碳纳米管类型对CNTs/Lyocell复合纤维结构与性能的影响

分别采用单壁碳纳米管（SWNTs）和多壁碳纳米管（MWNTs）这两种碳纳米管（CNTs）制备不同的CNTs/Lyocell复合纤维,探讨了碳纳米管类型对复合纤维的结构与性能的影响。结果表明,碳纳米管类型并未影响CNTs/Lyocell纤维的结晶结构,质量分数为1%的SWNTs或MWNTs在Lyocell基体中分布都比较...     

一步法制备聚氨酯/碳纳米管复合泡沫材料及其性能

采用球磨法将碳纳米管分散到聚醚三元醇中,以水为发泡剂,采用一步法原位聚合制备了聚氨酯(PU)/碳纳米管(CNTs)复合泡沫材料,研究了发泡剂水的添加量和碳纳米管的含量对复合材料密度和性能的影响.结果表明,随水添加量的增加,泡沫材料的密度、压缩模量、拉伸模量以及断裂伸长率呈下降的趋势;碳纳米管的加入大幅度提高了材料的压缩...     

Hybrid carbon nanotube–carbon fiber composites with improved in-plane mechanical properties

In this study carbon nanotubes (CNTs) were grown on carbon fibers to enhance the in-plane and out-of-plane properties of fiber reinforced polymer composites (FRPs). A relatively low temperature synthesis technique was utilized to directly grow CNTs over the carbon fibers. Several composites based on carbon fibers with different surface treatments (e.g. growing CNTs with different lengths and distribution patterns and coating the fibers with a thermal barrier coating (TBC) layer) were fabricated and characterized via on- and off-axis tensile tests. The on-axis tensile strength and ductility of the hybrid FRPs were improved by 11% and 35%, respectively, due to the presence of the TBC and the surface grown CNTs. This configuration also exhibited 16% improvement on the off-axis stiffness. Results suggest that certain CNT growth patterns and lengths are more pertinent than the other surface treatments to achieve superior mechanical properties.     

Preparation and characterization of carbon nanotubes/aluminum matrix composites

2024Al matrix composite reinforced with 1 wt.% carbon nanotubes (CNTs) was fabricated by cold isostatic pressing, followed hot extrusion techniques. The microstructure characteristics and the distribution of carbon nanotubes in the aluminum matrix were investigated. The mechanical properties of the composite were measured at room temperature. Experimental results showed that CNTs were distributed homogeneously in the composite, and the interfaces of Al–CNTs bonded well. The grain size of the matrix was as fine as 200 nm, and with a small amount of CNTs additions, the elastic modulus and the tensile strength were enhanced markedly over those of the 2024Al matrix fabricated under the same process. The reasons for the increments could be due to the extraordinary mechanical properties of CNTs, the bridging and pulling out role of CNTs in the Al matrix composite.     

Effects of functional group of carbon nanotubes on mechanical properties of carbon fibers

The effects of surface functionalization of carbon nanotubes (CNTs) on the mechanical properties of carbon fibers (CFs) have been investigated. The surface functionalization of CNTs was carried out with a diazonium reagent. Compared to pure PAN, only the fluoro phenyl functionalized CNTs (F-Ph-CNT) incorporated PAN composites showed a significant increase up to 22 °C of T_g and displayed the second peak due to the interfacial interaction between F-Ph-CNT and PAN. Among the samples, 0.5wt% of F-Ph-CNT reinforced CFs exhibited a 46% increase in tensile strength (4.1 GPa) and a 37% increase in modulus (302 GPa), respectively compared to that of pure CFs.     

Multi-Wall Carbon Nanotubes/Styrene Butadiene Rubber (SBR) Nanocomposite

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high-quality and -quantity carbon nanotubes. The design parameters like the hydrogen flow rate; reaction time and reaction temperature were optimized to produce high yield and purity of Multi-Wall Carbon Nanotubes (MWCNTs). Multi-Walled Carbon Nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/styrene butadiene rubber (SBR) nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Using different percentages of carbon nanotubes from 1 wt% to 10 wt%, several nanocomposites samples were fabricated. Significant improvements in the mechanical properties of the resulting nanocomposites showed almost 10% increase in the Young's modulus for 1 wt% of CNTs and up to around 200% increase for 10 wt% of CNTs.     

