碳纤维-Ni/尼龙66复合材料的制备与性能表征

为制备低电阻率的尼龙66基复合材料,以碳纤维和镍粉(Ni)填充尼龙66制备碳纤维-Ni/尼龙66高导电复合材料。研究填料表面改性和含量对碳纤维-Ni/尼龙66复合材料导电性能和力学性能的影响。结果表明:KH550改性碳纤维和Ni有助于降低碳纤维-Ni/尼龙66复合材料的电阻率。碳纤维-Ni/尼龙66复合材料的电阻率随着碳纤维和Ni含量的增加而减小,且碳纤维和Ni填充尼龙66的导电逾渗阈值均为20wt%,此时制备的碳纤维-Ni/尼龙66复合材料的电阻率为455Ω·cm,熔融温度为202.2℃。碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度随着碳纤维或Ni含量的增加而先增大后减小。当Ni含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度在碳纤维含量分别为20wt%和10wt%时达到最大值,分别为98MPa和70 MPa;当碳纤维含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度则在Ni含量为30wt%和20wt%时达到最大值,分别为120 MPa和67 MPa。     

碳纤维-尼龙6混编织物复合材料的制备及性能

为了探究合适的碳纤维表面处理方法,改善碳纤维-尼龙6织物复合材料界面结合效果,提高复合材料的力学性能,通过混编的方式制备碳纤维-尼龙6预制件,将预制件浸泡在不同浓度的醇溶尼龙无水乙醇溶液中,最后将预制件通过热压成型,制备碳纤维织物-尼龙6复合材料。采用万能拉伸试验机、SEM、TGA、DSC、XRD分析碳纤维-尼龙6复合材料的力学性能、微观形貌、耐热性能、结晶度及晶型变化。结果表明:将预制件在浓度为1wt%的尼龙溶液处理后,并采用1℃/min的降温速率制备的碳纤维-尼龙6织物复合材料力学性能最佳,抗拉强度、弹性模量、弯曲强度、弯曲模量、冲击强度分别为449.32 MPa、5.32 GPa、657.67 MPa、44.08 GPa、138.42 kJ/m2。纤维拔出后,单根碳纤维表面附着部分尼龙基体,碳纤维与尼龙基体形成了良好的界面层。碳纤维-尼龙6织物复合材料的起始分解温度较尼龙6纤维提高了13℃,耐热性有所增强,尼龙6树脂主要以α晶型存在,结晶较为完善。      

尼龙短纤维增强PVC复合材料研究

用尼龙－６短纤维增强ＰＶＣ树脂。实验研究了纤维特性参数，用量及共混条件等对复合材料力学性能的影响规律，探讨了该复合材料用于制备１次挤出的中，低压树脂软管的可能性。     

反应挤出纳米类水滑石/尼龙6复合材料的结构与性能

采用自制的双甲氧基苯甲酸根离子柱撑镁铝类水滑石(MgAl-HTlcs)和己内酰胺(CL)为主要原料,利用反应挤出工艺制备了纳米MgAl-HTlcs/尼龙6复合材料,研究了MgAl-HTlcs含量对复合材料结构与性能的影响。TEM照片显示:MgAl-HTlcs在复合材料中呈纳米级均匀分散,当MgAl-HTlcs含量为1.0wt%(占MgAl-HTlcs与CL总质量的质量分数)时出现了部分片层剥离的类水滑石。紫外光谱结果表明:与纯尼龙6相比,少量均匀分散的MgAl-HTlcs使复合材料对近紫外波长为320~380nm的紫外线吸收效果明显。XRD和DSC结果表明:少量均匀分散的MgAl-HTlcs对尼龙6起到了很好的异相成核剂的作用,不仅提高了其结晶温度,也增加了其结晶度。热重分析显示:部分片层剥离MgAl-HTlcs的存在明显提高了复合材料的热稳定性。     

Effect of flame retardants on mechanical properties,flammability and foamability of PP/wood–fiber composites

