In Vembanad Lake and its confluent rivers (Kerala, India), the catches of Macrobrachium rosenbergii (de Man) were reported
to have dwindled to a mere 39 t in the 1980s from average landings of 300 t during the 1960s. This decline is due to the impact
of a number of human interventions affecting the ecosystem and, hence, the stocks of M. rosenbergii. Monitoring of landings in
1994-1995 and 1995-1996 indicates an improvement in catches. This paper discusses the reasons for the decline and revival
in stocks and suggestions for their replenishment.
ABSTRACT: The rheological and extrudate behaviour of natural rubber/latex
reclaim blends were evaluated using a capillary viscometer . The study shows
that the viscosity of natural rubber decreases marginally on the addition of
latex reclaim while the variation of viscosity with shear rate is not affected.
The temperature sensitivity of the blends is not affected significantly with the
addition of latex reclaim . The extrudates of natural rubber/latex reclaim
blends are smooth up to the addition of about 50 wt. percent latex reclaim in
filled natural rubber compounds.
Sunil K Narayanankutty(Taylor & Francis Inc., August 23, 2004)
[+]
[-]
Abstract:
The rheological characteristics of short Nylon-6 fiber-reinforced Styrene
Butadiene rubber (SBR) in the presence of epoxy resin-based bonding agent were
studied with respect to the effect of shear rate, fiber concentration , and temperature
on shear viscosity and die swell using a capillary rheonzeter. All the composites
containing bonding agent showed a pseudoplastic nature, which decreased
with increasing temperature. Shear viscosity was increased in the presence of
fibers. The temperature sensitivity of the SBR matrices was reduced on introduction
of fibers. The temperature sensitivity of the melts was found to be lower at
higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity
of the composites increased with shear rate. In the presence of epoxy resin
bonding agent the temperature sensitivity of the mixes increased. Die swell was
larger in the presence of bonding agent.
Sankar, T V; Ramachandran, A(John Wiley & Sons, 2002)
[+]
[-]
Abstract:
The gel strength, compressibility and folding characteristic of suwari (set) and kamaboko (set and cooked) gels prepared from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) surimi were examined to understand the occurrence of suwari and modori phenomena in surimi from major freshwater carps. Suwari setting of gels did not take place at lower temperatures. Suwari gels showed good gel strength at 50 °C for rohu and at 60 °C for catla and mrigal after 30 min setting time. Incubation for 60 min decreased the gel strength at 60 °C for rohu and catla. Setting at 25 °C followed by cooking at 90 °C increased the gel strength. Increased setting temperature, however, decreased the gel strength of cooked gels. Gel strength and compressibility data were supported by folding characteristics.
The rheological behavior of a short-polyester-fiber-filled polyurethane
elastomer composite containing different bonding agents
has been studied in the temperature range 120-160°C and in the
shear rate range 63-608 s-'. The composite with and without
bonding agents showed a pseudoplastic behavior which decreased
with the increase of temperature. Composites containing bonding
agents based on polypropyleneglycol and 4,4'-diphenylmethanediisocyanate
showed the lowest viscosity values at a particular
shear rate, whereas composites containing a glycerol- (GL) based
bonding agent showed the highest viscosity. The viscosity of the
composite decreased sharply after a particular temperature (140°C) and the fall was less drastic in the composite containing
a GL-based bonding agent.
Sunil K Narayanankutty(Taylor & Francis Inc., 2005)
[+]
[-]
Abstract:
The rheological characteristics of short Nylon-6 fiber reinforced styrene butadiene
rubber (SBR) were studied using a capillary rheometer. The study was done with
respect to the effect of shear rate, fiber concentration, and temperature on shear
viscosity and die swell. All the melts showed pseudoplastic nature, which
decreased with increasing temperature. Shear viscosity increased in the presence
of fibers. Introduction of fiber reduces the temperature sensitivity of the rubber
matrix. A reduction in die swell was found in presence of fibers.
