Fluorine Rubber Research Articles

Design and Test of Silent Chain Including Silicon Fluorine Rubber Link Plate

In order to reduce the meshing noise of silent chain drive, a new concept of the chain (silent chain including silicon fluorine rubber link plate) was proposed. It could change the meshing contact state by changing the shape of traditional steel chain plate and arranging the silicon fluorine rubber link plate reasonably, which reduced meshing impact, so the meshing noise was reduced. Through the platform contrast test, a noise test was made with different types of silent chain at the same speed, and the results shown that the silent chain including silicon fluorine rubber plate drove more smoothly than other silent chains, the level of noise was reduced 2dB～3dB, which verified the fact that the silent chain including silicon fluorine rubber link plate could reduce noise.

Theoretical study on the diffusive transport of 2,4,6-trinitrotoluene in polymer-bonded explosive

Molecular dynamics (MD) simulations were performed to study the migration of 2,4,6-trinitrotoluene (TNT) in the fluorine rubber binder of polymer-bonded explosives (PBX) over a wide range of temperatures. The diffusion coefficient (D) of TNT is determined via microcanonical (NVE) MD simulation using the COMPASS force field. The calculated diffusion coefficient (D) was then used to compute the migration time of TNT based on Fick's second law and the results agree well with the experimental data. The relation between D of TNT and temperature was confirmed and the results confirm the temperature-dependence of diffusion coefficients of TNT in the binder, but a break is seen about the melt point (the temperature at which the elastomeric state of the binder changes to a viscosity state) in the Arrhenius plot of ln(D) versus 1/T.

エタノール添加ガソリンによるゴムの膨潤について

The swelling behavior of vulcanized acrylonitrile-butadiene rubber (NBR) having different nitrile content, styrene-butadiene rubber (SBR) and fluorine rubber (FKM) were examined in ethanol blended gasoline. For NBRs, the swelling rate of extra and medium high nitrile NBR is highest in the gasoline containing 25 vo1% ethanol (E25). In the gasoline containing less than 50 vol% ethanol, extra high CN NBR showed higher resistance to the solvent than the other whereas no such clear difference was observed in the gasoline containing 85 or more vol% of ethanol (E85). For SBR, the swelling rate is highest in gasoline without ethanol (E0) and decreased with the content of ethanol. FKM showed almost no swelling in the mixture with wide range of ethanol content.Although the ethanol-blended gasoline can be considered as a mixture of aliphatic and aromatic hydrocarbon and polar ethanol, aromatic hydrocarbon was selectively absorbed in NBR and SBR. This can be explained using the Hansen solubility parameter.

Molecular dynamics simulations of RDX and RDX-based plastic-bonded explosives

Molecular dynamics simulations have been performed to investigate well-known energetic material cyclotrimethylene trinitramine (RDX) crystal and RDX-based plastic-bonded explosives (PBXs) with four typical fluorine-polymers, polyvinylidenedifluoride (PVDF), polychlorotri-fluoroethylene (PCTFE), fluorine rubber (F 2311), and fluorine resin (F 2314). The elastic coefficients, mechanical properties, binding energies, and detonation performances are obtained for the RDX crystal and RDX-based PBXs. The results indicate that the mechanical properties of RDX can be effectively improved by blending with a small amount of fluorine polymers and the overall effect of fluorine polymers on the mechanical properties of the PBXs along three crystalline surfaces is (0 0 1) > (0 1 0) ≈ (1 0 0) and PVDF is regarded to best improve the mechanical properties of the PBXs on three surfaces. The order of the improvement in the ductibility made by the fluorine polymers on different surfaces is (0 0 1) ≈ (0 1 0) > (1 0 0). The average binding energies between different RDX crystalline surfaces and different polymer binders are obtained, and the sequence of the binding energies of the PBXs with the four fluorine polymers on the three different surfaces is varied. Among the polymer binders, PVDF is considered as best one for RDX-based PBXs. The detonation performances of the PBXs decrease in comparison with the pure crystal but are superior to those of TNT.

