Effects of ?CH2CH2CF3 on properties of RTV polysiloxane rubber: Processability,thermal stability,and oil/solvent resistance

Room temperature vulcanizing fluorosilicone rubbers (FSRs) were prepared from polydimethylsiloxane (PDMS), vinyl fluorosilicone‐oil (VFS‐oil), and precipitated silica (PDMS/VFS/SiO₂). Rheological tests showed appropriate processing condition could be obtained when shear rate > 10 s^?1. Mechanical tests indicated that tensile strength and elongation at break were not much affected by VFS‐oil and no decline was observed after being aged in 70 °C ASTM 1# oil. The ? CF₃ group could not only increase oil‐resistance, but also decrease surface energy, which were proved by ATR‐FTIR and contact angle tests. The PDMS oil immersion tests showed that the higher the content of VFS‐oil, the better oil resistance can be obtained. The solvent‐resistance tests indicated that the VFS‐oil improved resistance to nonpolar/low‐polar solvent. TGA results showed that the increasing content of VFS‐oil could slightly decrease FSRs' thermal stability but increase FSRs' residual mass ratio at 790°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39708.     

Effects of CH2CH2CF3 on properties of RTV polysiloxane rubber: Processability,thermal stability,and oil/solvent resistance

Room temperature vulcanizing fluorosilicone rubbers (FSRs) were prepared from polydimethylsiloxane (PDMS), vinyl fluorosilicone‐oil (VFS‐oil), and precipitated silica (PDMS/VFS/SiO₂). Rheological tests showed appropriate processing condition could be obtained when shear rate > 10 s^?1. Mechanical tests indicated that tensile strength and elongation at break were not much affected by VFS‐oil and no decline was observed after being aged in 70 °C ASTM 1# oil. The ?CF₃ group could not only increase oil‐resistance, but also decrease surface energy, which were proved by ATR‐FTIR and contact angle tests. The PDMS oil immersion tests showed that the higher the content of VFS‐oil, the better oil resistance can be obtained. The solvent‐resistance tests indicated that the VFS‐oil improved resistance to nonpolar/low‐polar solvent. TGA results showed that the increasing content of VFS‐oil could slightly decrease FSRs' thermal stability but increase FSRs' residual mass ratio at 790°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39708.     

Preparation and properties of heat curable blended methylfluorosilicone rubber

Heat curable blended methylfluorosilicone rubber (MFSR) was prepared by combination of methylsilicone rubber (MSR) and fluorosilicone rubber (FSR). 2,5‐Bis(tert‐butylperoxy)‐2,5‐dimethylhexane (DBPMH) was chosen as a curing agent. Poly(methylsiloxane‐co‐fluorosiloxane) with low molecular weight was used as an interfacial agent. Curing characteristics, mechanical properties, low temperature performance, and hot oil resistance of blended MFSR was studied in details. The results showed that MSR and FSR could reach co‐vulcanization by DBPMH in blended MFSR. Higher FSR content could improve the scorch safety, lower the rate of curing reaction, and lead to the poor processability of blended MFSR. An increase of FSR content also improved the hot oil resistance of blended MFSR. Interfacial agent could limit the phase separation of MSR and FSR, make the blended system more thermodynamically stable and elevate the mechanical properties of blended MFSR. Differential scanning calorimetry (DSC) measurements revealed that increasing MSR content lowered the glass transition temperature (T_g) and improved the low‐temperature flexibility of blended MFSR when MSR was no more than 15%. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

The effect of ceria nanoparticles on improving heat resistant properties of fluorosilicone rubber

The thermal aging behavior of poly(3,3,3‐trifluoropropyl)methylsiloxane was investigated by thermal gravimetric analysis and isothermal aging tests, and the results indicated the degradation mechanism II, oxidation scission of the side groups, played a more important role when the temperature was below 350 °C. The addition of ceria had significantly improved the thermal stability of fluorosilicone rubber (FSR) by inhibiting the oxidation scission. Moreover, two types of ceria including laminar‐structure ceria (LS‐CeO₂) and nanoparticle ceria (N‐CeO₂) were prepared and surface was modified by KH570 and characterized by scanning electron microscopy, transmission electron microscope, and X‐ray diffractometer. FSR incorporated with modified LS‐CeO₂ and N‐CeO₂ revealed a significant improvement on the heat resistant properties. In particular, after having been thermal oxidative aged for 70 h at 250 °C, FSR containing 2 wt % of modified N‐CeO₂ maintained 72.6% of tensile strength and 63.9% of elongation at break, respectively, while FSR without ceria completely failed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44117.     

