Mailadil,Sebastian T; Sam,Solomon; Ravindran,Ratheesh(Regional Research Laboratory, April , 1999)
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Abstract:
Microwave ceramic dielectric resonators (DRs) based on RETiNbO6
(RE = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, and Yb)
have been prepared using the conventional solid -state ceramic
route. The DR samples are characterized using XRD and SEM
methods. The microwave dielectric properties are measured
using resonant methods and a net work analyzer . The ceramics
based on Ce, Pr, Nd, and Sin have dielectric constants in the
range 32-54 and positive coefficient of thermal variation of
resonant frequency (r,). The ceramics based on Gd, Tb, Dy, Y.
and Yb have dielectric constants in the range 19-22 and
negative Tf
Lynta, Job; Dr. Rani, Joseph(Cochin University of Science & Technology, January , 1999)
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Abstract:
The primary objective of this investigation has been to develop more efficient and
low cost adhesives for bonding various elastomer combinations particularly NR to NR,
NR/PB to NR/PB, CR to CR,NR to CR and NR to NBR.A significant achievement of the investigation was the development of solventless
and environment friendly solid adhesives for NR to NR and NR/PB to NR/PB particularly
for precured retreading. Conventionally used adhesives in this area are mostly NR based
adhesive strips in the presence of a dough. The study has shown that an ultra accelerator
could be added to the dough just before applying it on the tire which can significantly
bring down the retreading time resulting in prolonged tire service and lower energy
consumption. Further latex reclaim has been used for the preparation of the solid strip
which can reduce the cost considerably.Another significant finding was that by making proper selection of the RF resin,
the efficiency and shelflife of the RFL adhesive used for nylon and rayon tire cord dipping
can be improved. In the conventionally used RFL adhesive, the resin once prepared has to
be added to the latex within 30 minutes and the RFL has to be used after 4 hours maturation
time maximum shelf life of the RFL dip solution being 72 hours. In this study a
formaldehyde deficient resin was used and hence more flexibility was available for mixing
with latex and maturing. It also has a much longer shelf life. In the method suggested in this study, formaldehyde donors were added only in the rubber compound to make up the
formaldehyde deficiency in the RFL. The results of this investigation show that the pull
through load by employing this method and the conventional method are comparable.
This study has also shown that the amount of RF resin with RFL adhesive can be partially
replaced by other modifying agents for cost reduction.Cashew nut shell liquid (CNSL) resin can
be employed for improving the bonding of dipped nylon and rayon cord with NR.Since
CNSL resin cannot be added in the dip solution since it is not soluble in water, it was
added in the rubber compound. The amount of wood rosin in the rubber compound can be
reduced by using CNSL resin.Another interesting result of the investigation was the use of CR based adhesive
modified with chlorinated natural rubber for CR to CR bonding. Addition of chlorinated
natural rubber was found to improve sea water resistance of CR based adhesive. In the
bonding of a polar rubber like nitrile rubber or polychloroprene rubber to a non polar
rubber like natural rubber, an adhesive based on polychloroprene rubber was found to be
effective.
Description:
Department of
Polymer Science and Rubber Technology, Cochin University of Science and
Technology
Sugunan, S; Bindhu, Jacob; Binoy, Jose(Indian Journal of Chemistry, October , 1999)
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Abstract:
The results of a detailed study of the propionylation of anisole over various medium and large pore zeolites such as H-ZSM-5, H-beta, H-Na-beta. H-mordenite. H-Y and H-RE- Y are presented and discussed. In addition, homogenous catalysts and amorphous Si02-Al2O3 are also included for comparison, The catalyst and process parameters are optimised to enhance the conversion of propionyl chloride(PC) and selectivity to 4-methoxypropiophenone(4-MOPP).
Sugunan, S; Seena, C R K(Indian Journal of Chemistry, September , 1999)
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Abstract:
The surface acidity/ basicity of TiO2 (rutile) and its sulphate modified
form have been determined by titration method using Hammett
indicators after activation at different temperatures. The electron
donating properties of these oxides are also studied from the adsorption
of electron acceptors of different electron affinity values. The
data have been correlated with the catalytic activity of these oxides
towards esterification of acetic acid using n-butanol, reduction of
cyclohexanone in isopropanol and oxidation of cyclohexanol in benzophenone.
Catalytic activity for esterification and oxidation reaction
parallels the acidity while that for reduction reaction parallels
the basicity of these oxides.
Abdul Khader, K M; Dr. Mohandas, A(Cochin University of Science & Technology, 1999)
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Abstract:
Instead of developing easily degradable, and low-priced insecticides, we are
going after highly sophisticated chemicals. Here, an attempt is being made to develop
safer formulations of insecticides of botanical origin.
Different parts of the plants were chosen based on their use in countryside and
villages The dried plant materials were extracted with petroleum ether, and were
applied on Tribolium castaneum. The results were statistically analysed.
The active principles from Croton tigilium and Leea sambucina, the most
potential plants, were isolated using Column Chromatography, TLC, and Hydrolysis.
The isolated principles were analysed spectroscopically ( UV-Vis., IR, NMR,
and MS ) to identify their chemical nature. The active principles from Leea and
Croton were identified as a cholisterate derivative and a phorbol derivative
respectively.
In order to ascertain the environmental combatibility of the principles,
degradation by soil bacteria was studied.
The isolated principles were made into three type of formulations using
stabilizers .The formulations were applied on Snake gourd semilooper, Pulse beetle,
and mosquito larvae. Also the biocidal activity of the formulations was studied.
Both Leea derivative and Croton derivative could be formulated effectively
and were effective against a variety of pests. They are eco-friendly, as there is no
artificial chemicals involved.
Description:
School of Environmental Studies,
Cochin University of Science And Technology
Vallabhan, C P G; Thomas, J; Pillai, V N S; Nampoori, V P N(Springer, 1999)
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Abstract:
The electrical conductivity and thermal diffusivity of pristine and iodine doped vanadyl naphthalocyanine (VONc) were studied. In the pristine sample, the temperature dependence was very weak below 300 K. The increase in conductivity at higher temperature must be due to an enhancement in carrier density with increase in thermal energy. The electrical conductivity of VONc increased when doped with iodine. The behavior of VONcI indicated that considerable changes have occurred in the electronic environment of the molecule as a result of doping. Iodine doping enhanced the thermal diffusivity of VONc. The increase in thermal diffusivity of the iodine doped sample may be due to the disorder of iodine atoms occupying the channels in one dimensional lattices.
Sankara Raman, S; Nampoori, V P N; Vallabhan, C P G; Saravanan, N; Mohammed Yusuff, K K(Springer, 1999)
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Abstract:
The thermal diffusivities of some polystyrene supported Schiff complexes of Co(II) and Cu(II) were determined by the laser induced photoacoustic technique. The effect of metal as well as the halogen part on thermal diffusivity of polymer supported complexes was studied. The thermal diffusivity of Co complexes increases while it decreases in Cu complexes with Cl, Br and I substitutions, respectively.