Mechanical Properties of Silicon Carbon Black Filled Natural Rubber Elastomer

A pyrolyzed ash containing about 50% carbon,named silicon carbon black(SiCB),was prepared by the anoxic pyrolysis of rice husk.Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA), Brunauer-Enunett-Teller(BET),transmission electron microscopy(TEM)and universal material testing machine were used to analyze the stress-strain relationship,Mullins effect and static viscoelastic properties of SiCB-filled vulcanized natural rubber(NR),and SiCB was compared with a commercially available semi-reinforcing fumace(SRF) carbon black.The results show that the vulcanized natural rubber filled with SiCB had similar reinforcing properties to those of that filled with traditional SRF,but obvious differences between them exist in stress-strain properties and stress softening resistance.We tried to discuss the related phenomena with the aid of the modified two-layer theory. And it is successfully predicted and verified that SiCB has good compression resistance and obvious stress relaxation advantages in compression stress relaxation.     

稀土化合物改性炭黑/天然橡胶复合材料的制备与性能

用铕（Eu）、钬（Ho）、饵（Er）和镝（Dy）4种稀土（Ln）氧化物（Ln2O3）制备了稀土氢氧化物改性炭黑，然后加入天然胶乳（NRL），采用凝聚共沉法制备了粉末状的稀土改性炭黑，天然橡胶复合材料P[NR／HAF-Ln（OH）3]。研究了稀土种类和用量对P[NR／HAF-Ln（OH）3]的粒径分布及其硫化胶物理机械性能的影响。结果表明，稀土可以提高NRL与乳化炭黑构成的粉末体系的成粉率，当Ho，Er的用量为1．0％或Dy的用量为0．5％时均可使粒径小于0．9mm的产物达100％；稀土的存在可显著提高P[NR／HAF-Ln（OH）3]硫化胶的拉伸强度和撕裂强度，而Er和Dy还可明显降低硫化胶的永久变形；SEM分析表明，HAF-Dy（OH）3以团粒形态存在于NR基体中，团粒表面覆盖一层NR膜，团粒与NR构成的界面模糊，说明HAF-Dy（OH）3与NR基体结合紧密，这是P[NR／HAF-Ln（OH）3]具有较好物理机械性能的主要原因。     

One-step Synthesis of End-Functionalized Hydrogenated Nitrile-Butadiene Rubber by Combining the Functional Metathesis with Hydrogenation

End-functionalized hydrogenated polymers obtained from nitrile-butadiene rubber (NBR) yield new materials with suitable properties for a number of applications as sealing material and adhesives. We investigated the one-step synthesis of ester end-functionalized hydrogenated nitrile-butadiene rubber (EF-HNBR) by combining the functional metathesis with the hydrogenation of NBR in the presence of the 2^nd generation Grubbs catalyst and a functionalized olefin as a chain transfer agent (CTA). We established the operating conditions for the effective production of saturated functional polymers with a high degree of hydrogenation, high chemo-selectivity and moderate molecular weight. The structures of the products were confirmed by FT-IR and ¹H-NMR spectroscopy, rubber molecular weight, and distribution determined by using gel permeation chromatography (GPC); their thermal properties were determined by thermo-gravimetric analysis (TGA) and different scanning calorimetry (DSC).     

木质素增强丁苯橡胶复合材料研究

采用木材水解木质素为原料,均匀溶解在碱性溶液中,与天然橡胶复合形成互穿网络结构,再通过共沉淀法制得一种木质素/天然橡胶复合物。采用该复合物部分代替商用橡胶补强剂——白炭黑,通过三段混炼法对丁苯橡胶进行混炼。结果表明,这种木质素/天然橡胶复合物对丁苯橡胶具有一定的补强作用,其拉伸强度及断裂伸长率均得到一定改善;而热机械性能研究发现,该复合物部分代替白炭黑后,橡胶材料的滚动阻力及耐寒性均得到改善,但抗湿滑性能有一定程度下降。     

