Natural Rubber –
Alternate Possibilities
Dr. S.N. Chakravarty
KPS Consultants & Impex Pvt. Ltd.,
New Delhi
(e.mail – kpsimpex@airtelmail.in)
Natural rubber, obtained almost exclusively from
Hevea brasiliensis tree, a unique biopolymer of
strategic importance in many of its most significant
applications, cannot be replaced by SR alternatives.
Several pressing motives lead to search for alternative
sources of NR.
NR price is continuously rising since last about a year
causing serious problem to the rubber products
manufacturer. Now even international price of NR has
become higher than the national price level - becoming
difficult to contain price of finished product & maintain
quality level simultaneously.
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As per latest IRSG report Global rubber consumption
reached 23.1 million MT (June 2009 – June 2010) , +
11.2% over earlier year. NR consumption rose by 0.3
million MT in 2nd qtr of 2010
& + 7.9% YOY
consumption growth in June 2010. Global NR supply
fell back in 2nd qtr of 2010 with production growth
slowing down from 4.9% to 3.5%. NR market moved
into deficit in 2010.
Global rubber out put reached 23 million MT in the 12
months to June 2010, compared to 21.2 million MT
during same period in 2009 giving an increase of 8.9%
in the out put. Global SR production was 13.3% higher
in the period of 12 months to June 2010 compared to
same period in 2009.
3
NR production in India during 2009 -10 was 831,400 MT
compared to 864,500 MT during 2008 – 09 & which was 3.8%. India emerged as the second largest consumer of
NR after China by overtaking USA & Japan. Total
consumption was 930,565 MT (+ 6.8% ) as against
871,720 MT during the previous year.
Production of SR in India during 2009-10 increased to
106,743 MT from 96,739 MT during 2008-09 , ( + 10.3%).
SR consumption increased to 347,710 MT during 2009-10
( + 18.7%) compared to previous year.
Gap between domestic NR production & consumption in
2010 – 11 is likely to be around 175,000 MT & may grow to
over 200,000 MT as per ATMA.
4
Potential shortages of supply due to increasing demand
& changes in land use, &
general trend towards
replacement of petroleum-derived chemicals with
renewable are forcing users of NR to look into
alternative products. Two plant species have received
considerable attention as potential alternative sources of
NR, Mexican shrub Guayule & Russian Dandelion.
Reduction in world production of NR to the extent of
about 5% last year coupled with increasing demand of
NR due to increased volume of steel radial tyre
production are major factor of NR price increase. Global
NR consumption is expected to fall 5.5% in 2009.
5
NR output in seven member countries India, China,
Vietnam & Sri Lanka as well as three top producers fell
5.1 percent to 8.67 million MT in 12 months ended Sept.
30, 2009, compared to 9.13 million MT in 2008.
Malaysian NR output plummeted 23.6 % to 865,000 MT
from the 1.07 million MT in 2008.
NR production also fell in India (10.8 %), Thailand (8.3
%), Indonesia (6.3 %), Sri Lanka remained even at
129,000 MT, while China saw a 28.5 % increase to
646,000 MT.
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NATURAL RUBBER PRICE
November 2008
Rs.78 / Kg
November 2009
Rs.113 / Kg
November 2010
Rs.202 / Kg
December 2010
Rs.206 / Kg
January 2011
Still increasing
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Value of NR produced in 2010 – Rs. 14,778 Crore
An increase of around 75% compared to 2009
Gains to small growers which account for 94% of total
NR produced.
Productivity was 1776 Kg / hector / year
Consumption of NR in India registered a fall of 1.3% in
Dec. 2010
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Are there any alternative to NR ?
Are there any way to reduce dependence on NR by
conserving its usage & suitably modify compound
without sacrificing the performance of the product?
What are the possibilities to conserve NR & reduce
its usage in different products ?
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Press release of 2nd December 2010.
Bridgestone Corp. Plans to cut rubber consumption
by 50% over the next 10 years.
Bridgestone is in the process of developing technology
that will decrease the use of both NR & SR
in each Bridgestone tyre by half.
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GM Rubber
Field trials
with Genetically Modified Rubber are
expected to start next year by RRII in Kerala &
Maharashtra.
GM Technology will make rubber plantation hardy &
more capable of withstanding weather pattern. GM
Rubber will be more sturdy plant, may give 10% more
yield than existing verities. GM Rubber to lead
additional revenue of Rs. 300 Crore / Year as per RRII.
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What are the alternate to NR ? Possibilities are :
1.
Blends with other Elastomers like
GP SR - SBR, BR, IR, NBR / PVC etc.
2.
Go for usage of specialty SR like EPDM
& CPE for particular application
3.
Guayule Rubber
4.
Dandelion
5.
Conserving NR by reducing RHC in
compound without affecting properties for
different application .
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Blends with other elastomers like GP SRSBR, BR, IR, NBR / PVC.
It is common & widely used practice of blending NR
with SBR, BR etc - should go for higher dosage level of
SR or even 100% level of SR in different compounds.
Usage of synthetic Poly-isoprene rubber in India is
negligible. NR, IR provide certain advantages like no
need for mastication – thus saving of energy & machine
capacity , transparency & lower requirement of
pigments etc.
Recently sample tyres made with Bio-Isoprene rubber
with renewable biomass , alternative to Petrochemically
produced SR. This tyre was demonstrated in
Copenhagen during Climate Conference. Bio-Isoprene
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offers vast potential in other applications.
Go for usage of specialty SR like EPDM & CPE for
particular application , often in blend with NR.
