Polymers: An

OverviewPRESENTED BYJOHN M. LONG

JMLong Rubber Consultants, LLC

TOChicago Rubber Group

May 10, 2011

Natural RubberNatural Rubber

Cis- 1,4 polyisoprene

Natural rubber is composed of virtually 100% Cis-1,4 polyisoprene.

Natural Rubber

Rib Smoked SheetProduced from latexDried and smokedPackaged in 75 or 220 lb. balesSubject to crystallizationHeat treatment

Natural Rubber

Technically Specified Rubber (TSR)Produced from air dried latexGround and washedDried and baled in 75 lb balesGraded by dirt contentHeat treatmentSpecial grades made from latex

Natural Rubber

Used in application where high loads and temperatures are encounteredAircraftOTRRadial MT

Used for tack and green strengthTend to go to the hot roll

Natural Rubber

Abrasion resistance lower than SBR/PBD in passenger tire applications

Synthetic Polyisoprene

Cis-1,4 polyisoprene

Synthetic polyisoprene has from 92 to 98% cis content.

Synthetic Polyisoprene

Lacks the non rubber constituents of Natural Rubber ProteinsAmines

Solution PolymerizedStereo specific catalysts

Synthetic Polyisoprene

Augments Natural Rubber usageEasier to mixDoes not have to be heat softenedMore consistent than Natural RubberPoorer tack and green strength than Natural

Rubber

Styrene Butadiene Rubber (SBR)

Styrene Butadiene Rubber (SBR)

Emulsion PolymerizedWater and SoapChemicals to start and stop reactionCoagulation with acid or saltsCold (4 ºC) or Hot (50 ºC)Styrene content normally 23.5%Styrene randomly distributedCis, trans, vinyl content Wide Viscosity ranges available

Styrene Butadiene Rubber (SBR)

Emulsion PolymerizedOil extended versions

Processing of high molecular wt. polymers

Black MasterbatchesWith or without oilEliminates the need for extra mixing stepsAssures excellent carbon black dispersion

Styrene Butadiene Rubber (SBR)

Emulsion PolymerizedEasy to mix and processTend to go to the hot rollHighest strength when used with Carbon Black or SilicaWidely used in tires

Treads w/ polybutadiene (wear and traction)Sidewalls w/ polybutadiene and natural rubberCarcass w/ natural rubberLow cost

Styrene Butadiene Rubber (SBR)

Solution PolymerizedMade by solution processStereo specific catalystsStyrene insertion controllableCis, trans, vinyl ratio controllableOil extended versions available

Styrene Butadiene Rubber (SBR)

Solution PolymerizedMore difficult to process than emulsion SBR

Additional mixingMore die swell

They tend to go to the hot rollMore expensive than emulsion SBRUsed predominately in treads for low rolling

resistance passenger tires.

Polybutadiene

Polybutadiene

Solution Process using stereo specific catalystNormally 92-98% cis

Some polymers with high vinylDifficult to process by themselves

Poor green strength, die swell, baggingNormally blended with SBR or Natural Rubber

Tend to go to the hot roll

Polybutadiene

Used in passenger tiresTreads

Improved abrasion resistanceImproved rolling resistanceImproved flex cracking resistanceHigh vinyl polybutadienes in low rolling resistance

compounds

SidewallsImproved flex fatigue resistance

Butyl

Butyl

Solution PolymerizedLow unsaturation (0.7 to 2.2%)Mostly saturated backboneStrong cure package neededUsed for Curing Bladders and InnertubesCan be difficult to disperse fillersCan be sticky on the millTends to go to the COLD roll

Butyl

Will not co-cure with SBR, Natural, etc.Will cause separations and failures if mixed into

unsaturated polymers.Can be cured with sulfur or resin curing systems

Halogenated Butyl

Halogenated Butyl

Solution PolymerizationHalogenation of cementNeutralization and stabalization

Can co-cure with unsaturated polymersProcessing

Mix temperatures over 290 ºF can cause “carbon black scorch”