炭黑在异戊橡胶中的分散及其对动静态性能的影响北大核心CSCD

橡胶在使用时往往需要在生胶中加入填料颗粒以提高其力学强度,填料在橡胶中的分散状态对其使用性能有显著影响。为了明晰填料分散状态对橡胶动静态性能的影响规律,设计了不同的胶料混炼工艺,进而获得具有不同分散程度的橡胶材料,并对其分散等级、颗粒聚集体尺寸分布、胶料硫化性质、橡胶拉伸以及疲劳等性质进行了系统研究。结果表明,在所研究的密炼时间4~16 min范围内,随着密炼时间的延长,填料在基体中的分散度等级有较大程度的提高,密炼时间为16 min时填料分散等级达到了8.1级,胶料的门尼粘度下降显著,但胶料的拉伸性能变化不明显,而动态疲劳性能得以显著改善。随着开炼包辊时间的延长,填料在基体中的分散度等级呈先升高后降低的趋势,橡胶的动态疲劳性能也先升高后降低,当开炼包辊时间为20 min时,硫化胶的伸张疲劳寿命达到4×10~4次,继续延长包辊时间硫化胶的伸张疲劳寿命下降至2.3×10~4次;但是胶料整体的拉伸性能变化不明显。由此可见,通过调整混炼工艺可以改善填料在橡胶基体中的分散状态,进而提高胶料的疲劳性能。     

Fullerene-Like Structures as Interaction Sites between Carbon Black and Rubber

Ball-milling of N660 carbon black and graphite causes a deep activation of its surface activity which can be measured by a significant increase in the bound rubber level and in the amount of grafted rubber in comparison to the pristine untreated samples. The bound rubber measurement has been done also on a natural rubber masterbatch filled with extracted fullerene carbon black (EFCB). Also in this case extremely high levels of rubber grafting have been achieved in comparison to pure untreated graphite. It is discussed and demonstrated that the fullerene-like nanostructures in carbon blacks play a key role in the formation of bound rubber phenomenon and in grafting natural rubber on carbon black surface.     

Influence of Carbon Black and Silica Filler on the Rheological and Mechanical Properties of Natural Rubber Compound

Rubber compounds are reinforced with fillers such as carbon black and silica. In general, filled rubber compounds shows smooth rheological behavior and mechanical properties. Variation in rheological behavior and mechanical properties was studied in terms of the filler composition using natural rubber compounds filled with both carbon black and silica CB/Si = 0/60, 20/40, 30/30, 40/20 and 60/0 phr (parts per hundred rubber is parts of any non-rubbery material per hundred parts of raw gum elastomer (rubbery material)). The rheological behaviour can be showed in measurement of Mooney viscosity and cure time. The Mooney viscosity of rubber compounds increase with the increasing the carbon black in the compounds. The compound filled with CB/Si of 30/30 and 60/0 showed abnormal rheological behaviour in which the cure time decreased suddenly and the increased at certain ratio during the measurement. The mechanical properties such as hardness, abrasion resistance and tensile stress at 300% elongation were studied. In the hardness and abrasion resistance measurement, the higher ratio CB/Si decrease contribution of silica, which resulting smaller of hardness value. Ratio CB/Si 40/20 gives an optimum filler blended. It is also clearly understood that higher abrasion resistance mainly due to the lower hardness value under the same condition. The tensile stress at 300% elongation of rubber compound increased with the increasing carbon black filler.     

Mechanical Properties of Regenerated Cellulose Fibres for Composites

Summary: A broad variety of regenerated cellulose fibres was subjected to single fibre tensile tests in order to determine the modulus of elasticity, tensile strength, and failure strain. The results were compared to glass fibres and flax fibres, which are considered the most important technical and natural fibres, respectively. With regard to their modulus of elasticity and tensile strength, regenerated cellulose fibres showed clearly lower values than glass fibres, even when their low density was taken into account. The average modulus of elasticity and tensile strength of regenerated cellulose fibres was also lower than the values measured for flax fibres, but when variability was considered, both fibres performed similarly. In terms of interfacial shear strength with polypropylene, lyocell fibres performed significantly less well than sized glass fibre and ramie fibre. The most important difference between regenerated cellulose fibres and both glass and flax fibres is their high failure strain and thus high work to fracture. The high work to fracture of regenerated cellulose fibres makes them particularly useful for composite applications where high fracture toughness is required.     

