Fluorine Rubber Research Articles

High toughness, flexible and thermally conductive fluorine rubber composite films reinforced by hexagonal boron nitride flakes for thermal management

The rapid advancement of electronic information technology has generated a substantial demand for polymer-based thermal management materials. In order to address the challenges of heat dissipation and avoid signal interference, it is essential to develop polymer-based thermal management materials with both high thermal conductivity and low dielectric properties. Herein, hexagonal boron nitride flakes (h-BNFs) with a high aspect ratio and some hydroxyl groups were prepared using the high pressure homogenization technique. Subsequently, h-BNF/fluorine rubber (h-BNF/FKM) composite films were fabricated through a simple and scalable blade coating method. During the blade coating process, most of the h-BNFs can align with their (002) crystal planes paralleling to the horizontal direction. In addition, the rest of the h-BNFs will randomly distribute and overlap with each other, combining with the horizontally aligned h-BNFs to form a distinctive three-dimensional packing network. This unique network structure enables the h-BNF/FKM composite films to have thermal conductivities of up to 0.44 W/(m·K). Moreover, the introduction of h-BNFs can effectively reduce the dielectric constants and dielectric losses of FKM films. More importantly, the h-BNF/FKM composite films also exhibit outstanding mechanical toughness, excellent flexibility, good adhesion and improved flame-retardancy, providing promising applications in the electronic device thermal management.

A Soft-Fiber Bioelectronic Device with Axon-Like Architecture Enables Reliable Neural Recording In Vivo under Vigorous Activities.

Implantable neural devices that record neurons in various states, including static states, light activities such as walking, and vigorous activities such as running, offer opportunities for understanding brain functions and dysfunctions. However, recording neurons under vigorous activities remains a long-standing challenge because it leads to intense brain deformation. Thus, three key requirements are needed simultaneously for neural devices, that is, low modulus, low specific interfacial impedance, and high electrical conductivity, to realize stable device/brain interfaces and high-quality transmission of neural signals. However, they always contradict each other in current material strategies. Here, a soft fiber neural device capable of stably tracking individual neurons in the deep brain of medium-sized animals under vigorous activity is reported. Inspired by the axon architecture, this fiber neural device is constructed with a conductive gel fiber possessing a network-in-liquid structure using conjugated polymers and liquid matrices and then insulated with soft fluorine rubber. This strategy reconciles the contradictions and simultaneously confers the fiber neural device with low modulus (300kPa), low specific impedance (579kΩµm2), and high electrical conductivity (32700Sm-1) - ≈1-3 times higher than hydrogels. Stable single-unit spike tracking in running cats, which promises new opportunities for neuroscience is demonstrated.

Preparation of ADN-based energetic composite microspheres with excellent anti-moisture absorption and safety

Ammonium dinitramide (ADN) is an ideal solid composite propellant oxidizer. But it also exhibits high hygroscopicity and low safety. Solving these issues will be crucial of ADN in practical applications. In this study, three ADN-based energetic composite microspheres were prepared by suspension assembly process coating ADN with different polymeric materials (glycidyl azide polymer (GAP), fluorine rubber(F2602), and hydroxyl-terminated block copolyether(HTPE)). The experimental results showed that the three prepared samples were spherical particles with regular morphology and uniform particle size. The crystal structure was not changed. The contact angle, moisture absorption and mechanical sensitivity test showed that the ADN-based energetic composite microspheres have low moisture absorption and mechanical sensitivity. In particular, the ADN/F2602 sample, which possesses a lotus-like hydrophobic effect, exhibits a 57.24 % reduction in water absorption compared to the raw ADN, and the contact angle of ADN/F2602 (93.91°) is 4.24 times higher than that of the raw ADN (22.15°). The critical friction susceptibility of ADN/F2602 (168 N) is 2.1 times higher than that of raw ADN (80 N), and the critical impact susceptibility of ADN/F2602 (17 J) is 2.43 times higher than that of raw ADN (7 J). The combustion test showed that the combustion duration of ADN/F2602 increased from 1.353 s to 1.578 s for the raw ADN, and the flame intensity was enhanced. The successful ignition and flame stabilization of ADN/F2602 samples after 24 h storage under a relative humidity of 60 % indicates its good energy release performance in a propellant. Through this study, F2602 as a capping material has good anti-hygroscopic effect, mechanical insensitivity and combustion stability for ADN, which can support the application of ADN as an oxidizer in composite solid propellants.