Impact of dimethyl ether on engine seal materials

The resistance of many kinds of rubber materials to dimethyl ether (DME) was studied. Both the mass and volume change of rubber materials, which were put in DME and then exposed to the air for different periods of time were measured. The results show that fluorine rubber (FKM), silicone rubber (SIR), and nitrile rubber (NBR) are unsuitable as seal materials for DME engines. Common polyvinylchloride (PVC) dissolved completely in DME, which has almost no impact on vulcanizing nylon material. The constitution of ethylene propylene terpolymer rubber (EPDM) has a major impact on its resistance to DME. A kind of EPDMwith good resistance to DME was found, whose reliability was validated by 100 hours of DME engine operation.

Molecular Dynamics Simulations of trans-1,4,5,8-Tetranitro-1,4,5,8-tetraazadecalin-Based Polymer-Bonded Explosives

Molecular dynamics has been applied to investigate the low-sensitivity explosive TNAD (trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin)-based polymer-bonded explosives (PBXs) with four typical fluorine polymers, PVDF (polyvinylidenedifluoride), PCTFE (polychlorotrifluoroethylene), F(2311) (fluorine rubber), and F(2314) (fluorine resin). The elastic constants, mechanical properties (tensile modulus, bulk modulus, shear modulus, and Poission ratio), binding energies, and detonation performances are first reported for the TNAD-based PBXs. The results show that the mechanical properties of TNAD can be effectively improved by the addition of small amounts of fluorine polymers, and the overall effect of fluorine polymers on the mechanical properties of the PBXs along three crystalline surfaces is (001) > (010) > (100). On each crystal surface, improvement in the ductibility made by the fluorine polymers changes approximately in the sequence of PVDF > F(2311) > F(2314) > PCTFE. The binding energies between different TNAD crystalline surfaces and different polymer binders with the same chain segment or mass fraction both decrease in the order of (010) > (100) > (001). The binding properties of the polymers with the same chain segment on each crystal surface of TNAD increase as PVDF < F(2311) < F(2314) < PCTFE, while those of different polymers in the same content decrease in the sequence of PVDF > F(2311) > F(2314) > PCTFE. The detonation performances of the PBXs decrease in comparison with the pure crystal, but they are superior to those of TNT.

Application of a new modified epoxy adhesive for bonding fluorine rubber to metal

Adhesion of fluorine rubber to metals is an important issue. The aim of this work was to develop a new kind of adhesive for bonding fluorine rubber to metals. A new modified epoxy adhesive containing a special tackifier resin obtained from polysulfones with a high heat deflection temperature (HDT) was prepared. Study on the curing behavior of the adhesive was carried out. Properties of the adhesive and the effects of several main factors were studied by gelation time test, differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. The optimum amount of the tackifier resin was found to be 50 phr; the average tensile lap shear strength could be achieved to a level of 8–10 MPa. Infrared attenuated total reflection (IRATR) spectroscopy indicated that the tackifier resin accelerated the establishment of epoxy resin adhesion to steel, and also promoted bonding and vulcanization of fluorine rubber. Easy diffusion of cyanamide (decomposition compound of dicyandiamide (DICY) in the curing process) into epoxy resin and fluorine rubber facilitated the dissolution and reaction of DICY, and also promoted formation of complex bond between fluorine rubber and adhesive, hence an enhanced adhesion of fluorine rubber to metal was achieved.

Molecular Dynamics Simulations for Pure ε-CL-20 and ε-CL-20-Based PBXs

Molecular dynamics has been employed to simulate the well-known high energy density compound epsilon-CL-20 (hexanitrohexaazaisowurtzitane) crystal and 12 epsilon-CL-20-based PBXs (polymer bonded explosives) with four kinds of typical fluorine polymers, i.e., polyvinylidenedifluoride, polychlorotrifluoroethylene, fluorine rubber (F(2311)), and fluorine resin (F(2314)) individually. The elastic coefficients, isotropic mechanical properties (tensile moduli, bulk moduli, shear moduli, and poission's ratios), and bonding energy are first reported for epsilon-CL-20 crystal and epsilon-CL-20-based polymer bonded explosives (PBXs). The mechanical properties of epsilon-CL-20 can be effectively improved by blending with a small amount of fluorine polymers, and the whole effect of the adding fluorine polymers to improve mechanical properties of PBXs along the three crystalline surfaces of epsilon-CL-20 is found to be (100) approximately (001) > (010). The interaction between each of the crystalline surfaces and each of the fluorine polymers is different, and the ordering of binding energy for the three surfaces is (001) > (100) > (010); F(2314) always has the strongest binding ability with the three different surfaces. F(2314) can best improve the ductibility and tenacity of PBX when it is positioned on epsilon-CL-20 (001) crystal surface. The calculations on detonation performances for pure epsilon-CL-20 crystal and the four epsilon-CL-20-based PBXs show that adding a small amount of fluorine polymer into pure epsilon-CL-20 will lower detonation performance, but each detonation parameter of the obtained PBXs is still excellent.

