Chemical corrosion resistant fluoroelastomer

Abstract

A tetrafluoroethylene-propylene copolymer with a solidification point monomer is mixed with a five-membered copolymer of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluorinated methyl vinyl ether (PMVE), and ethylene (PE), using a peroxide as an initiator and an aid TAIC as a crosslinking agent, and the resulting co-solidified fluoroelastomer shows improved curing performance, improved mechanical properties, and improved compression set. The co-solidified fluoroelastomer shows improved chemical resistance to solvent aging systems, and better retention of mechanical properties after high temperature aging in solvent systems.

Description

[0001] Cross-referencing of related patent applications

[0002] This PCT application claims priority to U.S. non-provisional patent application No. 18 / 651,928, filed May 1, 2024, entitled “Chemical-resistant fluororubber elastomer,” and is a continuation-in-the-part application thereof, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to elastomers. Specifically, it relates to co-cured fluorinated elastomers. Background Technology

[0004] Copolymers of tetrafluoroethylene (TFE) and propylene (PP) (FEPM) are known to exhibit excellent resistance to nucleophilic attacks (e.g., primary and secondary amines), but relatively poor resistance to many hydrocarbons, particularly aromatics. These copolymers are also known to have relatively poor processability and molding ability.

[0005] Developing new fluorinated elastomers with improved chemical resistance and compression set would be advantageous. Summary of the Invention

[0006] One embodiment of this disclosure is a co-cured elastomer blend comprising fluoropolymer A and fluoropolymer B. In one embodiment, fluoropolymer A comprises monomer units of tetrafluoroethylene (TFE), propylene (PP), and curing point monomer (CSM). In one embodiment, fluoropolymer B comprises monomer units of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). In one embodiment, fluoropolymer A and fluoropolymer B are crosslinked with a peroxide initiator and a triazine crosslinking agent. In one embodiment, the propylene content of fluoropolymer A may be in the range of 35-55%. In one embodiment, the blend may contain 25-100 pphr (parts per hundred parts rubber or polymer) of polymer A. In one embodiment, the blend may contain 25-100 pphr of fluoropolymer B. In one embodiment, the peroxide crosslinking initiator is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH). In one embodiment, DBPH is present at 3 parts per 100 parts of the polymer blend, and may range from 1 to 7 parts. In one embodiment, the alternative peroxide initiator may be di(tert-butylperoxyisopropyl)benzene. In one embodiment, the triazine co-crosslinker is triallyl isocyanurate (TAIC). In one embodiment, TAIC is present at 5 parts per 100 parts of the polymer blend, and may range from 1 to 7 parts. In one embodiment, carbon black is used as a curing agent for the polymer blend. In one embodiment, carbon black is present at 0 to 60 parts per 100 parts of the polymer blend to achieve the desired Shore hardness (Duro). In one embodiment, the curing point monomer may contain bromine atoms, iodine atoms, or a combination thereof. In one embodiment, the co-cured fluorinated elastomer has improved curing properties and molding ability. In one embodiment, the curing time is reduced. In one embodiment, the fluorinated elastomer blend has improved mechanical properties, including but not limited to: tensile strength, modulus at 50% elongation, modulus at 100% elongation, and tear strength. In one embodiment, the blend exhibits a synergistic effect and improved compression set, with the compression set decreasing from 37% in fluoropolymer A to 24% in the blend. In one embodiment, the blend has two glass transition temperatures (Tg) corresponding to single fluoropolymers A and B, indicating phase separation and a two-phase structure. In one embodiment, after solvent aging tests at 200°C for 168 hours in an autoclave, the swelling percentage shows a smaller percentage of swelling than the calculated average. In one embodiment, the blend exhibits a smaller decrease in hardness compared to single fluoropolymer A. In one embodiment, the blend exhibits a higher retention of tensile strength compared to single fluoropolymers A or B.In one embodiment, the blend exhibits a higher tear strength retention rate compared to a single fluoropolymer A or B.

[0007] In one embodiment, fluoropolymer A and fluoropolymer C are co-cured to form a co-cured fluoroelastomer blend. Fluoropolymer A comprises monomer units of propylene (TFE), propylene (PP), and curing point monomer (CSM). Fluoropolymer C comprises monomer units of VDF, TFE, and fluorinated vinyl ether (PMVE). Fluoropolymer A and fluoropolymer C are crosslinked with a peroxide initiator and a triazine crosslinking agent. In one embodiment, the propylene content of fluoropolymer A may be in the range of 35-55%. In one embodiment, the blend may contain 25-100 pph of fluoropolymer A. In one embodiment, the blend may contain 25-100 pph of fluoropolymer C. In one embodiment, the peroxide crosslinking initiator is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH). In one embodiment, DBPH is present at 3 parts per 100 parts of the polymer blend. In one embodiment, the triazine crosslinking agent is triallyl isocyanurate (TAIC). In one embodiment, TAIC is present at 5 parts per 100 parts of the polymer blend. In one embodiment, carbon black is used as a curing agent for the polymer blend. In one embodiment, carbon black is present in the range of 0 to 60 parts per 100 parts of the polymer blend to achieve the desired Shore hardness (Duro). In one embodiment, the curing point monomer may contain bromine atoms, iodine atoms, or a combination thereof. In one embodiment, the co-cured fluorinated elastomer has improved curing properties and molding ability. In one embodiment, the curing time is reduced.

[0008] In another embodiment, the co-cured elastomer blend comprises a fluoropolymer A and a fluoropolymer C. Fluoropolymer A may comprise monomer units of tetrafluoroethylene (TFE), propylene (PP), and a curing point monomer (CSM). Fluoropolymer C comprises a monomer unit of at least one perfluorinated vinyl ether (PMVE); and fluoropolymer A and fluoropolymer C are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

[0009] In another embodiment, the co-cured elastomer blend comprises fluoropolymer A and fluoropolymer C. Fluoropolymer A comprises monomer units and a curing point monomer (CSM). Fluoropolymer C comprises a monomer unit of at least one perfluorinated vinyl ether (PMVE); and fluoropolymer A and fluoropolymer C are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

[0010] Optionally, in any embodiment, fluoropolymer A is present in approximately 25-75 parts per 100 parts of the blend.