氟硅密封剂热老化性能研究

以不同三氟丙基含量的端羟基液体氟硅橡胶作为生胶,采用共混法制备氟硅密封剂。以拉伸强度和断裂伸长率为衡量指标,采用单因素试验法探讨了三氟丙基含量、硫化剂和耐热助剂类型等对氟硅密封剂耐热老化性能的影响。结果表明,三氟丙基含量越高,氟硅密封剂的耐热老化性能越差;硫化剂类型对氟硅密封剂的耐热老化性能影响不大;耐热助剂类型对氟硅密封剂的常温力学性能影响不大,但三氧化二铁(Fe2O3)和氧化铈(CeO2)均能明显提高氟硅密封剂的耐热性能。     

Preparation and characterization of polymethyltrifluoropropylsilicone modified acrylonitrile–butadiene rubber/fluorosilicon rubber blend

The blending of polymethyltrifluoropropylsilicone‐modified acrylonitrile–butadiene rubber (MNBR) and fluorosilicon rubber (FSR) at 70 : 30 ratio was investigated. The grafting of mercapto‐functionalized polymethyltrifluoropropylsilicone onto acrylonitrile‐butadiene rubber (NBR) by thiol‐ene reaction was carried out with 2,2′‐azobisisobutyronitrile as initiator in a Haake torque rheometer. The rheological properties of NBR grafting obtained at varying dosages of polymethyltrifluoropropylsilicone in a Haake torque rheometer were studied using torque curves. Grafting reaction was confirmed by ¹H nuclear magnetic resonance and energy‐dispersive X‐ray spectroscopy. Results of scanning electron microscopy and dynamic mechanical analysis showed better compatibility of MNBR/FSR blend than NBR/FSR reference blend. Meanwhile, the macro‐mechanical properties of the blend significantly improved. The tensile strength and tear strength of MNBR/FSR blend were improved to 14.34 MPa and 44.94 KN/m, respectively, which were 2.92 MPa and 13.03 KN/m higher than those of NBR/FSR reference blend. The low‐temperature brittleness of the blend was improved to ?57°C, an increase of ?6°C compared with that of NBR. These results indicated that MNBR/FSR blend at 70 : 30 ratio had improved compatibility because of the grafting chains that acted as interfacial agents. The low‐temperature resistance of the blend was also enhanced. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42328.     

Lightweight and flame retardant fluorosilicone rubber composited foam prepared by supercritical nitrogen

Improving the flame retardancy and lightweight of fluorosilicone rubber (FSR) foam is important for its application in aerospace, rail transportation, petrochemical equipment, etc. In this work, ammonium polyphosphate (APP) and expandable graphite (EG) were used as synergistic flame retardants, and the lightweight FSR composite foam with flame retardancy was prepared by supercritical N₂ foaming. When there were 12.5 phr APP and 7.5 phr EG, the composite foam with density of 0.254 g/cm³ showed superiority in foaming performance and flame retardancy, and the limit oxygen index was 36.4%, the UL-94 grade reached V-0, the ignition time was 12 s and the fire performance index was 0.071 s·m²/kW. In addition, the aging, oil and solvent resistance of FSR foam was not affected. This work provided data support for the production and application of the flame retardant FSR foam.     

