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        Kynar? Resin - Design Properties, Irradiation

        DESIGN PROPERTIES FOR SPECIAL APPLICATIONS

        SOLUBILITY

        Kynar? PVDF resins have limited solubility. Tables 1 and 2 list active and latent solvents. Generally, Kynar? resins are not soluble in aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated solvents, alcohols, acids, halogens, and basic solutions. Kynar Flex? PVDF copolymers tend to be slightly more soluble than the Kynar? PVDF homopolymers due to lower crystallinity. Kynar Superflex? PVDF and Kynar Ultraflex? PVDF can be highly soluble in select solvents.

         

         

        ACTIVE* SOLVENTS - TABLE 1

        Solvent Boiling Point °C Flash Point °C
        Tetrahydrofuran 65 -17
        Methyl Ethyl Ketone 80 -6
        Dimethyl Formamide 153 67
        Dimethyl Acetamide 166 70
        Tetramethyl Urea 177 65
        Dimethyl Sulfoxide 189 35
        Trimethyl Phosphate 195 107
        N-Methyl-2-Pyrrolidone 202 95

        *Solvent will dissolve at least 5-10 weight percent Kynar? resin at ambient temperature. 

        LATENT** SOLVENTS - TABLE 2

        Solvent Boiling Point °C Flash Point °C
        Acetone 56 -18
        Methyl Isobutyl Ketone 118 23
        Glycol Ethers*** 118 40
        Glycol Ether Esters*** 120 30
        N-Butyl Acetate 135 24
        Cyclohexanone 157 54
        Diacetone Alcohol 167 61
        Diisobutyl Ketone 169 49
        Ethyl Acetoacetate 180 84
        Butyrolactone 204 98
        Isophorone 215 96
        Triethyl Phosphate 215 116
        Carbitol Acetate 217 110
        Propylene Carbonate 242 132
        Glyceryl Triacetate 258 146
        Dimethyl Phthalate 280 149

        **As a rule, latent solvents do not dissolve or substantially swell Kynar? homopolymer resin at room temperature. 

        ***Based on ethylene glycol, diethylene glycol, and propylene glycol. 

        RADIATION CROSS-LINKING

        The different grades of Kynar? homopolymer and copolymer resins are readily cross-linked and do not degrade when irradiated with moderate doses of high energy electron or gamma radiation.

         

        The efficiency of cross-linking is influenced by the grade selection and molecular weight. Examples of Kynar? PVDF-fabricated products utilizing radiation technology are heat-shrinkable tubing and insulated wire capable of withstanding continuous temperatures as high as 180°C (356°F).

        RESISTANCE TO NUCLEAR RADIATION

        The resistance of Kynar? fluoropolymers to nuclear radiation is excellent. The original tensile strength of the resin is essentially unchanged after exposure to 100 megarads (Mrads) of gamma radiation from a Cobalt-60 source at 50°C (122°F) and in high vacuum (10-6 torr). The impact strength and elongation are slightly reduced due to cross-linking. This resistance to effects of radiation, combined with chemical resistance, has resulted in the successful use of Kynar? components in nuclear reclamation plants.

         

        Tables 3 and 4 below show minimal changes in tensile properties of Kynar? homopolymer and Kynar Flex? copolymer resins exposed to electron beam radiation in doses up to 20 Mrads according to ASTM D882 testing.

        TENSILE MODULUS VS. RADIATION DOSE EXPOSURE (PSI) - TABLE 3:

         

        RESIN GRADE

        0

        2 MRADS

        4 MRADS

        8 MRADS

        20 MRADS

        Kynar? 460

        170

        180

        170

        200

        190

        Kynar? 720

        230

        220

        230

        220

        240

        Kynar? 740

        200

        230

        200

        220

        220

        Kynar? 760

        200

        190

        190

        210

        220

        Kynar Flex? 2850

        130

        130

        120

        130

        130

        ULTIMATE TENSILE STRENGTH VS RADIATION DOSE EXPOSURE (PSI) - TABLE 4:

         

        RESIN GRADE

        0

        2 MRADS

        4 MRADS

        8 MRADS

        20 MRADS

        Kynar? 460

        6200

        6300

        6000

        6900

        7200

        Kynar? 720

        7400

        7400

        7300

        7300

        8400

        Kynar? 740

        6900

        6900

        6900

        7200

        7900

        Kynar? 760

        6300

        6500

        6700

        7400

        7800

        Kynar Flex? 2850

        4700

        4700

        4900

        4900

        5600

         

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