Mathew,T; Stephen,D S; Aanandan,C K; Mohanan,P; K G Nair(Department of Electronics, 1994)
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Abstract:
A trapezoidal strip grating surface that eliminates specular
reflections almost over the entire X-band frequency range for TM
polarisation is reported. This new grating structure ovemmes the
bandwidth limitation of conventional rectangular strip grating
surfaces.
The dielectric ceramics BaNd2Ti3Oto, BaNd2Ti4O12 and BaNd2Ti5O14 have been prepared by
Conventional solid state ceramic route. The sintered ceramic samples have been characterized by
X-ray diffraction and Scanning Electron Microscopy (SEM). The dielectric properties in the
microwave frequency range have been measured using conventional microwave dielectric
resonator methods. The BaNd2Ti1O10, BaN2Ti4O12 and BaNd2Ti5O14 have dielectric constants
(Er) ~ 60, 84 and 77 respectively. They have relatively high quality factors
Rani, Joseph(Huthig & Wepf Verlag, Basel, June 5, 1991)
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Abstract:
Antioxidants were attached to hydroxy-terminated liquid natural rubber by modified
Friedel-Crafts alkylation reaction using anhydrous zinc chloride as catalyst. The rubber
bound antioxidants were found to be less volatile and less extractable compared to
conventional antioxidants. The bound antioxidants were tried both in latex compounds
and dry rubber compounds. The vulcanizates showed improved ageing resistance
compared to vulcanizates based on conventional antioxidants.
Rani, Joseph(Huthig & Wepf Verlag,Basel, April 16, 1993)
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Abstract:
Scrap latex products contain rubber hydrocarbon of very high quality, that is only
slightly crosslinked. A novel economic technique for converting such latex waste into
a processible material is developed. This paper reports the effect of adding this latex
reclaim to natural rubber. It is shown that latex reclaim can replace raw natural rubber
up to about 50 wt.% without affecting mechanical properties.
Rani, Joseph(Elsevier Science Limited, July 3, 1994)
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Abstract:
Diphenylamine was chemically attached to depolymerised natural rubber by
photochemical reaction. The rubber-bound diphenylamine was characterised
by TLC, HNMR, IR and TGA. The efficiency and permanence of the bound
diphenylamine was compared with conventional amine type antioxidant in
natural rubber vulcanizates. The rubber-bound diphenylamine was found to be
less volatile and less extractable compared to the conventional antioxidant.
The vulcanizates showed improved ageing resistance in comparison to vulcanizates
containing conventional antioxidant . Also, the presence of liquid
rubber-bound diphenylamine reduces the amount of plasticiser required for
compounding.
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.
Paraphenylenediamine and diphenylamine were chemically
attached to natural rubber during mastication . The rubber bound antioxidants
were characterized by TLC, 'H-NMR, IR and TGA. The efficiency and
permenance of these bound antioxidants were compared with a conventional
amine type antioxidant in filled natural rubber vulcanizates . The rubber
bound antioxidants were found to be less volatile and less extractable as compared
to conventional antioxidants. The vulcanizates showed improved ageing
resistance as compared to vulcanizates containing conventional antioxidants.
This semisolid rubber bound antioxidant can reduce the amount of plasticizer
required for compounding.
Para-phenylenediamine (PD) was chemically attached to depolymerized natural rubber by
a photochemical reaction . The rubber bound PD was characterized by TLC, 1H-NMR, IR,
and TGA. The efficiency and permanence of the bound PD were compared with conventional
antioxidants in NBR vulcanizates . The rubber bound PD was found to be less volatile and
more resistant to water and oil extraction . The vulcanizates showed improved aging resistance
in comparison to vulcanizates containing conventional antioxidants. The liquid rubber
bound antioxidant reduces the amount of plasticizer required for compounding
In natural rubber/high styrene resin microcellular sheets, part of
natural rubber was replaced by latex reclaim prepared from waste
latex products. The mechanical properties and cell structure of
the products were evaluated. It was found that latex reclaim can
replace about 30% of natural rubber without affecting the technical
properties of the microcellular sheets.