四丙氟橡胶/氟硅橡胶并用胶性能研究

制备四丙氟橡胶( FEPM)/氟硅橡胶(FMVQ)并用胶,并对其性能进行研究.结果表明:FEPM与FMVQ能够实现共硫化;与FEPM相比,FEPM/FMVQ并用胶耐低温性能改善,拉伸强度减小,压缩永久变形增大,耐热空气老化性能和热稳定性有所下降.     

宽温域耐15#航空液压油氟硅橡胶性能的研究

采用均聚氟硅橡胶和改性共聚氟硅橡胶,通过机械共混法制备宽温域氟硅橡胶,研究均聚氟硅橡胶/改性共聚氟硅橡胶并用比对胶料物理性能、耐15^#航空液压油性能及耐低温性能的影响。结果表明:随着改性共聚氟硅橡胶用量增大,胶料的硬度逐渐降低,拉伸强度变化很小,拉断伸长率和拉断永久变形逐渐增大但增幅不大,耐15^#航空液压油性能有所降低,耐低温性能明显提高;当均聚氟硅橡胶/改性共聚氟硅橡胶并用比为50/50时,胶料的脆性温度(多试样法)达到-64.7℃,在-50,-55,-60℃下的压缩耐寒系数分别达到0.51,0.44,0.39,低温回缩试验10%回缩率对应的温度达到-67.2℃;当均聚氟硅橡胶/改性共聚氟硅橡胶并用比为70/30时,胶料的耐低温、耐15^#航空液压油综合性能最佳,动密封圈在10个循环周期的台架试验中未出现泄漏、损伤和永久变形现象,在-60~150℃宽温域、15^#航空液压油环境中具有良好的密封性能。     

Study on characterization and properties of nanosilica‐filled thermoplastic vulcanizates

Thermoplastic vulcanizates (TPVs) are a special class of thermoplastic elastomer, produced by simultaneously mixing and cross‐linking a rubber with a thermoplastic at elevated temperature. Dicumyl peroxide‐cured TPVs based on blends of maleated ethylene propylene rubber (m‐EPM) and polypropylene (PP) thermoplastic using maleated‐PP as a compatibilizer have been developed. To reinforce the properties of these TPVs, nanosilica was added at different levels. With the increase of nanosilica concentrations, significant improvement in tensile strength, modulus, and impact strength of TPVs have been achieved. Morphology study shows that nanosilica is uniformly dispersed in the polymer matrices. Dynamic mechanical analysis shows that tan δ value at low temperature decreases with increasing nanosilica concentration indicating less damping characteristics. Thermogravimetric study revealed that thermal stability of TPVs is improved in presence of nanosilica. Equilibrium swelling study confirms that solvent resistance of TPVs could be improved by nanofiller incorporation. Rubber process analyzer found a very useful tool to understand the melt rheology of nanosilica filled TPVs in terms of dynamic functions over a wide range of strain amplitude and frequency. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Mechanical properties,flame retardancy,hot‐air ageing,and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber/hydrogenated nitrile‐butadiene rubber/magnesium hydroxide composites

The mechanical properties, flame retardancy, hot‐air ageing, and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber (EVM)/hydrogenated nitrile‐butadiene rubber (HNBR)/magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/MH composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot‐air ageing resistance and hot‐oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (T_g) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot‐oil ageing, and hot‐air ageing resistance combined with good mechanical properties performance in a wide temperature range (?30°C to 150°C) make the EVM/HNBR/MH composites ideal for cables application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Plasma surface modification of poly(m-aramide) fabric for adhesion improvement to fluorosilicone rubber

Poly(m-phenylene isophthalamide) fabric is important as a reinforcement for highperformance rubber diaphragms, such as fluorosilicone diaphragms. Because of their low affinities for each other, it is difficult to develop a good adhesion bond between poly(m-aramide) fiber and fluorosilicone rubber. The present study demonstrates that the bond strength between a poly(maramide) fabric and fluorosilicone rubber can be improved through N₂ plasma treatment of the fabric in combination with a silane coupling agent. The effectiveness of the treatment is dependent on the gas species, the plasma input power, and the time of exposure. The chemical changes in the fabric surface were studied by X-ray photoelectron spectroscopy (XPS). It turned out that free radicals were formed on the surface after the N₂ plasma treatment, which enabled the bonding of the coupling agent to the fabric surface.     

