纳米碳纤维在预应力混凝土结构中的增强作用研究

纳米碳纤维作为复合材料增强体,可改善混凝土的强度、弹性和耐久性等方面。文章在预应力混凝土材料中掺入不同质量分数的纳米碳纤维,制备了纳米碳纤维掺量改性预应力混凝土材料,探究纳米碳纤维在预应力混凝土结构中的增强作用。结果表明：随着纳米碳纤维掺量的增加,试样的抗压强度、抗折强度和劈裂抗拉强度呈现先上升后降低的趋势;预应力混凝土的磨损量呈现先下降后上升的趋势。当纳米碳纤维掺量为0.3%时,预应力混凝土的孔隙率和磨损量均为最低,分别为26.23%和1.2 kg/m2。因此,适量添加纳米碳纤维（质量分数为0.3%）可有效提高预应力混凝土的力学性能和磨损性能。     

电子束辐射接枝对PAN基碳纤维的表面改性

采用电子束加速器辐射接枝方法对聚丙烯腈(PAN)基碳纤维进行表面改性,研究了接枝单体种类对接枝率及其环氧树脂基复合材料力学性能的影响,分析了辐射接枝前后PAN基碳纤维的表面形貌与化学结构以及其复合材料界面断口的形貌变化。结果表明:电子束辐射接枝改性的PAN基碳纤维表面粗糙度增加,表面活性官能团增多,与树脂的机械锲合作用增强,其树脂基复合材料断口表而较为平整;乙二胺/水溶液体系是辐射接枝改性的理想溶液,在200 kGy的电子束辐射下,PAN基碳纤维表面的接枝率为6.66%,复合材料的层间剪切强度提高了45.1%。     

阳极氧化处理对PAN基碳纤维性能的影响

利用阳极氧化技术对聚丙烯腈(PAN)基碳纤维表面进行改性处理,研究了处理前后PAN基碳纤维表面润湿性能及力学性能的变化,分析了阳极氧化处理时电流强度对PAN基碳纤维及其增强环氧树脂基复合材料性能的影响。结果表明:阳极氧化处理后,PAN基碳纤维的润湿性提高,其中碳纤维与水、乙醇的接触角分别由处理前的64.6°,50.9°降至处理后的24.6°,28.1°,其表面能由未处理的37.4 m N/m提高到处理后的83.3 m N/m,经水洗干燥处理后,碳纤维润湿性及表面能有所降低;阳极氧化过程中,随着电流强度的提高,PAN基碳纤维的线密度及拉伸强度出现先升高后降低现象;阳极氧化处理后,碳纤维表面活性提高,碳纤维/环氧树脂基复合材料层间剪切强度较未处理时的最大增幅达到86%;阳极氧化处理PAN基碳纤维的最佳电流强度为14 A。     

短切碳纤维混凝土的力学强度实验与分析

为探究短切碳纤维对混凝土力学强度的影响机制,以C40和C50矿渣水泥混凝土为研究对象,考察了短切碳纤维长度和掺量对混凝土的抗压强度、劈裂抗拉强度和抗折强度的影响规律,特别是与不掺纤维混凝土的强度对比.实验结果表明,碳纤维的加入可使混凝土的力学强度有不同程度的提高,其中以抗折强度的增长最为明显,劈拉强度次之,而抗压强度比的增幅相对最小,在高纤维掺量时抗压强度甚至低于不掺纤维混凝土;纤维长度的增大对混凝土的力学强度增长更为有利,在低强度等级(C40)混凝土中的表现更为明显.力学分析认为,随机分布的短切碳纤维可显著提高混凝土对劈裂或弯折式破坏的抵抗作用,但对受压时所发生的剪切式破坏却难以发挥明显效果.     

短碳纤维的分散性与CFRC复合材料的力学性能

碳纤维增强水泥基复合材料(CFRC)是新发展起来的一种功能材料,制备CFRC复合材料过程中,碳纤维在水泥基体中的分散性直接影响CFRC复合材料的力学性能。借助超声波和分散剂羟乙基纤维素(HEC),实现了短碳纤维在水泥基体中的均匀分散。对所制备的CFRC复合材料的断口形貌,作了SEM观察和能谱分析;测试了试件的抗压强度和抗折强度。结果发现,水灰质量比为0.44,碳纤维均匀分散,其质量掺量为0.6%时,复合材料的抗压强度可提高20%,抗折强度提高129%。     

碳纤维含量对PMMA-PMA基复合材料显微结构及力学性能的影响(英文)

以甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)和丙烯酸甲酯(polymethyl acrylate,PMA)为原料、短切碳纤维(Cf)为增强相,采用悬浮聚合法制备碳纤维增强聚甲基丙烯酸甲酯-聚丙烯酸甲酯基复合材料(carbon fiber-reinforced polymethyl methacrylate-polymethyl acrylate matrix composites,Cf/PMMA-PMA)。研究碳纤维含量(质量分数,下同)对Cf/PMMA-PMA显微结构及力学性能(抗折强度、抗压强度和拉伸强度)的影响。结果表明:随碳纤维含量增加,Cf/PMMA-PMA的挠度呈线性增长,而抗折强度、抗压强度和拉伸强度呈先增大后减小趋势。当碳纤维含量为15%时,Cf/PMMA-PMA的抗折强度、抗压强度和拉伸强度分别达到最大值115.5、244.6MPa和158.6MPa。     

硅灰对碳纤维混凝土强度及电阻率影响研究

通过在碳纤维混凝土中加入硅灰,研究了硅灰对碳纤维混凝土抗压强度、抗折强度和劈裂强度的影响规律,同时研究了硅灰对碳纤维混凝土电阻率的影响作用。结果表明:碳纤维混凝土相对素混凝土,抗压强度降低了5.9%,抗折强度提高了25.8%,劈裂强度增加了了21.1%;加入硅灰后,碳纤维混凝土抗压强度、抗折强度和劈裂强度都有所增加;10%硅灰掺量时,抗压强度增加了39%,抗折强度提高了40.6%,劈裂强度提高了34.3%。加入硅灰后碳纤维混凝土电阻率也明显降低,3 d时两者电阻率降低了8.6Ω,随着时间的推移,差值越来越小。说明硅灰对碳纤维混凝土的电阻率也有明显作用,进一步证明了加入硅灰可以有效提高碳纤维在混凝土中的分散性。     

异氰酸酯基偶联剂改性PAN基碳纤维增强聚三唑复合材料的研究

采用异氰酸酯基偶联剂(A1)对聚丙烯腈(PAN)基碳纤维表面进行处理,制备了碳纤维增强聚三唑(PTA)复合材料;考察了偶联剂A1改性PAN基碳纤维的工艺;对比了溶剂丙酮中水分的影响。结果表明:工业丙酮为溶剂时,加入偶联剂A1缩短了PTA树脂胶液贮存期,需现配现用;偶联剂A1处理PAN基碳纤维,预处理法使T700碳纤维布/增强复合材料剪切强度提高39.2%,迁移法提高9.5%,相比用分析纯丙酮为溶剂的体系,改性效果降低;偶联剂A1在PAN基碳纤维表面生成脲类等极性化合物,增强了与树脂基体的氢键吸附,改善了复合材料的界面粘结,但工业丙酮中的水分消耗了偶联剂的作用基团,过量的杂质削弱了偶联剂与纤维的化学作用。     

碳纤维水泥基复合材料力电性能及尺寸效应研究进展

碳纤维水泥基复合材料(CFRC)是一种新型功能材料,既可作为结构材料又可作为智能材料,与普通混凝土相比,它不仅具有纤维增强所带来的较高的抗拉、抗压、抗折强度与韧性,还具有相对较小的电阻率与力电机敏性等优越性能。本文介绍了碳纤维水泥基复合材料的制备方法、力电性能、应用及其尺寸效应的最新研究进展,展望了其在功能材料方面的研究应用前景。     

三维针刺C/SiC复合材料的结构特征和力学性能

采用化学气相渗透法制备了在厚度方向上具有纤维增强的三维针刺碳纤维增强碳化硅(C/SiC)陶瓷基复合材料,复合材料的密度和气孔率分别为2.15 h/cm3和16%.三维针刺C/SiC复合材料中的针刺纤维将各层紧密结合在一起,其层间抗剪切强度显著提高,为95MPa,比二维碳布叠层C/SiC复合材料的剪切强度(35MPa)高171.4%.三维针刺C/SiC复合材料的拉伸强度和弯曲强度分别为159MPa和350MPa,断裂模式为非脆性断裂,包括:裂纹扩展、偏转,碳纤维的拉伸断裂和逐步拔出.     

