炭黑填充顺丁橡胶(BR)复合材料中多重相互作用的研究

通过溶液浸泡及高速离心的方法分离了填料与聚合物间的强弱相互作用,研究了炭黑填充BR复合材料中多重相互作用与炭黑含量的关系,基于不同结合橡胶含量与储能模量的关系,提出了该多重相互作用随炭黑含量的演变模型.结果表明,存在于炭黑凝胶Ⅰ中的玻璃化转变温度和结晶熔融峰在炭黑凝胶Ⅱ中均完全消失,该现象意味着炭黑凝胶Ⅰ中测得的玻璃化转变及结晶行为只是与炭黑形成弱相互作用的那部分分子链段的贡献.在选用玻璃化转变温度考察炭黑-橡胶相互作用时应综合考虑样品特性以及测试方法.当炭黑含量不高于50 phr时,结合橡胶Ⅱ的含量随炭黑含量的增多呈线性增大,结合橡胶Ⅲ的含量则受炭黑含量的显著影响.炭黑填充橡胶复合材料中的多重相互作用可通过重叠模型进行描述,当炭黑含量分别为25~30phr,50~55 phr以及70~80 phr时,填充复合材料体系中分别存在结合橡胶Ⅲ的重叠层,结合橡胶Ⅲ和结合橡胶Ⅱ的重叠层,以及结合橡胶II的重叠层.     

白炭黑/炭黑混合填料补强仿生橡胶的性能

白炭黑/炭黑混合填料是近年来发展最快的一种新型橡胶材料补强剂,主要用来改善橡胶材料的动态性能.为了探究混合填料比例和密炼工艺对仿生橡胶动静态力学性能的影响机制,设计了两组实验:(1)固定密炼时间为6 min,采用不同混合比例的白炭黑/炭黑填料填充仿生橡胶,并对其分散、拉伸、疲劳及滚动阻力等性能进行系统研究.结果表明,当白炭黑在填料中的质量分数<50%时,随着白炭黑质量分数的增加,硫化胶拉伸强度显著下降,这是由于混合填料引起的分子链最大交联程度下降所致.进一步增加白炭黑含量,硫化胶的拉伸性能变化不明显,但分散等级由约1级提升至约9级,填料团聚体尺寸的减小使硫化胶的断裂伸长率和伸张疲劳寿命显著提高.(2)在固定混合比(填料中白炭黑的质量分数为75%)条件下,研究了密炼时间对硫化胶动静态力学性能的影响.结果表明,在2～10 min密炼时间范围内, 4 min密炼即显著提升拉伸强度、 300%定伸应力以及断裂伸长率,同时降低滚动阻力.主要原因是此时分子链的最大交联程度较大,分散等级和分散度较高.进一步延长密炼时间(6～10 min),填料在橡胶中易发生重新聚集,聚集体平均粒径增大且分散度...     

不同品种环保橡胶填充油对乳聚丁苯橡胶性能影响研究

通过使用差示扫描量热仪(DSC)、橡胶加工分析仪(RPA)和动态压缩生热仪测试,分别研究了采用国内外不同品种的环保型橡胶填充油所制备的乳聚丁苯橡胶的热性能、动态力学性能以及动态压缩生热性能,并与非环保型丁苯橡胶SBR1712及环保型丁苯橡胶SBR1723进行了对比。结果表明,采用环保型芳烃油(TDAE)所制备的乳聚丁苯橡胶损耗因子最大,生热稍高于其它品种环保油;采用克拉玛依石化环保型环烷油(AP-10)所制备的乳聚丁苯橡胶动态压缩生热性能最好。     

白炭黑增强型硅橡胶的组成及抗原子氧性能分析

为明确空间级硅橡胶的化学组成及填料添加对材料物理性能的影响, 采用填料复合方式制备硅橡胶高聚物材料, 并通过化学成分测试、 原子氧暴露试验及力学性能测试等研究其结构组成与物理性能. 经微观粒径测试得出硅橡胶中白炭黑填料粒径主要分布在8~16 μm; 经傅里叶变换红外光谱(FTIR)、 核磁共振波谱( ¹H NMR和 ²⁹Si NMR)和溶胶凝胶渗透色谱(GPC)测试得出硅橡胶中含有Si—Me, Si—Ph, Si—O—Si等基团和甲基、 苯基等官能团, 其分子量分散系数为1.56, 并进一步推断出硅橡胶的分子结构及基胶与交联剂的反应类型为脱羟胺型; 经原子氧暴露试验及力学试验证实, 与未改性白炭黑填充的硅橡胶高聚物材料相比, 经硅烷改性白炭黑填充的硅橡胶高聚物材料表现出更好的抗原子氧性能, 动态力学测试后储能模量高54%, 并具有更好的应力应变响应性能. 研究结果表明, 采用表面改性处理方式可增强填料与硅橡胶基质的相互作用, 从而提高填料复合型硅橡胶高聚物材料的抗原子氧性能及综合力学性能.     

