Lakshmi Rubber Industries
(An ISO 9001:2008 Certified Company)
Rubber Products - The Engineering Way
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LAKSHMI RUBBER INDUSTRIES
Plot No:12, 2nd Street,
2nd Lane Harbour Colony, Kodungaiyur
Chennai, Tamilnadu 600118
India
ph: +91-44-25553839 (Direct Sales)
fax: +91-44-25553839
alt: +91-9444252044
lakshmir
Basic Polymer Properties
Basic Polymer Properties
Following are the basic polymer properties to choose a polymer for particular application.
SILICONES
Silicone retains good elastomeric properties at both low and high temperatures. Should not be exposed to fuels, solvents or silicone fluids. Silicone has excellent resistance to ozone, aging and weather. Serviceable temperature range from -67°F to +400°F, intermittent to +450°F. Also available in an FDA compound
Common Name Silicone ASTM D-2000 Classification FC, FE, GE Military (MIL STD 417) TA Chemical Definition Polysiloxane General Characteristics
Durometer Range (Shore A) 30 - 90 Tensile Range (P.S.I.) 200 - 1500 Elongation (Max. %) 700 Compression Set Good Resilience - Rebound Good Abrasion Resistance Fair to Poor Tear Resistance Poor Solvent Resistance Poor Oil Resistance Fair to Poor Low Temperature Usage (F°) -60° to -150° High Temperature Usage (F°) to 450° Aging Weather - Sunlight Excellent Adhesion to Metal Good Comment
Silicone Rubber has a great many variations and can be compounded to meet any number of applications. Silicone can be compounded to have tensile in the area of 1500 PSI and tear up to 200 lbs.; low compression set and good resilience; moderate solvent resistance; excellent heat resistance; good release characteristics; extreme low temperatature properties; and can be highly resistant to oxidation and ozone attack.
Silicone is generally attacked by most concentrated solvents, oils, concentrated acids and dilute sodium hydroxide.EPDM / EPR
EPDM combines excellent resistance to deteriorative effects of ozone, oxygen, weather, heat and many chemicals. Its serviceable temperature range is -40°F to +250°F and intermittent to +275°F. It is not recommended for use in contact with petroleum oils or fluids. Also available in an FDA compound.
Common Name EPR, EPT, EPDM, NORDEL® ASTM D-2000 Classification CA Military (MIL STD 417) RS Chemical Definition Ethylene Propylene General Characteristics
Durometer Range (Shore A) 30 - 90 Tensile Range (P.S.I.) 500 - 2500 Elongation (Max. %) 600 Compression Set Good Resilience - Rebound Good Abrasion Resistance Good Tear Resistance Fair Solvent Resistance Poor Oil Resistance Poor Low Temperature Usage (F°) -20° to -60° High Temperature Usage (F°) to 350° Aging Weather - Sunlight Excellent Adhesion to Metal Fair to Good Comment
Ethylene Propylene is a polymer with outstanding properties. It was exceptionally good weather aging and ozone resistance; excellent water and chemical resistance; excellent resistance to gas permeability, and excellent resistance to aging due to exposure to steam, and heat resistance excellent up to 350°F. Ethylene Propylene is a polymer where oil and solvent resistance is poor, however, it is fairly good in ketones and alcohols. It is not recommended for food applications or exposure to aromatic hydrocarbons. FLUOROELASTOMER (VITON®)
Viton® has excellent resistance to high temperatures, ozone, oxygen, fuels, mineral oil and synthetic hydraulic fluids. Maximum operating temperatures run from 400°F in continuous service up to 500°F in intermittent service. Also available in an FDA compound.
Common Name Fluoro Elastomers, Viton® ASTM D-2000 Classification HK Military MIL R-25897 and MIL R-83248 Chemical Definition Fluorinated Hydrocarbon General Characteristics
Durometer Range (Shore A) 60 - 90 Tensile Range (P.S.I.) 500 - 2000 Elongation (Max. %) 300 Compression Set Fair to Good Resilience - Rebound Fair Abrasion Resistance Good Tear Resistance Good Solvent Resistance Excellent Oil Resistance Excellent Low Temperature Usage (F°) +10° to -10° High Temperature Usage (F°) 400° to 600° depending on time and service condition Aging Weather - Sunlight Excellent Adhesion to Metal Good Comment
Fluoro Elastomers have heat resistance up to 600°F. and resistance to a wide range of oils and solvents; especially all ahphatic, aromatic, and halogenated hydrocarbons, acids, animal and vegetable oils.
Fluoro Elastomers are not recommended for ketones, low molecular weight esters and nitro containing compounds.NATURAL RUBBER
Crude natural rubber is found in the juices of many plants, including the shrub guayule, Russian dandelion, goldenrod and dozens of other shrubs, vines and trees. The principal source is the tree Hevea Brasiliensis which is native to Brazil. Natural rubber has high resilience, good tensile strength and good tear resistance. It does not perform well when exposed to chemicals and petroleum derivatives. Natural rubber is inferior to many of the synthetics in heat aging, resistance to sunlight, oxygen, ozone, solvents and oils. The temperature range is -55°C to +55°C (-67°F to +122°F).