Pultruded fiber-reinforced poly(methyl methacrylate) composites. II. Static and dynamic mechanical properties,environmental effect,and postformability

This paper presents a novel process developed to manufacture poly(methyl methacrylate) (PMMA) pultruded composite. The mechanical, thermal, and dynamic mechanical properties, environmental effect, postformability of various fiber (glass, carbon, and Kevlar 49 aramid fiber) reinforced pultruded PMMA composites have been studied. Results show mechanical properties (i.e., tensile strength, specific tensile strength, tensile modulus, and specific flexural strength) and thermal properties (HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest specific tensile strength and HDT, carbon fiber/PMMA composites show the highest tensile strength and tensile modulus, and glass fiber/PMMA composites show the highest specific flexural strength. Pultruded glass-fiber-reinforced PMMA composites exhibit good weather resistance. These composite materials can be postformed by thermoforming under pressure, and mechanical properties of postformed products can be improved. The dynamic shear storage and loss modulus (G′, G″) of pultruded glass-fiber-reinforced PMMA composites increased with decreasing pulling rate, and their shear storage moduli are higher than those of pultruded Nylon 6 and polyester composites.     

纤维混掺改性高强自密实混凝土试验与分析

为研究不同结构层次纤维混掺对混凝土力学性能的改善作用,以镀铜微丝钢纤维和纳米碳纤维的掺量为参数,设计制备了纤维混掺改性高强自密实混凝土.试验表明:相较对照组,纤维改性混凝土的工作性能略有降低,而力学性能有不同幅度的提高,立方体抗压、轴压、劈裂、抗折强度的最大增幅分别为18.52％、21.10％、57.17％和54.40％.将数值分析与非线性回归结合,获得非样本纤维掺量下混凝土强度分析值的基础上,确定不同纤维的最优掺量.研究结果显示:适当掺量且分散良好的镀铜微丝钢纤维和纳米碳纤维混掺对高强自密实混凝土抗压、劈拉及抗折强度的提高分别存在超叠加、叠加及负混杂效应.     

碳纳米管定向排列增强碳纤维/环氧树脂复合材料制备及力学性能

采用高频电场诱导法制备了碳纳米管定向有序填充的碳纤维/环氧树脂复合材料。研究了电场频率对复合材料力学性能的影响规律,对复合材料的显微形貌进行观察。结果表明:在富树脂区碳纳米管沿着电场方向存在明显的有序排列现象;高频电场诱导后复合材料的层间剪切强度最大提高28.9%,压缩强度提高28.83%,弯曲强度提升15.01%,断口粗糙度增加,树脂与碳纤维的界面结合状态改善。     

碳玻混编单向复合材料的性能分析

采用碳纤维质量含量分别为7.4%、10.7%、13.8%的三种碳玻层间混编单向织物制备了纤维增强环氧树脂复合材料,分析了该类材料的力学性能与工艺性能。结果表明:碳玻层间混编复合材料的0°拉伸模量和0°压缩模量均随碳纤维含量的提高而升高,掺入碳纤维后碳玻混杂复合材料的0°拉伸强度比纯玻纤复合材料的有所降低,但随碳纤维含量的增加而升高,碳玻层间混编复合材料的0°压缩强度则没有明显的变化规律;掺入碳纤维后,碳玻层间混编复合材料的90°拉伸强度和模量均有所下降;低碳纤维含量的碳玻层间混编单向织物具有良好的Z向渗透性能。该类新材料未来有望在风电叶片结构减重和成本优化上发挥重要作用。     

酸化石墨烯改性环氧树脂及其碳纤维复合材料力学性能研究

针对石墨烯在复合材料增强增韧上的应用,对石墨烯进行了酸化处理,采用超声分散方法制备酸化石墨烯/环氧树脂(EP)浇注体,并在此基础上制备了酸化石墨烯/碳纤维(CF)/环氧树脂(EP)复合材料。分别利用红外光谱和透射电镜表征了酸化石墨烯表面结构和微观形貌,利用拉伸、弯曲、冲击等机械测试手段评价了酸化石墨烯改性EP和CF-EP的力学性能,并利用扫描电镜对复合材料拉伸断面形貌进行观察。试验结果表明:石墨烯酸化处理后,成功在表面引入了羟基、羧基等极性基团;酸化石墨烯可对EP和CF/EP进行有效增强增韧,当其添加量为0.2wt%时,EP拉伸强度和冲击强度分别提高了23.3%和109.8%,CF/EP拉伸强度、弯曲强度分别提高了6.0%和10.6%,当酸化石墨烯添加量为0.5wt%时,CF/EP复合材料层间剪切强度提高了7.4%。微观形貌分析表明,酸化石墨烯对CF/EP增强改性主要是通过对EP进行增强增韧,同时提高CF和EP之间的界面性能来实现的。     

环氧树脂/短切碳纤维复合材料性能研究

制备出了短切碳纤维增强TDE-85环氧树脂复合材料,研究了碳纤维的含量对复合材料力学性能和耐热性能的影响。结果表明,碳纤维的加入有利于复合材料力学性能和耐热性能的提高,并在碳纤维含量为0.25%时,复合材料的拉伸强度、冲击韧性、弯曲强度和弯曲模量达到最大,分别提高了29.33%、25.31%、30.28%和68.93%。此外,对复合材料的弯曲断裂面进行了微观形貌分析,结果表明一定量的碳纤维可以较好地分散在树脂基体中,同时,碳纤维原丝和树脂基体的界面结合比较弱,主要依赖于两相之间的物理嵌合。     

