Rubber Science

EFFECT OF SURFACE ACTIVE AGENTS ON RUBBER -FILLER INTERACTION IN SILICA-FILLED NATURAL RUBBER LATEX VULCANIZATESResearch Articles
Pages 1 - 9
N. R. Peethambaran & A. P. Kuriakose
- Abstract
- Keywords
The influence of four surface active agents on rubber-filler interaction in natural rubber latex vulcanizates has been studied. The surface active agents studied are casein, polyvinyl alcohol, ammonium alginate and sodium carboxymethylcellulose. Silica-filled natural rubber latex vulcanizates were found to show better tensile properties in the presence of polyvinyl alcohol and casein. The enhancement in tensile properties is attributed to better rubber-filler interaction.

Surface active agent, Precipitated silica, Latex-filler interaction, Reinforcement, Crosslinks

TISSUE CULTURE PROPAGATION OF RUBBER (HEVEA BRASILIENSIS (WILLD. EX ADR. DE JUSS.) MUELL. ARG.) CLONE GT (GONDANG TAPEN) 1.Research Articles
Pages 10 - 12
M. P. Asokan, P. Sobhana, S. Sushamakumari & M. R. Sethuraj
- Abstract
- Keywords
An in vitro propagation system for clone GT 1 is reported. The optimal growth regulator range for shoot and root development was 1.5 - 3.0 mg l^-1 indoleacetic acid (IAA) with 0. 5- 1.5 mg l ^-1 kinetin. Rooted plantlets were successfully transplanted in the field.

Hevea brasiliensis, Tissue culture, In vitro propagation

SOLAR-CUM-SMOKE DRIER FOR RAW SHEET RUBBERResearch Articles
Pages 13 - 21
N. Radhakrishnan Nair, K. T. Thomas, L. Verghese & N. M. Mathew
- Abstract
- Keywords
A solar-cum-smoke drier for drying raw rubber sheets has been designed and fabricated combining the facilities of solar drying and smoke drying. The main source of energy used in the system is sunlight, harnessing the energy using flat plate solar collectors. Hot smoke obtained by burning firewood provided the subsidiary source of energy. Evaluation of the drier showed that, without subsidiary heating, the drying period was 8-12 days as against 4-5 days in conventional smoke drying. However, with the subsidiary heating using firewood, the drying time could be brought down to 5 days. As compared with conventional smoke drying, the saving in firewood while using solar-cum-smoke drier is found to be around 70 per cent. The rate of drying of sheet rubber in the drier and the overall efficiency of the solar drying system have been determined and discussed.

Solar drying, Firewood back-up, Sun drying, Solar intensity, Drying efficiency

EFFECT OF PROCESS AIDS ON ENGINEERING PROPERTIES OF NATURAL RUBBERResearch Articles
Pages 30 -40
K. T. Thomas, Baby Kuriakose & N. M. Mathew
- Abstract
- Keywords
Six different process aids - naphthenic oil, paraffinic oil, aromatic oil, pine tar, white factice and CI resin-in natural rubber were evaluated for their effect on physical properties of vulcanizates, with special reference to those relevant to engineering application. Creep, stress relaxation, set, hysteresis, heat build-up and resilience were studied. It was found that naphthenic oil showed the optimum properties, where as CI resin gave the least desirable set of properties. These two process aids were further evaluated to study the effect of their concentrations on properties. It was found that the engineering properties were improved by the addition of naphthenic oil upto 10 phr. However, CI resin showed abnormal behaviour. A rating of process aids was made as far as general engineering properties were concerned.

Process aid, Creep, Stress relaxation, Hysteresis, Heat build-up, Set, Resilience

STUDIES ON THE INTRAXYLARY PHLOEM AND ITS ASSOCIATION WITH CERTAIN GROWTH CHARACTERS IN HEVEA BRASILIENSIS (WILLD. EX ADR. DE JUSS.) MUELL. ARG.Research Articles
Pages 41 - 44
D. Premakumari & A.O.N. Panikkar
- Abstract
- Keywords
Quantitative differences in the number of primary xylem points, number of intraxylary phloem points and the thickness of xylem and phloem in one year old twigs were assessed in eight clones of Hevea brasiliensis. The linear relationship of these structural characteristics on the growth characters such as diameter of the twigs of the tapping trees and girth increment on tapping were also examined.

The data revealed marked differences of anatomical and growth characters among clones. The number of intraxylary phloem points had significant association with the number of primary xylem points (r = 0.8158**), twig diameter (r = 0.5067**) and the rate of girth increment on tapping (r = 0.4231*). The number of primary xylem points also was correlated with the twig diameter (r = 0.5258**). This trait also showed a positive relationship with the rate of girth increment on tapping though not significant.

Hevea, Intraxylary phloem, Protoxylem