共查询到20条相似文献,搜索用时 15 毫秒
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Unidirectional carbon fiber stitched composites were subjected to off-axis compression under static and low-velocity impact loading. Specimens were cut such that the fibers were at angles of 15°, 30°, 45° and 60° to the direction of loading. A modified compression fixture was used to carry out the tests. Static tests were carried out on a hydraulically activated MTS loading frame, where specimens were subjected to displacement controlled loading. Low-velocity impact tests were conducted on a drop tower facility. A three-strain-gauge rosette was used to measure global strains. Load was measured using a load cell. Owing to the unique microstructure of the specimens, a modified three-parameter characterization of the inelastic response was used, and the constants associated with this characterization were determined uniquely. Independently, Iosipescu shear tests were carried out to determine the shear response of the material under static and low-velocity impact conditions. The shear response so determined was checked against the off-axis test results. It is shown that rate-dependent interfacial effects are predominant in these materials. Polym. Compos. 25:397–406, 2004. © 2004 Society of Plastics Engineers. 相似文献
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Evgenia Kollia Xrisoula Saridaki Dimitrios Karagiannis Vassilis Kostopoulos 《应用聚合物科学杂志》2020,137(13):48787
Present work investigates the effect of hydrothermal aging of flax fiber-reinforced bio-based epoxy resin laminates on the mechanical and thermomechanical properties of the composites. Three different types of bio-based resins were used. Plates reinforced with eight layers plain weave flax fibers of 150 g/m2, manufactured using Resin Transfer Molding (RTM), compression molding or autoclave technique depends on type of the resin. One dimensional Fickian behavior shows a good fitting to the experimental data derived from weight measurements. The water uptake at the equilibrium state in the case of 60 °C temperature was slightly greater than that at 40 °C. The mechanical properties after hydrothermal aging show a significant reduction and do not return to their initial values even after the drying process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48787. 相似文献
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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 相似文献
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Valery P. Privalko Dmitry I. Sukhorukov Jozsef Karger-Kocsis 《Polymer Engineering and Science》1999,39(8):1525-1533
Model composites of polycarbonate (PC) containing single, multiple and chopped carbon fibers (CF) with and without and epoxy sizing were prepared by hot pressing. The thermoelastic behavior of model CF/PC composites was characterized by stretching calorimetry at room temperature. For small strains ? (i.e., ? ≈ 0.01) the specific mechanical work, specific heat effects and specific internal energy changes ΔU were completely reversible in stretching/contraction cycles and quantitatively obeyed the standard relationships for elastic solids. Young's moduli E and ΔU were significantly higher, whereas the linear thermal expansivities αL were lower for model CF/PC composites compared to those for the neat PC. Smaller values of the above parameters for composites reinforced with sized CF suggested weaker CF/PC interfacial interactions. Current theoretical models of thermoelastic properties of composite materials suggest the existence of unusually stiff, highly oriented PC structures in fairly thick boundary layers around CF. The onset of inelastic deformation, as well as mechanical failure in CF/PC model composites at significantly smaller strains compared to the neat PC were tentatively explained by the yield and subsequent plastic flow of the matrix polymer initiated by heat effects of fiber fragmentation processes, and by higher concentration of microvoids generated in fiber fragmentation/debonding events, respectively. 相似文献
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炭纤维增强水泥基复合材料(CFRC)的电磁性能 总被引:1,自引:0,他引:1
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。 相似文献
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Carbon fiber (CF)/ultra-high modulus polyethylene (UHMPE) fiber hybrid composites were fabricated using vinyl ester resin as a matrix. Interfacial adhesion of carbon fiber/vinyl ester composites and UHMPE fiber/vinyl ester composites as model composites was optimized using low temperature plasma treatment. Interlaminar shear strengths of carbon fiber/vinyl ester and UHMPE fiber/vinyl ester homocomposite were greatly increased by plasma and silane coupling agent treatment. From the result of the impact test, total absorbed energy of carbon fiber/UHMPE fiber hybrid composites was correlated with laminating sequences at optimized interfacial adhesion between the reinforcing fiber and matrix resin. UHMPE fiber layers of hybrid composites played an important role in absorbing energy. Elastic and plastic deformation of UHMPE fiber layers also played a key role in improving the impact properties of carbon fiber/UHMPE fiber hybrid composites. 相似文献
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The current study examines the tribological performance of polyimide and carbon fiber reinforced polyimide (CF/PI) under dry sliding condition. Different contents of carbon fibers were employed as reinforcement. All filled and unfilled polyimide composites were tested against CGr15 ball and representative testing was performed. The effects of carbon fiber content on tribological properties of the composites were investigated. The worn surface morphologies of neat PI and its composites were examined by scanning electron microscopy and the wear mechanisms were discussed. Moreover, all filled polyimides have superior tribological characteristics to unfilled polyimides. The optimum wear reduction was obtained when the content of carbon fiber is 20 vol %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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用碳纤维(CF)作增强相、氯丁橡胶(CR)作基相及硅烷偶联剂作相容剂,制备了CF/CR复合材料,考察了CF用量、硅烷偶联剂的种类及用量、硫化条件对复合材料热老化前后性能的影响,并用扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)仪对其结构进行了表征。结果表明,制备CF/CR复合材料的最佳配方为:CR 100份,CF 12份,KH 550 2.5份;最佳硫化条件为:温度175℃,压力10 MPa,时间30 min。SEM和FTIR分析表明,KH 550处理的CF比未处理及用Si 69处理的CF与CR的相容性更好。 相似文献