Fully burnt rice hull (rice hull ash) was tried as a low cost filler in place of precipitated
silica in NBR/PVC based microcellular soles. The mechanical properties of the soles
containing silica and ash are found to be comparable. The expansion is marginally
higher in the presence of ash, which permits to reduce the amount of blowing agent. Cell
structure of microcellular sheets remains unchanged when silica is replaced by ash.
Nampoori, V P N; Kamalasanan, M N; Patel, M M(IOP, 1975)
[+]
[-]
Abstract:
Indium monofluoride was excited in a high-frequency discharge and the C-X system was photographed at a reciprocal dispersion of 0.3 AA mm-1 using a plane-grating spectrograph. Rotational analyses of the 0,0 1,0 2,2 3,3 4,4 2,4 3,5 4,6 and 5,7 bands have been carried out and the following molecular constants have been evaluated. Be'=0.2670(+or-3) cm-1, Be"=0.2628(+or-4) cm-1, alpha e'=0.0050(+or-4) cm-1, alpha e"=0.0020(+or-1) cm-1, De'=3.65(+or-5)*10-7 cm-1, De"=2.5(+or-3)*10-7 cm-1, beta e'=0.5(+or-2)*10-7 cm-1, beta e"=0.2(+or-1)*10-7 cm-1, re'=1.9672(+or-3) AA, re"=1.9853(+or-2) AA. The re" value agrees with the microwave absorption value 1.9854 AA.
Rani, Joseph(John Wiley & Sons. Inc, August 20, 1998)
[+]
[-]
Abstract:
ABSTRACT: Rubber seed oil was used as a multipurpose ingredient in natural rubber
(NR) and styrene butadiene rubber (SBR) compounds. The study shows that the oil,
when substituted for conventional plasticiser, imparts excellent mechanical properties
to NR and SBR vulcanizates. Further, it also improves aging resistance, reduces cure
time, increases abrasion resistance and flex resistance, and reduces blooming.
Rani, Joseph(John Wiley & Sons, Inc., October 22, 1997)
[+]
[-]
Abstract:
Rubber solutions were prepared and used for bonding wood pieces. The
effect of the variation of chlorinated natural rubber (CNR) and phenolformaldehyde
(PF) resin in the adhesive solutions on lap shear strength was determined. Natural
rubber and neoprene-based adhesive solutions were compared for their lap shear
strength. The storage stability of the adhesive prepared was determined. The change
in lap shear strength before and after being placed in cold water, hot water, acid,
and alkali was tested. The bonding character of these adhesives was compared with
different commercially available solution adhesives. The room-temperature aging
resistance of wood joints was also determined. In all the studies, the adhesive prepared
in the laboratory was found to be superior compared to the commercial adhesives.
Mohammed Yusuff, K K; Pearly Sebastian, Chittilappilly; Sridevi, N(Elsevier,Journal of Molecular Catalysis A: Chemical 286 (2008) 92–97, February 5, 2008)
[+]
[-]
Abstract:
Zeolite Y-encapsulated ruthenium(III) complexes of Schiff bases derived from 3-hydroxyquinoxaline-2-carboxaldehyde and 1,2-
phenylenediamine, 2-aminophenol, or 2-aminobenzimidazole (RuYqpd, RuYqap and RuYqab, respectively) and the Schiff bases derived from
salicylaldehyde and 1,2-phenylenediamine, 2-aminophenol, or 2-aminobenzimidazole (RuYsalpd, RuYsalap and RuYsalab, respectively) have
been prepared and characterized. These complexes, except RuYqpd, catalyze catechol oxidation by H2O2 selectively to 1,2,4-trihydroxybenzene.
RuYqpd is inactive. A comparative study of the initial rates and percentage conversion of the reaction was done in all cases. Turn over frequency
of the catalysts was also calculated. The catalytic activity of the complexes is in the order RuYqap > RuYqab for quinoxaline-based complexes and
RuYsalap > RuYsalpd > RuYsalab for salicylidene-based complexes. The reaction is believed to proceed through the formation of a Ru(V) species.
