Rubber: History, Rubber: History,

Properties and StructureProperties and Structure

Katrina CzenkuschKatrina Czenkusch

Physical Chemistry of MacromoleculesPhysical Chemistry of Macromolecules

April 9, 2009April 9, 2009

Definition of Rubber/Definition of Rubber/ElastomerElastomer

�� ““A material that can be stretched to at A material that can be stretched to at

least twice its original length and will least twice its original length and will

retract rapidly and forcibly to substantially retract rapidly and forcibly to substantially

its original dimensions upon release of the its original dimensions upon release of the

force.force.””

Rosen; p389Rosen; p389

Natural Rubber: Where?Natural Rubber: Where?

�� Hevea brasiliensisHevea brasiliensis–– Most common sourceMost common source

–– Responds to wounding by producing Responds to wounding by producing more latexmore latex

–– Produces cisProduces cis--1,41,4--polyisoprenepolyisoprene

–– Native to Amazon RainforestNative to Amazon Rainforest

�� GuttaGutta--PerchaPercha–– Produces transProduces trans--1,41,4--polyisoprenepolyisoprene

–– Native to MalaysiaNative to Malaysia

�� Rubber Plantations in MalaysiaRubber Plantations in Malaysia

Pictures: http://en.wikipedia.org/wiki/Natural_rubber

Rubber in PrehistoryRubber in Prehistory

�� 60 million BC 60 million BC –– Europe Europe --rubberrubber--producing plantsproducing plants

�� First millennium BC First millennium BC –– Mexico Mexico ––First evidence of the First evidence of the Mesoamerican ballgameMesoamerican ballgame

�� 66thth century century –– Mexico and Central Mexico and Central America America –– Aztecs/MayansAztecs/Mayans

–– BallsBalls

–– Dipped Feet to make shoesDipped Feet to make shoes

–– Coated FabricsCoated Fabrics

Pictures: http://en.wikipedia.org/wiki/Mesoamerican_ballgame

Rubber and EuropeRubber and Europe

�� First European exposureFirst European exposure–– Columbus supposedly watched a Columbus supposedly watched a Mesoamerican ballgameMesoamerican ballgame

–– Early explorers learned native Early explorers learned native waterproofing techniqueswaterproofing techniques

�� Charles Marie de la Condamine Charles Marie de la Condamine and Francois Fresneau and Francois Fresneau –– Popularized rubber in France Popularized rubber in France starting mid 1730starting mid 1730’’ss

–– Discovered first solventsDiscovered first solvents

–– Wrote about propertiesWrote about properties

Picture: http://en.wikipedia.org/wiki/Charles_Marie_de_La_Condamine

VulcanizationVulcanization

�� 18391839

–– Goodyear and HancockGoodyear and Hancock

–– Mixed natural rubber, sulfur and white lead on a hot Mixed natural rubber, sulfur and white lead on a hot

stovestove

–– Rubber was Rubber was ‘‘curedcured’’ of all its defectsof all its defects

�� 1846 1846

–– Alexander Alexander ParkesParkes invented a coldinvented a cold--cure process using cure process using

sulfur chloride gas in solutionsulfur chloride gas in solution

[ ]n

[

CH3

R'R + S8

S

CH3

R2

R3

SS

CH3

R

R1

2-8 Sulfurs

] ][

Natural Rubber the Real StoryNatural Rubber the Real Story

�� 1860 1860 -- Williams (UK)Williams (UK)–– Decomposed natural Decomposed natural

rubber to isoprenerubber to isoprene

�� 1879 1879 -- Bouchardat Bouchardat (France)(France)–– Repolymerized isoprene to Repolymerized isoprene to

make rubbermake rubber

�� 1910 1910 –– PicklesPickles–– Rubber is made of long Rubber is made of long

chains of isoprenechains of isoprene

CH2

CH2

CH3

CH3

R'R [ ]n

Isoprene

cis-Polyisoprene

Origins of Rubber ElasticityOrigins of Rubber Elasticity

�� Energy elasticity Energy elasticity –– elongation resulting elongation resulting

from rotation around single bonds and the from rotation around single bonds and the

straining of bond angles and lengthsstraining of bond angles and lengths

Statistics of Ideal Rubber ElasticityStatistics of Ideal Rubber Elasticity

�� Ideal rubberIdeal rubber

�� Slope of the stressSlope of the stress--strain curve or Youngstrain curve or Young’’s Modulus s Modulus

