The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform

John A Hiltz - One of the best experts on this subject based on the ideXlab platform.

  • characterization of Fluoroelastomers by various analytical techniques including pyrolysis gas chromatography mass spectrometry
    Journal of Analytical and Applied Pyrolysis, 2014
    Co-Authors: John A Hiltz
    Abstract:

    Abstract Fluorocarbon elastomers are specified for a number of applications where excellent high temperature and chemical resistance is required. To ensure that a fluoroelastomer with the required properties for a particular application is used, characterization techniques that allow the positive identification of the elastomer are required. In this paper the characterization of four fluoroelastomer formulations – a vinylidene fluoride/hexafluoropropene (VDF/HFP) dipolymer, a vinylidene fluoride/hexafluoropropene/tetrafluoroethylene terpolymer, and two vinylidene fluoride/perfluoro(methyl vinyl ether)/tetrafluoroethylene (VDF/PMVE/TFE) tetrarpolymers – is described. The characterization techniques included pyrolysis gas chromatography/mass spectrometry (py-GC/MS), Fourier transform infrared (FT-IR) spectrometry, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Py-GC/MS was the only characterization technique that could identify the four formulations unambiguously. The positive identification was based on differences in the pyrolytic degradation products of the flouroelastomer formulations.

  • Characterization of Fluoroelastomers by various analytical techniques including pyrolysis gas chromatography/mass spectrometry☆
    Journal of Analytical and Applied Pyrolysis, 2014
    Co-Authors: John A Hiltz
    Abstract:

    Abstract Fluorocarbon elastomers are specified for a number of applications where excellent high temperature and chemical resistance is required. To ensure that a fluoroelastomer with the required properties for a particular application is used, characterization techniques that allow the positive identification of the elastomer are required. In this paper the characterization of four fluoroelastomer formulations – a vinylidene fluoride/hexafluoropropene (VDF/HFP) dipolymer, a vinylidene fluoride/hexafluoropropene/tetrafluoroethylene terpolymer, and two vinylidene fluoride/perfluoro(methyl vinyl ether)/tetrafluoroethylene (VDF/PMVE/TFE) tetrarpolymers – is described. The characterization techniques included pyrolysis gas chromatography/mass spectrometry (py-GC/MS), Fourier transform infrared (FT-IR) spectrometry, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Py-GC/MS was the only characterization technique that could identify the four formulations unambiguously. The positive identification was based on differences in the pyrolytic degradation products of the flouroelastomer formulations.

Xueyan Li - One of the best experts on this subject based on the ideXlab platform.

  • Reduction of liquid terminated-carboxyl Fluoroelastomers using NaBH4/SmCl3
    RSC Advances, 2020
    Co-Authors: Yunfei Chang, Mingyi Liao, Xueyan Li
    Abstract:

    Using a simple one-pot method, the reduction of liquid terminated-carboxyl Fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl Fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

  • reduction of liquid terminated carboxyl Fluoroelastomers using nabh4 smcl3
    RSC Advances, 2020
    Co-Authors: Yunfei Chang, Mingyi Liao, Xueyan Li
    Abstract:

    Using a simple one-pot method, the reduction of liquid terminated-carboxyl Fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl Fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

Jiri George Drobny - One of the best experts on this subject based on the ideXlab platform.

  • Chapter 10 – Fluoroelastomers
    Introduction to Fluoropolymers, 2020
    Co-Authors: Jiri George Drobny
    Abstract:

    The introduction of fluorine into the elastomeric macromolecule generally produces materials exhibiting an improved retention of properties at high temperatures; reduced flexibility at low temperatures; and an improved resistance to solvents, fuels, oils, and greases. Essentially, there are two groups of Fluoroelastomers: fluorocarbon (or fluorohydrocarbon) elastomers and fluoro-inorganic elastomers.

  • Fluid Resistance of TFE–Olefin Fluoroelastomers
    Fluoroelastomers Handbook, 2020
    Co-Authors: Jiri George Drobny
    Abstract:

    The TFE–olefin Fluoroelastomers are resistant to strong aqueous bases and amines and exhibit low swelling in polar liquids. The results from copolymers and terpolymers are shown in extensive tables. These materials are recommended for the use for severe conditions in automotive, aeronautical, chemical processing, and oil field environment.

  • Cure Systems for Fluoroelastomers
    Fluoroelastomers Handbook, 2020
    Co-Authors: Jiri George Drobny
    Abstract:

    This chapter covers cure systems for fluorocarbon elastomers. Curing is the process that produces stable networks for good mechanical properties and environmental resistance comparable to the base polymers. The networks are creating by cross-linking of the polymeric chains by specific chemical reaction. In addition to produce stable polymeric system, the curing process must be controlled to prevent premature cross-links during processing, typically at temperatures between 100°C and 140°C (212–284°F). This chapter discusses the major curing systems for four fluoroelastomer families: VDF/HFP/TPE, VDF/PMVE/TFE, perFluoroelastomers, and TFE/olefin elastomers. The systems covered are diamine cure, bisphenol cure, and peroxide cure.

