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 [email protected]