Common Name Natural Rubber ASTM D-2000 Classification AA Military (MIL STD 417) RN Chemical Definition Polyisoprene General Characteristics
Durometer Range (Shore A) 20 - 100 Tensile Range (P.S.I.) 500 - 3500 Elongation (Max. %) 700 Compression Set Excellent Resilience - Rebound Excellent Abrasion Resistance Excellent Tear Resistance Excellent Solvent Resistance Poor Oil Resistance Poor Low Temperature Usage (F°) -20° to -60° High Temperature Usage (F°) to 175° Aging Weather - Sunlight Poor Adhesion to Metal Excellent Comment
Natural Rubber has many good characteristics. It has high resilience, good compressions set, food roll building behavior and molding properties; very good friction surface, but not a fine smooth surface when ground; high tear strength, low crack growth; usable for ketones and alcohol; and good low temperature properties.
Natural rubber is not recommended for oil and solvent resistance and ozone attacks it.POLYURETHANE
Polyurethane Elastomer, as a class, have excellent wear resistance and high tensile strength, along with excellent ozone and oxidation resistance.
Common Name Urethane, Polyurethane ASTM D-2000 Classification BG Military (MIL STD 417) SB Chemical Definition Polyester/Polyether Urethane General Characteristics
Durometer Range (Shore A) 35 - 100 Tensile Range (P.S.I.) 500 - 6000 Elongation (Max. %) 750 Compression Set Poor Resilience - Rebound Good Abrasion Resistance Excellent Tear Resistance Excellent Solvent Resistance Poor Oil Resistance Good Low Temperature Usage (F°) -10° to -30° High Temperature Usage (F°) to 175° Aging Weather - Sunlight Excellent Adhesion to Metal Fair to Good Comment
The castable types have excellent abrasion resistance; good compression set at high hardness levels; low friction surface; tensile strengths up to 6000 PSI; good ozone resistance; good oil and solvent resistance; and poor heat and hot water resistance.
The millable types of Polyurethane are in wide use today. Through the use of reinforcing pigments and other chemicals, desirable characteristics can be obtained to fit a variety of applications; wear resistance is excellent and greatly superior to most other polymers; the surface is of low friction nature; oil resistance is good and equivalent to the better nitriles but is not recommended for use in water or heat above 175°F.; plus good ozone resistance and low rebound characteristics.
Urethane is not normally attacked by moderate chemicals and hydrocarbons. It is generally attacked by concentrated acids, ketones, esters, chlorinated and nitro hydrocarbons.
SBR (BUNA S)
SBR is a co-polymer of styrene and butadiene and has properties similar to natural rubber. It has greater abrasion resistance than natural rubber, better wear resistance and better low temperature flexibility. Though superior in water resistance to natural rubber, it has about the same resistance to solvents and chemicals. It has better heat resistance and heat aging qualities than natural rubber, and in excess heat it hardens and becomes brittle instead of softening as does natural rubber. Resistance to sunlight and ozone is similar to natural rubber. The temperature range of SBR is -55°C to +70°C (-67°F to +158°F). SBR rubber is available in sheet material, but we do not carry it in cord stock.
Common Name SBR, GRS ASTM D-2000 Classification AA, BA Military (MIL STD 417) RS Chemical Definition Butadiene General Characteristics
Durometer Range (Shore A) 30 - 100 Tensile Range (P.S.I.) 500 - 3000 Elongation (Max. %) 600 Compression Set Good Resilience - Rebound Good Abrasion Resistance Excellent Tear Resistance Fair Solvent Resistance Poor Oil Resistance Poor Low Temperature Usage (F°) 0° to -50° High Temperature Usage (F°) to 225° Aging Weather - Sunlight Poor Adhesion to Metal Excellent Comment
SBR is a low cost, non-oil resistant material. It has good water resistance and resilience up to 70 durometer; compression set becomes poorer with higher durometer; generally satisfactory for most moderate chemicals and wet or dry organic acids. SBR is not recommended for ozone, strong acids, oils, greases, fats and most hydrocarbons. BUTYL
Butyl rubber is a co-polymer of isobutylene and isoprene. It has exceptionally low gas and moisture permeability and outstanding resistance to heat aging, weather, ozone, chemical attack, flexing, abrasion and tearing. It has good resistance to phosphate ester based hydraulic fluids, and has excellent electrical isolation performance. Butyl is not recommended for use when in contact with petroleum oils and fluids. The temperature range is -55°C to +120°C (-67°F to +248°F). We carry only in sheet material.Common Name Butyl ASTM D-2000 Classification AA, BA Military (MIL STD 417) RS Chemical Definition Isobuylene Isoprene General Characteristics
Durometer Range (Shore A) 40 - 90 Tensile Range (P.S.I.) 500 - 3000 Elongation (Max. %) 850 Compression Set Fair to Good Resilience - Rebound Fair Abrasion Resistance Fair Tear Resistance Good Solvent Resistance Poor Oil Resistance Poor Low Temperature Usage (F°) -10° to -60° High Temperature Usage (F°) to 250° Aging Weather - Sunlight Excellent Adhesion to Metal Good Comment
Butyl rubber is impermeable to most common gases and has good resistance to sunlight and ozone. Butyl is normally satisfactory when exposed to animal and vegetable oils and oxidizing chemicals. Butyl is not recommended for use with petroleum solvent, coal tar and aromatic hydrocarbons. TEFLON
When parts are fabricated from TFE (polytetrafluroethylene) the exceptional chemical, electrical, mechanical and thermal properties, become apparent. TFE properties are as follows: extreme corrosion resistance, excellent weathering, nonflammable, very low frictional coefficient, no-adhesive, high heat resistance, and surface resistivity, FDA compliant, USDA approved. The working temperature range for Teflon is -200°C to +260°C (-328°F to +500°F).NEOPRENE (CHLOROPRENE)
Neoprene has good resistance to oils, sunlight and aging. Temperature range is -40°F to +230°F, intermittent to +250°F. Resistance to compression set is good. Chemical resistance to silicone oil and grease, refrigerants, ammonia and carbon dioxide. Also available in an FDA compound.