–– ρρ = density= density

–– R = Gas ConstantR = Gas Constant

–– T = temperatureT = temperature

–– Mc = number average molecular weight of the network Mc = number average molecular weight of the network chainschains

–– αα = extension ratio, l/l= extension ratio, l/l00–– l/ll/l00 = current length/unstretched length= current length/unstretched length

E=ρRTMc

(2α+ α-2)

Deviations from IdealityDeviations from Ideality

�� Under predicts modulus for Under predicts modulus for αα > 1.5> 1.5

�� Chain endsChain ends

�� Stress induced crystallizationStress induced crystallization

Butadiene RubberButadiene Rubber

�� PolybutadienePolybutadiene–– First synthesized in 1910 by S. LebedevFirst synthesized in 1910 by S. Lebedev

–– Very durable but cis/trans issuesVery durable but cis/trans issues

–– Side walls of truck tires and golf ballsSide walls of truck tires and golf balls

–– Modern day use is as copolymerModern day use is as copolymer

CH2

CH2

cis-1,4-PBD 1,2-PBD

trans-1,4-PBD

R

R2

CH2

And its copolymersAnd its copolymers

�� Buna N/ Buna NNBuna N/ Buna NN

–– Butadiene and Butadiene and

acrylonitrileacrylonitrile

–– Increased acrylonitrile Increased acrylonitrile

increases stiffness and increases stiffness and

oil resistanceoil resistance

�� Buna SBuna S

–– Butadiene and styreneButadiene and styrene

–– Increased styrene Increased styrene

leads to stiffer rubberleads to stiffer rubber

RR

N

[ ]

RR[ ]

The War YearsThe War Years

�� Japan captured Pacific Rubber plantationsJapan captured Pacific Rubber plantations

�� US synthetic rubberUS synthetic rubber

–– 1939 1939 –– 2000 tons/yr2000 tons/yr

–– 1945 1945 –– 830,000 tons/yr 830,000 tons/yr

–– Butyl rubberButyl rubber

�� German synthetic rubberGerman synthetic rubber

–– Before Before –– 22,000 tons/yr22,000 tons/yr

–– Middle Middle –– 100,000 tons/yr100,000 tons/yr

Butyl RubberButyl Rubber

�� Copolymer of 98% isobutene Copolymer of 98% isobutene

–– 2% isoprene or butadiene2% isoprene or butadiene

–– Cationic polymerizationCationic polymerization

–– Air impermeableAir impermeable

–– Inner tubes for tiresInner tubes for tires

CH2

CH3

CH3

RR

1

CH3

CH3R+

n

Thermoplastic ElastomersThermoplastic Elastomers

�� Rubbers which can Rubbers which can be melt processed be melt processed after after ““crosslinkingcrosslinking””

�� Immiscible block Immiscible block copolymerscopolymers–– Form matrix of Form matrix of

rubbery polymer with rubbery polymer with spheres of hard spheres of hard segmentssegments

–– Most common: Most common: StyreneStyrene--ButadieneButadiene--Styrene (SBS)Styrene (SBS)

Pictures: http://en.wikipedia.org/wiki/Copolymer

Requirements to make a RubberRequirements to make a Rubber

�� High Molecular WeightHigh Molecular Weight–– Rubber elasticity is due to the coiling/uncoiling of chainsRubber elasticity is due to the coiling/uncoiling of chains

�� Use temperature must be above TgUse temperature must be above Tg–– To allow for molecular motionTo allow for molecular motion

