Self-vulcanizable rubber blend system based on epoxidized natural rubber and chlorosulphonated polyethylene

A mill-mixed blend of epoxidized natural rubber and chlorosulphonated polyethylene becomes vulcanized during moulding in the absence of any vulcanizing agent. Such a system of self-vulcanizable rubber blend is miscible, as is evident from differential scanning calorimeter studies and dynamic mechanical analysis. The physical properties of the blend are comparable to those of conventional rubber vulcanizates and the blend can be reinforced by carbon black filler.     

天然橡胶与其环氧化物并用胶基复合材料的黏弹阻尼性能

为改善天然橡胶（NR）的阻尼性能,在密炼机中以质量比20：80混合不同环氧度环氧化天然橡胶（ENR）与天然橡胶制备ENR-NR并用橡胶基体,在橡胶基体的混炼与开炼过程加入其他填充组分（硫磺、促进剂2,2'-二硫代二苯并噻唑（DM）、促进剂N-环己基-2-苯并噻唑次磺酰胺（CZ）、ZnO、硬脂酸、炭黑）得到了宽温域阻尼ENR-NR基复合材料。采用橡胶加工分析仪和动态力学热分析仪,研究了ENR-NR混炼胶和硫化胶的动态力学和阻尼性能。结果表明：NR环氧化增强了分子链局部刚性,改善了胶体与填料的黏结性,但ENR吸附较多炭黑后不易均匀分散于连续相NR中。因此,ENR-NR并用混炼胶的黏度和储能模量随ENR环氧度增大而增加;在NR中加入ENR可改善硫化胶的弹性和阻尼性能。ENR-NR并用胶的有效阻尼温度范围拓宽到较高温度,环氧度为25的ENR与NR并用后,有效阻尼温度范围为-57~1℃,明显宽于NR的-57~-20℃,但高环氧度并用胶则出现阻尼失效区。加入少量ENR对NR的硬度、模量和断裂伸长率影响不大。     

全氟辛基季胺碘化物改性碳纳米管对天然橡胶胶乳性能的影响

用水溶性的阳离子表面活性剂全氟辛基季胺碘化物FC-134对碳纳米管进行非共价键改性,并用液相法制备改性碳纳米管/天然橡胶复合材料,研究了改性碳纳米管对天然橡胶复合材料的影响。结果表明,改性碳纳米管在水介质中具有很好的稳定性。佩恩效应表明,碳纳米管经过表面修饰增强了与橡胶的相互作用,降低了碳纳米管之间的相互作用。橡胶加工分析仪的结果表明,碳纳米管均匀地分散到复合材料中。与未改性碳纳米管/天然橡胶胶乳复合材料相比,改性碳纳米管/天然橡胶胶乳复合材料硫化胶的撕裂强度提高了65%,拉伸强度提高了29%。     

Modified phosphate pigments as high performance reinforcing materials for rubber vulcanizates

This study is focusing on the synthesis of novel modified micronized phosphate pigments as reinforcing materials for the vulcanizates of styrene-butadiene rubber (SBR), natural rubber (NR) and their blends. The metal phenyl phosphate pigments were prepared via co-precipitation process from the reaction of equimolar ratios of the disodium phenyl phosphate solution and the water soluble salts of the investigated metals. The white prepared phosphate pigments were introduced in the rubber formulations to replace carbon black the highly common and commercial reinforcing material in rubber vulcanizates. The rheometric characteristics, physico-mechanical properties in addition to the accelerated aging properties of the rubber vulcanizates were investigated, discussed and interpreted in the light of previous studies. The results showed that, phenyl phosphate pigments exercised a great effect on the rheological characteristics (scorch time, cure time…etc.), and achieved high performance and pronounced mechanical properties. The stress and strain at yield and at rupture of the loaded rubber with modified phosphates are better than that loaded with carbon black and Hisil e.g. tensile strength data were (20.0–23.4), 18.01 MPa and 15.05 for rubber blend vulcanizates loaded with 30 phr of modified phosphate pigments, carbon black and Hisil, respectively.     