Seal Material and Base Fluid Compatibility: An Overview

This study compares the seal material compatibility of environmentally adapted base fluids with that of mineral and synthetic base fluids. The seal materials studied were nitrite rubber (NBR), hydrogenated nitrile rubber ( HNBR), and fluorine rubber (FKM) elastomers, which are common in lubricated applications. The base fluids studied were synthetic esters (monoester, polyol ester, complex ester, and diester), a natural ester (i.e., vegetable oil), different types of mineral base oils, polyalphaolefin, and a fluid of very high viscosity index. The base fluids have been studied without additives. The elastomeric properties measured include volume, hardness, tensile strength, and elongation. A small elastomer volume increase was observed for mineral base oils whereas a significant increase was noted for all synthetic esters when tested on NBR and HNBR. The mechanical properties of the elastomers deteriorated in all cases. The amount of deterioration (i.e., in the tensile strength and the elongation) was in general less than 30%.

Molecular dynamics simulation of mechanical properties of TATB/fluorine-polymer PBXs along different surfaces

The mechanical properties of PBXs composed of the well-known insensitive explosive TATB (1,3,5-Triamino-2,4,6-trinitrobenzene) crystal and four kinds of typical fluorine-polymers, i.e. poly (vinylidene difluoride) (PVDF), polychlorotrifluoroethylene (PCTFE), fluorine rubber (F 2311 ) and fluorine resin (F2314) individually, have been simulated by molecular dynamics (MD) method. The results show that the mechanical properties of TATB can be effectively improved by blending with a small amount of fluorine-polymers. Different mechanical properties of PBXs are obtained by putting fluorine-polymer binders parallel to different crystalline surfaces. The whole effect of im-proving mechanical properties is found to be (010)≈(100)>(001).

Physical modification of elastomers to improve their tribological properties

An attempt is made to obtain an elastomeric material for shaft seals which does not demand permanent lubrication. Composites based on oil-resistant elastomers (nitrile rubber (NBR), chlorosulphonated polyethylene (CSM) or fluorine rubber (FPM)) were physically modified to improve the tribological properties of their vulcanizates. Different substances and methods of application were tested. The influence of the modification on the coefficient of friction and the wear of the samples was measured in dynamic conditions by means of a ring-on-disc apparatus. The best results were obtained form surface modification by molybdenum disulphide (MoS 2) which until now has mainly been used for rigid, stiff materials. The results obtained have been interpreted taking into consideration both the adhesional and hysteretical properties of the system. The preparation methods of the special suspensions or pastes for covering the rubber surface and an explanation how they work was the main aim of the study.

Linear flexible-chain polymer electrification conditions and pattern at T &gt; TG

A study has been made concerning the static electrification of such linear flexible-chain polymers as polybutadiene, polyisoprene, and fluorine rubber with wide and narrow molecular-weight distributions at T > Tg. It has been found that static electrification occurs as a result of a relaxation transition of polymers from the fluid to high-elastic state, accompanied by breakdown of the specimens and their detachment from the walls confining the flow, which leads to slippage of the polymers. This phenomenon is explained in terms of the activation theory of polymer friction. The dependence of static electrification on temperature, molecular weight, and molecular-weight distribution is determined by the effect of these parameters on the relaxation characteristics of a polymer, and, more particularly, its segmental mobility.

The crosslinking of the fluorine rubber SKF-26 by phosphorus containing hydroquinone derivatives

The fluorine rubber SKF-26 has been found to react with a bis-phosphorylated hydroquinone derivative, giving vulcanizates with valuable properties. The crosslinking is the result of phosphite alkylations by the SKF-26 and the formation of P — C bonds by the Arbuzov mechanism. The thermal-oxidative degradation of the crosslinked structures was studied by the continuous, high temperature chemical relaxation method.