Evaluation of rapid gas decompression (RGD) resistance of sealing materials for hydrogen-doped pipeline valves

Abstract With the rapid development of hydrogen-doped natural gas pipelines, the evaluation of the applicability of hydrogen to natural gas pipeline systems is bound to gradually involve all aspects of natural gas pipelines. Targeted at the non-metallic sealing materials for valves of hydrogen-doped natural gas pipelines, this paper, according to the ISO 23936-2 standard, carried out the rapid gas decompression (RGD) tests of hydrogenated nitrile butadiene rubber (HNBR), fluorine rubber 246 (FKM246) and fluorine rubber 26 (FKM26), and the damage level of cracking failure for the rubber materials in the course of rapid release of gaseous medium was obtained (DL). The mechanical properties and volumetric dissolution rate of the three rubber materials were tested before and after the high-pressure gas mixture treatment, which explains the reason for the cracking failure of the rubber materials during the RGD test. The study obtained the influence law of high-pressure gas mixture with different hydrogen volume fractions on the RGD resistance of HNBR, FKM246, and FKM26, and selected the material with the optimal RGD resistance as FKM26, which can be used as a reference for the selection of sealing materials for the valves of hydrogen-doped natural gas pipelines in engineering.

Enhancing mechanical property, thermal conductivity, and radiation stability of fluorine rubber through incorporation of hexagonal boron nitride nanosheets

AbstractFluorine rubber (FKM) stands as a pivotal sealing material extensively employed in aerospace and nuclear industries. However, its efficacy will be seriously affected by ionizing radiation. Enhancing its radiation resistance becomes imperative to uphold the stability and safety of associated equipment. This study introduced hexagonal boron nitride (h‐BN) into the FKM as radioprotective fillers through mechanical blending. The interfacial interaction between matrix and h‐BN, the mechanical performances, thermal properties, and radiation stability of composites were systematically examined. Noteworthy findings highlight the presence of robust interaction forces between h‐BN and the matrix, leading to increased crosslink density and improved mechanical properties. The tensile strength of composite with 10 phr fillers (BN/FKM‐10) increased by 30% compared to that of pure FKM. Simultaneously, the introduction of h‐BN greatly enhanced thermal conductivity and radiation stability. The absorbed dose required to achieve a 50% reduction in elongation at break of BN/FKM‐10 surpassed that of FKM by 1.69 times. These results underscore the potential of incorporating h‐BN to simultaneously enhance the mechanical performance, thermal property, and radiation resistance of fluorine rubber.Highlights The chemical interaction force between h‐BN and FKM was confirmed. FKM composites tensile strength was enhanced by h‐BN as an additive crosslinker. The incorporation of h‐BN improves FKM composites thermal conductivity. The radiation resistance of FKM composites has been improved with h‐BN.

An Experiment on the Dwell Time Effect of Rubber Seal O-Rings: Friction Force in Intermittent Reciprocating Motion

The adhesive force between two contact surfaces often leads to an increase in the friction force of the rubber seal O-ring after a certain dwell time, forming dwell time effects and affecting the reliability of sealing. The dwell time effect may result in substantial instability with respect to the frictional behavior of rubber O-rings, which needs to be carefully taken into account in the design of rubber seals. Therefore, in this paper, the dwell time effect of the friction force was studied experimentally for intermittent reciprocating rubber seal O-rings coupled with stainless steel 316L and a sealing air medium. The friction force of three kinds of rubber materials, including fluorine rubber (FPM), silicone rubber (SI), and nitrile rubber (NBR), was measured under different dwell times, compression ratios, and seal pressure. The results showed that there was a rolling frictional force, and the second peak value of the frictional force caused by the O-ring’s rolling under shear action and after the maximum static frictional force was observed at the starting stage of reciprocating motion. For FPM O-rings, the rolling friction force was much greater than the maximum static frictional force at about four times the value of the compression ratio at 9% and seal pressure at 0; moreover, the force was much greater at greater compression ratios. The dwell time effect was significant in the friction forces of rubber O-rings. The friction force increases with an increase in dwell time. The increase in maximum static friction force exceeded 50% after 5 dwell days. The increase in seal pressure led to the disappearance of the rolling friction feature and the rapid increase in friction during the starting stage. Under gas seal pressure conditions, the dwell time effect still led to a significant increase in friction force. The obtained results might provide guidance for the material selection of sealing designs.