[0011] Optionally, in any embodiment, the fluoropolymer C is present in about 25-75 parts per 100 parts of the polymer blend, more specifically, in about 25-65 parts per 100 parts of the polymer blend.

[0012] Optionally, in any embodiment, the CSM (curing point monomer) contains iodine atoms, bromine atoms, or a combination thereof.

[0013] Optionally, in any embodiment, the peroxide initiator comprises di(tert-butylperoxyisopropyl)benzene, and the di(tert-butylperoxyisopropyl)benzene is present in about 1 to 5 parts per 100 parts of the polymer blend.

[0014] Furthermore, the co-cured elastomer blend comprises fluoropolymer A and fluoropolymer D. Fluoropolymer A comprises monomer units and curing point monomer (CSM). Fluoropolymer D is a pentadiene copolymer comprising monomer units of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoromethyl vinyl ether (PMVE), and ethylene (PE); and fluoropolymer A and fluoropolymer D are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

[0015] Optionally, in any embodiment, the fluoropolymer D is present in about 25-75 parts per 100 parts of the polymer blend, more specifically, in about 25-65 parts per 100 parts of the polymer blend.

[0016] In addition, the co-cured elastomer blend comprises fluoropolymer A and fluoropolymer D. Fluoropolymer A comprises monomer units of propylene (TFE), propylene (PP), and curing point monomer (CSM). Fluoropolymer D comprises at least one monomer unit of vinylidene fluoride (VDF). Fluoropolymer A and fluoropolymer D are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

[0017] Finally, the co-cured elastomer blend may comprise fluoropolymer A and fluoropolymer D. Fluoropolymer A comprises monomer units and a curing point monomer (CSM). Fluoropolymer D comprises at least one monomer unit of vinylidene fluoride (VDF). Fluoropolymer A and fluoropolymer D are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

[0018] The features of this disclosure have been outlined rather broadly above to facilitate a better understanding of the detailed description that follows. Additional features and advantages of this disclosure, which form the subject matter of the claims, will be described below. Attached Figure Description

[0019] To achieve the above and other enhancements and objectives of this disclosure, a more specific description of the disclosure briefly described above will be presented by reference to specific embodiments of the disclosure illustrated in the accompanying drawings. It should be understood that these drawings depict only exemplary embodiments of the disclosure and are therefore not to be considered as limiting its scope. The disclosure will be described with additional specificity and detail using the drawings, in which: Figure 1 MDR curing curves of fluorinated elastomers co-cured from fluorinated polymers A and B were plotted. Figure 2 The compression set of a co-cured fluoroelastomer derived from fluoropolymers A and B is depicted. Figure 3 Compression set of a co-cured fluoroelastomer derived from fluoropolymers A and D is depicted.

[0020] Figure 4 TGA curves of co-cured fluorinated elastomers from fluorinated polymers A and B were plotted. Figure 5 DSC curves of co-cured fluorinated elastomers from fluorinated polymers A and B were plotted. Figure 6 DSC curves of fluorinated elastomers co-cured from fluorinated polymers A and C were plotted.

[0021] Figure 7 TGA curves of co-cured fluorinated elastomers from fluorinated polymers A and D were plotted; Figure 8 DSC curves of the co-cured fluorinated elastomers from polymers A and D were plotted.

[0022] Figure 9 Unaged tensile specimens and solvent-aged tensile specimens of fluorinated elastomer A100 were depicted. Figure 10 Unaged and solvent-aged tensile specimens of co-cured fluorinated elastomer A50 were depicted. Figure 11 Experimental and calculated swelling percentages of co-cured fluoroelastomers from fluoropolymers A and B are depicted; Figure 12a Unaged tensile specimens and solvent-aged tensile specimens of the fluorinated elastomer AD50 were depicted. Figure 12b Unaged tensile specimens and solvent-aged tensile specimens of fluorinated elastomer D100 were depicted. Figure 13 Experimental and calculated swelling percentages of co-cured fluoroelastomers from fluoropolymers A and D are depicted; Figure 14The tensile strength retention, tear strength retention, and swelling percentage of a co-cured fluoroelastomer derived from fluoropolymers A and B after aging in an alkane solvent at 200 °C for 168 hours are described (ISO 23936 A.1.ii). Figure 15 The tensile strength retention, tear strength retention and swelling percentage of the co-cured fluoropolymers from fluoropolymers A and D after aging in an alkane solvent at 200 °C for 168 hours are described (ISO 23936 A.1.ii). Detailed Implementation

[0023] The details shown herein are by way of example and are intended only for illustrative discussion of preferred embodiments of this disclosure, and are presented to provide the most useful and readily understood description of the principles and concepts of various embodiments of this disclosure. In this regard, no attempt is made to show the structural details of this disclosure in more detail than is necessary for a basic understanding of it, and the description taken in conjunction with the accompanying drawings makes it clear to those skilled in the art how several forms of this disclosure will be embodied in practice.

[0024] The following definitions and interpretations are intended to control any future interpretations unless clearly and explicitly modified in the following embodiments, or when the application of the meaning renders any interpretation meaningless or substantially meaningless. If the structure of a term renders it meaningless or substantially meaningless, the definition from Merriam-Webster, 3rd edition, shall apply.

[0025] Before describing the embodiments, terms, methods, systems, and materials have been described; it should be understood that this disclosure is not limited to the specific terms, methods, systems, and materials described, as these can vary. It should also be understood that the terminology used in this specification is for the purpose of describing a particular version of the embodiments only and is not intended to limit the scope of the embodiments. For example, as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly specifies otherwise. Furthermore, the word “comprising” as used herein is intended to mean “including, but not limited to,” [the specific meaning is missing here]. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0026] Unless otherwise stated, all figures used in the specification and claims that indicate the amount of ingredients, properties (e.g., size, weight, reaction conditions, etc.) should be understood to be modified by the term "about" in all cases.

[0027] Therefore, unless otherwise indicated, the numerical parameters listed in the following description and appended claims are approximate values ​​that may vary depending on the desired properties sought to be obtained according to the invention. At least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques.

