纳米二氧化硅填充辐射硫化三元乙丙橡胶

用辐射硫化法替代传统硫化法,并以纳米二氧化硅为填料成功制备了纳米填充型三元乙丙橡胶密封材料。研究结果表明,纳米二氧化硅对辐射硫化三元乙丙橡胶有明显的补强效果,其最佳用量为40phr;吸收剂量超过20kGy后,橡胶总体性能下降;硫化胶的凝胶含量随填料含量的增加而增加,且凝胶含量的增大有利于提高辐射硫化胶的性能。对所得辐射硫化胶的透气透水性进行测试,数据显示与传统硫化法相比,辐射硫化法制备的橡胶其透气率和透水率均明显下降,表明材料的密封性较好。     

表面改性SiO2对SSBR/BR绿色轮胎胎面胶结构与性能的影响

采用4种含不同官能基团修饰剂改性的二氧化硅SiO₂增强溶聚丁苯橡胶(SSBR)/顺丁橡胶(BR)共混体系, 制备了SSBR/BR/SiO₂橡胶纳米复合材料, 研究了其结构与性能. 结果表明, 在混炼胶体系中, 与未改性SiO₂填充的SSBR/BR相比, 改性SiO₂填充的SSBR/BR门尼黏度及结合橡胶含量显著增大, 表明填料-橡胶相互作用显著提高; 硫化焦烧时间缩短60%, 硫化速度增大了35%~40%. 在硫化胶体系中改性SiO₂填充的SSBR/BR具有更大的交联密度, 填料分散性明显改善, 同时也表现出更为优异的物理机械性能, 100%和300%定伸模量提高47%以上, 旋转滚筒式磨耗机法(DIN)磨耗降低5%~12%, 生热降低了约7%~13%, 热空气老化性能提升4%~22%, 代表滚动阻力的tanδ在60 ℃降低8%~13%. 此外, 与SSBR/BR/1165MP硫化胶相比, 用90 mmol/kg氨基改性SiO₂填充的SSBR/BR硫化胶的抗湿滑性能提高6.9%, 表现出最优的综合性能. 填料的良好分散及填料与聚合物的相互作用增强对于提高SSBR/BR/SiO₂胎面胶综合力学性能具有重要意义.     

高耐磨低生热NBR/TBIR复合材料的结构与性能

采用高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)对丁腈橡胶(NBR)进行改性, 制备了高耐磨、 低生热输送轮用白炭黑填充的NBR/TBIR橡胶纳米复合材料. 研究了NBR/TBIR橡胶纳米复合材料的交联密度、 物理力学性能及填料分散性, 探讨了材料的结构对性能的影响. 研究结果表明, 与纯NBR相比, NBR/TBIR橡胶纳米复合材料的硫化速率和交联密度随TBIR用量的增加而增大; 在保持NBR硫化胶基本力学性能、 耐老化性能和耐溶剂性能基本不变的前提下, TBIR的加入使NBR/TBIR硫化胶的耐磨性提高15%, 动态压缩生热降低5%, 动态压缩永久变形降低22%, 白炭黑分散水平提高; 与丁腈橡胶/顺丁橡胶[NBR/BR(80/20), 质量份数比]硫化胶相比, NBR/TBIR(80/20, 质量份数比)硫化胶具有更低的动态压缩生热和动态压缩永久变形及更好的填料分散性.     