Fretting Wear Behavior of Fluorine Rubber and Short Carbon Fiber Reinforced Fluorine Rubber Matrix Composites

The fretting wear behavior of fluorine rubber (FKM) and short carbon fiber (SCF) reinforced fluorine rubber matrix composites (SCF/FKMCs) is investigated experimentally under air condition. Four kinds of SCF/FKMCs with different SCF concentrations (5 phr, 10 phr, 15 phr, and 20 phr in every 100 phr of FKM) are considered. The contact model utilizes the sphere-on-flat contact between a 440 C stainless steel ball and an FKM or SCF/FKMCs coating perfectly bonded to a ceramic sheet in fretting experiments. The impacts of SCF concentration, normal force, and displacement amplitude on the fretting wear behavior are investigated. Scanning electron microscope (SEM) is used to analyze the fretting wear surface morphology and wear mechanism, while three-dimensional (3D) white-light interference profilometer is used to describe the characteristics of 3D surface wear profile and determine the wear volume. The fretting wear performances of FKM and SCF/FKMCs with different SCF concentrations are compared under different fretting test conditions. The results show that adding an appropriate amount of SCFs to FKM can improve wear resistance and reduce the coefficient of friction (COF). SCF/FKMC with SCF concentration of 15 phr has the smallest COF. SCF/FKMCs with SCF concentration of 5 phr or 15 phr have the best wear resistance for small normal force or large displacement amplitude.

NOVEL THERMOPLASTIC ELASTOMERS BASED ON PVDF/SKF-32: EFFECT OF COMPOSITION ON TECHNOLOGICAL AND PERFORMANCE CHARACTERISTICS

Thermoplastic elastomers (TPE) based on SKF-32 fluorine rubber and polyvinylidene fluoride, PVDF (polyvinylidene fluoride content ranges from 30 to 70% relative to rubber) were investigated. The mixes have been produced by using a Brabender-type rotary micromixer. Such thermoplastic elastomers can be an alternative to traditional oil & fuel resistant butadiene-nitrile-based rubbers and can be used in manufacture of sleeves, hoses and tubes for pumping aggressive liquids and gases, wires/cables insulation, fuel storage tanks, valves, etc. Traditional methods of plastics processing can be used to manufacture this materials. It was established that the crystallinity degree increases with the rise of PVDF content. That fact is confirmed by the IR-Fourier spectroscopy data and differential scanning calorimetry. It was shown that the hardness and strength of TPEs increases with the rise of PVDF content. The tensile stress for TPEs containing 50% or more of PVDF are higher than those for conventional oil & fuel resistant rubber IRP 1078. The obtained TPEs possess high resistance against AI-92 grade gasoline, 80% sulfuric acid, 50% sodium hydroxide, and I-40 oil. They also retain their physical and mechanical properties even after three cycles of reprocessing. The TPE with the 1:1 thermoplastic : elastomer ratio, has been vulcanized using a peroxide vulcanizing system at varying concentrations. The dynamic vulcanization is confirmed by a decrease in the swelling degree of the obtained materials in solvents with an increase in the content of the vulcanizing agent. Peroxide dynamic vulcanization has not lead to a significant increase in physical and mechanical parameters, however, it resulted in an increase in chemical resistance of against aggressive solvents.

Effect of Graphene Oxide-Modified CaAl-Layered Double Hydroxides on the Carbon Dioxide Permeation Properties of Fluoroelastomers.