[0028] As used in this article, the term “about” refers to a numerical value that is added to or subtracted by 10% when used with it. Therefore, about 50% means in the range of 45% to 55%.

[0029] Fluorinated elastomers offer excellent high-temperature and corrosion-resistant fluid properties in sealing and fluid transport applications in automotive, oil and gas, chemical processes, small engines, and other harsh sealing environments. Fluorinated elastomers are widely used due to their unique non-stick and low-friction properties, as well as their excellent thermal and chemical properties.

[0030] As a type of specialty fluorinated elastomer, a special copolymer (FEPM) of tetrafluoroethylene (TFE) and propylene (PP) is known to exhibit excellent resistance to nucleophilic attacks (such as primary and secondary amines), but it exhibits relatively poor resistance to many hydrocarbons, especially aromatics. They are also known for their relatively poor processability and molding ability. To address this problem, this invention discloses the development of novel fluorinated elastomers by introducing the alkali-resistant fluorinated elastomer FKM V-type, thereby overcoming these shortcomings through the design of microstructure and phase structure.

[0031] Combining FKM-type fluorinated elastomers of type II, III, or V with FEPM to manufacture new fluorinated elastomers through the design of microstructure and phase structure will facilitate the development of new fluorinated elastomers.

[0032] Specifically, the objective of this invention is to improve high-temperature performance and chemical resistance (alkanes) by introducing alkali-resistant FKM (Type V) through co-curing, while maintaining its alkali resistance. Type V FKM is a pentagonal copolymer of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoromethyl vinyl ether (PMVE), and ethylene (PE).

[0033] In one embodiment, a blend of fluorinated elastomers of tetrafluoroethylene-propylene copolymer (FEPM) (a monomer with a curing point) and a pentagonal copolymer of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluorinated methyl vinyl ether (PMVE), and ethylene (PE) is co-cured using peroxide as an initiator and TAIC as a crosslinking agent. The co-cured fluorinated elastomer exhibits dual glass transition temperatures, indicating a two-phase structure, corresponding to a single polymer (FEPM) and a single polymer D (FKM). The co-cured fluorinated elastomer shows improved curing properties, improved mechanical properties, and improved compression set. The co-cured fluorinated elastomer exhibits improved chemical resistance to solvent aging systems and better retention of mechanical properties after high-temperature aging in solvent systems.

[0034] Unlike FKM fluorinated elastomers, traditional FEPM (TFE-P) fluorinated elastomers (such as Aflas 100H, 150P, etc.) do not possess curing point monomers; their curing occurs through crosslinking of unsaturated propylene segments. However, curing point monomer technology can provide more ordered crosslinking. The addition of curing point monomers allows for ordered crosslinking (electropophilic rather than nucleophilic) processes, thereby making the triazine structure crosslinked. In particular, recently, novel FEPM (TFE-P) with curing point monomers have been developed.

[0035] High-temperature applications of fluoroelastomers frequently occur in various chemicals. Generally, FEPM (TFE-P) exhibits excellent chemical resistance at high temperatures, particularly superior alkali resistance compared to other FKMs (Type I, Type II, etc.). However, due to the approximately 50% propylene segment in its chain structure, it exhibits excessive swelling in alkanes compared to FKM fluoroelastomers. Furthermore, PEPM (TFE-P) is more challenging to process, extrude, and mold than FKM.

[0036] The purpose of this invention is to provide new fluorinated elastomers by co-curing different fluorinated elastomers to overcome the aforementioned drawbacks. Specifically, the objective of this invention is to introduce alkali-resistant FKM (Type V) to improve performance at high temperatures and chemical resistance (alkanes), while maintaining its alkali resistance. Type V FKM is a pentagonal copolymer of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoromethyl vinyl ether (PMVE), and ethylene (PE).

[0037] Fluoropolymer A is a grade of fluorinated elastomer FEPM, which is a copolymer of tetrafluoroethylene (TFE) and propylene (PP) with curing point monomer (CSM). This differs from conventional FEPMs that do not contain CSM. In one embodiment, the polymer may be Aflas 600X from Asahi Glass Corporation.

[0038] Fluoropolymer B is a Type II FKM according to ASTM D1418. Polymer B is a terpolymer of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). In one embodiment, the polymer is Tecnoflon P959.

[0039] Fluoropolymer C is a Type III FKM according to ASTM D1418. Polymer C is a terpolymer of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), and fluorinated vinyl ether (PMVE). In one embodiment, the polymer is Tecnoflon PL958.

[0040] Fluoropolymer D is a type V FKM according to ASTM D1418. Fluoropolymer D is a pentadienoic copolymer containing monomer units of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluorinated methyl vinyl ether (PMVE), and ethylene (PE).

[0041] Triallyl isocyanurate (TAIC) is a triazine crosslinking agent used in elastomer-forming rubbers. In one embodiment, Vulcofac TAIC-72 DLC is commercial grade and has an active content of 72%.

[0042] 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH) is a peroxide initiator used for crosslinking. In one embodiment, Varox DBPH-50 HP is commercial grade and has an effective content of 45% on an inert support.

[0043] Carbon black N326 is commercial grade, and its small size and aspect ratio contribute to better mechanical properties in elastomers.

[0044] In one embodiment, the fluoroelastomer formulation is compounded using a two-roll mill at room temperature for 30 minutes to achieve mixing of all components and additives. In another embodiment, all formulation components are pre-blended before being introduced into the two-roll mill.

[0045] The premixed adhesive, after open milling, was molded and cured at 177 °C for 10 minutes using a flatbed press, followed by post-curing at 200 °C for 4 hours, and then at 204 °C for 16 hours. Test samples were prepared using standard compression molding. In one embodiment, the test samples included molded sheets and button-shaped (short columnar) specimens.

[0046] Table 1. Fluoropolymer A, Fluoropolymer B, Fluoropolymer C, and Fluoropolymer D

[0047] In one embodiment, the formulation contains 45 pphr N326 carbon black and has a hardness of approximately 90 on a hardness tester. Various sample formulations are provided in Tables 2A, 2B, and 2C.

