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1.
碳纳米管增强PA6纤维的性能   总被引:9,自引:0,他引:9  
将碳纳米管(CNT)在分散剂或分散剂和聚合物(PA6)载体中处理后制备出两种母粒,将其作为增强材料分别和PA6切片熔融共混纺丝,制备出碳纳米管的增强PA6纤维,研究其结构和力学性能.CNT含量低于0.5%(质量分数)时,使用两种母粒制备出的纤维强度和模量都提高,NT含量为0.03%时增强的效果最好.由碳纳米管和分散剂组成的母粒增强效果更好,NT的含量为0.03%时就能使PA6纤维的强度和模量分别提高23%和76%.这种增强纤维是一种微纤增强纤维,纳米CNT在纤维中均匀分散且沿着纤维轴的方向取向.这种结构能有效地转移载荷,具有增强作用,且取向性越好,增强效果越好.  相似文献   

2.
流体排布法是实现碳纳米管定向排列的一种简单的方法。采用流体排布法在具有浸润性图案化的基底上成功地对单壁碳纳米管(SWNTs)束进行了水平方向上的排布。将SWNTs悬浮液滴入光刻胶制成的微通道中,在流体剪切力作用下,弯曲的SWNTs在一定程度上会被拉伸并且平行地排列在纳米级宽度的微通道中。将排列好的SWNTs阵列转移到一些不同间距的金电极对上面,制作成碳纳米管场效应晶体管(CNTFET)。CNTFET的电性能测试结果表明,制备的SWNTs束可以制造出不同电极间距同时具有良好电性能的CNTFET。  相似文献   

3.
Alumina reinforced with 1 wt% single-wall carbon nanotubes (SWNTs) was fabricated by hot-pressing. The fracture toughness of SWNTs/Al2O3 composite reaches 6.40 ± 0.3 MPa m1/2, which is twice as high as that of unreinforced alumina. Nanoindentation introduced controlled cracks and the damage were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SWNTs reinforcing mechanisms including CNT pullout, CNT fracture, CNT bridging and crack deflection were directly observed, and the relationship between carbon nanotubes microstructures in the matrix and mechanical properties was also discussed in detailed.  相似文献   

4.
《Composites Part B》2013,44(8):3281-3287
Agglomerate structure of nano-fillers in polymer composite definitely plays a key role in the functionalization of nanocomposite. As nano-fillers are prone to agglomerating, the agglomerate structure is unstable and will experience a remarkable evolution in the melt state of the composite. In this work, the influence of melt annealing on the microstructure of multi-walled carbon nanotubes/poly(vinylidene fluoride) composites has been investigated by a combination of rheological behavior and electrical properties. The simultaneous measurement, which is combined with investigations of rheological behavior and resistance, reveals that the evolution of microstructures during melt annealing shows a significant effect on both the viscoelasticity and electrical conductivity of composites. Besides, a watershed behavior is found for the evolution of microstructure in samples with the content of MWCNTs higher and lower than the electrical percolation threshold (φC) during annealing. Particularly, samples with the content of MWCNTs above φC exhibit a noteworthy increment in storage modulus and a dramatic decrease in resistance, while those with the content of MWCNTs below φC display a quick decrease in electrical conductivity and only a slight increment in storage modulus.  相似文献   

5.
Agglomerate structure of nano-fillers in polymer composite definitely plays a key role in the functionalization of nanocomposite. As nano-fillers are prone to agglomerating, the agglomerate structure is unstable and will experience a remarkable evolution in the melt state of the composite. In this work, the influence of melt annealing on the microstructure of multi-walled carbon nanotubes/poly(vinylidene fluoride) composites has been investigated by a combination of rheological behavior and electrical properties. The simultaneous measurement, which is combined with investigations of rheological behavior and resistance, reveals that the evolution of microstructures during melt annealing shows a significant effect on both the viscoelasticity and electrical conductivity of composites. Besides, a watershed behavior is found for the evolution of microstructure in samples with the content of MWCNTs higher and lower than the electrical percolation threshold (φC) during annealing. Particularly, samples with the content of MWCNTs above φC exhibit a noteworthy increment in storage modulus and a dramatic decrease in resistance, while those with the content of MWCNTs below φC display a quick decrease in electrical conductivity and only a slight increment in storage modulus.  相似文献   