Preparation and properties of powder styrene-butadiene rubber composites filled with carbon black and carbon nanotubes

Carbon nanotubes (CNTs) and carbon black (CB) filled powder styrene-butadiene rubber (SBR) composites were prepared by spray drying of the suspension of CNTs and CB in SBR latex. The powders were sphere like and fine with uniform diameters of 10-15 μm. Experimental results showed that the introduction of CNTs into the matrix was beneficial to improve the security of the vulcanization of the rubber composites, and the dynamic and basic mechanical properties of the CNTs/SBR composites were better than those of CB/SBR and neat SBR composites. Observations on the microstructure of the composites indicated that CNTs were well dispersed in the matrix. Morphology of the fracture confirmed that the bonding between CNTs and rubber matrix was strong and load can be transferred to CNTs efficiently during the mechanical property tests. Moreover, the powder SBR composites containing well-dispersed CNTs could be perfect candidate as additives for other polymers.     

环氧化天然橡胶改性石墨烯-炭黑/天然橡胶复合材料的制备及性能

以环氧化天然橡胶(ENR)为界面改性剂,制备了石墨烯-炭黑/天然橡胶-ENR(GR-CB/NR-ENR)复合材料,研究了ENR用量对GR-CB/NR-ENR复合材料的加工性能、力学性能和动态力学性能的影响。结果表明,ENR的加入可以改善GR-CB/NR-ENR复合材料的加工性能及CB粒子在天然橡胶基体中的分散性,增加GR与NR的相容性,增强填料与NR基体间的界面相容性,同时改善GR-CB/NR-ENR硫化胶的动态力学性能、物理性能和耐老化性能。当ENR添加量为6 wt%时,GR-CB/NR-ENR复合材料撕裂强度和拉伸强度最高,硫化胶耐老化性最好。随着ENR含量的增加,GR-CB/NR-ENR复合材料的压缩疲劳温度先升高后降低;随着应变的不断增大,GR-CB/NR-ENR复合材料的储能模量G'不断减小,损耗因子tanδ先增大后减小;动态模量随着应变的增加急剧下降。      

Preparation and properties of natural nanocomposites based on natural rubber and naturally occurring halloysite nanotubes

A ‘green’ composite based on natural halloysite nanotubes (HNTs) and natural rubber (NR) was prepared by mechanical mixing. A silane coupling agent, bis (triethoxysilylpropyl)-tetrasulphide, was utilized to enhance the properties of these composites. It was observed that the reinforcing activity of HNTs was superior to commercial silica coupled with the same amount of silane coupling agent. Moreover the on-set thermal degradation decomposition temperature was improved by ∼64 °C with the addition of 10 parts HNTs per hundred of rubber. Transmission electron microscopic images confirmed the good dispersion of the HNTs in the rubber matrix, whereas X-ray diffraction studies showed a little change in interlayer spacing between the two silicate layers of HNTs.     

碳纳米管/丁苯橡胶复合材料的电学性能

采用喷雾干燥法可制备不同配比的碳纳米管（Carbon nanotubes,CNTs）/粉末丁苯橡胶复合材料,观察CNTs在橡胶基体中的分散情况,检测复合材料的导电性能及介电性能,并进行了简要的理论分析。结果表明:CNTs在橡胶基体中获得了充分均匀的分散,有利于CNTs改性补强作用的发挥。与纯胶样品及填充炭黑（Carbon black,CB）样品相比, 填充CNTs样品在8~18GHz下具有较高的介电常数及低介电损耗。随着CNTs加入量的增加,CNTs/粉末丁苯橡胶复合材料的电导率逐渐升高,当CNTs加入量为60phr（per hundred rubber）时,与纯胶样品及添加60phr CB样品相比,电导率提高近10个数量级;复合材料内部导电同时存在隧道导电机制和渗逾导电机制。采用喷雾干燥法制备的CNTs/粉末丁苯橡胶复合材料,将是一种综合性能良好的新型纳米复合材料,有望在抗静电橡胶、电磁屏蔽及介电材料等领域获得应用。      