The mechanical properties, flame retardancy, thermal degradation and foaming properties of wood–fiber/PP composites have been investigated. Ammonium polyphosphate (APP) and silica were used as flame retardants. The limiting oxygen index (LOI), thermal gravimetric analysis (TGA) and cone colorimeter (CONE) were employed for the study of fire retardance. At the same time, wood–fiber/PP composite foams were produced with the batch foaming technique using CO₂ as blowing agent. The effects of APP and silica content, pressure and temperature on the final cell structure were investigated. According to LOI, TGA and cone calorimeter results obtained from the experiments, APP and silica are effective flame retardants for wood–fiber/PP composites, and silica was shown to have a flame retardant synergistic effect with APP in wood–fiber/PP composite. The mechanical properties of the composites decreased with addition of flame retardants, except for the tensile strength of small amount of silica filled wood–fiber/PP composite. The results also revealed that the cellular morphologies of the foamed wood–fiber/PP composites are a strong function of the content of APP and silica as well as foaming conditions.     

改性酚醛树脂处理剂对石英纤维增强芳基乙炔复合材料性能的影响

采用改性酚醛树脂作为石英纤维表面处理剂来提高石英纤维增强芳基乙炔复合材料(SF/PAA)界面性能。通过性能测试,研究处理剂对力学性能和介电性能的影响。通过XPS和SEM分析方法,研究了酚醛树脂表面处理剂对复合材料界面官能团变化和微观形貌的影响。性能测试结果表明改性酚醛树脂处理剂可以显著提高PAA复合材料的力学性能和介电性能。XPS分析结果表明酚醛树脂处理后的石英纤维表面与酚醛树脂发生了化学反应,SEM研究表明酚醛树脂处理后的复合材料界面粘结性能得到显著提高。     

丝素蛋白含量对纳米羟基磷灰石仿生矿化和体外细胞相容性的影响

通过制备含有不同丝素蛋白(SF)含量的丝素蛋白/纳米羟基磷灰石复合材料, 着重研究丝素蛋白含量对纳米羟基磷灰石(n-HA)仿生矿化过程中晶体成核与生长及体外细胞相容性的影响. 结果表明: SF的加入对n-HA晶体的成核和生长具有明显的调控作用; 丝素含量的大小对n-HA晶体成核和生长没有明显的区别, 但对晶粒在有机大分子中的聚集状态有明显的影响: 当SF含量不超过20wt%时, n-HA晶粒呈现放射状团簇, 当SF含量超过20wt%时, n-HA晶粒无序团聚. 体外细胞相容性结果显示, SF的加入可以促进材料与细胞的界面亲和性, 但SF含量对这种亲和性的影响不明显, 20wt%和30wt%的SF含量对增殖能力具有较强的促进作用.     

Effect of Reactive Graphitic Nanofibers (r-GNFs) on Tensile Behavior of UHMWPE Fiber/Nano-Epoxy Bundle Composites

Ultra-high molecular weight polyethylene (UHMWPE) fibers have good mechanical and physical properties and effective radiation shielding functions, which are significant for aerospace structures. In our previous work, nano-epoxy matrices were developed based on addition of reactive graphitic nanofibers (r-GNFs) in a diluent to form a blend. It is found that improved wettability and enhanced adhesion of the matrices to UHMWPE fibers can be obtained. In this study, a series of nano-epoxy matrices with different concentrations of r-GNFs (up to 0.8 wt%) and different weight ratios of r-GNFs to a reactive diluent (1:4, 1:6, 1:7, and 1:9) were prepared. Composite bundle specimens of UHMWPE fiber/nano-epoxy were fabricated and their tensile behavior was investigated. All load-displacement curves of the UHMWPE/nano-matrix bundle composites under tensile loading showed three regions corresponding to the three deformation and failure stages of the materials: 1) elastic deformation stage, 2) plateau stage, and 3) UHMWPE fiber failure stage. The nano-epoxy with 0.3 wt% of r-GNFs and with 1:6 ratio of r-GNFs to the diluent proved to be the best matrix for UHMWPE fiber composites with enhanced tensile properties. For the resulting composite, the load level and consumed energy in the plateau stage were increased by 8% and 30% over the UHMWPE fiber/pure-epoxy specimens, respectively. This UHMWPE fiber composite with the optimized nano-epoxy matrix also possesses the highest initial stiffness and ultimate tensile strength among all the resulting UHMWPE fiber composites. These results laid a foundation for us to fabricate UHMWPE fiber reinforced composite laminates in the near future.     