Sugunan, S; Benny, Thomas(Indian Journal of Chemistry, February , 1995)
[+]
[-]
Abstract:
The Setschenow parameter and thermodynamic
parameters of transfer of 2- and 4- hydroxybenzoic acids
from water to salt solutions have been reported. The data
have been rationalised by considering the structure
breaking effects of the ions of the salts, the localized
hydrolysis model, the internal pressure theory and the
theory of water structure due to Symons.
The Setschenow parameter and thermodynamic parameters of transfer of 2-, 3-, and 4-methylbenzoic acids
from water to salt solutions have been reported. The data have been rationalized by considering the structure breaking
effects of the ions of the salts, the localized hydrolysis model, and the internal pressure theory.
Sugunan, S; Benny, Thomas(Journal of Solution Chemistry, 1994)
[+]
[-]
Abstract:
The Setschenow parameter and thermodynamic parameters of transfer of
2-, 3- and 4-fluorobenzoic acid from water to salt solution are reported.
The data have been rationalized by considering the structure breaking effects of the ions of the salts, the localized hydrolysis model and the internal
pressure theory.
Kriashnan Nair, P R; Nandakumaran, V M; Ambika, G(Pramana, December , 1994)
[+]
[-]
Abstract:
We establish numerically the validity of Huberman-Rudnick scaling relation for
Lyapunov exponents during the period doubling route to chaos in one dimensional maps. We
extend our studies to the context of a combination map. where the scaling index is found to
be different.
Sunil K Narayanankutty(Gordon and Breach Science Publishers, December 10, 1991)
[+]
[-]
Abstract:
Tear and wear properties of short kevlar fiber, thermoplastic polcurethane (TPU) composite with
respect to fiber loading-and fiber onentation has been studied and the fracture surfaces were examined
under scanning electron microscope (SEM). Tear strength first decreased up to 20 phr fiber loading
and then gradually increased with increasing fiber loading. Anisotropy in tear strength was evident
beyond a fiber loading of 20 phr. Tear fracture surface of unfilled TPU showed sinusoidal folding
characteristics of high strength matrix. At low fiber loading the tear failure was mainly due to fibermatrix failure whereas at higher fiber loading the failure occurred by fiber breakage. Abrasion loss
shows a continuous rise with increasing fiber loading, the loss in the transverse orientation of fibers
being higher than that in the longitudinal orientation. The abraded surface showed lone cracks and
ridges parallel to the direction of abrasion indicating an abrasive wear mechanism. In the presence of
fber the abrasion loss was mainly due to fiber low.
Chandran, A R; Gopikrishna, M; Aanandan, C K; Mohanan, P; Vasudevan, K(Progress In Electromagnetics Research, 2007)
[+]
[-]
Abstract:
The scattering behaviour of fractal based metallodielectric structures loaded over metallic targets of different shapes such as flat plate, cylinder and dihedral corner reflector are investigated for both TE and TM polarizations of the incident wave. Out of the various fractal structures studied,square Sierpinski carpet structure is found to give backscattering reduction for an appreciable range of frequencies. The frequency of minimum backscattering depends on the geometry of the structure as well as on the thickness of the substrate. This structure when loaded over a dihedral corner reflector is showing an enhancement in RCS for corner angles other than 90◦.
A comprehensive overview of reclamation of cured rubber with special emphasis on latex reclamation is depicted in this
paper. The latex industry has expanded over the years to meet the world demands for gloves, condoms, latex thread, etc.
Due to the strict specifications for the products and the unstable nature of the latex as high as 15% of the final latex
products are rejected. As waste latex rubber (WLR) represents a source of high-quality rubber hydrocarbon, it is a
potential candidate for generating reclaimed rubber of superior quality. The role of the different components in the
reclamation recipe is explained and the reaction mechanism and chemistry during reclamation are discussed in detail.
Different types of reclaiming processes are described with special reference to processes, which selectively cleave the cross
links in the vulcanized rubber. The state-of-the-art techniques of reclamation with special attention on latex treatment are
reviewed. An overview of the latest development concerning the fundamental studies in the field of rubber recycling by
means of low-molecular weight compounds is described. A mathematical model description of main-chain and crosslink
scission during devulcanization of a rubber vulcanizate is also given.