Do not mix with zinc oxide in first mixing pass

Halogenated Butyl

Processing (Continued)Some AO’s and resins can pre cure halobutylsWatch workaway materialsHalobutyl compounds tend to go to the COLD

roll

Halogenated Butyl

Used in Innerliners (impermeability)WSW, BSW, cover strips (Ozone resistance)Innertubes (impermeability, heat resistance)

EPDM

EPDM Third Monomers

Polymerizable double bond*

EPDM

Solution PolymerizedThird monomer activity

DCPD<Hexadiene<ENB1.5 to 11% in polymers8-11% used when blending with unsaturated

polymers.Low unsaturation can give same problems as

butyl in blends with unsaturated polymers

EPDM

Ethylene50-75 weight %

ProcessingIn tires usually blended with other polymers Compounds process the same as the base

polymers the EPDM is blended withLower ethylene tend to mix easier

EPDM

UsesWhite Sidewall, Cover strips, Black Sidewalls

because of outstanding ozone resistanceWhite Sidewall and Coverstrips

Blended with halobutyls and natural rubber and possibly SBR

Black SidewallsBlended with natural rubber and polybutadiene

EPDM

UsesIndustrial Rubber Goods

Good high temperature resistance Can be highly extended with fillers and oil for

reduced cost compoundsCan be compounded to give low compression set

Nitrile

Acrylonitrile/Butadiene (NBR)

NitrileAcrylonitrile/Butadiene (NBR)

Acrylonitrile/Butadiene ratios typically 18/82 to 45/55Very good oil resistance, high strength The higher the Acrylonitrile content the better the oil

resistanceCommon polymer in industrial rubber goods

GasketsShoe SolesBeltingHosesV-belts

Nitrile

Acrylonitrile/Butadiene (NBR)Sulfur curableConventional curativesSome times used with blends

PVCSBR (cost)

Need to use polar plasticizers such as esters DBP,DOP,DOA

Emulsion polymerized

Nitrile

Acrylonitrile/Butadiene (NBR)Also exists in the Hydrogenated version (HNBR)

Excellent high temperature resistanceExpensiveUsually peroxide cured for maximum performance

Chloroprene (Neoprene)

Emulsion polymerizedApproximately 88-92% trans

Chloroprene (Neoprene)

Emulsion polymerizedApproximately 88-92% trans

Chloroprene (Neoprene)

ChloropreneExcellent oil resistanceHigh strengthGood abrasion resistanceGood weather resistanceGood chemical resistance

Chloroprene (Neoprene)

UsesWire and CableHoseBelts (flat and v-belts)AdhesivesMolded and extruded

CuringMetal oxides ZnO MgO most commonThioureas and/or organic accelerators thiurams or

guanadines

Chloroprene (Neoprene)

CuringSulfur is also used in compounds requiring a slow cure

rate

PolyurethaneThree Types

LiquidsThermoplasticMillable Gums

Production of UrethanesPolyols reacted with a Diisocyanate to form

PrepolymersPrepolymers are reacted with diamines to form

Polyurethane

PolyurethaneProperties

High strengthAbrasion resistanceCut and tear strength Ozone resistancePoor when subjected to high temperature water

(hydrolysis)Poor when subjected to high temperatures (melting)

Specialty Polymers

Polyacrylate rubber (ACM)Ethylene-Acrylic Elastomers (AEM)Chlorinated Polyethylene (CM)Chorosulfonated Polyethylene (CSM)Fluoroelastomer (FKM)Silicone Elastomer (MQ,VMQ, PMQ, PVMQ,

FVMQ)

Oil vs Temperature Resistance

100

150

200

250

300

350

400

450

500

0 1 2 3 4 5 6 7 8 9 10 11

EPDM

Chloroprene

VMQ

AEM ACM

NBRCO/ECOHNBR

FVMQ

FKM

SBR

SummaryThis has been a quick review of significant

polymers used in tires and industrial products.

If anyone would like to discuss any of these in more detail please call me.

John LongJMLong Rubber Consultants, LLC2204 Donner St. NWNorth Canton, OH 44720Phone 330-244-9680Fax 330-244-9684Email JMLongRC@NEO.RR.COM