稻壳基二氧化硅/碳复合材料的表面改性及对天然橡胶的影响

以稻壳基二氧化硅/碳复合材料(SiCB)作为天然橡胶(NR)的补强填料, 采用表面化学改性的方法将天然乳胶(NRL)接枝到SiCB表面, 改善其与NR基体的相容性. 研究了不同处理方法对接枝NRL效率的影响, 以及填料填入NR后对硫化橡胶力学性能的影响. 结果表明, 经过硝酸和γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(γ-MPTMS)预处理, NRL能高效接枝在SiCB表面, 得到的样品SiCB_MR10比未处理的SiCB_P有更强的补强能力. 硫化胶NR/SiCB_MR10的拉伸强度、 300%定伸和撕裂强度较NR/SiCB_P分别提高了61.06%, 27.15%和15.90%, 与传统炭黑产品N774填充的硫化胶NR/N774的力学性能相近. 经过NRL接枝改性的SiCB_MR10具有替代商业炭黑的应用前景.     

Preparation and Properties of Nanostructured Rubber Composites with Montmorillonite

Montmorillonite exfoliated nanoclay was prepared by treating montmorillonite with an alkyalmmonium salt. It has been characterized by FT-IR spectroscopy and thermal analysis (TGA-DTA). The nanoclay composites, in which the rubber matrix was introduced by mixing solutions of the elastomer with the organically modified clay was then compounded with carbon black filler at 2.5, 5, 10, 15 phr loading level of nanoclay. The sulfur cured rubber samples were tested against a reference compound not filled with the nanoclay. Rheometrical and scorch measurements have shown that the nanoclay increases the curing speed and reduces the scorch safety. A very high reinforcement and stiffening effect due to the nanoclay was observed especially at 5 and 10 phr nanoclay filling level and especially at low extension modulus which can be increased up to 40% its original level than in the reference compound. An anisotropic behavior has been recorded in the stress-strain curve: for instance the 50% modulus was found >20% higher when measured parallel to the alignment of the exfoliated nanoclay lamellae in comparison to the modulus perpendicular to the lamellae orientation. The compounds with nanoclay show no adverse effects in tensile strength and in tear resistance, in De Mattia crack initiation and in abrasion resistance. Nanoclay reduces also the hysteresis and heat build up of the rubber compounds.     

炭黑表面含氧量对HDPE—CB复合物导电性能的影响

通过硝酸氧化处理炭黑（CB）,使其表面含氧量（氧元素与碳元素的摩尔百分比）由1．0％（CB1）提高到7．0％（CB2）。分别以CB1和CB2为填料,以高密度聚乙烯（HDPE）为基体,制备了两种导电复合材料。与碳粒子填充极性聚合物相反,表面含氧量高的CB2填充HDPE复合物的渗流阈值低。采用SEM、动态电渗流效应和Payne效应分析了两种炭黑在HDPE中的分散和凝聚特征。结果表明：CB2在HDPE中分散更不均匀,更容易凝聚形成网络。炭黑在非极性HDPE中凝聚形成导电网络的能力随炭黑表面含氧量的增加而提高。     

硅橡胶/氟橡胶并用胶的制备及力学性能

硅橡胶和氟橡胶作为国防、航天等重要领域的耐热材料一直被人们青睐,但其有着各自地优缺点且价格昂贵,本文尝试将这两种橡胶制成并用胶以解决氟橡胶不耐低温和加工性差的问题,以期增大其使用温度范围。采用机械共混法制备硅橡胶/氟橡胶并用胶,研究了硅橡胶和氟橡胶的混炼工艺、并用比、共硫化体系和硫化条件对并用胶力学性能的影响。结果表明,当硅橡胶/氟橡胶的质量比为10∶90,共硫化体系为3~#硫化剂/过氧化二异丙苯(DCP),一段硫化温度为170℃、硫化压力为10MPa、硫化时间为30min,二段硫化温度为200℃、硫化时间为6h时,并用胶的力学性能达到最好。     