This work aimed to investigate the CO2 gas barrier and mechanical properties of fluorine rubber nanocomposites filled with Ca/Al layered hydroxide (graphene oxide [GO]/LDH-Ca2Al) modified by GO. GO/LDH-Ca2Al nanocomposite fillers were prepared by depositing Ca/Al layered hydroxide (LDH-Ca2Al) into the surface of alkalized GO (Al-GO). The prepared GO/LDH-Ca2Al nanocomposite fillers and complexes were characterized by Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) for structural and micromorphological characterization. The results showed that GO/LDH-Ca2Al was successfully prepared with strong interactions between Al-GO and LDH, and the compatibility of GO/LDH-Ca2Al nanocomposite fillers with the polymer was significantly improved compared with that of LDH-Ca2Al. Consequently, both the fracture strength (σb) and strain (εb) of GO/LDH-Ca2Al nanocomplexes remarkably increased, and they exhibited excellent mechanical properties. Differential scanning calorimetry and thermogravimetric analysis were used to characterize the thermal stability of GO/LDH-Ca2Al nanocomposite fillers, and GO/LDH-Ca2Al nanocomposite fillers have better thermal stability than LDH-Ca2Al. The reaction products (S-LDH-Ca2Al and S-GO-Ca2Al) of LDH-Ca2Al and GO/LDH-Ca2Al with CO2 were characterized using XRD and TGA, respectively, and the results show that LDH-Ca2Al reacts readily and chemically with CO2, resulting in a lower diffusion coefficient of CO2 in the LDH-Ca2Al nanocomplexes than that of the GO/LDH-Ca2Al nanocomplexes and leading to the destruction of the laminar structure of LDH-Ca2Al, while GO/LDH-Ca2Al has better CO2 resistance stability. GO/LDH-Ca2Al nanocomplexes exhibited a reduced content of hydroxyl groups with pro-CO2 nature exposed on the surface of LDH-Ca2Al, improving the interfacial interaction between the nanofillers and the rubber matrix and enhancing the dispersion of GO/LDH-Ca2Al in the polymers. Moreover, CO2 in the soluble GO/LDH-Ca2Al nanocomposites was significantly reduced, while the diffusion properties demonstrated weak temperature dependence on solubility. The mechanism of the CO2 gas barrier of polymers filled with GO/LDH-Ca2Al was proposed on the basis of the Arrhenius equation.

The protective performance of rubber pads for penetration fuze

To ensure the reliable functioning of hard target-penetration fuze on the battlefield, this study focuses on research related to fuze protective pads. The main factors causing fuze functional failure are summarized, and a simplified model of projectile penetration into target plates is established. The design conditions for the yield stress parameter of the fuze casing material are derived based on stress wave propagation theory. Modal analysis of the projectile is conducted using dynamic simulation software ANSYS to determine its vibration modes and low-pass filtering frequency. Static compression experiments are performed on different rubber materials (nitrile rubber, fluorine rubber, silicone rubber, and natural rubber) to obtain stress–strain curves and constitutive model parameters. Marshall hammer tests were carried out on rubber pads of different materials and thicknesses, confirming the validity of the simulation results and the feasibility of rubber filtering. The study indicates that when using a 2 mm thick rubber pad for protection, natural rubber provides the best protection. When using a 6 mm thick rubber pad, nitrile rubber shows the best protective performance. Under a 13-tooth tooling impact load, the best protection is achieved using a 2 mm thick natural rubber pad. When using a 6 mm thick pad, silicone rubber provides the best protection. Under a 15-tooth tooling impact load, fluorine rubber provides the best protection when using a 2 mm thick pad, while silicone rubber offers the best protection when using a 6 mm thick pad. Under a 17-tooth tooling impact load, natural rubber offers the best protection when using a 2 mm thick pad, and fluorine rubber demonstrates the best protection when using a 6 mm thick pad. The obtained research results provide a reference for protective methods of hard target-penetration fuze.

