特种氟橡胶耐油介质老化性能研究

对特种氟橡胶在125℃、150℃、175℃三个温度点上耐15W/40CD柴油机油老化进行了试验研究.结果表明,氟橡胶在油介质中随着老化温度的升高和老化时间的延长,材料的拉伸强度和拉断伸长率降低,压缩永久变形、硬度和回弹性增大.当老化到一定时间后试样表面开始出现裂纹,而且裂纹的数量和宽度随老化时间的延长而逐渐增加;氟橡胶...     

木塑复合材料加速老化性能的研究

研究了木塑复合材料在氙灯加速老化环境老化后的性能变化。结果表明,材料老化后表面发生褪色现象,弯曲强度和弯曲弹性模量分别损失10%和20%。通过扫描电子显微镜可以看出材料老化后表面出现微孔和细小裂缝,表面细长物质增多。接触角测试则证明了老化50 h后增多的细长物质为木粉,老化75 h和100 h后增多的细长物质为HDPE老化断链后的低分子物。通过X射线光电子能谱对材料表面元素状态及含量的变化分析可知,老化后材料表面发生了氧化。     

碳纳米管改性氟橡胶的性能研究

开展了碳纳米管材料对氟橡胶复合材料的改性研究,探究碳纳米管含量对氟橡胶复合体系物理性能、热性能、微观结构形貌、透气性以及宏观力学性能的影响。在此基础上模拟高温高压条件进行老化试验,对老化试验前后材料的硬度变化、体积变化、拉伸性能、撕裂性能和压缩永久变形量进行了测量与分析。结果表明,拉伸强度和撕裂强度随碳管含量增加表现增加的规律,基于脆断表面和热失重断面证实了本文实现了高含量碳纳米管的均匀分散,并且一维纳米材料构筑的碳纳米管网络结构有助于氟橡胶复合材料气体阻隔性能提升;基于老化前后的性能对比数据,表明碳纳米管的存在有助于老化后氟橡胶宏观性能的保持。     

氟橡胶/丁腈橡胶共混体系性能研究

将氟橡胶与丁腈橡胶以不同比例进行共混,考察了共混体系的硫化特性、力学性能以及不同温度条件下的耐介质性能。结果表明,随着丁腈橡胶并用比例的增加,胶料的硫化速率减慢,硬度提高,伸长率增大,相对密度减小。在耐久性方面,随着丁腈橡胶并用比例的增加以及各种介质温度的升高,胶料的质量变化率增大,在并用比例为85/15时共混胶具有较好的综合性能。     

填料对氟橡胶热空气老化性能的影响

研究了片层状、颗粒状和金属氧化物等填料填充改性氟橡胶的耐热空气老化性能。结果表明,片层状填料改性的氟橡胶的耐热性能较差;颗粒状填料BaSO4填充改性的氟橡胶具有优良的耐热老化性,300℃老化24h后,氟橡胶力学性能的保持率在50％左右;金属氧化物Fe2O3和SnO2填充改性的氟橡胶具有较好的耐热老化性,300℃老化24h后,仍保持较好的力学性能,其强度分别为9．3MPa和10．3MPa。     

特种氟橡胶老化过程中玻璃化转变温度的变化

通过采用动态热机械分析仪（DMA）对特种氟橡胶热空气老化试样和耐柴油机油老化试样进行分析研究,获得了氟橡胶在老化过程中最大损耗因子和玻璃化转变温度的变化规律。研究结果表明,氟橡胶在热空气和柴油机油老化过程中,材料最大损耗因子和玻璃化转变温度随老化时间的增加而降低,材料的结构向着能降低玻璃化转变温度的方向转变。     

原油介质中丁腈橡胶与氟橡胶的磨损性能

在原油介质（不含砂）中以丁腈橡胶（ＮＢＲ）和氟橡胶（ＦＰＭ）与４５＃钢配副为研究对象,采用ＭＰＶ－６００型微机控磨粒磨损试验机研究了２种硫化胶的摩擦磨损性能,通过扫描电子显微镜及能量色散Ｘ射线分析表征了硫化胶的磨痕表面形貌及化学元素含量。结果表明,在载荷为１００Ｎ的条件下,ＮＢＲ硫化胶的摩擦因数随着转速的增大而增加,当转速超过２５０ｒ／ｍｉｎ时,摩擦因数略有下降;ＦＰＭ 硫化胶的摩擦因数随着转速的增大而呈线性增加;ＦＰＭ硫化胶的磨损量略小于ＮＢＲ硫化胶;ＮＢＲ及ＦＰＭ硫化胶的磨损机制均以疲劳磨损为主,低转速下橡胶磨痕比较明显,磨痕由循环应力引起的裂纹萌生和扩展造成;磨损前ＮＢＲ硫化胶表面主要有Ｃ、Ｏ、Ｎ、Ｓ、Ｓｉ等化学元素,磨损后Ｃ元素含量减少,Ｏ元素含量增加,其他化学元素无明显变化;磨损前ＦＰＭ硫化胶表面有Ｃ、Ｏ、Ｆ、Ｓ、Ｓｉ等化学元素,磨损后Ｃ元素和Ｏ元素含量均有所增加,而Ｆ元素含量明显减少。     

