炭黑网络化程度对填充天然橡胶体系拉伸疲劳过程中介观结构和动态粘弹性的影响

研究炭黑网络化程度对填充天然橡胶硫化胶伸张疲劳过程中介观结构和动态粘弹性的影响。结果表明:疲劳寿命与炭黑用量几乎呈线性关系;随着疲劳程度的增大,硫化胶损耗模量(E″)和损耗因子(tanδ)均有所降低;炭黑网络化程度较低时,未疲劳硫化胶tanδ的温度依赖性较弱,而炭黑网络化程度较高时则依赖性较强,且此时E″出现了峰值;未疲劳硫化胶中炭黑聚集体呈球状排列,而疲劳后炭黑聚集体垂直于拉伸方向的平面呈链状排列。     

炭黑网络化程度对填充天然橡胶体系伸张疲劳过程中介观结构和动态粘弹性的影响

研究炭黑网络化程度对填充天然橡胶硫化胶伸张疲劳过程中介观结构和动态粘弹性的影响。结果表明:疲劳寿命与炭黑用量几乎呈线性关系;随着疲劳程度的增大,硫化胶损耗模量(E″)和损耗因子(tanδ)均有所降低;炭黑网络化程度较低时,未疲劳硫化胶tanδ的温度依赖性较弱,而炭黑网络化程度较高时则依赖性较强,且此时E″出现了峰值;未疲劳硫化胶中炭黑聚集体呈球状排列,而疲劳后炭黑聚集体垂直于拉伸方向的平面呈链状排列。     

炭黑粒径、粒径分布及结构对SSBR/BR并用胶性能的影响

研究了不同炭黑的粒径、粒径分布及结构对溶聚丁苯橡胶(SSBR)/顺丁橡胶(BR)并用胶硫化特性、力学性能及动态性能的影响。结果表明,与炭黑N234及炭黑N339相比,炭黑X2013一次结构略高,聚集体粒径分布较宽;炭黑X2013硫化胶回弹率增大,疲劳温升显著降低;在3种炭黑填充的混炼胶中,炭黑X2013混炼胶Payne效应最弱,其硫化胶60℃下tanδ最低,即滚动阻力最低。     

扫描探针对炭黑结构及其结合胶微观形貌的研究

以N234、N330、低滞后DZ13 3种不同结构的橡胶补强炭黑为材料,通过扫描探针对其聚集体形貌及其结合胶的微观形貌进行了研究。实验表明:N234的聚集体小,分布窄,二次结构影响较小;N330的聚集体形貌如同葡萄串,有链枝状;DZ13的聚集体分布较宽,大小不一。通过对结合橡胶结构观察发现,N234的结合方式不同于其它2种结构炭黑,结合胶的量更大,而DZ13表面的橡胶壳大于N330表面的橡胶壳,侧面证明了DZ13的表面活性较大。结合胶形貌的研究有助于了解炭黑结构对橡胶补强的影响,对炭黑补强机理的研究提供了直观的证据。     

动态疲劳对未填充天然橡胶硫化胶结构与动态黏弹性的影响

通过磁共振交联密度仪、衰减全反射傅里叶变换红外光谱仪和动态力学分析仪,对未填充天然橡胶(NR)硫化胶在拉伸疲劳前后结构及动态黏弹性的变化进行了研究.结果表明,未填充NR硫化胶的交联密度随拉伸疲劳时间的延长先增大后减小,拉伸强度和100%定伸应力在拉伸疲劳后期明显下降;未填充NR硫化胶在拉伸疲劳后生成了共轭二烯、三烯类结构,并导致拉伸疲劳后未填充NR硫化胶在高弹区的储能模量大幅度下降.损耗因子则随拉伸疲劳时间的延长明显增高.     