Influence of particle size and particle size distribution on MICA filled nylon 6 composite

Particulate reinforced thermoplastic composites are designed to improve the properties and to lower the overall cost of engineering plastics. In this study the effects of particle size and particle size distribution on the properties of mica filled nylon-6 was investigated. Composites of nylon-6 with varying concentrations (viz. 5 to 40 wt%) of mica were prepared by twin screw extrusion. The composite showed improved mechanical, thermal as well dielectric properties on addition of filler.     

Mechanical behavior of self-assembled carbon nanotube reinforced nylon 6,6 fibers

The versatile electrospinning technique was used to successfully align and disperse multiwalled carbon nanotubes (MWCNT) in nylon 6,6 matrix to obtain composite fibers. The morphology of the composite fibers and the dispersion of the CNTs within the fibers were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. TEM analysis revealed that the CNTs were well-dispersed, separated and aligned along the fiber axis. The thermal and mechanical properties of the composite fibers were characterized as a function of weight fraction of the CNTs. Incorporation of the CNTs in the fibers resulted in an increase in glass-transition temperature (T_g) by ∼7 °C, indicating that the addition of CNTs has restricted the mobility of the polymer chains and provided confinement to neighboring molecular chains. Tensile and nanoindentation experiments were performed to investigate the mechanical deformation behavior of the composite fibers. The results suggested that incorporation of high strength and high aspect ratio CNTs into the fiber matrix enhanced significantly the stiffness and strength of nylon 6,6 fibers. An understanding of the structure–property relationships can provide fruitful insights to develop electrospun fibers with superior properties for miniaturized and load-bearing applications.     

Carbon nanotubes dispersed polymer nanocomposites: mechanical,electrical, thermal properties and surface morphology

The various properties and surface morphology of the carbon nanotubes (CNTs) dispersed polydimethyl siloxane (PDMS) matrix were studied to determine their usefulness in various applications. The tensile strength, Young’s modulus and electrical breakdown strength of CNT/polymer composites were 0.35 MPa, 1.2 MPa and 8.1 kV, respectively. The thermal conductivity and dielectric constant for the material having 4.28 wt% CNT were 0.225 W m^?1 K^?1 and 2.329, respectively. The CNT/polymer composites are promising functional composites with improved mechanical and electrical properties. The scanning electron microscope analysis of surface morphology of PDMS/CNT composite showed that the rough surface texture on nanocomposite has large surface area with circular pores. The Fourier transform infrared spectroscopy showed the functional groups present in polymer nanocomposite.     

Fabrication and characterization of carbon nanotube reinforced poly(methyl methacrylate) nanocomposites

Multiwall carbon nanotube (CNT) reinforced poly(methyl methacrylate) (PMMA) nanocomposites have been successfully fabricated with melt blending. Two melt blending approaches of batch mixing and continuous extrusion have been used and the properties of the derived nanocomposites have been compared. The interaction of PMMA and CNTs, which is crucial to greatly improve the polymer properties, has been physically enhanced by adding a third party of poly(vinylidene fluoride) (PVDF) compatibilizer. It is found that the electrical threshold for both PMMA/CNT and PMMA/PVDF/CNT nanocomposites lies between 0.5 to 1 wt% of CNTs. The thermal and mechanical properties of the nanocomposites increase with CNTs and they are further increased by the addition of PVDF For 5 wt% CNT reinforced PMMA/PVDF/CNT nanocomposite, the onset of decomposition temperature is about 17 degrees C higher and elastic modulus is about 19.5% higher than those of neat PMMA. Rheological study also shows that the CNTs incorporated in the PMMA/PVDF/CNT nanocomposites act as physical cross-linkers.     

碳纳米管增强镁基复合材料导热性能研究

镁及其合金是目前最轻的金属结构材料,合金化虽然提升了镁合金的力学性能,但导致其导热性能严重下降,限制了镁合金的应用。碳纳米管(CNTs)因具有优异的力学、热学等性能,是最理想的增强体之一,可以用于改善镁合金的力学性能和热学性能。采用粉末冶金法分别以纯Mg、Mg-9Al合金、Mg-6Zn合金为基体制备了不同CNTs含量的镁基复合材料,利用光学显微镜、扫描电子显微镜、透射电子显微镜对复合材料微观组织、基体与增强体界面及析出相进行表征,并对复合材料的拉伸性能和热学性能进行测试。研究结果表明,当CNTs质量分数不超过1.0%时,可提高纯镁基复合材料的导热性能,力学性能仅有稍微降低;将CNTs添加到Mg-9Al合金中,可以促进纳米尺度β-Mg 17 Al 12相在CNTs周围析出,降低了Al在Mg基体中的固溶度,使CNTs/Mg-9Al复合材料的导热性能有所提高。此外,在CNTs/Mg-6Zn复合材料界面处存在C原子和Mg原子的相互嵌入区,这种嵌入型界面不仅有利于复合材料力学性能的提高,也使CNTs起到加速电子移动的“桥”的作用,有利于该复合材料热导率的提高。当CNTs质量分数为0.6%时,CNTs/Mg-6Zn复合材料具有较为优异的热学性能和力学性能,其热导率为127.0 W/(m·K),抗拉强度为303.0 MPa,屈服强度为204.0 MPa,伸长率为5.0%。     