甲基丙烯酸镁增强氢化丁腈橡胶的结构与形态和性能

用不同份量的甲基丙烯酸镁(MgMA)作增强剂,过氧化二异丙苯(DCP)作硫化剂,通过混炼和硫化过程的原位聚合制备了氢化丁腈橡胶/聚甲基丙烯酸镁(HNBR/PMgMA)纳米复合材料,用XRD、FTIR1、3C-NMR、SEM、TEM、DMA和交联密度分析等方法研究了其结构、形态和性能,并阐述了MgMA改性HNBR的相关机理.结果表明,MgMA在混炼过程中粒径明显变小,部分达到纳米级.硫化过程中发生原位自由基聚合,并部分接枝到HNBR分子链上,HNBR硫化胶和PMgMA有可能形成接枝互穿聚合物网络(接枝IPN).随着MgMA用量的增加,纳米复合材料硫化胶的定伸应力、拉伸强度、扯断伸长率、撕裂强度和热氧老化性能逐渐提高.当MgMA含量为30份时,体系的拉伸强度和扯断伸长率分别为38.5MPa和545%,并具有优异的热空气老化性能.MgMA能明显增加HNBR复合材料的储能模量,并降低其损耗因子.随着MgMA用量的增加,纳米复合材料硫化胶的总交联密度(Ve)和离子键交联密度(Ve2)增加,而共价键交联密度(Ve1)下降,表明离子键对HNBR/PMgMA纳米复合材料的力学性能起重要作用.     

TBIR应用于航空胎侧胶的热氧老化性能

研究了反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)应用于航空轮胎胎侧胶[天然橡胶(NR)/顺丁橡胶(BR)/TBIR]的耐热氧老化性能.结果表明,与NR/BR硫化胶相比,10～20份质量的TBIR取代BR后,NR/BR/TBIR硫化胶的交联密度明显提高,压缩温升降低2. 2～3. 4℃,耐屈挠疲劳性能提高约100%,填料分散性改善,填料团聚体体尺寸减小,拉伸性能基本不变.随热氧老化时间延长,硫化胶的交联密度先增加后降低,并用TBIR的硫化胶交联密度在老化48 h后趋于平缓.与NR/BR相比,老化后的NR/BR/TBIR硫化胶生热最低,耐屈挠疲劳性最高.     

高疲劳寿命氯丁橡胶基减振材料的结构与性能

以氯丁橡胶(CR)为基体材料, 将新型反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)引入传统CR减振基体中, 探讨TBIR在减振材料中的应用前景. 研究发现, 随着TBIR用量的增加, CR/TBIR混炼胶的强度及模量明显提升; CR/TBIR硫化胶的拉伸强度、 撕裂强度、 压缩永久变形、 动静刚度比及耐疲劳性能均得到改善, 特别是一级疲劳寿命提高了50%~400%(未填充体系)及40%~180%(填充体系), 六级疲劳寿命提高了60%~500%(未填充体系)及30%~120%(填充体系). 与未填充CR/TBIR硫化胶相比, 填充CR/TBIR硫化胶由于炭黑补强作用及填料-聚合物相互作用的引入, 屈挠疲劳寿命、 撕裂强度及拉伸性能均显著提高. 与填充CR硫化胶相比, 填充CR/TBIR质量比为90/10的并用胶能够在保持硫化胶的损耗因子基本不变的基础上, 实现综合性能的平衡提升.     

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。     

RE-C22/NR复合材料的机械性能和动态力学性能

通过沉淀法合成RE-C22配合物(RE代表La,Sm和Gd元素;C22代表C_(22)H_(34)O_6),分两步进行:用氢氧化钠中和C22,然后用RE盐酸盐进行双分解反应,沉淀出RE-C22配合物。通过红外光谱(IR)测定RE-C22配合物的结构。RE-C22配合物和天然橡胶(NR)通过共混制备得到RE-C22/NR复合材料。在160℃进行硫化,交联密度测量结果显示总交联密度随着RE-C22含量的增加而增加。分别研究了复合材料流变性能,静态和动态力学性能以及表面形貌。结果表明,RE-C22作为多功能填料可以加速交联过程中硫磺的硫化,并增强NR的物理力学性能。     