  • 11 – Fluoroelastomer Applications
    Fluoroelastomers Handbook, 2020
    Co-Authors: Jiri George Drobny
    Abstract:

    Fluorocarbon elastomers are used mainly in seals and other fabricated parts to provide barriers against a wide range of fluids under severe service conditions. About two-thirds of Fluoroelastomers are used in automotive applications, mainly in fuel and power train systems. Other applications are in a number of areas, including aerospace, chemical and pharmaceutical industries, oil fields, semiconductor manufacture, and a variety of other industries. This chapter summarizes the applications in some detail.

  • production of Fluoroelastomers
    Fluoroelastomers Handbook (Second Edition)#R##N#The Definitive User's Guide, 2016
    Co-Authors: Jiri George Drobny
    Abstract:

    Methods of producing fluorocarbon elastomers are the subject of this chapter. This includes free radical copolymerization, emulsion copolymerization, and suspension polymerization. The aspects discussed are reaction schemes, kinetics and mechanisms, polymer compositions, reactor design and operation, process control, molecular weight distribution and composition of the products, monomer recovery, polymer isolation, process safety. Attention is paid to commercial processes.

Yunfei Chang - One of the best experts on this subject based on the ideXlab platform.

  • Reduction of liquid terminated-carboxyl Fluoroelastomers using NaBH4/SmCl3
    RSC Advances, 2020
    Co-Authors: Yunfei Chang, Mingyi Liao, Xueyan Li
    Abstract:

    Using a simple one-pot method, the reduction of liquid terminated-carboxyl Fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl Fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

  • reduction of liquid terminated carboxyl Fluoroelastomers using nabh4 smcl3
    RSC Advances, 2020
    Co-Authors: Yunfei Chang, Mingyi Liao, Xueyan Li
    Abstract:

    Using a simple one-pot method, the reduction of liquid terminated-carboxyl Fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl Fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

Eric W Thomas - One of the best experts on this subject based on the ideXlab platform.

  • fluoroelastomer compatibility with bioalcohol fuels
    SAE International Journal of Fuels and Lubricants, 2009
    Co-Authors: Eric W Thomas
    Abstract:

    Global acceptance and use of biofuels is growing rapidly in the transportation sector. Diminishing reserves of limited and costly fossil fuel resources and a growing realization that world peak oil production will most likely occur within the next decade is driving significant investment in sustainable biofuels. Legislative, regulatory and market forces are driving developments which seek to reduce vehicle emissions, improve fuel efficiency, lower environmental greenhouse gases and strengthen the economy. The use of alternate, sustainable, renewable fuels, preferably of domestic origin, is fostering considerable investment in new technologies. One promising technology is the addition of aliphatic alcohols to gasoline and diesel fuels. The compatibility of seal and hose materials commonly used in automotive fuel systems with conventional hydrocarbon fuels is well known. Over the past forty-five years fluorohydrocarbon elastomers have been successfully used in passenger car and truck and offhighway gasoline and petrodiesel fuel delivery and metering systems. More recently, biofuels such as ethanol have become technically and economically attractive blending constituents for gasoline and diesel fuels. These biomass fuels present their own set of material compatibility challenges to automotive fuel storage, delivery, and metering system component hardware.

  • Fluoroelastomer and perfluoroelastomer compatibility with advanced gas turbine lubricants
    SAE transactions, 2003
    Co-Authors: Eric W Thomas
    Abstract:

    The progression of gas turbine engine design encompasses a relentless drive towards more powerful, higher thrust, lighter weight, fuel efficient engines, with accompanying reductions in noise and emissions, as well as better reliability, operating safety and longer time on wing. These trends converge to push engine thermodynamics to their limits, invariably culminating in higher operating temperatures. As a result, engine builders have adopted advanced lubricants with higher thermo-oxidative stability (HTS), in order to achieve long life engine performance. These HTS oils are proving to be significantly more aggressive towards standard Fluoroelastomers. As a result, there is a gradual migration to specialty grades that offer significantly improved compatibility with HTS oils. As temperatures have escalated, higher performance perFluoroelastomers have found greater use in aircraft engines. Selection and adoption is primarily a result of their ability to deliver outstanding seal performance in hot air and lube oils. In this presentation the compatibility of selected Fluoroelastomers and perFluoroelastomers with commercial gas turbine engine lubricants will be discussed. Fluoroelastomers that have historically been used will be compared to several new specialty types that display improved resistance to HTS oils. In addition, several perFluoroelastomers demonstrating superior compatibility to HTS turbine oils will be reviewed. Testing will characterize physical properties and property retention in lube oil through 2000 hours at 200°C and 232°C. Properties relevant to sealing applications will be discussed and best in class for each type of material will highlighted. In gaining a better understanding of the respective capabilities of these high performance fluorinated elastomers, the engineer may design more robust sealing systems.

  • low temperature sealing capabilities of Fluoroelastomers
    SAE transactions, 1990
    Co-Authors: Ronald D. Stevens, Eric W Thomas, James H Brown, William N K Revolta
    Abstract:

    The purpose of this article is to examine some traditional rubber methods of measuring low temperature properties and compare those results to a test designed to evaluate the low temperature static sealing of o-rings. Testing is performed on a variety of Fluoroelastomers to document differences and establish trends. By evaluating the performance of various Fluoroelastomers in a practical low temperature o-ring test, the design engineer may gain a better understanding of the low temperature sealing capabilities of these polymers. Although the test results disclosed in this article are of short duration, it is the intention of the authors to evaluate the effects of longer term compressive deformation, stress relaxation and hot/cold cycling with the static o-ring test device in future work.