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 1730ss

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 Youngs Modulus s Modulus

= 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

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

E=RTMc

(2+ -2)

Deviations from IdealityDeviations from Ideality

Under predicts modulus for Under predicts modulus for > 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