一种新型硅藻土填充橡胶纳米复合材料研究

橡胶的填料问题一直是人们的研究热点,针对炭黑和白炭黑在橡胶生产中存在的污染问题,本文选用成分结构与白炭黑类似的硅藻土来填充各种橡胶。首先对硅藻土进行了改性,并对不同改性剂改性硅藻土用于填充橡胶进行了研究。结果表明2.5份偶联剂Si69的改性效果最佳。通过机械共混法制备了改性硅藻土/橡胶纳米复合材料,通过力学性能测试确定了比较适合硅藻土填充的橡胶是氟橡胶、三元乙丙橡胶和丙烯酸酯橡胶。绿色环保且价格低廉的硅藻土可以替代白炭黑增强填充氟橡胶、三元乙丙橡胶和丙烯酸酯橡胶。     

三元乙丙橡胶/蒙脱土纳米复合材料制备中硫化体系的比较

采用了熔融插层和两种硫化体系硫磺 促进剂和过氧化物体系制备了三元乙丙橡胶 蒙脱土纳米复合材料 ,并将这两种体系形成的纳米复合材料进行了形态、力学性能和光学性能的比较 ,同时采用Flory Rehner方程对它们的硫化行为进行了评价 .X射线衍射 (XRD)、透射电镜 (TEM)、力学性能和光学性能的测试结果表明 ,由硫磺硫化体系制备的纳米复合材料为不透明和剥离型 .其原有的d0 0 1 衍射峰消失 ,有序层被剥离成 10 0～ 2 0 0nm的片层均匀分散在EPDM基体中 ,其力学性能有了极大的提高 ;而过氧化物体系制备的纳米复合材料为半透明和插层型 .对两种体系的硫化行为的评价结果表明 ,随着有机蒙脱土加入量的增加 ,硫磺 促进剂硫化体系的t90 延长 ,交联密度减小 ,最大 最小转矩也变小 ;而过氧化物硫化体系的相应值却变化不大     

Reinforcement effect of MAA on nano‐CaCo3‐filled EPDM vulcanizates and possible mechanism

Methacrylic acid (MAA) was used as in situ surface modifier to improve the interface interaction between nano‐CaCO₃ particle and ethylene–propylene–diene monomer (EPDM) matrix, and hence the mechanical properties of nano‐CaCO₃‐filled EPDM vulcanizates. The results showed that the incorporation of MAA improved the filler–matrix interaction, which was proved by Fourier transformation infrared spectrometer (FTIR), Kraus equation, crosslink density determination, and scanning electron microscope (SEM). The formation of carboxylate and the participation of MAA in the crosslinking of EPDM indicated the strong filler–matrix interaction from the aspect of chemical reaction. The results of Kraus equation showed that the presence of MAA enhanced the reinforcement extent of nano‐CaCO₃ on EPDM vulcanizates. Crosslink density determination proved the formation of the ionic crosslinks in EPDM vulcanizates with the existence of MAA. The filler particles on tensile fracture were embedded in the matrix and could not be observed obviously, indicating that a strong interfacial interaction between the filler and the matrix had been achieved with the incorporation of MAA. Meanwhile, the presence of MAA remarkably increased the modulus and tensile strength of the vulcanizates, without negative effect on the high elongation at break. Furthermore, the ionic bond was thought to be formed only on filler surface because of the absolute deficiency of MAA, which resulted in the possible structure where filler particles were considered as crosslink points. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1226–1236, 2006     

Radiation effects on styrene–butadiene–ethylene–propylene diene monomer‐multiple walled carbon nanotube nanocomposites: vulcanization and characterization

Varying compositions of styrene–butadiene rubber (SBR) and ethylene–propylene diene monomer (EPDM) 50:50 blend containing multiple walled carbon nanotube (MWNT) as nanoparticulate filler (0.5–5%) were prepared and their efficacy for radiation vulcanization was analyzed by gel‐content, Charlesby‐Pinner parameter, and crosslinking density measurements. Radiation sensitivity of the nanocomposites increased with increase in the MWNT fraction and radiation dose in the dose range studied. The elastic modulus, tensile strength increased with the radiation dose, while elongation at break exhibited downward trend. The extent of reinforcement as assessed using Kraus equation suggested high reinforcement of blend on MWNT addition. The reinforcing mechanism of nanocomposites was studied by various micromechanics models which predicted higher modulus than the experimentally observed results, indicating agglomeration in the nanocomposites. The thermal stability of the composites increased with increase in MWNT loading has been attributed to the antioxidancy induced by nanotubes and higher crosslinking extent of the nanocomposites. Copyright © 2010 John Wiley & Sons, Ltd.     