白炭黑补强环氧化溶聚丁苯橡胶

为探究环氧化对白炭黑(SiO₂粒子)在溶聚丁苯橡胶(SSBR)基体中分散性的作用,首先,以SSBR和环氧化溶聚丁苯橡胶(ESSBR)为基体,白炭黑为补强填料,分别制备了SiO₂/SSBR、SiO₂/ESSBR混炼胶和硫化胶;然后,采用FTIR、SEM和其他测试方法研究了材料的结构、形貌、硫化特性、耐磨性能、准静态力学性能和动态力学性能。结果表明:随环氧度从0增大到14.73%,生胶的门尼黏度增大。ESSBR分子链中的环氧基团与SiO₂粒子表面的硅羟基反应形成稳定的化学键,抑制SiO₂粒子团聚,促进其均匀分散;当环氧度为6.87%时, SiO₂粒子在ESSBR中的分散性最好。随环氧度增大, SiO₂/ESSBR硫化胶的拉伸强度先增大后减小、耐磨性能先增强后减弱、断裂伸长率降低、100%和300%定伸强度增大、玻璃化转变温度升高、0℃时的损耗因子显著增大、抗湿滑性增强、60℃时的损耗因子略有增加且滚动阻力增大。因此, SSBR硫化胶经环氧化改性后综合性能提高,当其环氧度在6.87%~8.51%范围内时, SiO₂/ESSBR硫化胶的综合性能最优。      

碳纳米管/天然橡胶复合材料的制备及性能

对碳纳米管/天然橡胶复合材料的制备工艺和材料性能进行了研究。碳纳米管与天然橡胶复合后,橡胶DSC曲线中结晶熔融峰变小,硫化返原现象减轻,焦烧时间略有缩短。经过分散-粘合体系处理,碳纳米管在橡胶中的分散程度及界面粘合状况改善,复合材料的整体力学性能提高,与炭黑增强样品相比,碳纳米管复合材料在回弹及动态压缩性能方面占有优势,动态模量和玻璃化转变温度高,热降解稳定性较好。      

环保型水切割胶粉对天然橡胶力学性能和动态性能的影响

采用环保型水切割胶粉及力化学改性胶粉（MRP）与天然橡胶（NR）复合制备胶粉-NR复合胶,并探讨了胶粉用量对复合胶力学性能和动态性能的影响。通过红外和热失重分析确定了胶粉的主要成分为NR和丁苯橡胶（SBR）,且改性后胶粉大分子链结构未发生明显变化。通过橡胶加工分析仪研究了胶粉用量及改性对复合胶加工性能的影响。采用炭黑分散仪研究并观察了胶粉在NR中的分散情况。结果表明,胶粉改性后与NR的相容性提高,二者界面结合力增大,MRP-NR复合胶加工性能改善。炭黑分散结果表明,胶粉用量越多,其分散性越差,改性后胶粉的分散性提高,MRP-NR复合胶的力学性能最优,拉伸强度为27.9 MPa。     

碳纳米管/天然橡胶复合材料的红外光谱和DSC分析

将催化裂解法制得的碳纳米管进行氢氟酸和混酸处理后，碳纳米管的纯度和团聚程度增大，热处理后碳纳米管的聚集情况略有改善。碳纳米管表面官能团与橡胶分子间可以形成氢键，并对天然橡胶的分子运动产生影响，随着碳纳米管的进一步处理，混炼胶的Tg有所升高，DSC曲线中的结晶熔融峰面积减小，热处理后碳纳米管填充胶料的Tg略有下降，结晶熔融峰面积增大。氢氟酸处理碳纳米管填充天然橡胶材料的力学性能较好。     

Development of nanocomposite with epoxidized natural rubber and functionalized multiwalled carbon nanotubes for enhanced thermal conductivity and gas barrier property

Multiwalled pristine carbon nanotubes (mwCNTs) were treated with conventional mixed acid to functionalize outer surface of nanotubes with two unique chemical approaches using aminosilane solution and TiO₂ dispersion. Pristine and functionalized mwCNTs were dispersed subsequently in matrices of natural rubber (NR)–chlorobutyl rubber (CIIR) and epoxidized natural rubber (ENR)–CIIR to prepare nanocomposites by simple and eco-friendly melt blending method. The effect of surface treatment of mwCNTs, and epoxidation of NR on the composite properties was evaluated for thermal conductivity and gas barrier property. Nanocomposites prepared with surface functionalized mwCNTs and epoxidized NR were found to exhibit greater thermal conductivity and excellent gas barrier properties compared to pristine mwCNT reinforced CIIR–NR nanocomposites. A maximum thermal conductivity was observed for nanocomposite obtained from 20% ENR and 3% (by weight) mwCNTs functionalized with aminosilane. While a maximum gas barrier property was exhibited by nanocomposite with 20% ENR and 3% (by weight) mwCNTs treated with TiO₂. Results indicate that the presence of epoxy moieties of ENR provided a stronger network formation between aminosilane treated mwCNT surface and rubber matrices to exhibit higher thermal conductivity and metal oxide particles adhered to TiO₂ treated mwCNTs found to impart maximum resistance in transfer of oxygen gaseous molecules nanocomposite.     

