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)
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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.
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)
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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.
Eby Thomas, Thachil; Renju, V S; Vidya Francis, K F; Ayswarya, E P(Elsevier, April , 2012)
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Abstract:
This paper presents the results of a study on the use of rice husk ash (RHA) for property modification of
high density polyethylene (HDPE). Rice husk is a waste product of the rice processing industry. It is used
widely as a fuel which results in large quantities of RHA. Here, the characterization of RHA has been done
with the help of X-ray diffraction (XRD), Inductively Coupled Plasma Atomic Emission Spectroscopy
(ICPAES), light scattering based particle size analysis, Fourier transform infrared spectroscopy (FTIR)
and Scanning Electron Microscope (SEM). Most reports suggest that RHA when blended directly with
polymers without polar groups does not improve the properties of the polymer substantially. In this
study RHA is blended with HDPE in the presence of a compatibilizer. The compatibilized HDPE-RHA blend
has a tensile strength about 18% higher than that of virgin HDPE. The elongation-at-break is also higher
for the compatibilized blend. TGA studies reveal that uncompatibilized as well as compatibilized HDPERHA
composites have excellent thermal stability. The results prove that RHA is a valuable reinforcing
material for HDPE and the environmental pollution arising from RHA can be eliminated in a profitable
way by this technique.
Rani, Joseph(John Wiley & Sons. Inc, August 20, 1998)
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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)
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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.
Sunil,K Narayanankutty(Gordon and Breach Science Publishers, December 10, 1991)
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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.
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.
The self adhesion behaviour of thermoplastic polyurethane (TPU) in itself and its
composite with short Kevlar fibre with respect to contact time, temperature, pressure, and fibre
loading has been studied. The adhesion strength showed two linear increments of different slopes
with respect to the square root of time: with temperature and pressure of contact, the adhesion
strength was improved. The maximum strength was obtained with 20 phr of short fibre in only one of
the mating substrates in the peel test sample. The duration for wetting and diffusion was shifted to
longer time intervals with fibres loaded in both the substrates.
Abraham, Thomas N; George,K E(Taylor & Francis, 2007)
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Abstract:
Short fiber reinforced thermoplastics have generated much
interest these days since fibrous materials tend to increase both
mechanical and thermal properties, such as tensile strength, flexural
strength, flexural modulus, heat deflection temperature, creep
resistance, and some times impact strength of thermoplastics. If
the matrix and reinforcement are both based on polymers the composite
are recyclable. The rheological behavior of recyclable composites
based on nylon fiber reinforced polypropylene (PP) is reported
in this paper. The rheological behavior was evaluated both using a
capillary rheometer and a torque rheometer. The study showed that
the composite became pseudoplastic with fiber content and hence
fiber addition did not affect processing adversely at higher shear
rates. The torque rheometer data resembled that obtained from
the capillary rheometer. The energy of mixing and activation energy
of mixing also did not show much variation from that of PP alone.
Rani, Joseph(OPA (Overseas Publishers Association), December 3, 1996)
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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.
Reactive extrusion is an attractive means of polymer processing since the shaping
and reaction take place in a single operation. In this paper we report the silane
grafting of polyethylenes in a single screw extruder. The optimum conditions for
silane grafting, viz. temperature, shear rate, silane and DCP concentrations, were
determined on a torque rheometer and then actual extrusion was performed
using these conditions. The study shows that an optimum low level of grafting/
crosslinking can be introduced into polyethylene during its extrusion for better
mechanical behavior and=or thermal stability without affecting the processability.
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.
Sunil,K Narayanankutty(Technomic Publishing Co., Inc., April , 1998)
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Abstract:
The stress relaxation behavior of polyurethane elastomer and
short polyester fiber filled elastomer composites with and without bonding
agents at different strain levels and strain rates was studied. It was found that
these compounds exhibit a multistage relaxation mechanism and that the rate
of relaxation and cross-over time depend on the strain level and strain rate.
The incorporation of fibers reduced the stage-I relaxation rate and increased
the cross-over time of the gum vulcanisate. A higher rate of relaxation (first
stage) was shown by the composites with longitudinal fiber orientation and
composites with bonding agents.
Rani, Joseph(Hitthig & Wepf Verlag, Basel, October 13, 1986)
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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.
Sunil,K Narayanankutty(Sage Publications, April , 2002)
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Abstract:
Cure characteristics and mechanical properties of acrylonitrile
butadiene rubber/reclaimed rubber blends were studied. Minimum torque,
(ma)dmum -minimum) torque, scorch time, cure time and cure rate decreased in
presence of reclaimed rul3ber. Tensile strength, elongation at break and
compression set increased'with increase in reclaim content. Resilience and
abrasion resistance decreased with reclaim loading. Heat build up was higher for
the blends. The ageing resistance of the blends was inferior to that of the gum
compound.