Characterization of a new type of bisphenol cured FKM.Fluoroelastomers (FKM FKM Fluoroelastomer FKM Fogarty Klein Monroe (Houston, Texas) FKM Field Kitchen, Modular ) co-polymerized from vinylidene fluoride fluoride, a salt of hydrofluoric acid; see hydrogen fluoride. See also fluoridation; fluorine. (V[F.sub.2]) and hexafluoropropylene (HFP HFP Healthy Families Program HFP Honda Factory Performance HFP Hexafluoropropylene (Shipboard Fire Fighting Agent) HFP Hostile Fire Pay HFP Hepatic Function Panel HFP Hexafluoro-2-Propanol HFP Hands Free Protocol ) are known for their heat resistance, fluid resistance and compression set resistance. Fluoroelastomers are often used in diverse sealing applications in the chemical process industry where hostile fluid environments include high temperature oils, fuels and acids. Typical parts fabricated fab·ri·cate tr.v. fab·ri·cat·ed, fab·ri·cat·ing, fab·ri·cates 1. To make; create. 2. To construct by combining or assembling diverse, typically standardized parts: from fluoroelastomers include o-rings, t-seals, bonded seals and numerous custom seal designs. FKM processing limitations at the molder mold·er v. mold·ered, mold·er·ing, mold·ers v.intr. To crumble to dust; disintegrate. v.tr. To cause to crumble. See Synonyms at decay. add cost to the finished articles. This cost is in the form of added process time and energy required to manufacture a part with optimized physical properties. Additional process factors that increase costs are rheological rhe·ol·o·gy n. The study of the deformation and flow of matter. rhe  o·log variability due to hygroscopic hygroscopic /hy·gro·scop·ic/ (hi?gro-skop´ik) readily absorbing moisture. hy·gro·scop·ic adj. Readily absorbing moisture, as from the atmosphere. acid acceptors, mold mold, name for certain multicellular organisms of the various classes of the kingdom Fungi, characteristically having bodies composed of a cottony mycelium. The colors of molds are caused by the spores, which are borne on the mycelium. sticking and difficulty dispersing an additional compound ingredient, calcium hydroxide calcium hydroxide, Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. . A new and unique type of fluoroelastomer, called Tecnoflon HS, (designated HS throughout) has been developed to improve fabricator fab·ri·cate tr.v. fab·ri·cat·ed, fab·ri·cat·ing, fab·ri·cates 1. To make; create. 2. To construct by combining or assembling diverse, typically standardized parts: efficiency with improved performance. This is an innovative technology to polymerize polymerize /po·lym·er·ize/ (pah-lim´er-iz) to subject to or to undergo polymerization. pol·y·mer·ize v. To undergo or subject to polymerization. fluoroelastomers (HS FKM) without ionic i·on·ic adj. Of, containing, or involving an ion or ions. ionic pertaining to an ion or ions. ionic medication iontophoresis. end groups (ref. 1). The HS type FKM polymer is an advance in fluoroelastomer technology because it addresses and solves processing problems of fluoroelastomers and offers improved physical properties. HS type FKM stocks can be compounded and cured efficiently without calcium hydroxide. Additionally, molded mold 1 n. 1. A hollow form or matrix for shaping a fluid or plastic substance. 2. A frame or model around or on which something is formed or shaped. 3. Something that is made in or shaped on a mold. parts from HS type FKM need only a short post cure (ref. 2). HS type FKM based compounds are vulcanized vul·ca·nize tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat by the same mechanism (ref. 3) as standard bisphenol AF cured fluoroelastomers; however, it is the innovative polymerization polymerization Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same. technology that allows for improved properties and processing. The ionic end groups of standard FKM polymers are thought to compete with the cure mechanism and require a lengthy high temperature post cure to fully optimize optimize - optimisation the compound's physical properties, primarily compression set resistance. The HS type FKM polymerization results in a polymer without ionic end groups, which improves processing performance and improves physical properties. Normally, orders for standard FKM seals placed by end users can only be satisfied by large inventories at the fabricator or distributor level. This is due in part to the long post cure period of 16 to 24 hours in length. HS type FKM is optimized with as low as a one hour post cure, giving the fabricator the ability to ship to the customer the same day as the order is placed. This