Optimization and verification of droplet infiltration model in contact line theory

In order to improve the theory of contact line density, the contact angle model of rectangular convex structure with anisotropy was established, and the integral method and cyclic assignment method were used to solve the droplet volume. Then, the characteristic dimensions of FKM (fluorine rubber) surface prepared by template method were collected by visual recognition technology. In addition, the gravity, surface tension and micro-droplet height of the droplet in the antenna model were verified. Finally, the error of theoretical droplet height and actual droplet height in the solution of droplet gravity and surface tension was calculated by regression model. It is shown that the empirical correction coefficient of the contact angle model is 0.04–0.112 when the droplet gravity and surface tension are equal. Moreover, the reliability of theoretical gravity and theoretical surface tension of droplets instead of actual values is 96.3% and 99.4% respectively. States of droplets on six FKM surfaces are all in accordance with Wenzel-Cassie transition state model. Optimizing the theory of contact line density is conducive to designing accurate and anisotropic rough structures.

Occurrence and risk assessment of perfluoroalkyl substances in the river basin around fluorine industry parks, China

ABSTRACT Fluorine industry parks (FIPs) play a fundamental role in the advancement of China’s fluorine industry. In this study, Target analysis was combined with traceability analysis to determine the type of PFASs present in the surface water and sediment around FIPs in China. Meanwhile, the risk they posed to the surrounding river was examined through risk characterisation ratio. Among the areas surveyed, 10 and 15 PFASs were detected in the surface water and sediment, with concentrations of up to 32,674.0 ng/L and 17.84 ng/g, respectively. There were a larger proportion of short-chain PFASs (C4-C7), and perfluoropentanoic acid was particularly prevalent. Source analysis indicates that the PFASs in the surface water may have originated from precursor degradation and atmospheric deposition. The fluorine rubber industry was the main source for the sediment PFASs, particularly for short-chain compounds. A risk characterisation ratio analysis identified perfluorododecanoic acid, perfluorobutane sulfonate, perfluoroheptanoic acid, perfluoropentanoic acid, and perfluorohexanoic acid as compounds with relatively high risks.

Theoretical Prediction on Properties of 3,4-Bisnitrofurazanfuroxan (DNTF) Crystal and its Polymer Bonded Explosives (PBXs) Through Molecular Dynamics (MD) Simulation

3,4-Bisnitrofurazanfuroxan (DNTF) is a typical high energy density compound (HEDC), it has high crystal density and detonation parameters, but also high mechanical sensitivity. To decrease its mechanical sensitivity, the DNTF based polymer bonded explosives (PBXs) was designed. The pure DNTF crystal and PBXs models were established. The stability, sensitivity, detonation performance and mechanical properties of DNTF crystal and PBXs models were predicted. Results show that PBXs models containing fluorine rubber (F2311) and fluorine resin (F2314) have higher binding energy, meaning that DNTF/F2311 and DNTF/F2314 is relatively more stable. PBXs models have higher value of cohesive energy density (CED) than pure DNTF crystal, DNTF/F2311 and DNTF/F2314 have the highest value of CED, implying that the sensitivity of PBXs is effectively decreased, DNTF/F2311 and DNTF/F2314 is more insensitive. PBXs have lower crystal density and detonation parameters than DNTF, the energy density is declined, DNTF/F2314 has higher energetic performance than other PBXs. Compared with pure DNTF crystal, engineering moduli (tensile modulus, shear modulus, bulk modulus) of PBXs models are obviously decreased, but Cauchy pressure is increased, implying that the mechanical properties of PBXs is superior to pure DNTF component, the PBXs containing F2311 or F2314 have more preferable mechanical properties. Consequently, DNTF/F2311 and DNTF/F2314 have the best comprehensive properties and is more attractive among the designed PBXs, indicating that F2311 and F2314 are more advantageous and promising in ameliorating properties of DNTF. The properties of DNTF crystal and PBXs models were predicted through molecular dynamics (MD) method under Materials Studio 7.0 package. The MD simulation was performed with isothermal-constant volume (NVT) ensemble, and the force field was chosen as COMPASS force field. The temperature was set as 295K, the time step was 1fs and the total MD simulation time was 2ns.

