酚醛气凝胶/碳纤维复合材料的结构调控及性能研究

以酚醛树脂为前体、碳纤维针刺预制体为增强体,采用溶胶-凝胶、常压干燥方法制备得到纳米孔酚醛气凝胶/碳纤维复合材料。在不改变材料密度的条件下,通过调节固化剂的用量来调控酚醛气凝胶的纳米颗粒尺寸及孔隙结构,改变气凝胶颗粒在碳纤维针刺预制体中的填充状态,制备出不同微观结构的复合材料。研究表明:随着固化剂用量的减少,气凝胶的颗粒粒径逐渐变小,平均孔径在230 nm~5μm范围内可调;与碳纤维复合后,随着气凝胶颗粒的减小,复合材料的力学性能逐渐提升、热导率逐渐降低、烧蚀性能明显提高。优化后的PAC复合材料具有极低的密度(0.27 g·cm~(-3))、高弯曲强度(8.9 MPa)、较低的热导率(0.065 W·m~(-1)·K~(-1));在2000℃、30 s的中等热流烧蚀条件下,质量烧蚀率为0.0081 g·s~(-1)、线烧蚀率为0.0204 mm·s~(-1)。通过调控材料的纳米结构,能够有效地提升材料的力学、隔热以及烧蚀性能,满足高性能热防护应用需求。     

SiO2气凝胶纳米复合材料的研究

在纳米结构的ＳｉＯ２气凝胶的基础上,实验了合成一系列新型的以纳米ＳｉＯ２气凝胶为骨架的多元纳米复合材料,讨论了一系列多组分ＳｉＯ２纳米气凝胶材料的微观纳米结构形式,包括胶粒尺寸,微孔尺寸分布等,同时探讨了在含金属组分的气凝胶骨架上采用气相裂解乙炔的方法制备出以Ｃ－ＳｉＯ２气凝胶为骨架的纳米材料与气凝胶骨架中的金属原子的关系,并初步了测定了几种ＳｉＯ２纳米复合凝胶材料的基本物理性能,进一步展望了这些     

气凝胶复合材料的研究进展

气凝胶材料是一种质轻、低密的多孔材料,对其研究较多。它具有良好的发展前景和巨大的科研价值。通过介绍高分子气凝胶、碳气凝胶等复合材料的制备方法,阐述了结构与性能的关系,并对气凝胶材料未来的发展作了展望。     

SiO2气凝胶/发泡水泥基复合材料的微观结构及性能

采用外掺法制备了SiO2气凝胶/发泡水泥基复合材料,并系统研究了复合材料的微观结构、导热系数以及稳泡剂、水胶比、H2O2添量、温度、SiO2气凝胶添量对复合材料密度和抗压强度的影响.研究结果表明,疏水性气凝胶颗粒均匀分散在发泡水泥孔壁上且使得水泥水化产物中针状物质增多,片状生成物之间连接紧密性降低.SiO2气凝胶添量为1.5wt％时,稳泡剂添量为0.4wt％,水胶比为0.60,H2O2添量为4.0wt％,温度区间为35 ～ 45℃,按此配比所得复合材料密度较低,抗压强度较高.固定发泡水泥料浆用量,随着气凝胶添量的增加,复合材料发泡高度、导热系数降低,密度、抗压强度增加.     

溶胶凝胶法制备SiO2气凝胶/纤维复合材料及其性能的表征

以正硅酸乙酯（TEOS）为前躯体,采用溶胶-凝胶工艺制备氧化硅溶胶,将其与无机陶瓷纤维预置体在常温下复合干燥后得到SiO2气凝胶隔热复合材料。利用扫描电子显微镜（SEM）对样品微观结构进行分析,利用热平板法对材料的热学性能进行表征,分析了氧化硅气凝胶隔热复合材料隔热机理。研究表明：采用溶胶凝胶工艺和真空技术,气凝胶充分填充在纤维预置体的空隙中,可以制得低导热系数、低热扩散系数和低比热容的SiO2气凝胶/纤维复合材料,导热系数为0.06815W/mK,热扩散系数为0.2677mm^2/s,比热容为0.2919MJ/m3K。     