[0048] Table 2A. Exemplary formulations of fluoroelastomers co-cured from fluoropolymers A and B

[0049] Table 2B. Exemplary formulations of fluoroelastomers co-cured from fluoropolymers A and C

[0050] Table 2C. Formulation of co-cured fluoroelastomers (from polymers A and D) The total amount of polymer A and polymer D is 100 parts.

[0051] According to ASTM, specimens are die-cut from molded sheets for all physical properties and solvent aging tests.

[0052] Curing properties: Compared to conventional FEPMs without curing point monomers, novel FEPMs containing curing point monomers exhibit faster curing times. Preferably, A100 (FEPM) (fluoropolymer A) and A0 (FKM) (fluoropolymer B) have similar curing times. By comparing curing times (Tc90 measured from ODR and Tc90 measured from MDR), A100 (FEPM) and A0 (FKM) have very similar curing times (Table 3A). According to ODR, A100 (FEPM) has a curing time of 7.83 min (Tc90), and A0 (FKM) has a curing time of 6.09 min (Tc90). According to MDR, A100 (FEPM) has a curing time of 6.03 min (Tc90), and A0 (FKM) has a curing time of 5.11 min (Tc90). The curing times indicate that co-curing systems comprising the two components should have matched curing times. The test results for ODR and MDR Tc90 of A75, A65, A50, A35, and A25 clearly support this hypothesis. Furthermore, from Table 3 and... Figure 1 It can be seen that the higher torque and faster curing rate indicate that A75, A65, A50, A35 and A25, which are incorporated with fluoropolymer B, have a more efficient curing response compared to pure fluoropolymer A (A100).

[0053] From Table 3A (fluoroelastomers co-cured from fluoropolymers A and B) and Table 3B (fluoroelastomers co-cured from fluoropolymers A and C), all formulation samples exhibit good scorch times (approximately 0.5 minutes and above), which will allow sufficient time for compression molding and other molding operations.

[0054] Compared to traditional FEPMs without curing point monomers, novel FEPMs containing curing point monomers exhibit faster curing speeds. When designing these new co-cured fluoroelastomer systems, A100 (FEPM) and D100 (FKM) preferably have similar curing times. By comparing curing times (Tc90 measured from ODR and Tc90 measured from MDR), A100 (FEPM) and D100 (FKM) show very similar curing times. According to ODR, A100 (FEPM) has a Tc90 of 7.83 min and D100 (FKM) has a Tc90 of 8.75 min. Similarly, according to MDR, A100 (FEPM) has a Tc90 of 6.03 min and D100 (FKM) has a Tc90 of 6.88 min. Therefore, these curing times indicate that co-cured systems comprising both components should have matched curing times. The test results for ODR and MDR Tc90 of AD75, AD50, and AD25 clearly support this hypothesis. Furthermore, as shown in Table 3, the higher torque and similar curing rate clearly demonstrate that AD75, AD50, and AD25, incorporating polymer D, have a more efficient curing response compared to pure polymer A (A100).

[0055] According to the MDR data in Table 3, all formulation samples have good scorch times (0.73 minutes and above), which will allow sufficient time for compression molding and other molding operations.

[0056] The ODR and MDR test results show that the fluorinated elastomers in this formulation series have good processing performance and extrusion molding performance.

[0057] The MH-ML value of fluorinated elastomers within the same series is an indicator of changes in crosslinking density. A higher value indicates a higher crosslinking density. In this study, the MH-ML value of the co-cured fluorinated elastomers increased with the addition of fluorinated polymer B (Table 3A). Although the chemical compositions of the fluorinated elastomers in the samples differed, we can still approximate an increase in crosslinking density. Figure 1The MDR curing curves of the co-cured fluorinated elastomers from fluorinated polymers A and B are shown, clearly demonstrating that the MH (high modulus) of the curing curves of the blended fluorinated elastomers increases with the addition of fluorinated polymer B. In this study (Table 3C), the MH-ML value increases with the addition of fluorinated elastomer D. Although the chemical compositions of the fluorinated elastomers in the samples differ, we can still approximate an increase in crosslinking density.

[0058] Table 3A. Rheological properties of fluoroelastomers co-cured from fluoropolymers A and B

[0059] Table 3B. Rheological properties of fluoroelastomers co-cured from fluoropolymers A and C

[0060] Table 3C. Rheological properties of co-cured fluoroelastomers from polymers A and D

[0061] Hardness: Measured according to ASTM D2240-85.

[0062] Compression set: Measured for 70 hours at 200 °C on button-shaped (short cylindrical) specimens according to ASTM 395-89.

[0063] Tensile test: Tensile properties were determined on die-cut specimens of post-cured sample plates according to ASTM D412 (ASTM D412 die C).

[0064] Tear test: Tear strength is determined on a sample cut from ASTM 624 die C using ASTM D 624.

[0065] Glass transition temperature (Tg) was measured on a TA instrument DSC Q20 using a heating rate of 10 °C / min, N2 gas flow, and a temperature range from -80 °C to 250 °C.

[0066] Thermal degradation was tested on a TA instrument TGA Q50, using a heating rate of 10 °C / min, heated to 700 °C in N2 gas, and then switched to air to heat to 900 °C.

[0067] Tables 4A (Fluoropolymers co-cured from fluoropolymers A and B) and 4B (Fluoropolymers co-cured from fluoropolymers A and C) show the physical properties of the co-cured fluoropolymers obtained by pressure curing (compression molding and curing at 177 °C for 10 minutes) and post-curing at 204 °C for 16 hours. The samples also exhibit Shore A hardness of 85 to 90 duro A. The test data for the pressure-cured samples clearly demonstrate good tensile strength, elongation, and tear strength. Good tensile properties and tear strength are good indicators of good moldability (no damage during demolding).

[0068] After post-curing at 204 °C for 16 hours, the Shore A hardness of the flatbed press-molded and cured samples increased by 4 to 5, and ranged from 90 to 94 duro A.