Evaluation of fiber surfaces treatment and sizing on the shear and transverse tensile strengths of carbon fiber-reinforced thermoset and thermoplastic matrix composites

The mechanical performance of advanced composite materials depends to a large extent on the adhesion between the fiber and matrix. This is especially true for maximizing the strength of unidirectional composites in off-axis directions. The materials of interest in this study were PAN-based carbon fibers (XA and A4) used in combination with a thermoset (EPON 828 epoxy) and a thermoplastic (liquid crystal poymer) matrix. The effect of surface treatment and sizing were evaluated by measuring the short-beam shear (SBS) and transverse flexural (TF) tensile strengths of unidirectional composites. Results indicated that fiber surface treatment improves the shear and trasverse tensile strengths for both thermosetting and thermoplastic matrix/carbon fiber-reinforced unidirectional composites. A small additional improvement in strengths was observed as the result of sizing treated fibers for the epoxy composites. Scanning electron microscope photomicrographs were used to determine the location of composite failure, relative to the fiber-matrix interface. Finally, the epoxy composites SBS and TF strengths appear to be limited to the maximum transeverse tensile strength of the epoxy matrix, while the thermoplastic composite SBS and TF strengths are limited by the LCP matrix shear and transverse tensile strengths, respectively.     

Pultruded fiber reinforced thermoplastic poly(methyl methacrylate) composites. Part II: Mechanical and thermal properties

A novel process has been developed to manufacture poly(methyl methacrylate) (PMMA) pultruded parts. The mechanical and dynamic mechanical properties, environmental effects, postformability of pultruded composites and properties of various fiber (glass, carbon and Kevlar 49 aramid fiber) reinforced PMMA composites have been studied. Results show that the mechanical and thermal properties (i.e. tensile strength, flexural strength and modulus, impact strength and HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest impact strength and HDT, while carbon fiber/PMMA composites show the highest tensile strength, tensile and flexural modulus, and glass fiber/PMMA composites show the highest flexural strength. Experimental tensile strengths of all composites except carbon fiber/PMMA composites follow the rule of mixtures. The deviation of carbon fiber/PMMA composite is due to the fiber breakage during processing. Pultruded glass fiber reinforced PMMA composites exhibit good weather resistance. They can be postformed by thermoforming, and mechanical properties can be improved by postforming. The dynamic shear storage modulus (G′) of pultruded glass fiber reinforced PMMA composites increased with decreasing pulling rate, and G′ was higher than that of pultruded Nylon 6 and polyester composites.     

黄麻纤维增强聚丙烯的力学性能

本文讨论了注塑成型黄麻纤维增强聚丙烯的制备方法和力学性能.将纤维重量含量分别为10%、20%和30%的复合材料进行比较,分析纤维含量对复合材料拉伸、弯曲和冲击性能的影响;将纤维分别切成约3mm、5mm和10mm长制成复合材料进行比较,分析纤维长度对复合材料拉伸、弯曲和冲击性能的影响.掺入黄麻纤维能使聚丙烯的拉伸和弯曲性能提高,但使其冲击强度降低;随纤维含量的增加或纤维长度的增加,复合材料的强度和模量是递增的,而冲击强度是递减的.     

Mechanical properties of pineapple leaf fiber-reinforced polyester composites

Pineapple leaf fiber (PALF) which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. The present study investigated the tensile, flexural, and impact behavior of PALF-reinforced polyester composites as a function of fiber loading, fiber length, and fiber surface modification. The tensile strength and Young's modulus of the composites were found to increase with fiber content in accordance with the rule of mixtures. The elongation at break of the composites exhibits an increase by the introduction of fiber. The mechanical properties are optimum at a fiber length of 30 mm. The flexural stiffness and flexural strength of the composites with a 30% fiber weight fraction are 2.76 GPa and 80.2 MPa, respectively. The specific flexural stiffness of the composite is about 2.3 times greater than that of neat polyester resin. The work of fracture (impact strength) of the composite with 30% fiber content was found to be 24 kJ m⁻². Significant improvement in the tensile strength was observed for composites with silane A172-treated fibers. Scanning electron microscopic studies were carried out to understand the fiber-matrix adhesion, fiber breakage, and failure topography. The PALF polyester composites possess superior mechanical properties compared to other cellulose-based natural fiber composites. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1739–1748, 1997