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Industrial Fluid Solutions Polymers and Compounding www.contitech.us
Agenda Polymers and Compounding 1 Compounding 2 Processing 3 Chemical Resistance 4 Elastomers 5 Polymers
Macromolecules = Polymers Poly - manyMer – partsMonomer, Dimer, trimer, tetramer, pentamer… 300,000+ unitsMolecular WeightWater (H2 O): 18 g/ mol UHMWPE > 1 million g/ molWhat is…
Basic homopolymersWhat is…
Molecular weights of polymers Entanglements = physical crosslinks Higher Molecular Weight higher strength, modulus, chemical resistance, lower elongation, permeation, less swelling, less environmental effects
Thermoplastics Polyethylene terephthalate PolyethylenePolyvinyl chloridePolypropylenePolystyreneNylon Polymers Elastomers Nitriles, NBR, HNBR, XNBR Neoprene, Chloroprene Hypalon , chlorosulfonated polyethylene Chlorinated polyethylene EPDM Viton, FKM Textiles Nylon PET Rayon Aramid Carbon fiber UHMWPE
Thermoplastics vs. Thermosets Elastomers are a subset of thermoset polymers Crosslinks are one key difference Polymers can be classified as thermoplastic or thermosets
Physical properties are more temperature dependent Typically not cross-linked (except XLPE and PEX)Tend to have fewer components/chemicals in formula (antioxidants, plasticizers, colors)Cleaner, less contaminationUsed in NSF 61 drink water and NSF 51 food applications: Clearwater, Nutriflo, Nutriflex Used in high chemical resistance applications: Hiper , FabchemTypically, poorer flexibility (higher force to bend and likely to kink) More difficult to couple (higher permanent set)Narrow temperature rangeProcessed by heating and subsequent cooling: reversible, recyclable, not a chemical reactionThermoplastic
Columbus first brought rubber to Europe from the Americas in 1493 Joseph Priestley: rub out pencil marks = ‘rubber’ Renewable resources: hevea treeWWI and WWII natural rubber was scarce: first synthetic rubber Not very useful unless crosslinked (chemical bonding between polymer chains): Sulfur vulcanization: Charles Goodyear 1839 Improvements with additives: Carbon black and silica, Plasticizers, anti-degradants for ozone, UV and heat resistance Due to chemical crosslinks, typically irreversible, incineration, grinding, limited de-vulcanization Elastomer caoutchouc : natural rubber
Isoprene (Natural Rubber) Ultra High Molecular Weight Polyethylene (UHMWPE) Teflon Nitrile (NBR) Polyvinyl Chloride Which of the following polymers are Thermoplastic OR Thermosetting ?
Which ones are advantages of rubber over plastic? More adaptable to construct hose with heavy reinforcement (i.e. higher max WP) Can operate in higher temperature environment Remains more flexible in lower temperature Hand built Only comes in black color
What Makes Up a Rubber Compound? PolymerMolecular weight = Mooney Viscosity% ACN, % PP, % diene, crystallization Polymerization technique Fillers Carbon black: structure, size, Silica, Clay: size, color, Accelerators: determine cure rate Activators Initiate cure process Zinc oxide and Stearic acid Curative Sulfur, sulfur donor, peroxide, resin Co-agentsAdditional crosslink sites: often metallic
Plasticizers Oils & low molecular weight polymersCrosslinkable (extraction resistance)Process aidsLubricants, peptizers , anti-stick agents Retarders Delay cure until processing is complete Pigments Flame Retardants Anti-degradants Ozone, UV, Heat Tackifiers Hold shape by being sticky What Makes Up a Rubber Compound?
Rubber Recipe Example Based on 100 phr (parts per hundred rubber) weight First Pass NBR 40% 75.00 NBR 28% 20.00 SBR 5.00 clay50.00 black60.00 zinc oxide4.00 plasticizer 110.00 plasticizer 2 25.00 silica 5.00 stearic acid 0.50 anti-ozonant 1.50 talc 25.00 Second Pass accelerator 1.00 sulfur 1.50 total 283.50
Mixing (Banbury) Ingredients mixed to a uniform level (dispersion): 1 or more stages Mixing time = 90-180 seconds Mixer are large (2-Story) Typically above a mill or extruderVolume: 270 liters (production)1.5 liter (lab)
Mixing (Banbury) Rotor design: 2 wing / 4 wing Tangential v. intermesh
Open Mill Increase rubber temp Additional mixing Convert bulk or slab to thinner gauge Feed into a calendar
Calendar 3 or 4 rollsUniform width and gaugeRubber onto rollsRolls used to make wrapped hose Could be lined with fabric for reinforcement
Continuous extrusion Plastic or rubber Screw or ram Feed pellets or strips Tubing head
Testing and Chemical Hose Recommendations
Testing: lab plates or production hoseTensile stress-strainFlexural modulus Flex fatigue Glass transition Adhesion CreepCompression set Abrasion Ozone Flame Hot air aging Fluid Immersion TearForce to bend Low temp flex UV resistance Green strength Friction Moving die rheometry Capillary Rheometer Cure Kinetics
For everyone’s safety, all fluids (except water) should be treated as a chemical. *DO NOT GUESS when it comes to making a recommendation* You will find some chemical recommendations in the Chemical Resistance Charts REMEMBER : Recommendations refer to the tube material only
Temperature Concentration Pressure Type of service (continuous or intermittent) Performance of previous hose in place All of the above Prior to making a chemical recommendation, which of the following parameters must be known?
Product conveyed: __________________ Give the chemical name and provide SDS (Safety Data Sheet)% Concentration : ___________________% The concentration is important, otherwise we have to assume 100% and it may limit your hose selection Temperature: ______________________ °F or °CInformation Needed:
Information provided by elastomer producers Chemical Resistance Guide for Elastomer III, Compass Publications Past performance Laboratory testing Which tools does a hose manufacturer use to make a chemical recommendation?
Hose Construction Importance of Cover and Tube CompoundsCommon Industry Compounds CARBOXILATED NITRILE Excellent oil and abrasion resistance. Good chemical resistance. NITRILE Excellent resistance to petroleum based fluids. Moderate resistance to aromatics. SBRGood abrasion resistance, little resistance to petroleum based fluids. EPDM Heat and cold resistance, ozone resistance, mild chemical resistance. Various version of EPDM depending on hose (I.E. Flexsteel 250 Steam EPDM, Frontier, Versiflo Water and Purple Flexwing).
Elastomer: Heat vs Oil Resistance
Choosing the Correct Hose Compound Choose the correct hose with the appropriate TUBE and COVER compound based on the application: Abrasion Resistance Chemicals (Chemical Chart Page 350 in the 2018 Hose Catalog) Petroleum (Gasoline, Diesel, B100, E85) Temperature (Low and High)Refer to compounds on page 394 – 395 in ContiTech Hose CatalogTube and Cover compounds are on every specification sheet
Lists the ContiTech Trade name of Compound Industry Designation Outstanding feature of compound Indicates an example of hose PGs 394, 395 Elastomer Info in the INH Full Line Catalog
Increase hardness Decrease hardness Volume swell Change in elongation Cracking Color change Smell Leakage Which of the following are signs of a chemical attack?
The Effects of Ozone vs The Effects of UV?
Discoloration Cracking along the axe of stretch Cracking perpendicular to the axis of stretch Increase hardness Which of the following are signs of a ozone attack?
Discoloration Cracking along the axe of stretch Cracking perpendicular to the axis of stretch Increase hardness Powdery surface Which of the following are signs of a UV attack?
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