[0069] Tear strength increased from 155 pli for A100 to 185 pli for A35 with the addition of fluoropolymer B. Tensile strengths of A65, A50, A35, and A25 increased slightly compared to A100. Both 50% and 100% moduli increased with the addition of fluoropolymer B (A75, A65, A50, A35, A25) (Table 4A).

[0070] Table 4A. Physical properties of co-cured fluoroelastomers obtained from flatbed press molding and post-curing of fluoropolymers A and B

[0071] Table 4B. Physical properties of co-cured fluoroelastomers obtained from flatbed press molding and post-curing of fluoropolymers A and C

[0072] Table 4C shows the physical properties of the compounded fluorinated elastomers (from fluorinated polymer A and fluorinated polymer D) obtained by flatbed press molding curing (flatbed press molding and curing at 177 °C for 10 minutes) and post-curing at 204 °C for 16 hours. The pressure-cured samples exhibit Shore A hardness of 83 to 90 duro A. The test data for the pressure-cured samples clearly demonstrate good tensile strength, elongation, and tear strength. Good tensile properties and tear strength are good indicators of good moldability (no damage during demolding).

[0073] After post-curing at 204 °C for 16 hours, the Shore A hardness of the pressure-cured sample increased by 4 to 7, reaching the range of 90 to 94 duro.

[0074] With the addition of polymer D, the tear strength increased from 155 pli for A100 to 176 pli for AD75 and 169 pli for AD25 (Table 4C). The tensile strength of AD75 was slightly improved compared to A100. Compared to A100, the 50% modulus increased from 1334 psi to 1517 psi (AD75) and 1779 psi (AD25) with the addition of fluoroelastomer D.

[0075] Table 4C. Physical properties of co-cured fluoroelastomers obtained from flatbed press molding and post-curing of polymers A and D

[0076] Compression permanent deformation

[0077] As shown in Table 5A and Figure 2 As shown, fluoropolymer A (A100) and fluoropolymer B (A0) exhibited compression set of 37% and 31%, respectively. All other co-cured formulations (A75, A65, A50, A35, A25) showed positive synergistic effects and improved compression set with lower values. The lower the value, the better the compression set performance. With the incorporation of fluoropolymer B, the compression set decreased from 37% in A100 to 24% in A35 and A25. The improved compression set and synergistic effect likely stem from the unique phase structure of the co-cured formulations (evidence from the two Tg (glass transition temperatures) suggests a two-phase structure).

[0078] The newly formulated fluoropolymer A (FEPM and CSM) combined with fluoropolymer B (FKM II) can be rapidly cured by peroxide and has better compression set.

[0079] Compared to fluoropolymer A, the compression set of co-cured fluoroelastomers incorporating fluoropolymer C decreased from 37% to 18% of AC25 (Table 5B).

[0080] Table 5A. Compression set of fluoroelastomers co-cured from fluoropolymers A and B Compression set was measured on button-shaped specimens that were molded at 177 °C for 45 minutes using a flatbed press and then post-cured at 204 °C for 16 hours.

[0081] Table 5B. Compression set of fluoroelastomers co-cured from fluoropolymers A and C Compression set was measured on button-shaped specimens that were molded at 177 °C for 45 minutes using a flatbed press and then post-cured at 204 °C for 16 hours.

[0082] As shown in Table 5C and Figure 3 As shown, polymers A (A100) and D (D100) exhibited compression set of 37% and 49%, respectively. All other co-cured samples (AD75, AD50, AD25) showed a positive synergistic effect and improved compression set with lower values. The lower the value, the better the compression set performance. The compression set decreased from 37% for A100 and 49% for D100 to 32% for co-cured samples AD50 and AD25. These improved compression set and synergistic effects likely stem from the unique phase structure of the co-cured samples (evidence from the two glass transition temperatures, Tg, suggests a two-phase structure).

[0083] The blend formulation sample, which combines polymer A (FEPM and CSM) and polymer D (FKM V-type), can be rapidly cured by peroxide and has better compression set.

[0084] Table 5C. Compression set of co-cured fluoroelastomers from polymers A and D

[0085] thermal stability

[0086] The thermal stability of fluorinated elastomers was studied using thermogravimetric analysis (TGA). Figure 4 The TGA curves show that thermal degradation of all fluorinated elastomers from fluorinated polymer A and fluorinated polymer B begins above 330 °C.

[0087] Glass transition temperature of fluorinated elastomers

[0088] The glass transition temperature of fluorinated elastomers was studied using DSC at a heating rate of 10 °C / min, starting from -60 °C. Figure 5 As shown in Table 6A, the Tg of fluoropolymer A (A100) is 2.1 °C, while the Tg of fluoropolymer B (A0) is -5.9 °C. Two distinct glass transition temperatures (Tg1 and Tg2) were measured. For the co-cured fluoropolymers (A65, A50, A35) from fluoropolymers A and B, Tg1 is close to the Tg of fluoropolymer A (A100), and Tg2 is close to the Tg of fluoropolymer B. The two glass transition temperatures indicate a two-phase structure in the co-cured fluoropolymers (A65, A50, A35), where the phase with Tg1 corresponds to the phase of fluoropolymer A, and the phase with Tg2 corresponds to the phase of fluoropolymer B.

[0089] Clearly, the two-phase structure of the co-cured formulation samples contributes significantly to the synergistic effect and the improvement of compression set.

[0090] Similarly, Figure 6 Table 6B shows the glass transition temperatures of the co-cured fluorinated elastomers from fluorinated polymers A and C. Two distinct glass transition temperatures (Tg1 and Tg2) were measured, indicating a two-phase structure in the co-cured fluorinated elastomers (AC75, AC50, AC25). The lower Tg2 (~ -24 °C) of the co-cured fluorinated elastomers may be more suitable for sealing applications at lower temperatures.

[0091] Table 6A. Glass transition temperatures of fluoroelastomers co-cured from fluoropolymers A and B

[0092] Table 6B. Glass transition temperatures of fluoroelastomers from fluoropolymers A and C

[0093] The thermal stability of fluorinated elastomers was studied using thermogravimetric analysis (TGA). Figure 7 The TGA curves show that thermal degradation of all fluorinated elastomers from fluorinated polymer A and fluorinated polymer D begins above 330 °C.