PP-g-AN对PP抗紫外老化效果评价及作用机理研究

通过力学性能测试、扫描电子显微镜形貌分析等对PP接枝丙烯腈(PP-g-AN)的抗紫外老化效果进行了评价;采用紫外可见光(UV–VIS)吸收光谱、X射线光电子能谱(XPS)等对PP/PP-g-AN共混物中PP-g-AN的抗紫外老化可能的作用机理进行了研究。结果表明,PP-g-AN具有明显的抗紫外老化作用,紫外加速老化2 000 h后,PP/PP-g-AN共混物的拉伸强度为22.5 MPa,远高于纯PP的13.4 MPa。PP-g-AN在共混物中通过发挥两种作用来提高PP的抗紫外老化性能:一是氰基的基态-激发态-基态跃迁过程,释放能量;二是氰基反应成环后的共轭结构N N NN易发生自由基加成反应,能够捕捉自由基,减少PP吸收的自由基数目。     

氟橡胶耐热氧老化性能的研究

研究炭黑N330/N990用量比对过氧化物硫化体系氟橡胶物理性能和耐热氧老化性能的影响,并与双酚A硫化体系氟橡胶进行比较。结果表明:随着炭黑N330/N990用量比增大,过氧化物硫化体系氟橡胶的物理性能和耐热氧老化性能提高,压缩永久变形明显减小;当炭黑N330/N990用量比较大时,氟橡胶的物理性能变化不大;与双酚A硫化体系氟橡胶相比,过氧化物硫化体系氟橡胶的硬度和定伸应力较小,拉伸强度和拉断伸长率较大,耐热氧老化性能较好。     

盐酸介质老化对三元乙丙橡胶结构与性能的影响

将两种不同硫化体系的三元乙丙橡胶(EPDM)硫化胶置于质量分数为10%的盐酸(HCl)溶液中,通过质量、交联密度、力学及表面性能变化,结合红外光谱分析探究其在酸性介质中的老化行为。结果表明,硫磺硫化体系的EPDM硫化胶的交联密度、拉伸强度及300%定伸应力均比过氧化二异丙苯(DCP)硫化体系高,但DCP硫化体系的耐酸性较好;DCP含量的增加能有效提高EPDM硫化胶的交联密度与力学性能,同时也会导致EPDM硫化胶表面极性增加,而硫磺硫化体系下加入防老剂可有效抑制其在酸性条件下老化后期的交联过程和表面极性的增加。     

氟橡胶/丁腈橡胶共混物的相态结构及性能

在六氟异亚丙基二酚(BAF)硫化体系和硫黄硫化体系的交联作用下,采用熔融共混法制备了氟橡胶(FKM)/丁腈橡胶(NBR)共混物,研究了共混物的硫化特性,考察了两组分不同配比对共混物的相态结构、物理机械性能和动态力学性能的影响.结果表明,BAF硫化体系和硫黄硫化体系可使FKM与NBR形成各自独立的交联体系;当FKM/NBR(质量比)为80/20时,共混体系具有最完善的两相共连续形态,共混物的拉伸强度和撕裂强度达到最大值,且只存在1个玻璃化转变温度,其值低于纯FKM.改善了耐低温性能.     

Vulcanization behavior and mechanical properties of organoclay fluoroelastomer nanocomposites

The vulcanization behavior and mechanical properties of clay/fluoroelastomer nanocomposites produced by melt‐mixing of Dyneon FPO 3741 (a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene) with 10 phr of unmodified montmorillonite (CloisiteNA) or di(hydrogenated tallow‐alkyl) dimethyl ammonium‐modified montmorillonites (Cloisite15A and Cloisite20A) were studied. The properties of clay/FKM nanocomposites were compared with composites prepared using 10 and 30 phr of carbon black. The effects of clay surfactant and surfactant concentration on the vulcanization behavior, mechanical, and dynamical properties of peroxide cured composites were studied. XRD results of cured composites showed a decrease in d‐spacing and indicated deintercalation of the clays after the vulcanization process. It was also found that organoclays retard the FKM peroxide vulcanization process. Significantly, higher maximum torque on vulcanization was obtained with organoclays versus unmodified clay and carbon black. Although the morphologies of organoclay/FKM nanocomposites studied by XRD and TEM suggest similar intercalated/exfoliated structures, the organoclay with the lowest concentration of surfactant (95 meq/100 g clay) resulted in the highest increase in torque, modulus, hardness, and tear strength in the clay/FKM nanocomposites. It was also found that organoclays can increase both the hydrodynamic reinforcement and hysteresis loss of FKM nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modeling of dynamic mechanical properties of vulcanized fluoroelastomer