平衡溶胀法研究谷氨酸二硫代氨基甲酸镧对SBR/SiO2复合材料界面作用的影响

通过合成一种含有二硫代羧基,羧基和镧离子的新型稀土促进剂——谷氨酸二硫代氨基甲酸镧(简称La-GDTC),并利用平衡溶胀法研究了La-GDTC对丁苯橡胶(SBR)/SiO2复合材料界面作用的影响.交联密度测试表明,SiO2的加入能够有效提高SBR/La-GDTC/SiO2复合材料的交联密度;而SBR/La-GDTC/S...     

Radiation effects on SBR–EPDM blends: A correlation with blend morphology

The effect of γ radiation on the morphological and physical properties of Styrene–butadiene rubber (SBR) and Ethylene–propylene–diene monomer (EPDM) blends has been investigated. An attempt has been made to establish a correlation between various parameters like Gordon–Taylor parameter (k), hydrodynamic interaction parameter (Δ[η]_mix), chemical shift factor (b), Charlesby–Pinner parameter (p₀/q₀) and polymer–polymer interaction parameter (χ). The results showed a close dependence of mechanical and physical properties of irradiated blends on these parameters. The probability of spur overlap has been found to increase with the increase in EPDM content in the blends, which in turn results in significant improvement in the mechanical properties of the irradiated SBR–EPDM blends with higher EPDM fraction. The efficiency of four multifunctional acrylates as crosslinking aid for the radiation‐induced vulcanization of SBR–EPDM blend was also studied. The results established lower efficiency of methacrylates over acrylates in the process and indicated that among the crosslinking agents studied trimethylolpropane triacrylate is the most efficient one. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1676–1689, 2006     

Radiochemical aging of ethylene–propylene–diene monomer elastomers. I. Mechanism of degradation under inert atmosphere

This article is devoted to the study of electron‐beam‐induced degradation under argon atmosphere of an ethylene–propylene–diene monomer (EPDM, based on 5‐ethylidene 2‐norbornene) and an ethylene–propylene rubber (EPR) containing the same molar ratio of ethylene/propylene. The chemical structure modifications of polymeric samples were analyzed by ultraviolet–visible and IR spectroscopies. Crosslinking reactions were deduced by measuring the changes in gel fraction and the degree of swelling in n‐heptane. Irradiation of EPDM and EPR created trans‐vinylene, vinyl, vinylidene, and dienic‐type unsaturations. The radiochemical yields for unsaturation formations in EPDM and EPR were similar. Degradation also involved crosslinking and the production of molecular hydrogen. The comparison between EPDM and EPR showed that the diene (in which a double bond is consumed with a high radiochemical yield) contributes to the increase in rate and intermolecular bridges density. Mechanisms are proposed to account for the main routes of EPDM degradation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1239–1248, 2004     

Molecular dynamics simulation for insight into microscopic mechanism of polymer reinforcement