[0094] Glass transition temperature of fluorinated elastomers

[0095] The glass transition temperature of fluorinated elastomers was studied using DSC at a heating rate of 10 °C / min, starting from -60 °C. Figure 8 The glass transition temperature (Tg) of fluorinated elastomer A (A100) is 2.1 °C, while that of fluorinated elastomer D (D100) is -8.8 °C. For co-cured fluorinated elastomers (AD75, AD50, AD25), two glass transition temperatures (Tg1 and Tg2) were measured, with Tg1 close to that of fluorinated elastomer A (A100) and Tg2 close to that of fluorinated elastomer D (Table 6C). These two glass transition temperatures indicate a two-phase structure of the fluorinated elastomers (AD75, AD50, AD25), where one phase with Tg1 corresponds to the phase of fluorinated elastomer A, and the other phase with Tg2 corresponds to the phase of fluorinated elastomer D.

[0096] Clearly, the two-phase structure of the co-cured formulation samples mainly contributes to the synergistic effect and the improvement of compression set.

[0097] Table 6C. Glass transition temperatures of co-cured fluoroelastomers from polymers A and D

[0098] Chemical aging test: Simulated produced fluid was prepared according to ISO 23936-2, section A.1.ii. Tensile specimens were die-cut from each material using ASTM D412 die C, and tear specimens were die-cut from each material using ASTM D624 die C. Weight change was determined according to modified D471, Shore A hardness was determined according to ASTM D471, and Shore A hardness was determined according to ASTM D2240.

[0099] The fluid aging conditions are as follows: According to ISO 23936-2, A.1.ii, the aging solution consists of (70% heptane, 20% cyclohexane, 10% toluene) / (water) 90% / 10%.

[0100] The aging temperature was 200 ℃ for 7 days (168 hours).

[0101] Aging is carried out in an autoclave (aging chamber).

[0102] Tensile specimen dimensions conform to ASTM D412 die C. Tear specimen dimensions conform to ASTM D624 die C.

[0103] Weight swelling is calculated as a percentage increase in weight per original sample weight.

[0104] High-temperature solvent aging test

[0105] Solvent aging tests were conducted for 168 hours in an autoclave at 200 °C, according to ISO 23936-2, A.1.ii. The solvent (ISO 23936-2, A.1.ii) consisted of 90% (70% heptane, 20% cyclohexane, and 10% toluene) and 10% (water). Tensile test specimens were die-cut according to ASTM D412 die C. Tear test specimens were die-cut according to ASTM D624 die C.

[0106] Figure 9 and Figure 10 Examples of unaged and solvent-aged stretched bars of A100 and A50 formulation samples are shown.

[0107] The weight swelling results of the co-cured fluoroelastomers from fluoropolymers A and B are summarized in Table 7A. Adding fluoropolymer B (FKM II) to the system reduced the weight swelling from 25% for pure fluoropolymer A (A100) (FEPM) to ~15% for formulation sample A35 with 35% fluoropolymer B (FKM II). This indicates that better solvent resistance can be achieved by forming co-cured fluoroelastomers compared to pure fluoropolymer A (A100) (FEPM).

[0108] Figure 11 Experimental and calculated swelling data for the co-cured formulations are shown. The experimental swelling data for the co-cured formulations are lower than those calculated based on the contents of fluoropolymer A and fluoropolymer B. Similarly, this positive synergistic effect is also observed in the compression set results. This positive synergistic effect is primarily attributed to the two-phase structure of the co-cured formulations. The swelling of A0 (fluoropolymer B) is significantly lower than that of A100 (fluoropolymer A) (40% lower). When formulation A50 containing 50% fluoropolymer B is formed, this formulation has more bicontinuous phases from fluoropolymer A and fluoropolymer B, with the fluoropolymer B phase providing more constraint on the swelling, thus the swelling is closer to A0 (fluoropolymer B). Similarly, fluoropolymer B forms the main phase in formulations A35 and A25, therefore, the swelling is more constrained by the fluoropolymer B phase and is very close to A0 (fluoropolymer B).

[0109] The weight swelling results of the co-cured fluoroelastomers from fluoropolymers A and C are summarized in Table 7B. Adding fluoropolymer C (FKM III) to the system reduced the weight swelling from 25.6% for pure fluoropolymer A (A100) (FEPM) to ~18% for formulations AC75 (with 25% fluoropolymer C added) and AC50 (with 50% fluoropolymer C added), and ~16% for formulation AC25 (with 75% fluoropolymer C added). This indicates that better solvent resistance can be achieved by forming co-cured fluoroelastomers compared to pure fluoropolymer A (A100) (FEPM).

[0110] Figure 12a and Figure 12b Examples of unaged and solvent-aged stretched bars of AD50 and D100 formulation samples are shown.

[0111] The weight swelling results of the co-cured fluorinated elastomers from fluorinated polymers A and D are summarized in Table 7C. It can be clearly seen that with the addition of FKM V (polymer D) to the blend system, the weight swelling decreased from 25.6% for pure FEPM (polymer A (A100)) to 20.5% for formulation AD 75 (with 25% FKM fluorinated polymer D), 17.8% for formulation AD50 (with 50% FKM fluorinated polymer D), and 15.5% for formulation AD25 (with 75% FKM fluorinated polymer D). This indicates that better solvent resistance can be achieved by forming co-cured fluorinated elastomers compared to pure FEPM (A100).

[0112] Figure 13Experimental and calculated swelling data for the co-cured formulation samples are shown. The experimental swelling data for the co-cured formulation samples are lower than the calculated swelling data based on the contents of fluoropolymer A and fluoropolymer D. Similarly, this positive synergistic effect is also observed in the compression set results. This positive synergistic effect is mainly attributed to the two-phase structure of the co-cured formulation samples.