Thermally resistant photocrosslinked damping poly(phenylene oxide)–fluorosilicone rubber films with broad and high effective damping temperatures

The development of an energy-efficient strategy to prepare thermally resistant damping materials with high damping capacities (tan δ values) and broad effective damping temperature ranges (ΔTs) at high temperatures (>150 °C) is still an interesting challenge. In this study, a graft copolymer (PSi-g-APPO) was synthesized through the reaction between hydrogen-terminated fluorosilicone and allyl poly(phenylene oxide) (APPO), and a unique kind of photocrosslinkable film (coded as GFA) consisting of FSR, APPO and PSi-g-APPO was prepared. The resultant GFA has high thermal resistance, wide ΔT, and high tan δ. When the weight ratio of APPO to FSR to PSi-g-APPO was 81:9:10, the obtained film exhibited a broad ΔT of 64 °C and a high tan δ (≤1.01) from 157 to 221 °C; this was the best comprehensive performance among the GFA systems. The mechanism behind the excellent integrated performance of GFA was studied and was proven to be due to the unique structure of the heterogeneous GFA system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47231.     

Graphene nanoplatelets/barium titanate hybrid nanoparticles via ball milling for enhanced dielectric and mechanical properties of fluorosilicone rubber composites

Dielectric elastomers have been widely used in flexible actuators, artificial muscles, soft generators, etc. However, there are still challenges in fabrication of dielectric elastomers with enhanced dielectric and mechanical properties through simple and environmentally friendly compound method. In this paper, graphene nanoplatelets (GNPs) and BaTiO₃ (BT) hybrid nanofillers are prepared by co-ball milling and then introduced into fluorosilicone rubber (FSR) to obtain composites with improved dielectric and mechanical properties. The X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscope results confirm the successfully exfoliation of GNP. With the increase of GNP content, the tensile strength and dielectric constant of FSR/GNP/BT nanocomposites both increase without the sacrifice of flexibility, while the dielectric loss tangent can be kept as low as 10^?2 magnitude. The FSR-G7B30-BM composite exhibits a dielectric constant of 14.54 at 100 Hz, and the dielectric loss tangent of 0.016 at 100 Hz. Besides, the FSR-G7B30-BM composite displays the tensile strength of 1.19 MPa, and elongation at break of 332.12%. This work provides a facile strategy to design dielectric elastomers, which shows promising applications in modern electronic devices.     

氟硅共聚生胶的合成及结构分析

以1,3,5-三(3,3,3-三氟丙基)-1,3,5-三甲基环三硅氧烷(D3F)和六甲基环三硅氧烷为原料合成了高分子量的氟硅共聚生胶,研究了反应时间和反应温度对产物分子量的影响,以及单体投料比对共聚物链节含量的影响.通过红外光谱和核磁共振波谱对共聚生胶的结构进行了表征,并用乌氏黏度计测定了其分子量.结果表明,在D3F用...     

Mechanical,dielectric, and thermal properties of fluorosilicone rubber composites filled with silica/multiwall carbon nanotube hybrid fillers

In this work, hybrid fillers consist of modified silica (SiO₂) and multiwalled carbon nanotube (MWCNT) were used to improve the mechanical, dielectric, and thermal properties of fluorosilicone (FSR) composites via a direct mechanical mixing method. With the increase of CNT loading in SiO₂/CNT hybrid loading ratio, the tensile properties, dielectric constant, electrical conductivity, and thermal properties all increase without a sharp sacrifice of flexibility. The dielectric constant of FSR-S15/C5 achieved 7,370 @1 kHz, which is about four orders of the FSR-S20, and the dielectric loss remains as low as 0.676 @1 kHz. Therefore, the linkage of SiO₂ and FSR chains not only enhances the interfacial interaction between the fillers and FSR matrix but also decreases the agglomeration of the fillers in matrix. What is more, modified SiO₂ and CNT were designed as the effective hybrid filler to improve the performance of the polymeric matrix through synergic effect.     