Common Name Neoprene® ASTM D-2000 Classification BC, BE Military (MIL STD 417) SC Chemical Definition Polychloroprene General Characteristics
Durometer Range (Shore A) 25 - 95 Tensile Range (P.S.I.) 500 - 3000 Elongation (Max. %) 600 Compression Set Good Resilience - Rebound Excellent Abrasion Resistance Excellent Tear Resistance Good Solvent Resistance Fair Oil Resistance Fair Low Temperature Usage (F°) +10° to -50° High Temperature Usage (F°) to 250° Aging Weather - Sunlight Good Adhesion to Metal Good to Excellent Comment
Neoprene is an all-purpose polymer with many desirable characteristics. It has additional plus features: high resilience with low compression set; flame resistant; compounds free of sulphur are easily made; and animal and vegetable oil resistance generally not affected by moderate chemicals, fats, greases and many oils and solvents.
Neoprene is generally attacked by strong oxidizing agents, esters, ketones, chlorinated aromatic and nitro hydrocarbons
BUNA N (NITRILE)
Has excellent resistance to petroleum oils and gasolines. Resistance to hydrocarbons, acids and bases is good. The temperature range is -40°F to +212°F, intermittent to +230°F. Excellent resistance to permanent compression. It does not possess good resistance to ozone, sunlight or weather. Also available in an FDA compound.FluroSilicones
Common Name
Fluorosilicone
ASTM D-2000 Classification
FK
Military
MIL R-25988 Amend 2
Chemical Definition
Fluorosilicone
General Characteristics
Durometer Range (Shore A)
50 - 80
Tensile Range (P.S.I.)
500 - 800
Elongation (Max. %)
300
Compression Set
Fair to Good
Resilience - Rebound
Excellent
Abrasion Resistance
Poor
Tear Resistance
Poor
Solvent Resistance
Fair
Oil Resistance
Good
Low Temperature Usage (F°)
-80°
High Temperature Usage (F°)
to 300°
Aging Weather - Sunlight
Excellent
Adhesion to Metal
Poor
Comment
Fluorosilicone is considerable more expensive than silicone, however it is developed for special applications where general resistance to oxidizing chemicals, aromatic and chlorinated solvent bases is required.
Fluorosilicone is not recommended and is generally attacked when exposed to brake fluids, hydrazine and ketones. Fluorosilicone should not be confused with silicone in regard to high heat resistance.
Polysulfide
Common Name
Polysulfide
ASTM D-2000 Classification
BK
Military (MIL STD 417)
SA
Chemical Definition
Polysulfide
General Characteristics
Durometer Range (Shore A)
40 - 80
Tensile Range (P.S.I.)
800 - 1200
Elongation (Max. %)
300
Compression Set
Poor
Resilience - Rebound
Fair
Abrasion Resistance
Poor
Tear Resistance
Poor
Solvent Resistance
Excellent
Oil Resistance
Excellent
Low Temperature Usage (F°)
-65°
High Temperature Usage (F°)
to 160°
Aging Weather - Sunlight
Good
Adhesion to Metal
Poor
Comment
Polysulfide is generally resistant to most ozone, oils, aromatic hydrocarbons, esters, ketones and thinners.
Polysulfide is not recommended for service where it is exposed to mercaptans, chlorinated hydrocarbons, nitro hydrocarbons, esters, amines and heterocyclics
LAKSHMI RUBBER INDUSTRIES
Plot No:12, 2nd Street,
2nd Lane Harbour Colony, Kodungaiyur
Chennai, Tamilnadu 600118
India
ph: +91-44-25553839 (Direct Sales)
fax: +91-44-25553839
alt: +91-9444252044
lakshmir