活性MgO改性流化床炉底渣-硅灰复合材料的力学性能及产物

为了充分利用流化床炉底渣,采用活性MgO改性法制备了具有良好力学性能的流化床炉底渣（CFB）-硅灰（SF）复合材料。研究了养护温度、MgO及SF掺量对MgO-CFB-SF复合材料的抗压强度、水化产物及微观结构的影响。初步研究了MgO活性和细度对抗压强度的影响。利用流变仪研究新拌浆体的屈服应力和塑性黏度。利用XRD、TGA、FTIR和SEM对不同龄期试样的反应产物及微观结构进行分析。掺入SF有助于提高该体系的强度,适量的SF （16wt%~20wt%）和20wt% MgO有助于提高MgO-CFB-SF浆体的流动性。常温条件下养护540天的试样微观分析结果表明：产物中的主要相是细小致密的网格状水化硅酸镁（M-S-H）、类水滑石相（Ht）或富铝硅酸盐相（M-S （A）-H）。     

Expanded graphite nanoplatelets as coupling agents in glass fiber reinforced polypropylene composites

The interfacial adhesion between E-glass fibers and various types of nanomodified polypropylene (PP) matrices have been investigated on single-fiber model composites. In particular, an evaluation of the fiber–matrix interfacial shear strength was performed by the fragmentation tests on model composites prepared by using PP matrices containing various amounts (up to 7 wt%) of expanded graphite nanoplatelets (xGnP).The presence of xGnP in the polymer matrix resulted in a remarkable increase of the interfacial shear strength values (up to a factor of about 6 for a 7 wt% content of xGnP) if compared to neat PP. Moreover, wettability measurements in various liquids evidenced that the work of adhesion of the polymer matrix with respect to glass fiber, was improved by the presence of xGnP.     

Low velocity impact properties of intra-ply hybrid composites based on basalt and nylon woven fabrics

In this paper, the low velocity impact behavior of homogenous and hybrid composite laminates reinforced by basalt–nylon intra-ply fabrics was experimentally investigated. Epoxy resin was used as matrix material. The purpose of using this hybrid composite is to combine the good mechanical properties of basalt fiber with the excellent impact resistant of nylon fiber. Five different types of woven fabrics were used as reinforcement with different volume percentages of nylon (0%, 25%, 33.3%, 50% and 100%). The effect of nylon/basalt fiber content on maximum force, maximum deflection, residual deflection, total absorbed energy, elastic energy, size and type of damage were studied at several low velocity impact nominal energy levels (16, 30 and 40 J). The results indicate that impact performance of these composites is significantly affected by the nylon/basalt fiber content. The visual inspection and ultrasonic C-scan of the impact damaged specimens reveals that content of nylon/basalt fiber controls the type and size of damage.     

Strength of unidirectional glass/epoxy composite with silica nanoparticle-enhanced matrix

A technique was developed to improve the strength of unidirectional composites by enhancing the matrix properties through nanoparticles infusion. A commercially available standard DGEBA epoxy with silica nanoparticles (Nanopox F 400) was used as the matrix to make fiber composites. The silica nanoparticles in Nanopox were grown in situ via a sol–gel process resulting in a concentration of 40 wt% which was later diluted to 15 wt% particle loading. TEM images showed very uniform dispersion of silica nanoparticles with a size distribution of about 20 nm. Compression test revealed a substantial improvement (40%) in elastic modulus of the modified epoxy. A modified vacuum assisted resin transfer molding process was used to fabricate unidirectional E-glass fiber reinforced silica/epoxy nanocomposites. Inclusion of silica nanoparticles dramatically increased the longitudinal compressive strength and moderately increased the longitudinal and transverse tensile strengths. A microbuckling model was used to verify the compression testing results.     