All‐Polymer Fiber Organic Electrochemical Transistor for Chronic Chemical Detection in the Brain

AbstractContinuous and precise monitoring of chemicals in the brain can assist in understanding the working mechanism of the brain and exploring therapeutics for nerve disorders. Organic electrochemical transistors (OECTs) are employed for this purpose due to their high sensitivity from the in situ amplification effect. However, the chronic and stable detection of chemicals in the brain is rarely reported for OECTs. It is possibly due to the chronic inflammation from mechanical mismatch between the device and soft brain tissue as well as the biofouling that hinder the diffusion of chemicals to decrease the sensitivity similar to other implanted devices. Therefore, an all‐polymer fiber OECT (PF‐OECT) is designed, composed solely of conductive polymers and fluorine rubber. The PF‐OECT shows matching modulus with the soft brain tissue and good anti‐biofouling performance. It also demonstrates both high sensitivity and electrochemical stability under dynamic deformations and in complex protein solutions. Finally, the PF‐OECT is implanted into the mouse brain, achieving a stable 14‐day ascorbic acid monitoring. The design strategy of PF‐OECT presents a potential avenue for developing more biomedical devices.

Study on the aging of three typical rubber materials under high- and low-temperature cyclic environment

Abstract As the key components of sealing applications, rubber seals are subject to complicated environmental conditions during the service lifetime. In this study, the aging of three typical rubber materials, ethylene–propylene–diene monomer rubber, liquid silicone rubber, and fluorine rubber, was tested under different high- and low-temperature cycle aging environments. The experimental results confirm that the reciprocating temperature cycle causes a type of fatigue failure, which could result in an increase in the rubber compression set. In addition, a novel accelerated aging test method was proposed based on the dominant damage mechanism of rubber material caused by the temperature cycle treatments. Based on this method, the long-term aging test results of rubber samples under high- and low-temperature cycle conditions can be predicted. This method could significantly shorten the aging test time and reduce the test cost.

Preparation of High-Strength and Excellent Compatibility Fluorine/Silicone Rubber Composites under the Synergistic Effect of Fillers.

Fluorine/silicone composite rubber is widely used as a sealing material in aerospace, missile, automotive, petroleum, and other industries, but the traditional process does not use synergistic fillers to strengthen the composite system. In this research, fumed SiO2 and black caron (N990) were used as synergistic fillers, fluorine/silicone composite rubber was prepared by mechanical mixing process, and three different fluorine rubber systems were used to find the best composite material. The mechanical properties, thermal properties, aging properties, moderate strength properties, and microstructure of the composites were evaluated. Studies have shown that mixing the two can produce a certain interface interaction and effectively improve the compatibility. The physical properties of the material tended to decrease during the increase in the added amount of silicone rubber (MVQ). The maximum tensile strength of the hybrid material can reach 15 MPa. The optimal mixing ratio is fluororubber/silicone rubber (FKM/MVQ) = 9/1. At this time, the mechanical properties of the composite material are in the best state, and SiO2 and black caron (N990) have a reinforcing effect, which can effectively improve the mechanical properties. After the composite was kept at 200 °C for 48 h, the tensile strength and elongation of the best sample A1 were 99.5 and 97.0%, respectively, showing excellent anti-aging properties. This work provides a method to fabricate high-strength fluorine/silicone composites using synergistic fillers that may be used in heat-medium-sealed environments.

The Preparation of a Superhydrophobic Fluorine Rubber Surface

Superhydrophobic materials have a good application prospect in self-cleaning, anti-fouling, anti-corrosion, and anti-freezing. However, creating large areas of simple, efficient, and environmentally friendly superhydrophobic surfaces remains a huge challenge. In this paper, a simple, environmentally friendly surface superhydrophobic preparation method is used based on 107 silicone rubber adhesive. A superhydrophobic coating with a micro/nano structure was constructed on the surface of fluorine rubber. The particle size and groups of HB-192V powder (mainly SiO2) were observed by Fourier-transform infrared spectroscopy and a scanning electron microscope (SEM). The structures of two kinds of rubber surfaces were observed by SEM, and the superhydrophobic surface materials were qualitatively analyzed by X-ray diffraction (XRD). The hydrophobic properties of the superhydrophobic surface and the bouncing properties of droplets were analyzed by a contact angle measuring instrument and a high-speed camera. The results show that the preparation of superhydrophobic fluorine rubber on the surface of the water meter contact angle could reach an average of 154.1°. The superhydrophobic surface prepared by this method has a better hydrophobic and droplet bounce property.