[0113] Table 7A. Swelling percentage of co-cured fluoroelastomers (from fluoropolymers A and B) after aging in a hydrocarbon solvent at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0114] Table 7B. Swelling percentage of co-cured fluoroelastomers (from fluoropolymers A and C) after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0115] Table 7C. Percentage of swelling of co-cured fluorinated elastomers (from polymers A and D) after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0116] Table 8A shows the change in Shore A duro hardness of the co-cured fluorinated elastomers after solvent aging. The hardness of each sample decreased after solvent aging. The change (decrease) value of the co-cured fluorinated elastomers from fluorinated polymers A and B became smaller with increasing fluorinated polymer B content, from -40 for pure fluorinated polymer A (A100) to -30 for A25.

[0117] Similarly, as can be seen from Table 8B, as the content of fluoropolymer C increases, the change (decrease) value of the fluoroelastomer co-cured from fluoropolymers A and C becomes smaller, from -40 for pure fluoropolymer A (A100) to -30 for AC25.

[0118] Table 8C shows the change in Shore A duro hardness of the formulation samples after swelling of the fluorinated elastomers after aging in a hydrocarbon solvent at 200 °C for 168 hours (ISO 23936 A.1.ii). The change becomes smaller as the polymer D content in the formulation samples increases, from -40 for pure fluorinated polymer A (A100) to -35 for AD25.

[0119] Table 8A. Changes in Shore A hardness of co-cured fluorinated elastomers (from fluorinated polymers A and B) after aging in a hydrocarbon solvent at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0120] Table 8B. Changes in Shore A hardness of co-cured fluorinated elastomers (from fluorinated polymers A and C) after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0121] Figure 14 Experimental and calculated swelling data for the co-cured formulations are shown. It is clear that the experimental swelling data for the co-cured formulations are significantly lower than the calculated swelling data based on the contents of polymers A and D (Table 7C). The experimental swelling (percentage) for all three co-cured formulations (AD75, AD50, and AD25) is 20% to 30% lower than the calculated swelling values. Similarly, this positive synergistic effect is also observed in the compression set results. This positive synergistic effect is primarily attributed to the two-phase structure of the co-cured formulations.

[0122] Table 8C shows the change in Shore A duro hardness of the formulation samples after swelling of the fluorinated elastomers after aging in a hydrocarbon solvent at 200 °C for 168 hours (ISO 23936 A.1.ii). The change becomes smaller as the polymer D content in the formulation samples increases, from -40 for pure polymer A (A100) to -35 for AD 25.

[0123] Table 8C. Changes in Shore A hardness of co-cured fluorinated elastomers (from polymers A and D) after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0124] The tensile properties of solvent-aged samples were measured according to ASTM D412C and compared with unaged samples to generate the tensile strength retention rate (%). Table 9A shows the tensile strength retention rates of the co-cured fluoropolymers from fluoropolymers A and B. The results show that the tensile strength retention rates of formulation samples A50 (59.8%), A35 (67.8%), and A25 (57.8%) are also higher than those of fluoropolymer A (A100, 46%) and fluoropolymer B (A0, 52.3%). Therefore, the increased tensile strength retention rate indicates that the formation of co-cured fluoropolymers improves the solvent aging resistance of fluoropolymers and exhibits a positive synergistic effect.

[0125] Table 9A. Tensile strength retention of co-cured fluorinated elastomers (from fluorinated polymers A and B) after swelling following aging in a hydrocarbon solvent at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0126] Table 9B also shows the co-cured fluorinated elastomers incorporated with fluorinated polymer C, which show an increased tensile strength retention rate compared to fluorinated polymer A, indicating improved solvent aging resistance.

[0127] Table 9B. Tensile strength retention of co-cured fluorinated elastomers (from fluorinated polymer A and fluorinated polymer C) after swelling following aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0128] The tensile properties of solvent-aged samples were measured according to ASTM D412C and compared with unaged samples to determine the tensile strength retention rate (%) of the co-cured fluoropolymers derived from fluoropolymers A and D. Table 9C shows the tensile strength retention rates of the formulation samples. The results show that the tensile strength retention rates of formulations AD75 (60.5%), AD50 (54.5%), and AD25 (59.8%) are increased compared to those of A100 (46%) and D100 (45.3%), and the latter three formulations also show higher tensile strength retention rates than A0 (52.3%). Therefore, the increased tensile strength retention rate indicates that the formation of co-cured fluoropolymers does indeed improve the solvent aging resistance of fluoropolymers.

[0129] Table 9C. Tensile strength retention rate after swelling after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0130] The tear strength of solvent-aged samples was measured according to ASTM D624C and compared with unaged samples to generate the tear strength retention rate (%). Table 10A shows that the tear strength retention rates of co-cured fluorinated elastomers A75 (48.1%), A65 (52.3%), A50 (53.8%), A35 (58.6%), and A25 (50.9%) were increased compared to both fluorinated polymer A (A100) (47.8%) and fluorinated polymer B (A0) (43.0%). Therefore, the increased tear strength retention rate indicates that the formation of co-cured fluorinated elastomers improves the solvent aging resistance of fluorinated elastomers and exhibits a positive synergistic effect.

[0131] Similarly, as shown in Table 10B, the tear strength retention rates of the co-cured fluorinated elastomers (AC75, AC50, AC25) from fluorinated polymers A and C are higher than those of fluorinated polymers A and C alone. Therefore, the increased tear strength retention rate indicates that the formation of co-cured fluorinated elastomers improves the solvent aging resistance of the fluorinated elastomers and exhibits a positive synergistic effect.

[0132] Table 10A. Tear strength retention of fluoroelastomers co-cured from fluoropolymers A and B after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0133] Table 10 B. Tear strength retention of fluoroelastomers co-cured from fluoropolymer A and fluoropolymer C after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0134] Table 10C shows the tear strength retention of co-cured fluoroelastomers from fluoropolymer A and fluoropolymer D. The results show that the tear strength retention of co-cured formulation AD75 (56.9%) is increased compared to polymer A (A100) (47.8%) and polymer D (D100) (45.4%). Co-cured formulations AD50 and AD25 show slight increases compared to polymer D (D100). Therefore, the increased tear strength retention indicates that the formation of co-cured fluoroelastomers does indeed improve the solvent aging resistance of fluoroelastomers.

