Rani, Joseph(Wiley lnterScience, February 12, 2006)
[+]
[-]
Abstract:
It is observed that reclamation of natural rubber
latex based rubber using 2,2'-dibenzamidodiphenvldisulphide
as reclaiming agent is an optional methodology for
recycling of waste latex rubber (WLR). For progressive replacement
of virgin natural rubber by the reclaim, two alternatives
curing system were investigated: adjustment or reduction of
the curing system with increasing reclaim content, to compensate
for the extra amount of curatives brought along by the reclaim.
For fixed curing system, as if the reclaim were equivalent
to virgin NR. The cure behavior, final crosslink density
and distribution, mechanical properties, and dynamic
viscoelastic properties of the blends with reclaimed WLR are
measured and compared with the virgin compound. The morphology of the blends, sulfur migration, and final distribution
are analyzed.The mechanical and dynamic viscoelastic
properties deteriorate for both curing systems, but to a lesser
extent for fixed curing system compared to adjusted curing
system. With the fixed cure system, many properties like tensile
strength and compression set do still deteriorate, but tan 6
and Mrrr„/Murxr, representative for the rolling resistance of tires
are improved. On the other hand, with the adjusted cure system
both mechanical and dynamic properties still deteriorate.
A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized
at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye
concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is
attractive on account of its reusability.
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.
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.
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.
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.
Rani, Joseph(OPA (Overseas Publishers Association), December 3, 1996)
[+]
[-]
Abstract:
Filled and gum compounds of Isobutylene-Isoprene rubber were extruded through a
laboratory extruder at various feeding rates, different temperatures and revolutions per
minute. The extruded compounds were vulcanized up to their optimum cure times and
the mechanical properties of the vulcanizates were determined. The properties suggest
that there is a particular feeding rate in the starved fed region, which results in maximum
mechanical properties. The study shows that running the extruder at a slightly
starved condition is an attractive means of improving the physical properties.
Filled compounds of natural rubber, isobutylene-isoprene rubber
and styrene-butadiene rubber compounds were extruded through a laboratory
extruder by varying the feeding rate at different temperatures and revolutions
per minute. The extruded compounds were vulcanized up to their optimum cure
times and the mechanical properties of the vulcanizates were determined. The
properties suggest that there is a particular feeding rate in the starved fed region
which results in maximum mechanical properties. The study shows that running
the extruder at a slightly starved condition is an attractive means of improving
the physical properties.
Gum and filled compounds of styrene-butadiene rubber are extruded
through a laboratory extruder by varying the feeding rase at different temperatures
and screw speed (rpm). The extruded compounds are vulcanized
up4o their optimum cure times and the mechanical properties of the vulcanizates
are determined. From the properties data obtained it Is concluded that
there is a specific feeding rate wit in the starved fed region, which results In
maximum Improved mechanical properties . The enhancement In properties
is found to be due to better thermal and shear homogeneity.
Rani, Joseph(Hitthig & Wepf Verlag, Basel, October 13, 1986)
[+]
[-]
Abstract:
A carbon black filled 50/50 natural rubber (NR)/styrene-butadiene rubber (SBR)
blend is vulcanized using several conventional curing systems designed by varying the
amounts of sulphur and accelerator. The cure characteristics and the properties of the
vulcanizates are compared. The quantity and quality of crosslinks in each case are
evaluated by chemical probes to correlate them with the properties.
Rani, Joseph(John Wiley & Sons,Inc., December 29, 1997)
[+]
[-]
Abstract:
ABSTRACT: The electrical conductivity of silicone rubber vulcanizates containing carbon
blacks [e.g., acetylene black, lamp black, and ISAF (N-234) black] were investigated.
The change in electrical conductivity with varying amounts of carbon blacks and the
temperature dependence was measured. The mechanical properties like tensile
strength, tear strength, elongation at break, hardness, etc., of the vulcanizates were
determined. A comparative study of the electrical conductivity of the composites revealed
that the electrical conductivity of the composites made with acetylene black was
higher than that of the composites made of other blacks.
Carbon Black is incorporated In natural rubber latex in , the presence of
polyethylene glycol. The dispersion of carbon blade in the vulcanizatea is
analyzed using polaroid M.4 land camera The mechanical properties of the
carbon black meeterbatched NR/SBR blend Is compared with that of conventional
NR/SBR blend before and after ageing , The resilience, flex resistance
and hardness are found to be superior for N-LCMISBR compounds.
The compression set and abrasion resistance are comparable for both types
of blends . The processebiity and die swell of these blends at different shear
rates are also compared.
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.
Rani, Joseph(Elsevier Science Limited, July 3, 1994)
[+]
[-]
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.
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
Studies conducted on butadiene-acrylonitrile copolymer (NBR)/poly(vinyl chloride) (PVC)
blends at different temperatures indicate that an optimum temperature exists for the formation
of a particular blend. The mechanical properties of the blends confirm this observation.
PVC stabilizer based on, magnesium oxide , zinc oxide, and stearic acid was found to be very
useful in NBR/PVC blends.
Rani, Joseph(Huthig & Wepf Verlag, Basel, June 5, 1991)
[+]
[-]
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(John Wiley & Sons,Inc., July 31, 1998)
[+]
[-]
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.