环戊烷/环己烷溶剂体系下溶聚丁苯橡胶结构与性能研究

以正丁基锂(n-BuLi)为引发剂,环己烷/环戊烷为溶剂,合成了溶聚丁苯橡胶(SSBR),并对反应过程中的现象、橡胶的结构与性能进行了研究。结果表明,用不同的结构调节剂并改变配比及用量,对共聚物中1,2-结构含量,二者相差不大,但是嵌段苯乙烯含量环戊烷体系明显低于环己烷体系。不同温度、不同调节剂配比下,两种体系下分子量相差不大,分子量分布趋同,物理机械性能也非常接近。     

硅土/白炭黑复合填料对天然橡胶硫化胶性能的影响

硅土主要是由低温石英和粘土矿物组成的非金属矿物,具有独特的粒片叠置结构。本工作采用经改性处理的硅土与白炭黑并用,测定硅土/白炭黑复合填料对天然橡胶(NR)的硫化特性和力学性能,探讨填料并用对天然橡胶性能的影响。实验结果表明:经改性处理,硅土平均粒径减小,疏水性增强。硅土与白炭黑并用,有利于增强NR硫化初期的流动性,延长焦烧时间而不明显降低硫化速率,能改善橡胶的加工性能。拉伸性能测试结果表明,复合填料与白炭黑或硅土单独使用相比,能显著提高填充NR硫化胶的拉伸强度、定伸应力、交联密度,而不降低橡胶弹性。当硅土占复合填料质量为40%时,NR硫化胶的拉伸强度达到最大。动态机械性能测定结果表明,相比白炭黑,硅土更有利于减小硫化胶的生热和滚动阻力。     

白炭黑填充羧基丁苯橡胶的多层次微观结构研究

分别采用悬浮液吸附混合法、胶乳混合并开炼法制备填充份数0~300 phr、0~60 phr的羧基丁苯橡胶/白炭黑(XSBR/A200)复合物,采用温度调制示差扫描量热法(TMDSC)研究复合物的玻璃化转变行为,采用动态流变法研究A200的补强机理.TMDSC测试结果显示,粒子表面玻璃化层含量与填充份数呈线性关系,且与混合方式无关.流变与TMDSC测试结果对比显示,A200粒子表面存在两层分子能动性不同的受限层,其中玻璃化层内层不能发生玻璃化转变,受限外层可发生玻璃化转变,但在高频下呈刚性行为.根据等价球形模型,在半径为6.8 nm的A200粒子表面,玻璃化层与受限外层厚度分别为1.0和1.6 nm.     

橡胶活性官能团对增韧环氧树脂动态力学性能的影响

用动态扭摆法测试聚丙烯酸丁酯橡胶增韧环氧树脂的动态力学行为,研究在环氧树脂低固化度和高固化度时,橡胶活性官能团种类(环氧基官能团与羧基官能团)和数量(官能度)对其影响。研究体系中橡胶玻璃化转变温度(Tg)的移动大小,与橡胶和基体树脂健合程度之间的关系。     

3-己酰基硫代-1-丙基三乙氧基硅烷的合成及其在SSBR/SiO2复合体系中偶联效果研究

以γ-巯丙基三乙氧基硅烷与己酰氯为单体,在N2保护与低温下合成偶联剂3-己酰基硫代-1-丙基三乙氧基硅烷(HXT),将HXT与双-(3-乙氧基硅基丙基)二硫化物(TESPD)分别添加于溶液聚合丁苯橡胶(SSBR)/SiO2混炼胶复合体系中.采用流变学方法表征复合体系的动态粘弹行为,发现HXT可改善填料和基体的相互作用,有效阻止SiO2粒子在加工过程中的团聚.与TESPD相比较,含HXT体系具有较高“Payne效应”临界应变值.     