[0135] Table 10C. Tear strength retention rate after swelling after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0136] Table 11A and Figure 14 The data summarized in this paper demonstrate the effect of solvent aging on the swelling, tensile strength retention, and tear strength retention of co-cured fluoropolymers derived from fluoropolymer A and fluoropolymer B. A positive synergistic effect is demonstrated through the formation of co-cured fluoropolymers, resulting in reduced swelling and increased tensile strength retention.

[0137] Table 11A. Summary of swelling percentage, tensile strength retention, and tear strength retention of co-cured fluoroelastomers (from fluoropolymers A and B) after aging in hydrocarbon solvents at 200 °C for 168 hours (ISO 23936 A.1.ii)

[0138] Table 11B and Figure 15 This paper summarizes data from co-cured fluoropolymers A and D to clearly illustrate the effects of solvent aging on the swelling, tensile strength retention, and tear strength retention of the co-cured formulation samples. By forming co-cured formulation samples, a synergistic effect (positive) in all three properties has been clearly observed, including reduced swelling and increased tensile strength retention. These results also indicate that co-cured formulation samples formed from both alkali-resistant polymer A and polymer D exhibit improved chemical resistance while maintaining their alkali resistance.

[0139] Table 11B. Summary of swelling percentage, tensile strength retention, and tear strength retention after aging in alkane solvents at 200 °C for 168 hours (ISO 23936 A.1.ii) Compression set was measured on button-shaped specimens that were molded at 177 °C for 45 minutes using a flatbed press and then post-cured at 204 °C for 16 hours.

[0140] experiment

[0141] Rheology and curing testing

[0142] Curing reaction under large deformation was tested on an oscillating disk rheometer (ODR).

[0143] Curing reaction tests under small deformations were conducted on a dynamic modulus rheometer (MDR). According to ASTM D 5289-3a, using an Alpha Technologies MDR model 2000, uncured premixed adhesive samples were tested at 177 °C without preheating for 12 minutes, with a radius of 0.5 degrees. Minimum torque (ML) and maximum torque (MH) were recorded.

[0144] According to this disclosure, all compositions and methods disclosed and claimed herein can be prepared and performed without excessive experimentation. While the compositions and methods of this disclosure have been described according to preferred embodiments, it will be apparent to those skilled in the art that variations may be made to the compositions and methods described herein, as well as the steps or order of steps of the methods, without departing from the concept, spirit, and scope of this disclosure. More specifically, it will be apparent that certain chemically relevant reagents may be substituted for the reagents described herein while achieving the same or similar results. All such similar substitutions and modifications that are apparent to those skilled in the art are considered to be within the spirit, scope, and concept of this disclosure as defined by the appended claims.

Claims

1. A co-cured elastomer blend comprising a fluoropolymer A and a fluoropolymer D, wherein: Fluoropolymer A contains monomer units of tetrafluoroethylene (TFE), propylene (PP), and curing point monomer (CSM); Fluoropolymer D is a pentadienomer comprising monomer units of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluorinated methyl vinyl ether (PMVE), and ethylene (PE); and Fluoropolymer A and fluoropolymer D are crosslinked using a peroxide initiator and a triazine co-crosslinking agent.

2. The blend according to claim 1, wherein, Fluoropolymer A is present in approximately 25-75 parts per 100 parts of polymer blend.

3. The blend according to claim 1 or 2, wherein, Fluoropolymer D is present in approximately 25-75 parts per 100 parts of polymer blend.

4. The blend according to claim 1, wherein, The peroxide initiator is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH).

5. The blend according to any one of claims 1-4, wherein, The peroxide initiator 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH) is present in about 1 to about 5 parts per 100 parts of polymer.

6. The blend according to any one of claims 1-5, wherein, The peroxide initiator is di(tert-butylperoxyisopropyl)benzene.

7. The blend according to claim 6, wherein, The peroxide initiator di(tert-butylperoxyisopropyl)benzene is present in about 1 to about 5 parts per 100 parts of polymer.

8. The blend according to any one of claims 1-7, wherein, The triazine crosslinking agent is triallyl isocyanurate (TAIC).

9. The blend according to any one of claims 1-8, wherein, TAIC exists at approximately 1 to approximately 7 parts per 100 parts of polymer.

10. The blend according to any one of claims 1-9, wherein, The solidification point monomer (CSM) contains iodine or bromine atoms.

11. The blend according to any one of claims 1-10, further comprising about 0 to about 60 parts of carbon black per 100 parts of polymer.

12. A co-cured elastomer blend comprising a fluoropolymer A and a fluoropolymer D, wherein: Fluoropolymer A contains monomer units of tetrafluoroethylene (TFE), propylene (PP), and curing point monomer (CSM); Fluoropolymer D contains at least one monomer unit of vinylidene fluoride (VDF); and fluoropolymer A and fluoropolymer D are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

13. The blend according to claim 12, wherein, Fluoropolymer A is present in approximately 25-75 parts per 100 parts of the blend.

14. The blend according to claim 12 or 13, wherein, Fluoropolymer D is present in approximately 25-75 parts per 100 parts of the blend.

15. The blend according to any one of claims 12-14, wherein, Fluoropolymer D also contains monomer units of hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluorinated methyl vinyl ether (PMVE), and ethylene (PE).

16. The blend according to any one of claims 12-15, wherein, The peroxide initiator comprises di(tert-butylperoxyisopropyl)benzene, and the di(tert-butylperoxyisopropyl)benzene is present in about 1 to about 5 parts per 100 parts of polymer.

17. The blend according to any one of claims 12-16, wherein, The solidification point monomer (CSM) contains iodine or bromine atoms.

18. A co-cured elastomer blend comprising a fluoropolymer A and a fluoropolymer D, wherein: Fluoropolymer A comprises monomer units and curing point monomers (CSM); fluoropolymer D comprises at least one monomer unit of vinylidene fluoride (VDF); and fluoropolymer A and fluoropolymer D are crosslinked with a peroxide initiator and a triazine co-crosslinking agent.

19. The blend according to claim 18, wherein, The solidification point monomer (CSM) contains iodine or bromine atoms.

20. The blend according to claim 18 or 19, wherein, Fluoropolymer D is present in approximately 25-75 parts per 100 parts of the blend.

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