莫来石与碳纤维协同填充的聚四氟乙烯基复合材料及其摩擦学性能

为了提高聚四氟乙烯（PTFE）的摩擦学性能,采用机械混匀、带温预压及烧结等工艺制备了莫来石和碳纤维填充的PTFE基复合材料,并通过FTIR、XRD、万能材料试验机、洛氏硬度计、DSC及热机械分析分别表征了PTFE基复合材料的显微结构、力学性能和热学性能;然后,使用MRH-3 型高速环块磨损试验机测定了复合材料的摩擦系数和磨损率,通过自制的硅油砂浆磨损装置测定了复合材料在不同温度下的耐砂浆磨损性能;最后,借助3D测量激光显微镜研究了复合材料摩擦面形貌,并分析了摩擦磨损机制。结果表明:莫来石和碳纤维在PTFE体系中起到填充增强作用,20wt%莫来石-10wt%碳纤维/PTFE复合材料的弹性模量由364 MPa增加至874 MPa;20wt%莫来石-10wt%碳纤维/PTFE复合材料的干摩擦系数较大,但其磨损率与纯PTFE相比降低了3个数量级以上,且此复合材料在水摩擦条件下仍能保持较好的摩擦系数和磨损率,摩擦系数为0.157,磨损率为7.40×10-6 mm3·N-1·m-1;此外,20wt%莫来石-10wt%碳纤维/PTFE复合材料在较高温度下仍能表现出良好的耐砂浆磨损性能。所得结论表明改性得到的PTFE 基复合材料的摩擦学性能显著提高,复合材料可用于有杆抽油井防偏磨。      

尼龙纤维增强纺织废胶吸声复合材料的性能

为了提高纺织废胶粉(TWRP)的回收利用的价值,首先,利用TWRP和单孔中空尼龙纤维(NF)制备了一系列NF/TWRP吸声复合材料。然后,通过动态热机械分析仪(DMA)、扫描电镜(SEM)、吸声仪及电子织物拉伸仪等仪器对复合材料的性能和微观结构进行了测试及分析。结果表明:NF的加入导致复合材料的阻尼损耗因子峰值及峰值对应的玻璃化转变温度下降;随NF含量的增加,阻尼损耗因子的峰值继续下降,而玻璃化转变温度变化不大。NF构成的中空纤维网络结构赋予了复合材料吸声性能,复合材料的刚强性得到了明显改善;NF含量越高,纤维网络结构越完善,复合材料的吸声性能就越高;复合材料的应力越大,应变越小。当NF含量为50wt%时,1mm厚的NF/TWRP复合材料在2 500 Hz下的吸声系数高达0.476;当NF含量从10wt%增加到50wt%时,NF/TWRP复合材料的应力从112.1 MPa增大到161.6 MPa,而对应的应变从136.6%变化到13.2%。所得结论为使用TWRP进行功能化开发吸声材料提供了理论基础。     

玻璃纤维表面纳米SiO_2改性对GF/PCBT复合材料力学性能的影响

为研究玻璃纤维(GF)表面纳米SiO2改性对GF增强树脂基复合材料力学性能的影响,利用真空辅助模压(VAMP)工艺制备了不同含量的纳米SiO2表面改性GF增强聚环状对苯二甲酸丁二醇酯(PCBT)复合材料。分析了GF表面改性对GF/PCBT复合材料力学性能的影响,研究了纤维表面改性对GF/PCBT复合材料抗湿热老化性能的影响规律。纤维拔出试验结果表明:经表面处理的GF/PCBT复合材料的界面剪切强度提高了1.16倍;采用含量为0.5wt%和2wt%(与树脂质量比)的纳米SiO2处理GF表面后,复合材料的三点弯曲强度分别提高1.5倍和1.67倍,弯曲模量分别提高1.03倍和1.17倍。SEM结果显示:当纳米SiO2用量为2wt%时,破坏后的纤维表面被树脂完全覆盖,树脂与纤维粘结良好。在湿热条件下,由于纳米SiO2颗粒的存在,水分子很难通过界面相扩散到改性后的材料内部,其抗湿热性能提高。     

纳米SiO_2表面处理对MC尼龙复合材料结构与性能的影响

为提高MC尼龙的综合性能,采用KH-550硅烷偶联剂处理纳米SiO2,根据阴离子聚合反应制备MC尼龙SiO2纳米复合材料,探讨了表面处理纳米SiO2与熔体的作用机理,并进行复合材料的结构表征与性能测试.研究表明：纳米SiO2表面包覆硅烷偶联剂,其有机官能团氨基进攻聚合反应体系中酰亚胺结构的羰基,两者通过化学键实现界面结...     