The dynamic mechanical properties of a vulcanized fluoroelastomer (FKM) were studied over a range of temperatures and shear frequencies. Dynamic mechanical analysis and differential scanning calorimetry were used for the purpose of the study. A model was developed in order to describe FKM's viscoelastic behavior at various temperatures. The model was fitted to experimental data using an algorithm, which was developed for this purpose. As a result the FKM discrete relaxation spectrum at two reference temperatures was obtained, as well as the Williams‐Landel‐Ferry (WLF) equation parameters or the activation energy equivalent. Further on, the model was applied on storage modulus and loss tangent values obtained from the experiments, during which the temperature increased linearly. It was observed that the WLF equation fits well with the results during the glass transition, while the Arrhenius‐type relationship predicted too rapid decrease of the storage modulus during the glass transition. The master curves were constructed using the previously calculated WLF parameters and the activation energy equivalent. The developed model may be readily applied for the prediction of the numerous FKM compounds' frequency–temperature behavior using the dynamic mechanical properties obtained from either isothermal or low linear heating rate program measurements. POLYM. ENG. SCI., 47:2085–2094, 2007. © 2007 Society of Plastics Engineers     

Dynamic viscoelastic properties of fluoroelastomer/clay nanocomposites

Nanocomposites based on fluoroelastomer and modified and unmodified sodium montmorillonite clays were prepared. Dynamic mechanical thermal analysis was performed on these nanocomposites over a range of temperatures (?60 to +60°C), frequencies (0.032–32 Hz), and strains (0.002%–2%). The results showed that there were significant changes in the glass transition temperature and storage modulus with the addition of small amount (4 phr) of the modified and the unmodified nanofillers. The tan δ peak heights decreased and the storage modulus increased in general, but it was more prominent in the case of the unmodified clay. With the addition of the nanoclays, the cross‐over point in the double logarithmic plot of storage modulus (E′) and complex viscosity (η*) with frequency, shifted toward higher frequency. Interestingly, with increasing strain, the nanocomposites demonstrated a sudden upturn in the storage modulus after ～0.2% strain amplitude, because of the formation of α‐crystallization in the elastomer structure. The uniaxial strain before strain sweep experiment increased the storage modulus remarkably. The results were explained with the help of X‐ray diffraction and transmission electron microscopy. POLYM. ENG. SCI., 47:1777–1787, 2007. © 2007 Society of Plastics Engineers     

填料改性氟橡胶的制备及性能研究

针对氟橡胶加工性能不良、耐磨性差、价格昂贵的问题,以耐磨炭黑和白炭黑为增强填料,二硫化钼为减磨填料对其进行改性,考察了不同填料种类及用量对氟橡胶力学及耐磨性能的影响。结果表明：炭黑和白炭黑用量分别为25份和20份时硫化胶的综合性能最优,在此基础上,随着二硫化钼用量的增加,炭黑增强氟橡胶的摩擦系数减小,耐磨性提高,但力学性能有所降低;对于白炭黑增强氟橡胶体系,随着二硫化钼用量增大,耐磨性和力学性能均先减小后增大。     

Frictional properties of polyolefins treated with fluoroelastomer processing aids

A friction measurement system was designed that made possible the measurement of the friction coefficient between a polymer melt and a metal die wall. The shear stresses developed in the capillary rheometer and the friction coefficient measured in the friction measurement system were compared in an attempt to understand the mechanism of fluoroelastomer processing aids (FPA) in the extrusions of polypropylene (PP) and linear low-density polyethylene (LLDPE). The apparent viscosity drops of LLDPE treated with FPA were larger than those of PP treated with FPA. The friction coefficient drops of LLDPE treated with FPA were also larger than those of PP treated with FPA. High viscosity FPA showed a moderate friction coefficient drop in the actual extrusion of PP even though it showed only a poor effect in the capillary rheometer. The frictional forces were calculated from the friction coefficient measurement made during extrusions of FPA-treated and untreated samples. © 1995 John Wiley & Sons, Inc.     

室温固化端羧基液体氟橡胶的性能研究

以高Mr(相对分子质量)氟橡胶(牌号F2461)为主要原料、BTEAC(苄基三乙基氯化铵)为相转移催化剂、丙酮为溶剂、H_2O_2(双氧水)为氧化剂和KOH(氢氧化钾)为碱,采用氧化降解法制得低Mr端羧基液体氟橡胶;然后以此为基体、PCDI(聚碳化二亚胺)为固化剂和THF(四氢呋喃)为溶剂,采用共混法制得可室温固化的端羧基液体氟橡胶。研究结果表明:当m(PCDI)∶m(液体氟橡胶中的—COOH)=1.200∶0.012时,端羧基液体氟橡胶固化产物的力学性能相对最好,并且具有优异的耐热性和耐介质性。侧链含醚键的端羧基液体氟橡胶固化产物与普通的端羧基液体氟橡胶固化产物相比,前者具有较好的低温性能(玻璃化转变温度为-33.26~℃),并且力学性能更优,但耐热性稍差。     

Structure and water—oil emulsifying properties of asphaltenes

Alphaltenes were selected on the basis of their capacity to form water—oil emulsions. They were characterized by electron microscopy, surface group analysis, g.p.c. and low-angle X-ray scattering. It appears that the high stability of water-oil emulsions is related to the ‘structuring’ capacity of asphaltenes at the water-oil interface. Some asphaltenes are able to form regularly stacked layers, resembling the behaviour of surfactant liquid crystals.