By employing an idealized model of a polymer network and filler, we have investigated the stress-strain behavior by tuning the filler loading and polymer-filler interaction in a broad range. The simulated results indicate that there actually exists an optimal filler volume fraction (between 23% and 32%) for elastomer reinforcement with attractive polymer-filler interaction. To realize this reinforcement, the rubber-filler interaction should be slightly stronger than the rubber-rubber interaction, while excessive chemical couplings are harmful to mechanical properties. Meanwhile, our simulated results qualitatively reproduce the experimental data of Bokobza. By introducing enough chemical coupling between the rubber and the filler, an upturn in the modulus at large deformation is observed in the Mooney-Rivlin plot, attributed to the limited chain extensibility at large deformation. Particularly, the filler dispersion state in the polymer networks is also characterized in detail. It is the first demonstration via simulation that the reinforcement mechanism stems from the nanoparticle-induced chain alignment and orientation, as well as the limited extensibility of chain bridges formed between neighboring nanoparticles at large deformation. The former is influenced by the filler amount, filler size and filler-rubber interaction, and the latter becomes more obvious by strengthening the physical and chemical interactions between the rubber and the filler. Remarkably, the reason for no obvious reinforcing effect in filled glassy or semi-crystalline matrices is also demonstrated. It is expected that this preliminary study of nanoparticle-induced mechanical reinforcement will provide a solid basis for further insightful investigation of polymer reinforcement.     

Fabrication of exfoliated graphite reinforced silicone rubber composites - Mechanical,tribological and dielectric properties

The effect of exfoliated graphite (EG) on the mechanical, tribological and dielectric properties of the silicone rubber (QM) composites has been systematically investigated and analysed. Morphological analysis of the composites helps to understand the interfacial interaction between the filler and the rubber matrix as well as wear mechanism respectively. An enhancement in the mechanical, tribological and dielectric properties was observed with an increase in filler loading and better performance was observed at 7 phr of filler loading. The improvement in performance is attributed to the better interaction between the QM chains and the EG layers as evident from the AFM and TEM analysis. It is also evident from the Kraus plot which supports the reinforcing effect of EG in QM matrix.     

Maleic-anhydride grafted EPM as compatibilising agent in NR/BR/EPDM blends

Incorporation of approximately 30 phr Ethylene-Propylene-Diene rubber (EPDM) into natural rubber (NR)/butadiene rubber (BR) is a means to achieve non-staining ozone resistance for tire sidewall applications. However, due to incompatibility of the elastomers and heterogeneous filler distribution in each of the rubber phases, the mechanical properties deteriorate. In the present work, maleic-anhydride modified EPM (MAH-EPM) is added as a compatibilising agent between NR/BR and EPDM. The addition of 5 phr of MAH-EPM results in significantly improved tensile and tear strength when compared to a straight NR/BR/EPDM blend. These improvements can mainly be attributed to a compatibilising effect of MAH-EPM, resulting in a more homogeneous phase distribution, but in particular a much better homogeneous carbon black distribution over the different rubber phases. In addition, ionic crosslinks are introduced into the blends by interaction of MAH-EPM with zinc oxide.     

Effects of UV irradiation on physico‐mechanical properties of EPDM/buckminsterfullerene composite

Ethylene propylene diene rubber‐fullerene (EPDM/C60) composite, partially crosslinked by ultraviolet (UV) radiation, was prepared and characterized for crosslink density, mechanical properties and thermal behavior. FT‐IR analysis showed peak disappearance at 1688 cm^?1, corresponding to the unsaturation of EPDM, and the appearance of new peaks relating to the formation of oxidation products of C60, such as epoxide, keto, aldehyde and carboxylic groups. Solubility studies demonstrated the dissolution of pristine EPDM in toluene even after a longer period of UV exposure, whereas EPDM/C60 composite became insoluble and/or swollen after 6 hr of UV exposure, indicating the formation of partial crosslinking between EPDM and C60. Differential scanning calorimetry (DSC) measurements revealed an increase in the glass transition temperature peak of UV‐cured EPDM. Thermogravimetric analysis (TGA) showed that UV exposure reduced the thermal decomposition temperature of EPDM/C60, pristine EPDM and dicumyl peroxide (DCP)‐cured EPDM. The modulus, tensile stress and elongation at break of EPDM/C60 composites were greatly influenced by the duration of UV irradiation. Comparison of UV‐cured EPDM/C60 composite with DCP‐cured EPDM confirmed the superior strength properties of the former system. Copyright © 2004 John Wiley & Sons, Ltd.     

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.