稀土改性剂对玻璃纤维-SiO2/聚四氟乙烯复合材料性能的影响

采用不同的稀土改性剂（La、Ce、Pr、Nd和Sm）对SiO₂和玻璃纤维（GF）进行改性处理,SiO₂含量为55wt%,GF含量为2wt%。填料改性处理后与聚四氟乙烯（PTFE）分散液在高速分散机中混合,然后通过热压烧结法制得GF-SiO₂/PTFE复合材料。考察了不同的稀土改性剂对GF-SiO₂/PTFE复合材料吸水性、介电性能、热膨胀系数和力学性能的影响。采用FTIR手段对稀土La改性剂,未改性的填料和改性后的填料结构进行了测试。并用SEM和EDS对复合材料的断口形貌及表面处理前后填料的形貌进行观察和能谱分析。结果表明：由于稀土La的电子层结构比其他轻稀土更稳定,对阴离子的吸引作用比其他轻稀土强,稀土La改性剂比其他的稀土改性剂能更好地促进填料GF与PTFE界面粘合,改善GF-SiO₂/PTFE复合材料性能。GF-SiO₂/PTFE复合材料的介电性能受到La含量的影响,当La含量为0.3wt%时介电性能最佳。     

聚乙烯醇纤维增强钢渣粉-水泥复合材料基本力学性能及微观结构

通过掺加钢渣粉来制备聚乙烯醇（PVA）纤维增强钢渣粉-水泥基复合材料,从宏微观两个方面研究了这种复合材料的性能。考虑了基体材料的水胶比（0.25和0.35）、不同钢渣粉质量分数（0、30wt%、60wt%、80wt%）,采用抗压强度试验、薄板四点弯曲试验研究了PVA纤维增强钢渣粉-水泥基复合材料的基本力学性能变化规律及其在弯曲荷载作用下的裂缝控制能力,采用扫描电镜观测了破坏后试样的微观结构。结果表明,水胶比和钢渣粉掺量均可明显影响PVA纤维增强钢渣粉-水泥基复合材料的基本力学性能,在低水胶比条件下（水胶比为0.25）,钢渣粉掺量达到80wt%时,试样表现出较高的韧性指数和良好的裂缝控制能力,基本满足工程所需强度要求,水胶比为0.35时钢渣掺量不宜超过60wt%;同时,从节能减排的角度考虑,利用钢渣粉制备PVA纤维增强钢渣粉-水泥基复合材料是可行的。      

Preparation of alumina–silica–nickel nanocomposite by in situ reduction through sol–gel route

Ceramic based composites with dispersion of nano sized metal/metal carbide particles have generated wide technological interest for their improved mechanical properties — hardness, fracture strength as well as fracture toughness, superior electrical properties and magnetic properties. In the present investigation alumina–silica gels have been prepared along with nickel chloride and dextrose distributed in the nanometric pores of the gel. The gels are prepared with different molar proportions of alumina and silica containing 5 wt% of nickel chloride and 50 wt% excess dextrose. During heat treatment at a temperature of 9008C for half an hour in nitrogen atmosphere, nickel chloride is reduced to metallic nickel by in situ generated hydrogen in the silica–alumina matrix. X-ray analyses indicate that no nickel chloride reduction is possible upto 50 mol% silica in alumina–silica matrix. Beyond this range, higher the silica content, higher is the reduction of nickel chloride. The presence of metallic nickel has been substantiated further by SAD analysis. Particle size analysis based on X-ray diffraction as well as transmission electron micrograph shows the presence of nickel particles of size ,20 nm distributed in the alumina–silica nanocomposite.     

Effect of colloidal silica on the mechanical properties of fiber–cement reinforced with cellulosic fibers

The effect of colloidal silica on the hydration reaction of the Portland cement system and its effect on the resulting mechanical properties are not completely understood. Silica nanoparticles can affect the behavior and performance of fiber–cement, such as the calcium–silicate–hydrate gel of the matrix and the fiber–matrix interface bonding. The main objective of this study is to evaluate the effects of various contents of colloidal silica (0, 1.5, 3, 5, and 10 % w/w) on the microstructure and mechanical performance of cement composites reinforced with cellulosic pulp. Fiber–cement composites with unbleached eucalyptus Kraft pulp as the micro-fiber reinforcement were produced by the slurry dewatering technique followed by pressing. The average values of the modulus of rupture of the fiber–cement decreased with increasing colloidal silica content. However, the pullout of the fibers increased significantly in the fiber–cement composites with additions between 3 and 10 % w/w of colloidal silica suspension, as indicated in the scanning electron microscopy images and by the improvement in the energy of fracture values.