Effect of expanded graphite and modified graphite flakes on the physical and thermo-mechanical properties of styrene butadiene rubber/polybutadiene rubber (SBR/BR) blends

The aim of the present research work is to develop expanded graphite (EG) and isocyanate modified graphite nanoplatelets (i-MG) filled SBR/BR blends, which can substitute natural rubber (NR) in some application areas. The present study investigated the effect of i-MG on the physical, mechanical and thermo-mechanical properties of polybutadiene rubber (BR), styrene butadiene rubber (SBR) and SBR/BR blends in the presence of carbon black (CB). Graphite sheets were modified to enhance its dispersion in the rubber matrices, which resulting in an improvement in the overall physical and mechanical properties of the rubber vulcanizates. Compounds based on 50:50 of BR and SBR with ∼3 wt% nanofillers with CB were fabricated by melt mixing. The morphology of the filled rubber blends was investigated by wide angle X-ray diffraction (WAXD) and high resolution transmission electron microscopic (HR-TEM) analyses. The intercalated and delaminated structures of the nanofiller loaded rubber blends were observed. Scanning electron microscopic (SEM) analysis of the cryo-fractured surfaces of the rubber compounds showed more rough and tortuous pathway of the fractured surfaces compared to the fractured surfaces of the only CB loaded rubber composites. Filled rubber compounds exhibit increase in the ΔS (torque difference) value, reduced scorch and cure time compared to their respective controls. Dynamic mechanical thermal analysis (DMTA) of the filled rubber compounds shows an increase in the storage modulus compared to the controls. Isocyanate modified graphite nanoplatelets (i-MG) containing rubber compounds in the presence of CB showed an increase in the mechanical, dynamic mechanical, hardness, abrasion resistance and thermal properties compared to the alone CB filled rubber vulcanizates.     

Scanning electron microscopy studies on tensile rupture of rubber

Tensile rupture of natural rubber (NR) and styrene-butadiene rubber (SBR), vulcanized by sulphur and peroxide systems, both with and without fillers, has been studied by scanning electron microscopy (SEM). NR gum fracture surfaces show evidence of straininduced crystallization, which is absent in SBR. The fracture surfaces of filler-reinforced NR and SBR vulcanizates are characterized by their roughness and by the presence of short and curved tear lines. Increase of cross-link density changes the fracture mode. Peroxide-cured SBR undergoes brittle fracture, whereas sulphur-cured SBR shows a smooth surface with a few straight tear lines.     

羧基丁苯/受阻酚阻尼材料的性能研究

通过向极性的橡胶基体羧基丁苯(CSBR)中添加受阻酚,制备了一系列羧基丁苯/受阻酚阻尼材料.通过动态力学分析表明,受阻酚与基体CSBR具有较好的相溶性,并且该类材料具有很好的阻尼性能.这种材料中受阻酚与基体橡胶形成了分子间的氢键,在受到交变的机械应力作用下,氢键会断裂而消耗大量的能量,从而具有良好的阻尼性能.这类材料的玻璃化转变温度较高,损耗因子(tanδ)出峰位置都高于室温,这类阻尼材料可以应用于室温附近,解决了橡胶材料只能用作低温阻尼材料使用的问题.     