Low-temperature resistance of fluorine rubber with modified Si-based nanoparticles

Fluorine rubber contains fluorine atoms with strong electronegativity, which endow it with novel properties, such as oil resistance, heat resistance, chemical resistance, but also lead to poor low temperature resistance. Si-based nanoparticles are used as the new active crosslinking point of fluorine rubber, which can break the original regular structure to improve the low-temperature resistance and ensuring the mechanical properties of fluorine rubber. The relative optimal silane coupling agent is selected according to the relative concentration and the interaction energy of the molecular interface in different models. The optimal silane coupling agent can avoid the agglomeration of Si-based nanoparticles in fluorine rubber and form flexible bridge between inorganic Si-based nanoparticles and fluorine rubber long chains. It is discovered that the mechanical and low-temperature properties of the modified Si-based nanoparticles/fluorine rubber (FKM-M Si) was optimal compared with pure fluorine rubber (P-FKM) and unmodified Si-based nanoparticles/fluorine rubber (FKM-UM Si). The brittleness temperature (T b ) is reduced from -18.0 °C to -29.0 °C, allowing for a wider range of applications for FKM-M Si. This study provided a potential for the application of fluorine rubber composites in harsh low-temperature environment. • The silicon nanoparticles have larger Si–O–Si bond angles, high orientation freedom and good flexibility. • Improving the dispersion of silicon nanoparticles in fluorine rubber by chemical modification. • Unique nanocomposite structure is the key point of the low temperature resistance.

Low-temperature preparation of novel fluoro-fluoro semi-interpenetrating polymer networks as a strong, tough and safe polymer binder for PBX

This work provides an energy saving strategy for strengthening and toughening fluoroelastomer (linear F2314) by using liquid fluorine rubber (HTLF-700). A series of semi-interpenetrating polymer networks based on the F2314 and the crosslinked HTLF-700 (namely F23-CLF-X semi-IPNs) were firstly prepared at low temperatures and characterized using FTIR, SEM, EDS, TGA, DSC, DMA and tensile testing et al. The as-prepared F23-CLF-30 semi-IPNs film possessed well interpenetrating co-continuous phases and thus exhibited prominent mechanical performance with the higher tensile strength (33.0 MPa), the larger elongation at break (165.0%), the better mechanical stability at high and low temperature shock and the higher high-temperature creep resistance compared with the F2314. Meanwhile, the arc Brazilian test indicates that F23-CLF semi-IPNs could be a promising candidate as a polymer binder for polymer bonded explosive (PBX).

Oxidation of lubricating oil and its influence on the aging behaviors of fluorine rubber

AbstractFluoroelastomer (FKM) has been widely used in aerospace and some particular fields, whose aging is a key problem to influence the service life of the systems. The aging behaviors of FKM in the lubricating oil have been investigated in our previous study. In this work, the influence of intentionally aged or oxidized lubricating oil (A‐O) on the aging process of FKM is reported for the first time comparing with the situation in the fresh oil (F‐O). As the oil medium aged at 200°C for different time, its color, acid number and contact angle with FKM change evidently indicating possible oxidation might occur although the Fourier transform infrared spectrometer (FTIR) has little change. Then, the influence of aged oil medium on the aging behaviors of FKM was further examined. Compared with F‐O, the aging process of FKM in A‐O was significantly accelerated as evidenced by FTIR, tensile strength, mass change, DMA, and macroscopic observation. With the increase of aging temperature from 150 to 200°C, the contrast between A‐O and F‐O conditions become more prominent. Specifically, at 200°C, the crosslinking density and tensile strength of FKM in A‐O decreased by 2.2 × 10−4 mol/cm3 and 2.5 MPa compared to that in F‐O, and the mass change reached to 3.8%, which might be due to the higher amount of oil medium by diffusion into the FKM matrix.