粒子-聚合物相互作用与粒子-粒子相互作用对聚合物基纳米复合物力学性能的影响

聚合物基纳米复合物(PNCs)具有比传统高分子材料更加优异的光学、力学、热力学等性能,广泛应用于各个工程领域.而纳米粒子(NPs)对材料性能提高的机理则是当前聚合物纳米复合物领域研究的重要问题,聚合物纳米复合体系相互作用的影响因素众多,至今尚未明确并完整建立复合体系相互作用与性能增强之间的关系.本文总结了近年来关于纳米粒子填充聚合物基体力学性能的研究,从粒子-聚合物相互作用和粒子-粒子相互作用角度阐述了聚合物纳米复合体系力学性能的增强机理,并根据体系中不同的结构关系分别总结了聚合物/未改性纳米粒子复合体系和聚合物/聚合物接枝纳米粒子复合体系中影响力学性能的因素.该部分内容具有重要的理论和实践意义,有助于构建复合体系微观结构与宏观性能之间的关系,进而对微观层面调控PNCs的力学性能提供指导.     

Nonlinear rheological behavior of silica filled solution‐polymerized styrene butadiene rubber

The reinforcement and nonlinear viscoelastic behavior have been investigated for silica (SiO₂) filled solution‐polymerized styrene butadiene rubber (SSBR). Experimental results reveal that the nonlinear viscoelastic behavior of the filled rubber is similar to that of unfilled SSBR, which is inconsistent with the general concept that this characteristic comes from the breakdown and reformation of the filler network. It is interesting that the curves of either dynamic storage modulus (G′) or loss tangent (tan δ) versus strain amplitude (γ) for the filled rubber can be superposed, respectively, on those for the unfilled one, suggesting that the primary mechanism for the Payne effect is mainly involved in the nature of the entanglement network in rubbery matrix. It is believed there exists a cooperation between the breakdown and reformation of the filler network and the molecular disentanglement, resulting in enhancing the Payne effect and improving the mechanical hysteresis at high strain amplitudes. Moreover, the vertical and the horizontal shift factors for constructing the master curves could be well understood on the basis of the reinforcement factor f(φ) and the strain amplification factor A(φ), respectively. The surface modification of SiO₂ causes a decrease in f(φ), which is ascribed to weakeness of the filler–filler interaction and improvement of the filler dispersion. However, the surface nature of SiO₂ hardly affects A(φ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2594‐2602, 2007     

Effects of rubber type on the curing and physical properties of silica filled rubber compounds

As environmental regulations are getting stricter, tire industries for automobiles have shown much interest in substituting silica for conventional carbon black partially or entirely. To take full advantage of silica as fillers for rubbers, it is essential to find a reasonable rubber system that shows an excellent performance with silica reinforcement. Therefore, in this study, several different rubber compounds comprising the same amount of silica were prepared with several different rubber systems, respectively. The processability, curing characteristics, and mechanical and viscoelastic properties of the rubber compounds were investigated to analyze the performance of the rubber compounds as tire tread materials. Among the rubber compounds studied, SBR1721 compound comprising natural rubber (NR) and styrene butadiene rubber (SBR) with high styrene content was considered the most appropriate for application to tire tread materials. Copyright © 2008 John Wiley & Sons, Ltd.     

Structure and properties of star‐shaped solution‐polymerized styrene‐butadiene rubber and its co‐coagulated rubber filled with silica/carbon black‐I: morphological structure and mechanical properties

The morphological structure and mechanical properties of the star‐shaped solution‐polymerized styrene‐butadiene rubber (SSBR) and organically modified nanosilica powder/star‐shaped SSBR co‐coagulated rubber (N‐SSBR) both filled with silica/carbon black (CB) were studied. The results showed that, compared with SSBR, silica powder could be mixed into N‐SSBR much more rapidly, and N‐SSBR/SiO₂ nanocomposite had better filler‐dispersion and processability. N‐SSBR/SiO₂/CB vulcanizates displayed higher glass‐transition temperature and lower peak value of internal friction loss than SSBR/SiO₂/CB vulcanizates. In the N‐SSBR/SiO₂/CB vulcanizates, filler was dispersed in nano‐scale resulting in good mechanical properties. Composites filled with silica/CB doped filler exhibited more excellent mechanical properties than those filled with a single filler because of the better filler‐dispersion and stronger interfacial interaction with macromolecular chains. N‐SSBR/SiO₂/CB vulcanizates exhibited preferable performance in abrasion resistance and higher bound rubber content as the blending ratio of silica to CB was 20:30. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of fly ash silica and precipitated silica fillers on the viscosity,cure, and viscoelastic properties of natural rubber