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《Ceramics International》2016,42(10):11568-11573
Thermoelectric properties of carbon fiber reinforced cement composites (CFRCs) have attracted relevant interest in recent years, due to their fascinating ability for harvesting ambient energy in urban areas and roads, and to the widespread use of cement-based materials in modern society. The enhanced effect of the thin pyrolytic carbon layer (formed at the carbon fiber/cement interface) on transport and thermoelectric properties of CFRCs has been studied. It has been demonstrated that it can enhance the electrical conduction and Seebeck coefficient of CFRCs greatly, resulting in higher power factor 2.08 µW m−1 K−2 and higher thermoelectric figure of merit 3.11×10−3, compared to those reported in the literature and comparable to oxide thermoelectric materials. All CFRCs with pyrolytic carbon layer, exhibit typical semiconductor behavior with activation energy of electrical conduction of 0.228-0.407 eV together with a high Seebeck coefficient. The calculation through Mott’s formula indicates the charge carrier density of CFRCs (1014–1016 cm−3) to be much smaller than that of typical thermoelectric materials and to increase with the carbon layer thickness. CFRCs thermal conductivity is dominated by phonon thermal conductivity, which is kept at a low level by high density of micro/nano-sized defects in the cement matrix that scatter phonons and shorten their mean free path. The appropriate carrier density and mobility induced by the amorphous structure of pyrolytic carbon is primarily responsible for the high thermoelectric figure of merit. 相似文献
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《Ceramics International》2016,42(9):10614-10618
SiOC modified carbon-bonded carbon fiber composites (CBCFs) with densities of 0.38, 0.61, 0.94 g cm−3 were prepared by precursor infiltration and pyrolysis method using dimethoxydimethylsilane and methyltrimethoxysilane as precursors. The densification behavior was investigated by analyzing the microstructure of CBCF-SiOC (CS) composites with different densities. The mechanical properties and oxidation resistance of the CS composites were studied. Results indicate that the CS composites with the density of 0.94 g cm−3 exhibit better mechanical and anti-oxidation properties. 相似文献
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Carbon fiber reinforced polymer composites are attractive because of their high stiffness and strength‐to‐weight ratios. In order to fully utilize the stiffness and strength of the reinforcement fiber, it is necessary to bring the polymer matrix and the reinforcement fiber together with homogeneous wetting. In this paper, a solution processing technique and the mechanical properties of carbon fiber reinforced polyethersulfone composites were investigated. The polymer was dissolved in cyclopentanone and fed onto a continuous carbon fiber tow using a drum winder. The solution‐processed composite prepregs were then layed up and compression molded into unidirectional composite panels for evaluation. The composite samples showed uniform fiber distribution and reasonably good wetting. The longitudinal flexural modulus was as high as 137 GPa, and longitudinal flexural strength 1400 MPa. In addition, the effects of polymer grade and processing conditions on the mechanical properties of the composites were discussed. It is suggested that the transverse properties and interlaminar fracture toughness could benefit from higher polymer matrix molecular weight. A careful design in the spatial distribution of the molecular weight would be necessary for practical applications. 相似文献
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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。 相似文献
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Carbon fiber (CF) filled low‐density polyethylene (LDPE) composites were prepared by the conventional melt‐mixing method. The distribution of CF in the composite was studied by wide‐angle X‐ray diffraction (WAXD) and scanning electron microscope (SEM) observations. A phenomenological model was proposed to illustrate the resistivity‐temperature behavior of CF‐filled semicrystalline composites. The effects of the content and aspect ratio of CF on the positive temperature coefficient (PTC) and the room temperature resistivity were elucidated. A balance between the PTC intensity and the room‐temperature resistivity can be achieved by using a mixture of CFs with low and high aspect ratios. The negative temperature coefficient (NTC) phenomenon can be effectively eliminated by crosslinking under γ‐ray radiation, and the crosslinked composite exhibits a higher PTC intensity and PTC transition temperature than the noncrosslinked counterpart. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1222–1228, 2004 相似文献
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Effect of carbon nanotube length and density on the properties of carbon nanotube-coated carbon fiber/polyester composites 总被引:2,自引:0,他引:2
Carbon nanotubes (CNTs) have been synthesized on the surface of carbon fiber/fabric using catalytic chemical vapor deposition (CVD) at a temperature of 550 °C. A coating of Ni catalyst on the fiber surface is applied using the electroless dip coating method. The dependence of the length and quantity of CNTs on the growth time is studied by varying the run time of the CVD reactor from 5 to 25 min. Scanning electron microscopy shows good coverage of the carbon fiber surface by the CNTs. It is observed that both the length and density of CNTs are functions of the growth time. Up to a critical growth time, both the storage modulus and the interfacial shear stress of CNT-coated carbon fiber/polyester composites are seen to increase substantially. 相似文献