丁腈橡胶的XeF2表面氟化改性研究

丁腈橡胶表面经ＸｅＦ２处理后，介质性能有显著的提高，摩擦系数降低６～８倍．用ＸＰＳ法研究了氟化处理的丁腈橡胶表面结构，并用曲线拟合分峰技术对Ｃ１ｓ谱进行数学处理．结果表明，随着氟化时间延长，橡胶表面氢被氟取代逐步生成—ＣＨ２—ＣＨＦ—ＣＨ２—、—ＣＨＦ—ＣＨ２—ＣＨＦ—和—ＣＨＦ—ＣＨＦ—ＣＨＦ—等．ＳＥＭ照片显示氟化膜厚度可达８～９μｍ．     

炭黑/炭纤维/聚甲基丙烯酸丁酯导电复合材料的导电性和气敏性

炭黑;气相生长炭纤维;聚合物基导电复合材料;气敏性     

聚乙烯/碳黑导电复合材料的导电性能

提出并验证了聚乙烯/碳黑(PE/CB)导电复合材料的网络导电性能和产生正温度系数(PTC)特性的原因,分析了加工过程、温度和辐射交联等后处理过程对其导电性能的影响.     

高填充量碳纳米管/丁苯粉末橡胶机械混炼的物理化学机制

将用喷雾干燥法制备的碳纳米管(CNTs)/丁苯粉末橡胶复合材料在开炼机上机械混炼, 考察机械混炼对复合材料常规力学性能的影响, 并对机械混炼对CNTs增强丁苯橡胶复合材料力学性能的影响进行相应的理论研究和机理分析. 结果表明, 与混炼前的复合材料相比, 机械混炼有效地提高了CNTs/丁苯橡胶复合材料的力学性能, 特别是当CNTs加入量较大时, 提高幅度更为显著, 与填充传统补强剂CB复合材料相比, 具有较大的优势. 这是因为机械混炼一方面使CNTs在橡胶基体中获得了更为充分均匀的分散; 另一方面, 混炼过程中产生的自由基以及巨大的剪切力, 使得CNTs与橡胶基体间界面结合如物理吸附、氢键作用、化学结合等得到了进一步增强, 提高了CNTs/丁苯橡胶复合材料的结合橡胶含量, 更好地发挥了CNTs对丁苯橡胶的补强效应, 从而提高了复合材料的拉伸强度和撕裂强度等力学性能. CNTs补强丁苯橡胶复合材料力学性能的机理符合“强键和弱键学说”.     

改性炭黑及其增强橡胶的研究

从炭黑在橡胶中的应用出发,介绍了炭黑的结构、各种炭黑改性的方法以及改性炭黑对橡胶物理机械性能的影响。     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足.通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料.深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响.结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高.但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同.其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差.     

Simultaneous Enhancement of Mechanical and Dynamic Mechanical Properties of Natural Rubber/Recycled Ethylene-Propylene-Diene Rubber Blends by Electron Beam Irradiation

Mechanical and dynamic mechanical properties of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends were simultanoeusly enhanced by electron beam (EB) irradiation. The cross-linking promoter, trimethylolpropane triacrylate (TMPTA), was also introduced into the blends to induce the cross-linking. By applying EB irradiation, the tensile modulus, hardness, swelling, cross-link density, and storage modulus increased with increase in the irradiation dose; an irradiation dose of 50 kGy was efficient to gain optimum tensile strength. The formation of irradiation-induced cross-links after EB irradiation is a major concern for the enhancement of mechanical, swelling resistance, and dynamic mechanical properties of the blends.