The viscosity, cure properties, storage, and loss moduli and tan δ of natural rubber (NR) filled with the same amounts of precipitated silica (PSi) and fly ash silica (FASi) fillers were measured. The fillers were treated with bis[3‐triethoxysilylpropyl‐]tetrasulfide (TESPT), or, used in the rubber untreated. TESPT is a sulfur‐containing bi‐functional organosilane that chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur cure. The dispersion of PSi and FASi in the rubber was investigated using scanning electron microscope (SEM). The effects of silica type and loading and surface treatment on the aforementioned properties were of interest. The SEM results showed that the FASi particles were larger in size and had a wider particle size distribution when compared with the PSi particles. The viscosity of the compounds decreased progressively with mixing time, and the compounds with FASi had a lower viscosity than those filled with PSi. The treatment with Si69 had no beneficial effect on the dispersion of the fillers in the rubber matrix. At low temperatures, the type and loading of the filler had no effect on the storage and loss moduli of the compounds, but the effect was more pronounced at high temperatures. There was also evidence from the tan δ and glass transition temperature (T_g) measurements that some limited interaction between the filler particles and rubber had occurred because of TESPT. Copyright © 2008 John Wiley & Sons, Ltd.     

Gamma radiation induced effects on silica and on silica-polymer interfacial interactions in filled polysiloxane rubber

We report in our studies to assess the impact of gamma radiation on silica and on the silica-polymer interface in filled polysiloxane rubber. Electron spin resonance (ESR) and solid-state nuclear magnetic resonance (NMR) studies have been performed on samples exposed to gamma radiation. In an effort to probe directly the effect of gamma radiation on the silica surface, we employed ¹H and ²⁹Si NMR. Our ESR studies show trapped paramagnetic species (positive holes and/or trapped electrons) within the host silica matrix for all samples exposed to gamma radiation. A sample of pure cab-o-sil irradiated to a dose of 50 kGy also shows an ESR signal. Our studies on real-time aged samples (derived from field trials) also show ESR signatures indicative of silica based trapped paramagnetic species. The growth of trapped paramagnetic species as a function of gamma dose was investigated. This shows that the build up of trapped species occurs rapidly at low gamma dose before reaching saturation at about 20-30 kGy. Radiation induced band gap excitation is the likely process leading to the creation of these paramagnetic species which may be trapped in regions of local charge deficit within the silica matrix. Species that are not trapped may take part in silica surface reactions leading to changes in filler-polymer interfacial interactions. NMR studies combined with ammonia modified swell studies have shown increased polymer segmental chain mobility (softening) at low gamma dose indicative of a possible reduction in filler-polymer interfacial interactions. For those samples exposed to high gamma dose, our ammonia modified swell studies suggest increased polymer-filler interactions presumably through silica-polymer crosslinking effects. Our ¹H and ²⁹Si NMR studies on irradiated silica suggest that the silica surface is sensitive to gamma radiation. Our observations are important as they highlight the need to better control the quality (size, purity, etc.) of the silica constituent in filled polymer components used in gamma radiation environments.     

The influence of non-rubber constituents on performance of silica reinforced natural rubber compounds

An in-rubber study of the interaction of silica with proteins present in natural rubber show that the latter compete with the silane coupling agent during the silanisation reaction; the presence of proteins makes the silane less efficient for improving dispersion and filler–polymer coupling, and thus influences the final properties of the rubber negatively. Furthermore, the protein content influences the rheological properties as well as filler–filler and filler–polymer interactions. Stress strain properties also vary with protein content, as do dynamic properties. With high amounts of proteins present in natural rubber, the interactions between proteins and silica are able to disrupt the silica–silica network and improve silica dispersion. High amounts of proteins reduce the thermal sensitivity of the filler–polymer network formation. The effect of proteins is most pronounced when no silane is used, but they are not able to replace a coupling agent.     