allows the fabricator to store mixed compound and mold it as orders are placed, thereby reducing inventory size and cost (ref. 4). Discussion An HS type FKM with a short post cure time was evaluated against a standard type FKM with a long post cure time in various test fluids and conditions relative to the chemical process industry and applications where fluoroelastomers are often used as seals. Table 1 shows the formulations for the HS type and standard FKM. The polymers are commercially available grades, and the filler fill·er 1 n. One that fills, as: a. Something added to augment weight or size or fill space. b. A composition, especially a semisolid that hardens on drying, used to fill pores, cracks, or holes in wood, plaster, loading is the same at 30 phr of MT N 990 carbon black. The standard FKM is compounded with 6 phr of calcium hydroxide and 3 phr of high activity magnesium hydroxide magnesium hydroxide: see milk of magnesia. . The HS polymer is compounded with 9 phr of high activity magnesium hydroxide. As shown in table 2, the HS type FKM allows for vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. without the use of calcium hydroxide at an economically viable rate. Although standard FKMs can be compounded with only magnesium hydroxide, their cure rate is too slow to be viable for most commercial applications. As shown in figures 1-3, the tensile strength tensile strength Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its , elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. and compression set resistance of HS type FKM show excellent properties with a one hour post cure time, and show little change after the initial one hour. Standard type FKMs display only fair properties after one hour, and take many more hours of post cure time to approach the quality of properties afforded by the HS type FKM after one hour. [FIGURES 1-3 OMITTED] Table 3 shows the physical properties of the standard and HS FKM as compounded to the formulation in table 1 and post cured as shown. The durometer of the standard FKM is higher than HS by 5 points. The tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. and elongation are higher after a short post cure with HS FKM compared to standard FKM, while the modulus See modulo. is lower with HS. The fluid resistance tests in table 4 were conducted in a variety of fluids including aromatics, hydrocarbons hydrocarbons (hīˈ·drō·kärˑ·b  nz),n. , reference fuels and acid. The HS FKM and standard FKM, despite different post cure conditions, show very similar fluid resistance performance. The length of the post cure time does not appear to influence fluid resistance. Table 5 shows additional fluid tests conducted with HS type FKM compounded with 5 phr more filler and a small quantity of a process aid. Test specimens were post cured two hours at 250[degrees]C. While not compared to standard FKM, these data provide a reference point for other fluid environments that may be encountered in the chemical process industry. Conclusion: It is shown that a shortened short·en v. short·ened, short·en·ing, short·ens v.tr. 1. To make short or shorter. 2. post cure with HS type FKM imparts physical properties that exceed standard FKMs with long post cure times. Fluid resistance is not compromised by shortened post cures in HS polymers. This indicates that HS FKM can be substituted for standard FKM, giving finished parts better physical properties and utilizing more efficient production. The shortened post cure allows the seal fabricator to shorten (audio, compression) Shorten - A form of lossless audio compression. lead time on critical seals and lower overhead costs overhead costs see fixed costs. , including energy, fabrication fabrication (fab´rikā´sh  n),n the construction or making of a restoration. time and inventory. Additionally, the quality feedback loop from the beginning of the molding process to the final article is shortened, allowing for improved process and quality control. References (1.) Stanga M., Brinati G. and Albano, M., "High performance HS fluoroelastomers," International Rubber Conference, Moscow, June 2, 2004. (2.) Jagels, Steven, "A new type of VDF-HFP copolymer copolymer: see polymer. fluoroelastomer, "Energy Rubber Group Technical Meeting, September 18, 2003. (3.) Arcella, et al., "Crosslinking chemistry of VF2 elastomers by bis-nucleophiles, "Rubber Division, ACS (Asynchronous Communications Server) See network access server. Meeting, Detroit, MI, October, 1991. (4.) "Finding the right cure, "Flow Control, November/December 2004, Vol. X, No. 11, 30-31.