硫化对炭黑填充SBR体系中多重相互作用的影响

本工作综合运用MDR,RPA以及DMA等表征手段,考察了硫化对炭黑填充SBR体系中多重相互作用的影响。结果表明,炭黑聚集体的絮凝在硫化初期完成。当炭黑含量达到一定值时,炭黑对混炼胶的增强效果优于相应的硫化胶,且应变扫描对混炼胶的增强效果影响较大。Payne效应与炭黑的体积含量间存在一定的对应关系。混炼胶的玻璃化转变温度随炭黑含量的增多升高的幅度大于硫化胶。未填充体系硫化前后的玻璃化转变温度之差大于填充体系。玻璃化转变温度及结合橡胶含量均随炭黑含量的增多而线性增大。     

底部填充胶及其环氧树脂的技术现状与趋势分析

作为电子封装领域的关键辅助材料,底部填充胶有其特定的使用要求和性能特点.本文分析了底部填充胶在使用中存在的关键问题,介绍了底部填充胶用环氧树脂的研究进展,对底部填充胶的未来发展提出了展望.     

废轮胎裂解炭黑的基本性质及其在丁苯橡胶中的应用

研究了废轮胎裂解炭黑(PCB)的基本性质及微观结构,考察了PCB对丁苯橡胶(SBR)混炼胶硫化特性和门尼黏度及其硫化胶物理机械性能的影响,并与填料炭黑N 330、N 774、碳酸钙进行了对比.结果表明,PcB的化学组成主要是C、O、S、Zn等元素,其灰分质量分数高达13.3%,含水量比较低;PCB的基本粒子比炭黑N 774小,但其聚集体尺寸比N 774大,而且聚集体粒径分布宽;当SBR中加入PCB后,混炼胶的门尼黏度增大,与炭黑N 330填充SBR混炼胶接近,焦烧时间和正硫化时间缩短;随着PCB用量的增加,SBR硫化胶的拉伸强度、撕裂强度、100%定伸应力和耐磨性明显提高;当PCB用量增至50份时.sBR硫化胶的拉伸强度提高至15 MPa,撕裂强度超过45 kN/m,其增强效果与炭黑N 774相当,次于炭黑N 330.     

炭黑对硫化胶基本性能定伸应力的影响

炭黑聚集体的形状与结构直接影响硫化胶的重要物理性质—定伸应力,就从炭黑对橡胶的补强理论出发,结合炭黑生产实践,从炭黑的生产过程控制,原料的选择以及工艺的调整对炭黑聚集体的形状与结构的影响进行了讨论,并提出了解决办法。     

增强氢化丁腈橡胶的结构与性能

研究了甲基丙烯酸锌(ZDMA)、SiO,和炭黑N 550分别填充氢化丁腈橡胶(HNBR)的流动性、硫化特性、物理机械性能、耐老化性能、压缩永久变形及动态力学性能,表征了填料在HNBR混炼胶及硫化胶中的形态结构.结果表明,3种填料填充的HNBR混炼胶均属非牛顿流体,其中ZDMA填充HNBR混炼胶具有较好的流动性;经过二段硫化后.3种填料填充HNBR具有较佳的物理机械性能、耐老化性能和耐压缩性能;zDMA和SiO2,对HNBR的增强效果显著,但HNBR硫化胶的压缩永久变形偏高,N 550填充HNBR硫化胶的扯断伸长率和压缩永久变形较低;SiO2填充HNBR混炼胶和硫化胶的Payne效应较ZDMA、N 550填充HNBR混炼胶和硫化胶显著;N 550、SiO2种填料在HNBR混炼胶和硫化胶中均能达到纳米尺度,ZDMA在HNBR混炼胶中呈微米尺度,而在HNBR硫化胶中呈纳米尺度.     

影响HTV硅橡胶撕裂强度的因素

考察了白炭黑种类、羟基硅油用量、含氢硅油用量以及不同乙烯基含量生胶并用对热硫化(HTV)硅橡胶撕裂强度的影响。结果显示,气相法白炭黑的补强效果强于沉淀法白炭黑,且比表面积越大,硅橡胶的撕裂强度越高;随着羟基硅油加入量的增加,硅橡胶的撕裂强度先增后趋于稳定;含氢硅油的用量对HTV硅橡胶的撕裂强度基本没有影响;高乙烯基含量生胶和低乙烯基含量生胶并用能显著提高HTV硅橡胶的撕裂强度。较佳配方是:166 g 110-0生胶,4 g 112生胶、80 g QS-102气相法白炭黑、8.5 g羟基硅油、1.0 g含氢硅油、0.5 g乙烯基硅油,此时,HTV硅橡胶的撕裂强度达到21 KN/m。     