6.
A new vertical floating catalytic technique is developed and used to prepare both single-walled carbon nanotubes (SWNTs) and carbon fibers (CFs). Scanning electron microscopy (SEM) observation shows a clear separation of these two materials. Thin films of SWNTs can be peeled easily from the CF substrate which just acts as a catalyst support for the SWNT growth. The production process is also semicontinuous, resulting in a yield of ∼1.0 g h−1 of SWNTs film with high purity. Structure and vibrational properties of these materials are investigated by electron microscopy and Raman spectroscopy, respectively.  相似文献   

7.
8.
Carbon nanotube based epoxy composites have been fabricated at room temperature and refrigeration process using sonication principle. Flexural moduli, electrical conductivity, glass transition temperature of epoxy resin as well as nanocomposite samples have been determined. Distribution behaviour of carbon nanotubes in the epoxy matrix was examined through scanning electron microscopy. Composite samples showed better properties than resin samples due to strengthening effect of the filled nanotubes. Refrigerated nanocomposites obtained increasing mechanical property because of better dispersion due to low temperature settlement of polymers. Improvement of electrical conductivity was due to the fact that aggregated phases form a conductive three-dimensional network throughout the whole sample. The increasing glass transition temperature was indicative of restricting movement of polymer chains that ascribe strong interaction presented between carbon nanotubes and epoxy chains that was again supplemented by Raman study and SEM.  相似文献   

9.
S.W. Ko 《Materials Letters》2009,63(11):861-863
Polymer coated nano-sized magnetite (Fe3O4) particles with multiwalled carbon nanotube (MWNT) nanohybrid were prepared by four step procedures in this study. Initially, magnetic particles were synthesized by a co-precipitation method with ammonium hydroxide and oleic acid, and then the produced particles were coated with polyacrylamide (PAAm). Finally PAAm coated magnetite particles (Mag-PAAm) were physically adsorbed onto multiwalled carbon nanotubes (MWNT) under ultrasonication. Transmission electron microscopy (TEM) was used to investigate the formation of Mag-PAAm-MW nanohybrids nanostructure, confirming that prepared Mag-PAAM particles were well adsorbed onto the surfaces of MWNT. In addition, MR characteristics of PAAm coated magnetite particles with MWNT (Mag-PAAm-MW) nanohybrids were investigated under six different external magnetic field strengths via a rotational rheometer, exhibiting typical MR behavior of yield stress and shear stress.  相似文献   

10.
Using the polymer blending method, conductive materials and waterborne polyurethane (WPU) were mixed to fabricate conductive composite films for application in electromagnetic shielding. First, nitric acid was used to purify the multi-walled carbon nanotubes (MWCNT). Second, sodium dodecyl sulfate (SDS) was utilized to disperse the carbon nanotubes, and then they were mixed with 8 microm diameter and 2 mm long stainless steel fibers (SSF) in the WPU by the polymer blending method. Finally, the thickness of 0.25 mm of conductive composite film was fabricated by means of coating. According to the ASTM D4935-99 standard, a coaxial transmission line was used to measure the electromagnetic shielding effectiveness (EMSE) of conductive composite film within the range of 50 MHz approximately 3.0 GHz. Moreover, the influence of the prior and posterior dispersion of carbon nanotubes dispersed on electromagnetic shielding was dealt with in the paper. Results demonstrated that the conductive composite film, within 50 MHz approximately 3.0 GHz, fabricated by the 15 wt% of the multi-walled carbon nanotubes and 30 wt% of the stainless steel fibers can achieve the maximum of the electromagnetic shielding effectiveness, 34.86 dB, and its shielding effect, 99.9%.  相似文献   