The kinetics of the thermal decomposition of poly(3‐hydroxybutyrate) and maleated poly(3‐hydroxybutyrate)

The thermal decomposition mechanism of maleated poly(3‐hydroxybutyrate) (PHB) was investigated by FTIR and ¹H NMR. The results of experiments showed that the random chain scission of maleated PHB obeyed the six‐membered ring ester decomposition process. The thermal decomposition behavior of PHB and maleated PHB with different graft degree were studied by thermogravimetry (TGA) using various heating‐up rates. The thermal stability of maleated PHB was evidently better than that of PHB. With increase in graft degree, the thermal decomposition temperature of maleated PHB gradually increased and then declined. Activation energy E_a as a kinetic parameter of thermal decomposition was estimated by the Flynn‐Wall‐Ozawa and Kissinger methods, respectively. It could be seen that approximately equal values of activation energy were obtained by both methods. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1789–1796, 2002; DOI 10.1002/app.10463     

Effect of norbornyl modified soybean oil on CB‐filled chloroprene rubber

Carbon black (CB)‐filled chloroprene rubber (CR) compounds and vulcanizates containing naphthenic oil (NO), soybean oil (SO), and two different levels of norbornyl modified soybean oil (MSO) were prepared and investigated. The MSO was prepared through the reaction of SO and dicyclopentadiene (DCPD) at different ratios. Various properties including gel fraction, crosslink density, bound rubber fraction, curing behavior, thermal, mechanical, and aging properties of CB‐filled CR containing different oils were compared. It was observed that the addition of SO and MSO could benefit the dispersion of the filler, lower the glass transition temperature, and increase the thermal stability of the CB‐filled CR/MSO compounds and vulcanizates, and also slightly decrease the crosslink density of the CB‐filled CR/MSO vulcanizates compared to that of the CR/NO vulcanizate. With the increase of the modification level of the MSO, the curing time of the CB‐filled CR/MSO compounds was found to be decreased, the tensile property, tear strength, abrasion resistance, and aging resistance of the CB‐filled CR/MSO vulcanizates were improved compared with those of the CB‐filled CR/NO vulcanizate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43809.     

Effects of fillers,maleated ethylene propylene diene diene rubber,and maleated ethylene octene copolymer on phase morphology and oil resistance in natural rubber/nitrile rubber blends

The phase morphology and oil resistance of 20/80 NR/NBR blends filled with different types of fillers and copolymers were investigated. In the case of filler effect, N220, N330, and N660 carbon blacks with different particle sizes were used. Additionally, the blends filled with nonblack‐reinforcing fillers, that is, precipitated and silane‐treated silica, were investigated. To study the compatibilization effect, maleated ethylene propylene diene rubber (EPDM‐g‐MA) and maleated ethylene octene copolymer (EOR‐g‐MA) were added to the blends. The results revealed that the addition of filler, either carbon black or silica, to the blend caused a drastic decrease in NR dispersed phase size. Carbon blacks with different particle sizes did not produce any significant difference in NR dispersed phase size under the optical microscope. Silica‐filled blends showed lower resistance to oil than did the carbon black–filled blends. In addition, it was determined that neither EOR‐g‐MA nor EPDM‐g‐MA could act as a compatibilizer for the blend system studied. The oil resistance of the blends with EPDM‐g‐MA is strongly affected by the overall polarity of the blend. In the case of EOR‐g‐MA, the oil resistance of the blends is significantly governed by both overall polarity of the blend and phase morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1156–1162, 2003     

国内氟硅橡胶的研究进展

介绍了氟硅橡胶的性质、应用状况以及国内的发展现状及动态，重点阐述了国内氟硅橡胶．尤其是氟硅橡胶配方（包括生胶、交联剂、补强剂、偶联刺、其它添加剂等）和加工工艺的研究开发进展．对目前存在的问题与发展方向提出了一些看法。