改性剂种类对白炭黑补强阻尼硅橡胶性能的影响

以阻尼硅橡胶母胶、气相法白炭黑、改性剂为原料,制成了热硫化阻尼硅橡胶。研究了羟基硅油、六甲基环三硅氮烷、乙烯基三乙氧基硅烷(A-151)、γ-氨丙基三乙氧基硅烷(KH 550)、γ-环氧丙氧基丙基三甲氧基硅烷(KH 560)及其并用对阻尼硅橡胶硫化性能、分散性能、力学性能和黏弹性能的影响。结果表明,硅烷偶联剂类改性剂能显著加快混炼胶的硫化速度、缩短硫化时间;羟基硅油、六甲基环三硅氮烷和KH 560作改性剂时白炭黑的分散效果良好,而采用A 151作改性剂时白炭黑填料网络的Payne效应较明显,但在宽温域(-120~100℃)范围内具有温度稳定性;不同改性剂并用对改善白炭黑分散性没有明显的协同作用;改性剂种类对硫化胶的力学性能影响不大;六甲基环三硅氮烷与KH 560并用时,硅橡胶的阻尼性能最高。     

气相法白炭黑的特性及其在硅橡胶中的应用

简述了气相法白炭黑的发展及国内生产情况，介绍了气相法白炭黑的结构和表面性质，以及在热硫化硅橡胶和室温硫化硅橡胶中的应用。     

Effect of surface chemistry and morphology of silica on the thermal and mechanical properties of silicone elastomers

In this study, high‐temperature vulcanized silicone rubbers (HTV‐SRs) using fumed silica (FSi), precipitated silica (PSi), and modified precipitated silica (MPSi) as reinforcing fillers were prepared. The effect of morphology and surface chemistry of the silica on the thermal and mechanical properties of the resultant silicone rubbers was investigated using curing rheometer, scanning electron microscopy, mechanical test, and dynamic mechanical analysis. The thermo‐oxidative stability and solvent resistance of the vulcanized silicone rubbers were further evaluated via heat ageing test, extraction, and swelling experiments. It is shown that the mechanical properties (tensile modulus and tensile strength) of the as‐prepared HTV‐SRs are in the order of FSi > PSi > MPSi, which could be attributed to the molecular interaction between the filler and the matrix. FSi has the highest surface area, which enhances the hydrogen bonding interaction between the filler and the silicone matrix; while MPSi, in which part of Si? OH groups have been consumed during modification, shows the weakest interaction among the three. The filler–matrix interaction could also explain the lowest swelling and sol fraction in FSi‐filled HTV‐SR, and the low viscosity and good processibility of PSi‐ and MPSi‐filled HTV‐SR. Furthermore, it is also shown that the MPSi‐filled HTV‐SR exhibits the highest retention of mechanical properties after thermal aging at 250 °C for 24 h, which could be attributed to the lowest acidity of the fillers. The possible mechanism for acid catalyzed hydrolytic chain scission and intramolecular chain backbiting has been proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46646.     

Bound rubber and “crepe hardening” in silicone rubber

Some recent results of the research aimed to correlate properties of filled silicone rubber compounds with surface properties of fumed silica fillers are reported. It is shown that the specific interaction between silica surface silanol groups and the siloxane chain of silicone rubber plays the main role in “crepe hardening” and bound rubber formation in compounds. The silanol coverage of silica determines the tightness of polymer–filler network in bound rubber. The experimental data fit Meissner's theory of bound rubber quite well. Remilling of “crepe hardened” compounds was also studied, and the structure of the remilled compounds is proposed. The activation energy of bound rubber formation on mixing was found to be 16.8 kj/mole; this suggests that physical rather than chemical processes are involved in the interaction between silica and silicone rubber.     