11.
采用熔融共混法制备了不同质量分数的羧基化多壁碳纳米管(CMWNTs)/聚己二酸己二胺(PA66)切粒, 并将切粒熔融纺丝制成CMWNTs/PA66复合纤维。 采用SEM、 DMA和单纤维电子强力仪等研究了CMWNTs对复合纤维形貌和力学性能的影响。CMWNTs在纤维中沿纤维轴向束状分布均匀。CMWNTs的加入提高了PA66纤维的力学性能和玻璃化温度。CMWNTs的质量分数为0.5%时, CMWNTs/PA66复合纤维的储能模量最大, 为PA66纤维的5.5倍; 玻璃化温度提高了27.6℃。CMWNTs的质量分数为0.3%时, 复合纤维的初始模量最大, 比PA66纤维增加了101.4%。当CMWNTs的质量分数为1%时, 复合纤维的断裂强度最大, 与纯PA66相比增加了48.8%。   相似文献   

12.
Optimum distribution of multi-walled carbon nanotubes (MWCNTs) within a polymer composite micro-beam is sought to achieve its highest natural frequencies given a weight percent (wt.%) of MWCNTs. To this end, the micro-beam is divided into ten segments which are perfectly bonded to their neighbors. Each segment is made of low-viscosity, thermosetting polyester epoxy/amine resin LY-5052 and is reinforced by MWCNTs. A computer program, written in the Python programming language, is compiled with ABAQUS to generate a three-dimensional (3D) finite element (FE) model of the micro-beam and subsequently to evaluate an optimum CNT distribution under various vibration modes and boundary conditions. The influence of uniform and optimum MWCNT distributions on the natural frequencies, mode shapes and equivalent stiffness of the micro-beams is investigated and the results are compared with those of the pure polymer micro-beam. Subsequently, after acquiring the optimum distribution of the MWCNTs, two new CNT dispersion functions are proposed for maximizing fundamental frequencies of the clamped-free and clamped–clamped micro-beams. The results of the FE analysis reveal that the optimal reinforcement distribution pattern significantly depends on vibration mode shapes, particularly the micro-beam curvature under each mode. It is observed that fundamental frequencies of clamped-free, clamped-guided and clamped–clamped micro-beams are enhanced up to 15.9%, 13.1% and 12.6%, respectively, by choosing optimum MWCNT distribution profiles along the micro-beam length.  相似文献   

13.
Carbon nanotubes were used to modify a polyacrylonitrile (PAN) polymer solution before the manufacture of the carbon fiber precursor. The modified PAN fibers were spun from a dimethylformamide solution containing a small amount of single-walled carbon nanotubes. The fibers were characterized by thermogravimetry and optical and scanning electron microscopy. Structure, morphology, and selected properties of the composite polymeric fibers and the fibers after carbonization are characterized. The mechanical properties of the fibers are examined. It is found that nanotubes in the PAN solution have a strong tendency to form agglomerates that inhibit suitable macromolecular chain orientation of the carbon fiber precursor. Fibers manufactured from such a solution have similar mechanical properties to those from a pure PAN precursor, and after carbonization the resultant carbon fibers are very weak. A comparison of pure carbon fibers and those containing nanotubes reveals slight differences in their structural ordering.  相似文献   

14.
Double-walled carbon nanotubes (DWNTs) may be interesting in many applications since the outer wall would provide an interface with the rest of the system, without modifying the inner wall. CNT-Fe/Fe3C-Al2O3 composite powders containing carbon nanotubes (CNTs) (65% of which are DWNTs) are prepared by reduction of an oxide solid solution in a H2-CH4 gas mixture. The powders and CNTs are studied by both local and macroscopical techniques. The influence of the reducing atmosphere composition and of the dwell time at 1050 degrees C is studied. There is a 6-fold increase in CNT content upon the increase in the CH4 content from 3 to 30 mol.%, but the formation of undesirable carbon nanofibers can also be promoted. A CH4 content of 12-18 mol.% is adapted for the particular iron content in these powders. Increasing the dwell time at 1050 degrees C results in the formation of CNTs with more walls.  相似文献   

