磺酸盐改性无烟煤对丁苯橡胶复合材料微观结构和力学性能的影响

无烟煤经磺酸盐球磨改性后,与丁苯橡胶(SBR)进行熔融共混,制得改性无烟煤/SBR复合材料,然后对改性无烟煤和无烟煤/SBR复合材料的表面性质、微观结构和力学性能进行了表征测试。结果表明,磺酸盐与无烟煤发生了酯化反应,改性无烟煤片层结构被剥离,多以细小鳞片状呈现,颗粒变小,分散均匀,改性无烟煤的微观结构和表面性质发生了明显变化;无烟煤颗粒在橡胶复合材料中均匀分散后,其填充橡胶复合材料的力学性能和交联密度显著增加,在填充70份时,拉伸强度达到10.7MPa,交联密度增大为116mol/m3,改性无烟煤补强效果明显。     

氧化石墨结构对电容性能的影响

研究了层状结构氧化石墨的片状尺度、结晶态及不同表面官能团含量对其电化学电容性能的影响.以光谱纯和化学纯石墨为原料,采用改进的Hummer法制备氧化石墨(GO),并将部分氧化石墨球磨.用FT-IR和XPS,对氧化石墨表面官能团进行了分析;XRD、FE-SEM和氮气吸附等温线,对氧化石墨结构和形貌进行了分析.利用恒电流充放...     

聚丙烯腈基碳纤维电化学改性机理研究

以NH4HCO3为电解质对碳纤维和石墨纤维进行电化学改性处理,通过SEM、WAXD、XPS对比分析了电化学改性对碳纤维和石墨纤维表面及本体结构的影响.结果表明电化学处理使碳纤维表面破坏严重,轴向沟槽消失,呈现出粗糙不平的表面,石墨纤维表面的轴向沟槽加深.电化学处理后二者的本体结构没有改变.从纤维内部结构分析了碳纤维电化学改性机理,杂原子的存在使碳纤维表面更易氧化刻蚀.     

细颗粒掺杂石墨高温热导率的研究

通过球磨分散方法制备了具有优良热机械性能的细颗粒掺杂石墨.该掺杂石墨材料具有致密的结构,细小的碳化物颗粒均匀分布在石墨基体中.研究表明;球磨分散方法制备的掺杂石墨比常规方法制备的石墨材料具有更优良的高温热性能以及抗热震性能.同时,本文对材料的性能与其微观结构进行关联.     

改性石墨/AB5合金复合材料的电化学储氢性能研究

以AB5型储氢合金为添加剂,采用球磨法对石墨进行表面改性,再将改性后的石墨与AB5型储氢合金组成复合材料.恒电流充放电测试结果表明,优化的复合材料组成为:10％(wt,下同)改性石墨十90％AB5合金,其中改性石墨含20％ AB5合金.该复合电极的0.2C容量达到315mAh/g,大电流放电性能明显优于AB5合金电极.电化学阻抗谱测试表明,与AB5合金电极相比,H在复合电极中的扩散速率明显增加,从而有利于电极充放电的进行.     

天然石墨球-热解炭核壳结构的制备及电化学性能研究

通过化学气相沉积的方法,以乙炔为碳源,天然石墨球为原料,采用不同流化床CVD工艺和不同的反应时间,制备出具有光滑表面或颗粒状热解炭包覆层的核-壳构型改性天然石墨球.改性天然石墨球的核体是具有高度有序石墨结构的天然石墨,而壳体是无序结构的热解炭.与天然石墨球相比,具有核-壳结构的改性天然石墨球的首次库仑效率和循环性能都得到显著改善.尤其是具有颗粒状热解炭包覆层的改性石墨具有优异的循环性能,在41次循环后其放电容量仍为首次容量的84%,这一改善归因于表面沉积的颗粒状热解炭有效地降低了改性天然石墨颗粒之间的接触电阻和增加了接触面积.     

球磨作用对改性二氧化硅热行为的影响

对天然二氧化硅分别经不同条件球磨改性,并分别采用TGA、X射线衍射分析、红外光谱分析和粒度分析等对改性二氧化硅样品进行表征,研究了球磨作用对改性二氧化硅热行为的影响.结果表明,在TGA曲线上,原料二氧化硅失重率很低,而球磨后二氧化硅失重率都较大.从TGA曲线可知,经球磨后硅烷偶联剂KH-560并不是简单的物理吸附而是化学吸附于改性二氧化硅表面.结构表征结果表明,不同球磨条件下所得改性二氧化硅的结构有显著差异.因此,不同球磨条件下所得改性二氧化硅的热行为差异主要是由相应改性二氧化硅的结构变化差异所引起的.     

