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Natural Rubber – Alternate Possibilities. Dr. S.N. Chakravarty KPS Consultants & Impex Pvt. Ltd., New Delhi (e.mail – firstname.lastname@example.org).
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Natural Rubber – Alternate Possibilities Dr. S.N. Chakravarty KPS Consultants & Impex Pvt. Ltd., New Delhi (e.mail – email@example.com)
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.
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.
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.
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.
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.
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
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
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 ?
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.
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.
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 .
Blends with other elastomers like GP SR- SBR, 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 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.
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.
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.
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.
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.
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 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.
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.
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.
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%.
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 • Usage of chopped fibers ( e.g. Aramid Fiber ) – application in RT, OTR, Mining , Industrial tyres. • CB + Silica + Silane system • Nano filler usage • New SR type with higher MWD & MW, Cis content – better properties
Higher Pressure curing • 7. Electron Beam Radiation curing. • 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 )
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) • Waste fibre for NR / SBR composite • 15. Energy efficiency – innovations needed for reducing energy intensity in manufacturing process.