Different products where either 100% SR could be used
in place of NR, e.g. rubber sheeting / electrical mats,
weather / water proof sheet etc. which could be made
with EPDM - price is close to NR, effective compound
cost could be lower as EPDM is heavily extended by
filler and process oil.
For specific application NR can be blended with CPE &
thus improve processing & quality level of product, e.g.
coated fabric, tubing , hose etc. - such blend will
process better than NR alone, compound safety &
impart better heat resistance & fire resistance
character.
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Guayule Rubber
This is known since long & serious attempts have been
made by different countries to produce rubber out of this
plant. Major efforts were put by USA / Mexico & large fund
was invested for this alternate to NR. However, its volume
& commercial usage has remained very restricted.
The chemical structure of both guayule and hevea rubber
is entirely cis-1,4-polyisoprene.
The molecular weight distributions (MWD) of guayule and
hevea rubber are roughly comparable.
Green strength of guayule rubber is intermediate between
that of hevea rubber and synthetic cis-1,4-polyisprene. 15
In all processes, the guayule bush must be ground into
small particles to allow plant cells to be exposed to an
organic solvent to dissolve resin or rubber or water to
coagulate the latex inside the plant cells into large
aggregates of rubber, called “worms”.
The preparation of suitable vulanisates with Guayule
rubber has always been questionable.
Basically, the Guayule rubber stock containing carbon
black gave lower modulus, tensile strength, rebound,
hardness, and tear strength than SMR. However, with the
exception of tear strength, the properties would be
sufficient for most industrial compounds.
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Dandelion
Researchers are therefore turning to other sources –
such as the Russian dandelion.
The dandelions that are actually needed to produce
rubber are from the Taraxacum koksaghyz family, a plant
that grows in Uzbekistan and it is also known as the
Russian dandelion. Currently the researchers from
Oregon State University are working with the Ohio
scientists to develop seeds that might increase yields.
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Conserving NR by reducing RHC in a compound
without affecting properties for different
application by judicious selection of particular
filler type & its dosage level.
Serious thoughts should be given in this
direction, both in case of tyre & non tyre
products.
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Crumb rubber and Reclaim rubber
are two well known & widely used alternate. These
alternate possibilities give certain technical advantages
besides cost aspect. - are used in tyre and non – tyre
industry in different compounds like calandering &
extrusion compound.
Crumb rubber of 80 mesh can be used at higher
proportion in a compound. Similar advantage provided
by chemically treated crumb rubber.
Also, with finer reclaim rubber higher proportion can be
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used in different compounds reducing NR level.
Fillers
Certain fillers like Nano filler e.g. Nano Calcium
Carbonate at specific dosage level have been studied &
practically tried in different rubber & Latex compounds
which show
possibility of reduction of RHC in
compound without affecting properties. This Nano filler
is less than 50% of NR price.
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Nano CaCO3 is very fine particle ( 40 to 100 nm ) &
when used in rubber compound imparts better air
impermeability & reinforces the compound at very low
dosage of 8 to 10 phr level - products like NR based
cycle tubes & latex based bladder By using 8 to 10 phr
of such filler in to existing compound one does not
loose properties but simultaneously reduces rubber
content by nearly half the price filler.
21
Certain natural occurring materials like agricultural
products ( Corn Starch , Rice husk etc.) have been used
in rubber products compound.
Goodyear used
corn starch in some of it’s tyre
compound like Carcass compound. This can provide an
opportunity for cost reduction of NR based compound.
Certain waste material can be used in non-critical
products thus reducing rubber content in the
compound.
22
Short cellulose fiber have been studied as reinforcing
fillers in rubber composites during last few decades.
Micro-crystalline cellulose (MCC) was used as a filler
replacing part of silica filler in a SBR + BR based
compounds .
Of the platelet type fillers available, including nano sized
materials, glass flake is one of the easiest to mix into
rubber compounds & once in the compound remain as a
stable entity. Glass flake of very fine size was mixed into
inner liner compound and aligned in the direction of
calandering to increase the diffusion path of gas
molecules across the rubber layer. For a relatively low
loading of glass flake, the permeation rate was reduced
significantly by 45%.
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Some thoughts about RHC reduction in tyre :
1. Compound - to improve Abrasion & Cut resistance
(Tear ), lower heat development ( Resilience ), Wet
grip etc.
Enabling to reduce NSD & Tyre Weight
2. Usage of chopped fibers ( e.g. Aramid Fiber ) –
application in RT, OTR, Mining , Industrial tyres.
3. CB + Silica + Silane system
4. Nano filler usage
5. New SR type with higher MWD & MW, Cis content –
better properties
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6. Higher Pressure curing
7. Electron Beam Radiation curing.
8. Reduced tyre weight – lower NSD, No. of Plies
(higher strength fiber ), Reduce compound weight in
Tread & Carcass.
9. Usage
of
replenishable
materials
&
no
Petrochemicals.
10. Better interaction between Silica & Polymer – usage
of Epoxidized NR.
11. Improvement of properties with filler dispersion
(additive such as Nanoprene )
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12. Solid Glass spheres derived from beneficated
pulverized fuel ash (Mini Tron 7 ) used to partially
substitute pptd. Silica in passenger tyre tread.
13. High aspect ratio Talc – green Tyre inner liner (good
barrier & thermal properties, lower rolling resistance
& cost saving)
14.
Waste fibre for NR / SBR composite
15.
Energy efficiency – innovations needed for
reducing energy intensity in manufacturing process.
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THANK YOU
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