Ceramic/natural rubber composites: influence types of rubber and ceramic materials on curing,mechanical, morphological,and dielectric properties

Influence of different types of rubber and ceramic material on cure characteristics, mechanical, morphological, and dielectric properties of natural rubber (NR) vulcanizate was studied. Two types of ferroelectric ceramic materials: barium titanate (BaTiO₃) and lead titanate (PbTiO₃) were prepared by solid-state reaction with calcinations at 1100 °C for 2 h. The ceramic powders were then characterized by X-ray diffraction (XRD), particle size analyzer, and SEM techniques. Ceramic/rubber composites were then prepared by melt mixing of rubber and ceramic powders. Two different types of NR (i.e., epoxidized NR [ENR] and unmodified NR) and two types of ceramic powders (i.e., BaTiO₃ and PbTiO₃) were exploited. It was found that incorporation of ceramic powders in rubber matrix and the presence of epoxirane rings in ENR molecules caused faster curing reaction, and higher delta torque but lower elongation at break. This is attributed to lower mobility of molecular chains and higher interaction between ENR molecules. Furthermore, SEM results revealed that the BaTiO₃ composites showed finer and better distribution of the particles in the rubber matrix than that of the PbTiO₃ composite. This caused superior mechanical properties of the BaTiO₃ composites. Furthermore, higher dielectric constant and loss tangent was observed in the ENR/BaTiO₃ composites.     

改性累托石粉体的制备及其填充橡胶复合材料的结构与性能

利用喷雾干燥法制备了硅烷偶联剂KH550改性的累托石粉体, 考察了喷嘴进口温度对制备的累托石粉体表面性质、结构及形貌的影响。将累托石粉体分别加入到丁苯橡胶(SBR)、天然橡胶(NR)和丁腈橡胶(NBR)中, 通过熔融共混法制备了改性累托石/橡胶复合材料, 研究了累托石在橡胶基体中的分散状态及其对基体的增强效果。结果表明: 随着进气温度的提高, 与累托石复合的KH550的量也随之增加; KH550分子插层进入累托石层间, 阻碍了片层的再聚集, 片层堆砌更加无序蓬松; 改性累托石在SBR中出现了局部团聚现象, 在NBR中分散较均匀, 而在NR中分散状态最好; 与相应的纯橡胶相比, 改性累托石填充的SBR和NBR基复合材料的各项力学性能均有所提高, 而其填充的NR基复合材料的定伸应力提高, 拉伸强度和撕裂强度基本不变, 断裂伸长率有所下降。     

碳纳米管/粉末丁苯橡胶复合材料的热学性能

将碳纳米管(CNTs)及其它配合剂制成悬浮液,与丁苯胶乳共混,然后利用喷雾干燥法制备CNTs/粉末丁苯橡胶复合材料,检测其热学性能,并进行相应的理论分析。结果表明,随着CNTs加入量的增加,橡胶复合材料的热分解温度逐渐增加,CNTs/橡胶复合材料的热导率逐渐提高,当CNTs体积百分比含量约为22%,即CNTs加入量为60 phr时,与纯胶样品相比,复合材料的热导率提高近1倍。理论分析表明,由于CNTs自身的弯曲和缠绕以及混酸氧化对CNTs自身导热性能的破坏,复合材料热导率的实测值与理论计算值存在一定差距。     

Role of rigid nanoparticles and CTBN rubber in the toughening of epoxies with different cross-linking densities

Experimental investigations were conducted to characterize the fracture behaviours of Bisphenol A diglycidyl ether (DGEBA) epoxies modified with rigid nanoparticles (nanosilica or halloysite) and a reactive liquid carboxylterminated butadiene–acrylonitrile (CTBN) liquid rubber to identify toughening mechanisms and toughenability in the cured epoxies with different cross-linking densities. The epoxy was cured using three different hardeners, a heterocyclic amine (piperidine), a cycloaliphatic polyamine (Aradur 2954) and an aromatic amine [4,4′-Diaminodiphenyl sulfone (DDS)] to form nanocomposites with different cross-linking densities. It was found that both the hybrid particles, nanosilica with CTBN rubber and halloysite with CTBN rubber, were effective additives that clearly increased the fracture toughness of the three epoxy composites. In particular, the use of halloysite nanoparticles as additives for the epoxies showed greater potential than nanosilica to increase strength and modulus due to the reinforcing effect of the halloysite nanotubes (HNTs). The epoxy systems cured with the hardeners (Aradur 2954 and DDS), which generated relatively high cross-linking densities, evidenced inferior toughenability of the hybrid particles, compared with the epoxy systems cured using the hardener (piperidine), which produced lower cross-linking densities. The CTBN rubber formed dissimilar domains in different epoxy systems, features which were attributed to the different toughenability of the hybrid particles in the systems due to variations in the dominant toughening mechanisms involved.