K was in the lattice and organic bound form. The organic carbon content of the soil had positive significant correlation with water soluble K, exchangeable K, fixed K, available K (Morgan extractant) and total K. The water soluble, exchangeable and available K had positive significant relationship with fixed K. The clay content of the soil also expressed positive significant relationship with the total K.

Hevea brasiliensis, Soil analysis, Potassium fractions, Profile study, Particle size distribution

DRY ROT DISEASE MANAGEMENT IN HEVEA BRASILIENSISResearch Articles
Pages 35 - 39
Sabu P. Idicula, Thomson T. Edathil, K. Jayarathnam & C. Kuruvilla Jacob
- Abstract
- Keywords
Three years trials on screening of different fungicides indicated that methoxyethyl mercury chloride, thiram, oxycarboxin, carbendazim, thiophanate methyl and propiconazole were effective in checking dry rot disease of rubber and were superior to Bordeaux paste. Comparison of two carriers for fungicides viz., pidivyl compound and petroleum wound dressing compound indicated a significant superiority of the latter. The interaction between fungicide and carrier was also significant. Incorporating the fungicide in petroleum compound and applying to the affected area was as effective as applying fungicide solution followed by subsequent application of petroleum compound.

Hevea brasiliensis, Dry rot disease, Fungicides, Carriers, Application methods

CLONAL VARIATIONS IN THE ACTIVITY OF 3-HYDROXY-3-METHYL GLUTARYL-CoA REDUCTASE IN BARK OF HEVEA BRASILIENSISResearch Articles
Pages 40 - 42
N. Usha Nair, Molly Thomas, S. Sreelatha, Sheela P. Simon, K. R. Vijayakumar & P. J. George
- Abstract
- Keywords
HMG-CoA reductase activity in the bark of Hevea brasiliensis was estimated in four clones with contrasting yield characteristics. Significant difference in bark enzyme activity was observed between the high yielding and low yielding clones.

Hevea brasiliensis, Clonal variation, HMG-CoA reductase, Rubber biosynthetic capacity

Digital library

Volume 03, Number 1, (June 1990) Articles 1 - 6