Enhancement in insulation and mechanical properties of PMMA nanocomposite foams infused with multi-walled carbon nanotubes

In this study, PMMA/CNTs composite materials with carboxyl-multi walled carbon nanotubes (c-MWNTs) or untreated MWNTs were prepared via in-situ bulk polymerization. The as-prepared PMMA/CNTs composite materials were then characterized by Fourier-Transformation infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The molecular weights of PMMA extracted from PMMA/CNTs composite materials and bulk PMMA were determined by gel permeation chromatography (GPC) with THF used as the eluant. The PMMA/CNTs composite materials were used to produce foams by a batch process in an autoclave using nitrogen as foaming agent. The cellular microstructure, insulation and compressive mechanical properties of PMMA/CNTs composite foams were also investigated in detail. Compared to neat PMMA foam, the presence of CNTs increases in cell density and reduces cell size. The insulation and compressive mechanical properties of PMMA/CNTs composite foams were found to improve substantially those of neat PMMA foam. In particular, 22.6% decrease in thermal conductivity, 19.7% decrease in dielectric constant and 160% increase in compressive modulus were observed with the addition of 0.3 wt% carboxyl-multi walled carbon nanotubes (c-MWNTs).     

Influence of carbon nanotube-polymeric compatibilizer masterbatches on morphological, thermal, mechanical, and tribological properties of polyethylene

Study was made of the effect of multiwall carbon nanotubes (MWCNTs) and polymeric compatibilizer on thermal, mechanical, and tribological properties of high density polyethylene (HDPE). The composites were prepared by melt mixing in two steps. Carbon nanotubes (CNTs) were melt mixed with maleic anhydride grafted polyethylene (PEgMA) as polymeric compatibilizer to produce a PEgMA-CNT masterbatch containing 20 wt% of CNTs. The masterbatch was then added to HDPE to prepare HDPE nanocomposites with CNT content of 2 or 6 wt%. The unmodified and modified (hydroxyl or amine groups) CNTs had similar effects on the properties of HDPE-PEgMA indicating that only non-covalent interactions were achieved between CNTs and matrix. According to SEM studies, single nanotubes and CNT agglomerates (size up to 1 μm) were present in all nanocomposites regardless of content or modification of CNTs. Addition of CNTs to HDPE-PEgMA increased decomposition temperature, but only slight changes were observed in crystallization temperature, crystallinity, melting temperature, and coefficient of linear thermal expansion (CLTE). Young’s modulus and tensile strength of matrix clearly increased, while elongation at break decreased. Measured values of Young’s moduli of HDPE-PEgMA-CNT composites were between the values of Young’s moduli for longitudinal (E₁₁) and transverse (E₂₂) direction predicted by Mori-Tanaka and Halpin-Tsai composite theories. Addition of CNTs to HDPE-PEgMA did not change the tribological properties of the matrix. Because of its higher crystallinity, PEgMA possessed significantly different properties from HDPE matrix: better mechanical properties, lower friction and wear, and lower CLTE in normal direction. Interestingly, the mechanical and tribological properties and CLTEs of HDPE-PEgMA-CNT composites lie between those of PEgMA and HDPE.     

熔融共混法制备羧基化多壁碳纳米管/PA66 复合纤维及其性能

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%。      

Experimental Study and Numerical Modelling of Low Velocity Impact on Laminated Composite Reinforced with Thin Film Made of Carbon Nanotubes

In this work, polymer laminated composites based on Epon 862 Epoxy resin, T300 6 k carbon fibers and carbon nanotubes (CNTs) were tested with the aim to elucidate the effect of CNTs on impact properties including impact force and capacity to absorb impact energy. The polymer matrix was reinforced by a random distribution of CNTs with fraction ranging from 0.5 to 4.wt%. Composite panels were manufactured by using the infusion process. Taylor impact test was used to obtain the impact response of specimens. Projectile manufactured from a high strength and hardened steel with a diameter of 20 mm and 1.5 kg of mass was launched by a compressed gas gun within the velocity of 3 m/s. Impact force histories and absorbed energy of specimens were recorded. A numerical model was employed to simulate the impact performance. This model has been accomplished by forming a user established subroutine (VUMAT) and executing it in ABAQUS software. Finally, the effect of CNTs amount on dynamic properties of laminated composites was discussed.     