15.
Carbon nanotubes (CNT) and short carbon fibers were incorporated into an epoxy matrix to fabricate a high performance multiscale composite. To improve the stress transfer between epoxy and carbon fibers, CNT were also grown on fibers through chemical vapor deposition (CVD) method to produce CNT grown short carbon fibers (CSCF). Mechanical characterization of composites was performed to investigate the synergy effects of CNT and CSCF in the epoxy matrix. The multiscale composites revealed significant improvement in elastic and storage modulus, strength as well as impact resistance in comparison to CNT–epoxy or CSCF–epoxy composites. An optimum content of CNT was found which provided the maximum stiffness and strength. The synergic reinforcing effects of combined fillers were analyzed on the fracture surface of composites through optical and scanning electron microscopy (SEM).  相似文献   

16.
High-density polyethylene (HDPE) composite films filled with carbon fibers (CF), carbon nanotubes (CNT) as well as hybrid filler of CF and CNT were prepared by melt mixing. The electrical and self-heating properties of the composite films were investigated. Results showed that: when the total content of filler was the same, (i) the electrical resistivity of composite films filled with hybrid fillers was lower than those with single filler; (ii) the composite films filled with hybrid fillers displayed more excellent self-heating performance such as a higher surface temperature (T s), a more rapid temperature response, and a better thermal stability. This indicates the synergetic effect of combination of CNT and CF on improvement of the electrical and self-heating properties of HDPE-based composite films. The synergy can be considered to be the result of the fibrous filler CF acting as long distance charge transporters and the CNT serving as an interconnection between the fibers by forming local conductive paths.  相似文献   

17.
18.
The heat capacity and thermal diffusivity of a polymer composite based on multiwalled carbon nanotubes (95%), produced by electrospinning in the temperature range of 300 ≤ Т < 450 K, are investigated during heating and cooling. Temperature hystereses are detected characteristic of first-order phase transitions.  相似文献   

19.
碳纳米管(CNTs)被修饰后表面接枝上聚丙烯腈(PAN),采用溶液聚合法合成复合纺丝液,并利用湿法纺丝技术制备PAN/CNTs初生复合纤维。采用FT-IR,HRTEM,TG等方法分析CNTs表面修饰前后状况,用XRD和SEM分析接枝CNTs对PAN初生纤维结构的影响。结果表明:CNTs表面成功接枝上PAN,二者之间具有较强的相互作用力,接枝CNTs的加入使PAN初生纤维的结晶度从36.92%提高到38.81%,晶粒尺寸从4.40nm增大到4.89nm,初生复合纤维的断面结构更加细化。  相似文献   

20.
An anisotropically conductive polymer composite (ACPC) based on carbon nanotubes (CNTs) and polycarbonate (PC)/polyethylene (PE) blend was fabricated via a slit die extrusion-hot stretch process. Under the influence of the shear flow and hot stretch, the PC phase is in situ deformed into aligned conductive fibrils in the PE matrix, whose surface region holds the majority of CNTs. When the stretch ratio rises to a certain level, the resistivity of the ACPC shows a strong anisotropy of three orders of magnitude difference between the perpendicular and parallel stretch directions. The fibrillar ACPC shows a weak positive temperature coefficient (PTC) effect, and two-process negative temperature coefficient (NTC) effect caused by the reorganization of PC fibrils below but near 230 °C, and the transformation from anisotropy to isotropy beyond 230 °C. The obtained ACPC allows it to have such potential applications as switch and sensor materials.  相似文献   

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