球磨转速对隐晶质石墨复合材料吸波性能的影响

为了考察球磨转速对隐晶质石墨复合材料吸波性能的影响,研究了不同球磨转速对隐晶质石墨的微观形貌、晶体结构、粒径分布以及隐晶质石墨/LDPE复合材料反射率的影响。研究结果表明:随着球磨转速的增加,隐晶质石墨有效细化,颗粒均匀度明显增加,平均粒径减小,晶体结构不变,在8~18GHz范围内,反射率峰值明显降低,吸波频段拓宽。当球磨转速为800r/min时,隐晶质石墨复合材料反射率峰值达到-23.4dB,小于-5dB和-10dB的有效带宽分别为5.95GHz和1.7GHz,说明隐晶质石墨通过球磨细化处理后能有效提高其吸波性能。     

新型抗凝血纳米复合材料的制备及其性能研究

利用溶液插层法合成了新型的硅橡胶/氧化石墨-十六烷基三甲基溴化铵-肝素抗凝血纳米复合材料.通过FT-IR、XRD、SEM和机械性能测试了解改性氧化石墨微观纳米结构对材料宏观性能的影响;溶血试验和血小板粘附试验测定表明硅橡胶/改性氧化石墨抗凝血纳米复合材料的血液相容性得到极大的改善;这种新型的、兼具优良血液相容性和良好力学性能的复合材料可望在生物医学工程方面得到应用.     

高能球磨合成纳米碳包覆α-Al2O3复合粉体

以膨胀石墨和α-Al2O3微粉为原料,采用高能球磨制备了纳米碳包覆的α-Al2O3复合粉体,研究了高能球磨时间和球磨速率对复合粉体物相及形貌的影响。采用X射线衍射仪、场发射扫描电子显微镜和透射电子显微镜对复合粉体的物相、形貌和微观结构进行了表征。结果表明:按膨胀石墨与α-Al2O3质量百分比为1:2,球磨速率为600 r/min,球磨5 h可得到被粒度为20～50 nm碳颗粒包覆的α-Al2O3复合粉体;随着球磨时间延长,石墨(002)晶面特征峰逐渐消失,膨胀石墨中纳米片层会随球磨时间延长不断剥离脱落,并逐渐龟裂成纳米碳颗粒;相同球磨时间下,提高球磨速率可以促进纳米碳颗粒形成,但超过一定速率后纳米碳颗粒粒度不再减少;480 r/min速率球磨5 h未形成纳米碳颗粒包覆复合粉体,600和700 r/min速率球磨5 h后复合粉体形貌基本一致。     

The effect of silane coupling agent (Si-69) on thermoxidative stability of butyl rubber compounds

Thermal analysis and the ageing studies of butyl rubber (IIR) compounds have been carried out in order to assess the effect of a silane coupling agent, Bis-(3-triethoxysilylpropyl)tetra sulphide (Si-69) on thermal and thermoxidative stability of IIR. The thermal stability of the raw rubber remained uneffected on adding Si-69, whereas the thermoxidative stability was enhanced. Similar behaviour, though to a lesser extent, has been observed for compounded rubber. The ageing properties and service life are also improved with Si-69. A suitable mechanism has been proposed.     

透明LED石墨烯/苯基硅橡胶复合封装材料

采用化学接枝技术,利用硅烷偶联剂γ-氨丙基三乙氧基硅烷（KH-550）、水合肼改性氧化石墨烯（GO）制备功能型石墨烯（FG）。将FG与苯基硅橡胶混合,采用氢化硅烷化法,在铂催化剂作用下制备了一种发光二极管（LED）封装用FG/苯基硅橡胶复合材料,考察了改性后FG结构、表面官能团变化以及其用量对FG/苯基硅橡胶复合材料力学性能及光学性能的影响,并分析了FG/苯基硅橡胶复合材料的微观相态及其热稳定性。结果表明:经KH-550改性后的FG表面附有特殊官能团,能提高其在苯基硅橡胶中的分散性。当苯基硅橡胶中引入0.010 0wt% FG时,FG/苯基硅橡胶复合封装材料的透光率仍可达到85%以上,耐紫外老化性能和力学性有明显提高。FG/苯基硅橡胶复合材料的热分解温度为690 ℃、GO/苯基硅橡胶复合材料的热分解温度为623 ℃,而纯苯基硅橡胶的热分解温度为491 ℃,且FG/苯基硅橡胶复合材料的放热量始终比纯苯基硅橡胶略低。苯基硅橡胶中引入0.010 0wt% 改性的FG,材料热分解温度提高了200 ℃,放热量有所减少,能更好满足功能型LED复合封装材料热稳定性能要求。      

细粒级掺杂石墨材料的制备及其出气特性的研究

通过球磨分散方法制备了细粒级掺杂石墨 ,采用SEM、EDX、TEM、XRD等手段分析了材料微观结构 ,并对其性能作了初步研究。研究表明 :当原始粉粒径小于 10 0nm时 ,材料具有高的热导率和优良的物理机械性能 (抗弯强度为 116MPa) ,与粗晶石墨材料相比 ,细晶石墨材料在电子束辐照前的出气性能与其基本相同。而辐照之后 ,细晶石墨材料释放的H2 、H2 O、CO ,特别是CO2 的量远远少于粗晶石墨材料释放的量     

Mechanical, thermal and electrical properties of aluminum nitride/polyetherimide composites

The mechanical, thermal and electrical properties of modified AlN/polyetherimide (PEI) composites were investigated. It revealed that the surface of AlN modified by silane could effectively increase the adhesion with matrix, which was beneficial for AlN to reinforce the polyetherimide matrix. After silane modification, the AlN showed good dispersion and wetibility in the polyetherimide matrix and imparted excellent mechanical, electrical and thermal properties. The tensile strength, modulus, electrical and thermal stability were improved with the increasing of AlN content. The tensile strength of AlN/PEI composites increased by 27% when 12.6 vol.% AlN was added to neat polyetherimide. The thermal conductivity of the 57.4 vol.% AlN/PEI composites increased three times compared with neat polyetherimide. Test results indicate that the silane grafted AlN incorporated into the polyetehetimide matrix effectively enhance the thermal stability, thermal conductivity and mechanical properties of the polyetherimide composites.     