�� Amorphous in its unstretched stateAmorphous in its unstretched state–– Crystals would hinder coiling/uncoilingCrystals would hinder coiling/uncoiling

�� Chains tied together to prevent flowChains tied together to prevent flow–– Traditionally through crosslinkingTraditionally through crosslinking

–– Hard/Soft DomainsHard/Soft Domains

–– EntanglementsEntanglements

�� All polymers above Tg act as rubbers due to entanglementsAll polymers above Tg act as rubbers due to entanglements

�� However, when the entanglements break, the polymer will begin toHowever, when the entanglements break, the polymer will begin toflowflow

Rubber: History, Rubber: History,

Properties and StructureProperties and Structure

Katrina CzenkuschKatrina Czenkusch

Physical Chemistry of MacromoleculesPhysical Chemistry of Macromolecules

April 9, 2009April 9, 2009

ReferencesReferences

�� GoritzGoritz, D., Muller, F. H., , D., Muller, F. H., SietzSietz, W.; , W.; ““TemperatureTemperature--induced and induced and StressStress--induced Crystallization in Oriented Polymersinduced Crystallization in Oriented Polymers””,, Progress in Progress in Colloid and Polymer ScienceColloid and Polymer Science; Springer Berlin/Heidelberg, 1977; Springer Berlin/Heidelberg, 1977

�� Herbert, Vernon; Herbert, Vernon; AttilioAttilio BisioBisio; ; Synthetic RubberSynthetic Rubber, Greenwood Press, , Greenwood Press, 19851985

�� HiemenzHiemenz, Paul C.; Lodge, Timothy P.; , Paul C.; Lodge, Timothy P.; Polymer Chemistry 2Polymer Chemistry 2ndnd ed., ed., CRC Press; 2007CRC Press; 2007

�� James, Hubert M., James, Hubert M., GuthGuth, Eugene; , Eugene; Theory of the Elastic Properties of Theory of the Elastic Properties of RubberRubber; J. Chem. Phys. ; J. Chem. Phys. 11,11, 455 (1943) 455 (1943)

�� LoadmanLoadman, John; , John; Tears of the TreeTears of the Tree, Oxford University Press, 2005, Oxford University Press, 2005

�� Rosen, Stephen L.; Rosen, Stephen L.; Fundamental Principles of Polymeric Materials Fundamental Principles of Polymeric Materials 22ndnd ed.ed., Wiley, Wiley--Interscience Publication, 1993Interscience Publication, 1993

�� Solo, Robert; Solo, Robert; Research and Development in the Synthetic Rubber Research and Development in the Synthetic Rubber IndustryIndustry; The Quarterly Journal of Economics; ; The Quarterly Journal of Economics; VolVol 68, No.1 (1954)68, No.1 (1954)

From Curiosity to Product From Curiosity to Product

(1820(1820--1840)1840)

�� T. HancockT. Hancock

–– Pickling Machine Pickling Machine –– produce produce

homogeneous rubber homogeneous rubber ‘‘doughdough’’

–– Spreader Spreader –– the standard the standard

coating machine used todaycoating machine used today

�� M. FaradayM. Faraday

–– Established empirical formula Established empirical formula

of natural rubber (Cof natural rubber (C55HH88))

Natural Rubber ProductionNatural Rubber Production

�� Wild ProductionWild Production–– Amazon River and its tributariesAmazon River and its tributaries

–– AfricaAfrica

�� 1876 1876 -- H. Wickham H. Wickham –– Sent 70,000 Hevea seeds to BritainSent 70,000 Hevea seeds to Britain

–– 2397 germinated2397 germinated

–– Plants sent to Singapore, India, MalaysiaPlants sent to Singapore, India, Malaysia

–– Foundation of the eastern rubber plantations (1895)Foundation of the eastern rubber plantations (1895)

�� 19131913--1914 1914 -- Plantation rubber exceeds wildPlantation rubber exceeds wild