Effect of surface modification of colloidal silica nanoparticles on the rigid amorphous fraction and mechanical properties of amorphous polyurethane–urea–silica nanocomposites

Colloidal silica nanoparticles (NPs) modified with eight different silane coupling agents were incorporated into an amorphous poly(tetramethylene oxide)‐based polyurethane–urea copolymer matrix at a concentration of 10 wt % (4.4 vol %) in order to investigate the effect of their surface chemistry on the structure–property behavior of the resulting nanocomposites. The rigid amorphous fraction (RAF) of the nanocomposite matrix as determined by differential scanning calorimetry and dynamic mechanical analysis was confirmed to vary significantly with the surface chemistry of the NPs and to be strongly correlated with the bulk mechanical properties in simple tension. Hence, nanocomposites with an RAF of about 30 wt % showed a 120% increase in Young's modulus, a 25% increase in tensile strength, a 15% decrease in elongation at break with respect to the neat matrix, which had no detectable RAF, whereas nanocomposites with an RAF of less than 5% showed a 60% increase in Young's modulus, a 10% increase in tensile strength and a 5% decrease in the elongation at break. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2543–2556     

Aging properties of styrene-butadiene rubber nanocomposites filled with carbon black and rectorite

To better understand the effect of rectorite and carbon black (CB) on the aging performance of styrene-butadiene rubber (SBR), SBR/CB, SBR/CB/rectorite and SBR/rectorite nanocomposites with the same total filler loading were prepared. The microstructure of the three SBR nanocomposites was characterized by XRD, TEM and SEM. After thermal aging, oxygen-containing molecules were found to be formed in the SBR nanocomposites, as verified by FTIR analysis. The SBR/rectorite nanocomposite showed the highest aging coefficient and the lowest change rate of tensile strength and stress at 100% strain among the three SBR nanocomposites, indicating that the introduction of nano-dispersed rectorite layers can enhance the thermal aging resistance of the nanocomposites. For the SBR/CB/rectorite nanocomposite, the addition of CB helped to improve the interfacial compatibility between the filler and matrix, resulting in the best crack resistance as the aged SBR/CB/rectorite nanocomposite always demonstrated the least cracks on the surface during either stretching or bending experiments.     

Relationship between the polymer/silica interaction and properties of silica composite materials

Cast film composites have been prepared from aqueous polymer solutions containing nanometric silica particles. The polymers were polyvinyl alcohol (PVA), hydroxypropylmethylcellulose (HPMC) and a blend of PVA‐HPMC polymers. In the aqueous dispersions, the polymer–silica interactions were studied through adsorption isotherms. These experiments indicated that HPMC has a high affinity for silica surfaces, and can adsorb at high coverage; conversely, low affinity and low coverage were found in the case of PVA. In the films, the organization of silica particles was investigated through transmission electron microscopy (TEM) and small‐angle neutron scattering (SANS). Both methods showed that the silica particles were well‐dispersed in the HPMC films and aggregated in the PVA films. The mechanical properties of the composite films were evaluated using tensile strength measurements. Both polymers were solid materials, with a high‐elastic modulus (65 MPa for HPMC and 291 for PVA) and a low‐maximum elongation at break (0.15 mm for HPMC and 4.12 mm for PVA). In HPMC films, the presence of silica particles led to an increase in the modulus and a decrease in the stress at break. In PVA films, the modulus decreased but the stress at break increased upon adding silica. Accordingly, the polymer/silica interaction can be used to tune the mechanical properties of such composite films. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1134–1146, 2006     

Novel biphasic structured composite prepared by in situ silica filling in natural rubber latex

The sol‐gel reaction of tetraethoxysilane in natural rubber (NR) latex was conducted to produce in situ silica‐filled NR latex, followed by adding sulfur cross‐linking reagents to the latex in a liquid state. The latex was cast and subjected to sulfur curing to result in a unique morphology in the NR composite of a flexible film form. The contents of in situ silica filling were controlled up to 35 parts per one hundred rubber by weight. The silica was locally dispersed around rubber particles to give a filler network. This characteristic morphology brought about the composite of good dynamic mechanical properties. Synchrotron X‐ray absorption near‐edge structure spectroscopy suggested that the sulfidic linkages of the sulfur cross‐linked composites were polysulfidic, S_x (x ≥ 2), and a fraction of shorter polysulfidic linkages became larger with the increase of in situ silica. The present observations will be of use for developing a novel in situ silica‐filled NR composite prepared in NR latex via liquid‐phase soft processing. Copyright © 2011 John Wiley & Sons, Ltd.