气相白炭黑的比表面积与表面特性对硅橡胶补强效果的影响

探讨了气相白炭黑的比表面积和表面特性对硅橡胶力学性能的影响,同时采用扫描电镜和溶胀法分别研究了不同表面特性白炭黑补强硅橡胶的拉伸断面形貌和交联密度。结果表明：随着疏水性白炭黑比表面积的增加,硅橡胶拉伸强度和断裂伸长率增加;对比发现,疏水性白炭黑的补强效果优于亲水性白炭黑,这是由于疏水性白炭黑在橡胶基体中分散更加均匀,而且疏水性白炭黑补强硅橡胶的交联密度更大。     

热空气硫化硅橡胶海绵的制备工艺

采用气相法白炭黑与沉淀法白炭黑并用的补强填料，以偶氮二甲酰胺作发泡剂，２，５－二甲基－２，５－二叔丁基过氧化己烷为硫化剂，配以适宜的发泡助剂，制得可发泡硅橡胶混炼胶，经挤出成形、硫化后，可制成不同截面形状的硅橡胶海绵条，其拉伸强度为０．５２ＭＰａ，扯断伸长率为１６０％。     

Effect of tetraphenylphenyl‐modified fumed silica on silicone rubber radiation resistance

Two kinds of treated fumed silica were prepared by treatment with either tetraphenylphenyltriethoxysilane (TPHTS) or both tetraphenylphenyltriethoxysilane and hexamethyldisilazane (TPHMTS), and were used as reinforcing filler for silicone rubber. The resistance to irradiation of the silicone rubber obtained was investigated by gamma ray of dose 500 kGy in air. The mechanical properties and the average molecular weight between crosslinking points (Mc) of the silicone rubber were determined before and after irradiation. The results show that the fumed silica treated by tetraphenylphenyltriethoxysilane (TPHPHS) can effectively improve the radiation resistance of silicone rubber while the fumed silica treated by both tetraphenylphenyltriethoxysilane and hexamethyldisilazane (MM^N) cannot only effectively improve the radiation resistance of silicone rubber but also has excellent reinforcing effect on silicone rubber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

氧化硅与氧化铝填充高硬度硅橡胶

以Wacker R401／70S为基础，通过加入气相二氧化硅或氧化铝获得了高硬度的硅橡胶。研究表明，通过加入气相二氧化硅和氧化铝可以由硬度为70(邵尔A)的硅橡胶制得硬度为90(邵尔A)的硅橡胶，为达到同样的硬度前者比后者的用量小得多，但采用后者作填料时具有更好的热稳定性；采用有机硅烷偶联剂可以显著改善高硬度硅橡胶的机械性能和热稳定性，用有机硅烷偶联剂对无机填料进行处理后再加入硅橡胶，比直接将偶联剂加入硅橡胶效果要好；加入氧化铈可以显著改善高硬度硅橡胶的热稳定性。     

Rheological behavior and network dynamics of silica filled vinyl‐terminated polydimethylsiloxane suspensions

Present article reports the rheological properties and network dynamics of fumed silica filled vinyl‐terminated polydimethylsiloxane suspensions. The results reveal that as filler loading increases, the span of the linear viscoelastic region with constant dynamic storage modulus is narrowed with increase in strain amplitude while the relaxation time of the compounds get shifted to longer time scales. The dynamics of filler‐network indicated significant Payne effect due to fumed silica incorporation into the PDMS matrix. Further, strain‐induced agglomeration of fumed silica particles, characterized by a peak in the dynamic loss modulus curve could also be observed. High loss‐tangent was observed for lower contents of filler in the suspension, an effect with an apparent relationship to the loosely formed filler‐network. The formation of a saturated network structure of fumed silica particles was evident from the dynamic modulus and complex viscosity data, that remained unaffected with frequency till a critical amount of fumed silica loading. Han plots (storage modulus versus loss modulus) revealed the microstructural changes for various filled systems that was attributed to build‐up of the filler‐network causing an apparent evolution of yielding phenomenon. Van Gurp‐Palmen plots (complex modulus versus phase lag) showed that flow behavior of the filled PDMS suspensions resembled to that of typical viscous fluids. POLYM. ENG. SCI., 57:973–981, 2017. © 2016 Society of Plastics Engineers