碳纳米管增强聚合物复合材料力学性能及摩擦磨损性能研究进展

本文主要就近几年来碳纳米管、增强聚合物复合材料制备及其力学性能、摩擦磨损性能影响方面研究进展,作一简要介绍.     

Processing and characterization of TLCP fibers reinforced by 1?wt% MWCNT

A thermotropic liquid crystalline polymer (TLCP) blend with 1?wt% multiwall carbon nanotubes (MWCNTs) was prepared by melt compounding. Morphological observations of the blend show that the chemical-treated MWCNTs were well dispersed in the TLCP matrix with a good interface. MWCNTs have little effects on the thermal and rheological properties of pure TLCP. TLCP fibers with and without MWCNTs were prepared at certain drawing ratios by a melt spinning method. The degree of orientation of TLCP chains is enhanced by MWCNT micro-clusters during the fiber formation. The mechanical properties of TLCP/MWCNT fibers are significantly increased by 34.5?% for tensile strength and 38.0?% for tensile modulus in comparison with those of pristine TLCP fibers, due to the synergistic effects of MWCNT and TLCP.     

Viscoelastic properties of multi-walled carbon nanotube/epoxy composites using two different curing cycles

Along with carbon nanotubes (CNT) morphology, impurity, and functionalization, polymer curing cycle is another important factor in determining the mechanical properties of the CNT/polymer composite samples. This work investigates the effect of two different curing cycles on mechanical and thermo-mechanical properties of the nanotube in the composite in order to optimize the curing condition in term of time and temperature. Nanocomposite samples were prepared by mixing multi-wall carbon nanotubes with epoxy resin using sonication method. The mechanical and viscoelastic properties of the resulting composite samples were evaluated by performing tensile and dynamic mechanical thermal analyses (DMTA) test. The results indicate that the mechanical and viscoelastic properties of pure epoxy and composite samples have been affected by the condition curing process. Concerning viscoelastic modeling, the COLE–COLE diagram has been plotted by the result of DMTA tests. These results show a good agreement between the Perez model and the viscoelastic behavior of the composite.     

Processing and properties of poly(methyl methacrylate)/carbon nano fiber composites

Single wall carbon nanotubes, multi-wall carbon nanotubes, as well as carbon nano fibers (CNF) are being used for reinforcing polymer matrices. In this study, poly(methyl methacrylate) (PMMA) nanocomposites have been processed by melt blending, containing two different grades (PR-21-PS and PR-24-PS) of CNF manufactured by Applied Sciences Inc. The amount of nano fibers used was 5 and 10 wt%, respectively. The PMMA/CNF composites were processed into 4 mm diameter rods and 60 μm diameter fibers using small-scale melt spinning equipment. At 5 wt% CNF, composite rods as well as fibers show over 50% improvement in axial tensile modulus as compared to the control PMMA rod and fibers, respectively. The reinforcement efficiency decreased at 10 wt% CNF. The PMMA/CNF nanocomposite fibers also show enhanced thermal stability, significantly reduced shrinkage and enhanced modulus retention with temperature, as well as improved compressive strength. The CNF reinforcement efficiency has been analyzed using the modified Cox model.     

Comparing carbon nanotubes and graphene nanoplatelets as reinforcements in polyamide 12 composites

We investigate the influence of nanofillers including carbon nanotubes (CNTs) and graphene nanoplatelets on a thermoplastic engineering polymer, polyamide 12 (PA12). The comparison between these two important nanofillers as to how they influence the structure and properties of the polymer is systematically studied. The polymer-nanofiller composites were prepared using a twin-screw micro-extruder and the composite was thereafter hot pressed into thin films. The structure (using wide angle x-ray diffraction and differential scanning calorimetry) and properties (through tensile testing and conductivity measurement) of the thin films have been investigated. The composites incorporating surfactant showed the best CNT distribution and dispersion, causing an improvement of up to 80% in the toughness modulus over pure PA12. Electrical percolation could also be achieved at nanofiller concentrations of 1 to 2?wt%. In this study we observed that CNT fillers bring about more pronounced improvements in PA12 compared to graphene nanoplatelets, as far as mechanical and electrical properties are concerned.