废胶粉的表面处理及在天然橡胶中的应用

采用硅烷偶联剂KH550对废胶粉进行表面处理,并将处理后的废胶粉与天然橡胶复合制备WRP/NR复合材料。借助L16(45)正交试验及单因素试验,探讨了废胶粉目数、废胶粉用量、硅烷偶联剂KH550用量对复合材料力学性能的影响;对处理后的废胶粉表面和橡胶拉伸试样断裂面进行了扫描电镜(SEM)观察;并通过热重分析研究了天然橡胶和复合材料的热降解性能。结果表明:当废胶粉目数为80目,废胶粉用量为10%,硅烷偶联剂KH550用量为1.5%时,复合材料的力学性能最优,拉伸强度为27.89MPa。SEM结果表明废胶粉表面粗糙度增大,比表面积增大,与NR基体的相容性得到了提高。而热重分析表明改性废胶粉的加入对天然橡胶的热稳定性能影响不大。     

纳米AT/NBR复合材料的制备与研究

纳米凹凸棒土(AT)是一种天然纳米填料,对其性质和改性方法的研究直接关系到它的应用性能和工业前景。采用熔融共混法制备了纳米凹凸棒土/丁腈橡胶(AT/NBR)复合材料,并进行了力学性能测试。具体考察了增塑剂、硅烷偶联剂、不同凹凸棒土填充量、改性方法等对复合材料力学性能的影响。结果表明,经Si-69改性的AT可以显著提高NBR的力学性能。     

Effect of surface treatment on performance of pineapple leaf fiber–polycarbonate composites

This research is to study the properties of pineapple leaf fiber reinforced polycarbonate composites (PC/PALF). Surface of pineapple leaf fiber (PALF) was pre-treated with sodium hydroxide (PALF/NaOH) and modified with two different functionalities such as γ-aminopropyl trimethoxy silane (PALF/Z-6011) and γ-methacryloxy propyl trimethoxy silane (PALF/Z-6030). The effects of PALF content and chemical treatment were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy and mechanical testing. The modified pineapple leaf fibers composite also produces enhanced mechanical properties. Young’s modulus is the highest in the case of the PALF/NaOH composites. The PALF/Z-6011 composites showed the highest tensile strength and impact strength. In thermal property, the results from thermogravimetric analysis showed that thermal stability of the composites is lower than that of neat polycarbonate resin and thermal stability decreased with increasing pineapple leaf fiber content.     

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.     

Evidences of Rubber Grafting on Activated Carbon Surfaces Containing Fullerene‐like Structures

Abstract

It is shown that graphite is converted into an high disordered carbon black by prolonged ball milling. The kinetics of this transformation has been followed by powder x‐ray diffraction, measurements of the crystallinity and of the surface area. Ball milling is able to introduce an high concentration of defective sites in the pristine graphite including the fullerene‐like structures. By mixing with natural rubber both the pristine and the ball‐milled graphite, it is shown by bound rubber measurements that the amount of rubber grafted (chemically linked) on the pristine graphite surface is negligible but reaches a very high level in the ball‐milled graphite. Similarly, ball‐milling of N660 carbon black 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 N660 sample. The bound rubber measurement has been performed also on a natural rubber masterbatch with extracted fullerene carbon black (EFCB). Also in this case extremely high levels of rubber grafting have been achieved in comparison to 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.     

Effect of filler load and high-energy ball milling process on properties of plasticized wheat gluten/olive pomace biocomposite

The increase of particles surface area can optimize the dispersion state of biocomposite components and enhance their properties. First in this paper, we aimed to elaborate a novel biocomposite without any treatments. Plasticized wheat gluten (WG), was filled with 0–20% of olive pomace (OP) powder. The second objective was the improvement of biocomposite properties using physical treatment. High-energy ball milling process was applied on the blend of wheat gluten and olive pomace powders (MPs). The grinding effect of particle shape, size and distribution in biocomposite was characterised by particle size distribution using a laser-light diffraction and by SEM analysis. The cryo-fractured surface of selected films, mechanical properties, moisture absorption and thermal properties of both biocomposites were described in details. It was found that the sensitivity of biocomposites to moisture absorption was reduced with the increase of filler content after the applying of high-energy ball milling process. The thermal stability of OP biocomposite decreased with the increase of loading, while that of MPs was unaffected by high-energy ball milling process. This process affects the physical and morphological characteristics of the powders. The mechanical properties were improved by grinding process at filler content lower than15%.