石墨烯气凝胶/MnO2复合材料强化电容去离子性能研究

选用石墨烯气凝胶(GA)作为载体,负载MnO2纳米颗粒,构建新型石墨烯气凝胶-MnO2复合材料(MnGA),并制备电容电极,研究复合材料的电容去离子性能。结果表明,MnO2在石墨烯片层上可形成一维线状结构,减弱石墨烯片层间的堆叠效应,提升材料电容,从而提高了电极的脱盐性能,最大电容脱盐量达到25.78 mg/g;NaCl溶液的初始浓度、供电电压和进水流速均会对电容脱盐量产生影响。     

气凝胶在高分子复合材料制备中的应用

气凝胶种类很多,从硅系、碳系、金属氧化物系和高分子系四方面综述了气凝胶的研究进展,并对气凝胶的发展方向进行展望。通过降低气凝胶制造成本,提高其本身力学性能,将有助于气凝胶在更广阔的空间发挥作用。气凝胶的高分子化及多功能化也将成为今后发展的重要方向之一。     

石墨烯气凝胶/白炭黑/丁苯橡胶复合材料的制备与性能研究

采用溶胶-凝胶法和冷冻干燥法制备的石墨烯气凝胶(GA)与白炭黑复合制得白炭黑/GA复合填料(s-GA),通过机械共混法制备s-GA/白炭黑/丁苯橡胶(SBR)复合材料,并对其性能进行研究。结果表明:在GA中填充白炭黑,可有效减少石墨烯片层的团聚,s-GA/白炭黑/SBR复合材料的t90缩短,抗湿滑性能提高;当s-GA中GA/白炭黑用量比为1/5时,s-GA/白炭黑/SBR复合材料的拉伸强度和拉断伸长率最大;随着s-GA中白炭黑用量的增大,s-GA/白炭黑/SBR复合材料的耐磨性能提高。     

酚醛有机气凝胶的制备及表征

对新型的炭材料的有机前驱体－ＲＦ气凝胶的合成工艺进行了探索研究。探讨了反应条件（反应物浓度、催化剂浓度、时间、温度等）对产物的影响，同时对产物进行了表征。     

纳米SiO2/邻甲酚醛环氧树脂复合材料的性能与固化特性

制备了纳米SiO2/邻甲酚醛环氧树脂(o-CFER)复合材料,通过力学性能、热性能、扫描电镜以及DSC等方法对该复合材料的性能进行了研究,确定了工艺参数.结果表明,纳米SiO2的加入较大地提高了o-CFER的拉伸强度、冲击强度、热稳定性等性能;通过动态DSC测定确定了纳米SiO2/o-CFER复合材料的固化反应放热量-△H=128J/g,活化能为48.9 kJ/mol,反应级数n=0.871,频率因子A=3.4×103s-1;固化工艺参数为T凝胶=71℃,T固化=133℃,T后处理=165℃.     

Mechanical and thermal transmission properties of carbon nanofiber‐dispersed carbon/phenolic multiscale composites

The present article reports the development and characterization of carbon nanofiber (CNF)‐incorporated carbon/phenolic multiscale composites. Vapor‐grown CNFs were dispersed homogeneously in to phenolic resin using an effective dispersion route, and carbon fabrics were subsequently impregnated with the CNF‐dispersed resin to develop carbon fiber/CNF/phenolic resin multiscale composites. Mechanical and thermal transmission properties of multiscale composites were characterized. Elastic modulus and thermal conductivity of neat carbon/phenolic and multiscale composites were predicted and compared with the experimental results. It was observed that incorporation of only 1.5 wt % CNF resulted in 10% improvement in Young's modulus, 12% increase in tensile strength, and 36% increase in thermal conductivity of carbon/phenolic composites. Fracture surface of composite samples revealed the formation of stronger fiber/matrix interface in case of multiscale composites than neat carbon/phenolic composites. Enhancement of above properties through CNF addition has been explained, and the difference between the predicted values and experimental results has been discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Moldability and properties of phenolic/artificial zeolite composites