Table 1--test formulation
Material Standard FKM, phr HS FKM, phr
Standard FKM 100 0
HS FKM 0 100
Calcium hydroxide 6 0
Magnesium hydroxide 3 9
(high activity)
MT N 990 carbon 30 30
Table 2--rheology
MDR at 177[degrees]C Standard FKM HS FKM
ML, Newton meter (lb*.in.) 0.17 (1.52) 0.16 (1.38)
MH, Newton meter (Ib.*in.) 3.64 (28) 2.26 (20.0)
Ts2, minutes 1.9 1.6
T'50, minutes 2.3 2.2
T'90, minutes 3.4 3.2
Table 3--physical properties
Standard FKM, HS FKM,
Physical press cured: 10 press cured: 10
properties, minutes @ minutes @
original 177[degrees]C 177[degrees]C
post cured: 16 post cured: 2
hours @ hours @
250[degrees]C 250[degrees]C
Durometer A, points 73 68
Tensile strength, MPa 14.9 18.1
Elongation at break, % 180 228
Modulus, 100%, Mpa 7.1 5.1
Compression set 15 13
resistance, AS568-214 o-ring,
70 hours @ 200[degrees]C, %
Table 4--fluid resistance
Fluid Toluene, 70 hours @ 60[degrees]C Standard FKM HS FKM
Durometer change, pts. -13 -15
Tensile change, % -42 -49
Elongation change, % -22 -22
Volume swell, % 26 27
Fluid: Reference fuel C 90%, ethanol 10% (CE10), 70 hours @
60[degrees]C
Durometer change, pts. -13 -16
Tensile change, % -49 -50
Elongation change, % -18 -18
Volume swell, % 25 25
Fluid: Kerosene, 70 hours @ 60[degrees]C
Durometer change, pts. -1 -2
Tensile change, % -4 -16
Elongation change, % 10 -1
Volume swell, % 1 2
Fluid: Diesel #2, 70 hours @ 60[degrees]C
Durometer change, pts. -2 -1
Tensile change, % -3 -14
Elongation change, % 14 7
Volume swell, % 1 1
Fluid: Reference oil, IRM 901, 70 hours @ 150[degrees]
Durometer change, pts. -2 -1
Tensile change, % -8 -15
Elongation change, % 0 4
Volume swell, % 1 1
Fluid Iso octane, 70 hours @ 60[degrees]C
Durometer change, pts. -1 -1
Tensile change, % -11 3
Elongation change, % 5 3
Volume swell, % 1 1
Fluid HCI (37%), 70 hours @ 23[degrees]C
Durometer change, pts. 0 1
Tensile change, % -6 -12
Elongation change, % 9 7
Volume swell, % 0 0
Table 5--properties and fluid resistance
Material HS FKM, phr
HS FKM, "O-ring grade" 100
Magnesium hydroxide (high activity) 9
MT N990 carbon black 35
FPA 1 0.75
Physical properties, original HS FKM,
press cured: 10 minutes
@ 177[degrees]C
post cured: 2 hours
@ 250[degrees]C
Durometer A, points 73
Tensile strength, MPa 17.2
Elongation at break, % 191
Modulus, 100%, MPa 7.5
compression set, AS568-214 34
o-ring, 336 hours @ 200[degrees]C
Fluid: Fuel C, 70 hours @ 23[degrees]C HS FKM
Durometer change, pts. -2
Tensile change, % -11
Elongation change, % -3
Volume swell, % 3
Fluid: Methanol, 70 hours @ 23[degrees]C
Durometer change, pts. -19
Tensile change, % -67
Elongation change, % -56
Volume swell, % 88
Fluid: Methanol, 70 hours @ 70[degrees]C
Durometer change, pts. -19
Tensile change, % -58
Elongation change, % -36
Volume swell, % 47
Fluid: Distilled water, 70 hours @ 100[degrees]C
Durometer change, pts. -1
Tensile change, % -20
Elongation change, % -6
Volume swell, % 4
Fluid: Reference oil IRM 903, 70 hours @ 150[degrees]C
Durometer change, pts. -1
Tensile change, % -11
Elongation change, % -7
Volume swell, % 2
Fluid: Benzene, 70 hours @ 23[degrees]C
Durometer change, pts. -4
Tensile change, % -16
Elongation change, % -5
Volume swell, % 9
Fluid: Benzene, 70 hours @ 100[degrees]C, Reflux
Durometer change, pts. -15
Tensile change, % -45
Elongation change, % -32
Volume swell, % 33
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