Rani, Joseph(John Wiley & Sons,Inc., July 31, 1998)
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Abstract:
ABSTRACT: Nylon tire cord (1680/2) was dipped in different adhesives based on resorcinol
formaldehyde resin and latex (RFL) and was bonded to natural rubber-based
compounds. The resin-rubber ratio in the RFL adhesive was optimized. The variation
of pull-through load was studied by varying the drying and curing temperature of the
dipped nylon tire cord. RFL adhesive based on vinylpyridine latex was found to have
better rubber-to-nylon tire cord bonding, compared with the one based on natural
rubber latex. Addition of a formaldehyde donor into the RFL adhesive/rubber compound
improves adhesion.
Bindhu, Jacob; Dr.Sugunan, S(Cochin University of Science & Technology, February , 1998)
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Abstract:
In this thesis an attempt has been made to compare the catalytic activity of
some medium and large pore zeolites in a few alkylation and acylation reactions. The
work reported in the present study is basically centered around the following zeolites
namely, ZSM-5, mordenite, zeolite Y and beta. The major reactions carried out were
benzoylation of o-xylene, propionylation of toluene and anisole and benzylation of 0xylene.The programme involves the synthesis, modifications and characterization of
the zeolite catalysts by various methods. The influence of various parameters such as
non-framework cations, Si/AI ratio of zeolites, temperature of the reaction, catalyst
concentration, molar ratio of the reactants and recycling of the catalysts were also
examined upon the conversion of reactants and the formation of the desired products
in the alkylation / acylation reactions.The general conclusions drawn by us from the results obtained are summarized
in the last chapter of the thesis. Zeolite beta offers interesting opportunities as a
potential catalyst in alkylation reactions and the area of catalysis by medium and large
pore zeolites is very fascinating and there is plenty of scope for further research in this
field. Moreover, zeolite based catalysts are effective in meeting current industrial
processing and more stringent environment pollution limits.
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology
Issac, R C; Varier, G K; Gopinath, P; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Springer Berlin / Heidelberg, 1998)
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Abstract:
A silver target kept under partial vacuum conditions
was irradiated with focused nanosecond pulses at
1:06 mm from a Nd:YAG laser. The electron emission monitored
with a Langmuir probe shows a clear twin-peak distribution.
The first peak which is very sharp has only a small delay
and it indicates prompt electron emission with energy as
much as 60 5 eV. Also the prompt electron emission shows
a temporal profile with a width that is same as that for the
laser pulse whereas the second peak is broader, covers several
microseconds, and represents the low-energy electrons
(2 0:5 eV) associated with the laser-induced silver plasma
as revealed by time-of-flight measurements. It has been found
that prompt electrons ejected from the target collisionally
excite and ionize ambient gas molecules. Clearly resolved
rotational structure is observed in the emission spectra of
ambient nitrogen molecules. Combined with time-resolved
spectroscopy, the prompt electrons can be used as excitation
sources for various collisional excitation–relaxation experiments.
The electron density corresponding to the first peak is
estimated to be of the order of 1017 cm?--3 and it is found that
the density increases as a function of distance away from the
target. Dependence of probe current on laser intensity shows
plasma shielding at high laser intensities.
Riju C, Issac; Pramod, Gopinath; Geetha K, Varier; Nampoori, V P N; Vallabhan, C P G(American Institute of Physics, July 13, 1998)
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Abstract:
Laser-induced plasma generated from a silver target under partial vacuum conditions using the
fundamental output of nanosecond duration from a pulsed Nd:yttrium aluminum garnet laser is
studied using a Langmuir probe. The time of flight measurements show a clear twin peak
distribution in the temporal profile of electron emission. The first peak has almost the same duration
as the laser pulse while the second lasts for several microseconds. The prompt electrons are
energetic enough ('60 eV) to ionize the ambient gas molecules or atoms. The use of prompt
electron pulses as sources for electron impact excitation is demonstrated by taking nitrogen, carbon
dioxide, and argon as ambient gases.