The purpose of this study is to improve the several properties of composites consisting of a phenolic and fly ash or artificial Zeolite such as sodium type Zeolite (Na? Ze) or calcium type Zeolite(Ca? Ze). And it also includes the improvement in the flowability of molding compounds. The molding compounds were prepared from a phenol novolac, a curing agent, and several fillers. The flowability of the compounds containing fly ash and artificial Zeolite as a filler, mentioned above, was superior to that of the compounds containing glass fiber (GF), calcium carbonate (CaCO₃), or talc as a filler. The phenolic composites were prepared from the above molding compounds by transfer molding. The phenolic composite containing Ca? Ze had most superior heat resistance, electrical insulation, and flexural strength, though in the lastly listed property it ranked next to the GF‐filled composite. The linear expansion coefficient of the composite containing Ca? Ze was as low as almost isotropic. The reasons of obtaining these excellent properties were thought to be as follows: (1) Ca? Ze could finely be dispersed in the phenolic resin to bring good impregnation. (2) The surface chemical and physical interaction between the resin and Ca? Ze was higher than that between the resin and the other fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Structure and properties of UHMWPE fiber/carbon fiber hybrid composites

Ultrahigh molecular weight polyethylene (UHMWPE) fiber/carbon fiber hybrid composites were prepared by inner‐laminar and interlaminar hybrid way. The mechanical properties, dynamic mechanical analysis (DMA), and morphologies of the composites were investigated and compared with each other. The results show that the hybrid way was the major factor to affect mechanical and thermal properties of hybrid composites. The resultant properties of inner‐laminar hybrid composite were better than that of interlaminar hybrid composite. The bending strength, compressive strength, and interlaminar shear strength of hybrid composites increased with an increase in carbon fiber content. The impact strength of inner‐laminar hybrid composite was the largest (423.3 kJ/m²) for the UHMWPE fiber content at 43 wt % to carbon fiber. The results show that the storage modulus (E′), dissipation factor (tan δ), and loss modulus (E″) of the inner‐laminar hybrid composite shift toward high temperature remarkably. The results also indicate that the high‐performance composite with high strength and heat resistance may be prepared by fibers' hybrid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1880–1884, 2006     

Thermal expansion and mechanical properties of phenolic resin/ZrW2O8 composites

Phenolic resin/ZrW₂O₈ composites were successfully fabricated and their coefficient of thermal expansion (CTE) as well as mechanical properties was investigated. The CTE of the composites decreases from 46 × 10^–6 to 14 × 10^–6 K^?1 when the ZrW₂O₈ volume fraction increases from 0 to 52 vol %. The CTE of the composites is analyzed by some theoretical models; Schapery's upper bound provides the best estimate of the reduction in CTE. The Barcol hardness of the composites increases with an increase in the ZrW₂O₈ volume fraction. The bending strength of the composites with 19–25 vol % of ZrW₂O₈ fillers shows a maximum value of 130 MPa, which is 45% larger than that of phenolic resin without fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Thermal conductivity of carbon fiber/liquid crystal polymer composites

Thermally conductive resins are needed for bipolar plates in fuel cells. Currently, the materials used for these bipolar plates often contain a single type of graphite in a thermosetting resin. In this study, varying amounts of two different types of polyacrylonitrile based carbon fibers, Fortafil 243 and Panex 30, were added to a thermoplastic matrix (Vectra A950RX Liquid Crystal Polymer). The resulting single filler composites were tested for thermal conductivity and a simple exponential thermal conductivity model was developed for the square root of the product of the in‐plane and through‐plane thermal conductivity . The experiments showed that the through‐plane thermal conductivity was similar for composites up to 40 vol % fiber. However, at higher loadings, the Panex 30 samples exhibited higher thermal conductivity. The experiments also showed that the in‐plane thermal conductivity of composites containing Panex 30 was higher than those containing Fortafil 243 for all volume fractions studied. Finally, the model agreed very well with experimental data covering a large range of filler volume fraction (from 0 to 55 vol % for both single filler systems). The model can be used with existing through‐plane thermal conductivity models to predict in‐plane thermal conductivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5456–5462, 2006     

Blocked diisocyanate polyester-toughened novolak-type phenolic resin: Synthesis,characterization, and properties of composites

A blocked diisocyanate polyester was synthesized to copolymerize with novolak-type phenolic resin. From the results of IR and NMR spectra, it was found that the blocked diisocyanate polyester reacts with the hydroxyl group of the novolak-type phenolic resin at high temperature. The deblocking temperature for the novolak-type phenolic resin is 120°C. The blocking agent, ε-caprolactam, is convenient for this system. The copolymer exhibited a single glass transition temperature and a negative deviation of the glass transition temperature. The results showed that the copolymer system is miscible and the molecular motion of the copolymer is increased with the addition of a modifier. The interface between the modified phenolic resin and the glass fiber is improved and the tensile strength of pultruded composite is increased with the modifier content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1119–1127, 1998     

炭纤维增强水泥基复合材料(CFRC)的电磁性能

炭纤维增强水泥基复合材料(Carbon Fiber Reinforced Cement Composites,CFRC)是新发展起来的一种电磁屏蔽材料,它是防止电磁污染的防护性功能材料之一。本文阐述了炭纤维增强水泥基复合材料的制备成型工艺;分析了炭纤维掺入量和长度、水灰比和密实成型制备工艺、炭纤维分散性、养护龄期、外加剂、炭纤维表面化学气相沉积(CVD)处理等因素对CFRC力学性能、导电性能、压敏性能及电磁性能的影响。合适的炭纤维掺入量和长度、炭纤维的均匀分散、合理的水灰比和炭纤维表面处理是影响CFRC导电性能和电磁性能的主要因素。CFRC对电磁波的屏蔽效果除利用屏蔽效能从反射电磁波角度衡量外,亦可从吸收电磁波角度利用反射率进行评价。     

PPS/recycled PEEK/ carbon nanotube composites: Structure,properties and compatibility

Blends of poly(phenylene sulfide) (PPS) and recycled poly(ether ether ketone) (r‐PEEK) were prepared using a twin‐screw extruder. The carbon nanotube (CNT) added to the blends not only improved the compatibility of the two polymers, but also affected the morphology of the immiscible PPS/r‐PEEK blends. R‐PEEK always forms the dispersed phase and PPS the continuous phase in such blends. In the composite, CNT particles were observed in the PPS phase, mostly distributes in the interface between PPS and PEEK. The results show that r‐PEEK improves the impact and tensile strength of PPS, but does not provide nucleation effect on PPS. However, CNT improved the flexural modulus of PPS/r‐PEEK blends and promoted the crystallization of r‐PEEK rather than that of PPS. The prepared PPS/r‐PEEK blends provided larger electrical conductivity than neat polymers. Adding 20 wt % CNT to blend resulted in composite with the minimum volume resistivity, a reduction of four orders of magnitude, compared with that of the neat blend. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42497.     

Structural,mechanical, thermal,and electrical properties of carbon black reinforced polyester resin composites

Carbon black (CB) reinforced polyester resin (PR) composites (CPC) have been fabricated from mechanical mixtures of liquid PR and CB powder having 0–50 wt% CB contents and cured with 1% of methyl ethyl ketone peroxide at room temperature under a pressure of 50 MPa. The samples have been examined by the Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD) technique, scanning electron microscopy (SEM), mechanical test, micromechanical test, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) and electrical test. FTIR spectra confirm the physical and chemical bond formations between CB and PR. XRD shows a very partial crystalline structure in cured PR and hexagonal structure in CB particles. SEM exhibits a clear dispersion of CB particles in PR matrix at lower loading and aggregates at higher loading. With the increase of fillers, while the tensile and flexural strengths of CPCs decrease, the Young's and tangent modulii increase by 80 and 100%, respectively. These increments are found consistent with the theoretical values. The degree of physical crosslinking between CB and PR as well as the aspect ratio of CB in CPCs are found to increase with the increase of filler. A remarkable increase in microhardness of about 61% at 50 wt% CB content is observed. The TGA represents that the thermal degradation temperature for pure PR is 373°C and that for CPC is 393°C. The dielectric constant of CPCs decreases with increasing frequency, whereas the ac‐ and dc‐ conductivities of CPC are found to increase with CB content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40421.     

Influence of elastomer distribution on the cryogenic microcracking of carbon fiber/epoxy composites

Carbon fiber/epoxy laminates containing three different types of rubber modifiers, separately and in combination, were developed for testing in a cryogenic environment. Preformed rubber particles, core shell rubber, and solid carboxyl‐functionalized rubber were chosen as additives to a model prepreg matrix to control the placement of the rubber within the resulting laminates. Cryogenic microcracking and mode I and II fracture toughness and interlaminar shear strength experiments were performed. Scanning electron microscopy was used to observe fracture surfaces of the rubber‐modified laminates. Fracture toughness properties were improved while the ILSS decreased because of the presence of these rubber modifiers. It was observed that the presence of these modifiers significantly reduced the microcrack density of the laminates exposed to cryogenic cycling, and in the case of one, even eliminated microcracking entirely. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2268–2275, 2003