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S. W. Kim S. H. Lee J. S. Kang K. H. Kang 《International Journal of Thermophysics》2006,27(6):1873-1881
With restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers such as jute, kenaf, flax, etc., have replaced automotive interior materials such as chemical plastics. In this study, the thermal conductivity of several kinds of thermoplastic composites in the form of board composed of 48.5 mass% polypropylene (PP) and 48.5 mass% natural fiber (NF), and reinforced with 3.0 mass% maleated polypropylene (MAPP) and 0.3 mass% silane as the coupling agents, were measured at temperatures of −10, 10, and 30°C, using a heat flow meter apparatus. The results show that the thermal conductivity is in the range of 0.05–0.07 W · m−1 · K−1, and the thermal conductivity increased about 10–15% by adding MAPP and about 10–25% by soaking in a silane aqueous solution. The tensile strength was also measured, and the result shows similar trends as the thermal conductivity.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic. 相似文献
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Wearable Devices: Ultrathin,Washable, and Large‐Area Graphene Papers for Personal Thermal Management (Small 44/2017)
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Yang Guo Chaochao Dun Junwei Xu Jiuke Mu Peiyun Li Liwen Gu Chengyi Hou Corey A. Hewitt Qinghong Zhang Yaogang Li David L. Carroll Hongzhi Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(44)
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Yang Guo Chaochao Dun Junwei Xu Jiuke Mu Peiyun Li Liwen Gu Chengyi Hou Corey A. Hewitt Qinghong Zhang Yaogang Li David L. Carroll Hongzhi Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(44)
Freestanding, flexible/foldable, and wearable bifuctional ultrathin graphene paper for heating and cooling is fabricated as an active material in personal thermal management (PTM). The promising electrical conductivity grants the superior Joule heating for extra warmth of 42 °C using a low supply voltage around 3.2 V. Besides, based on its high out‐of‐plane thermal conductivity, the graphene paper provides passive cooling via thermal transmission from the human body to the environment within 7 s. The cooling effect of graphene paper is superior compared with that of the normal cotton fiber, and this advantage will become more prominent with the increased thickness difference. The present bifunctional graphene paper possesses high durability against bending cycles over 500 times and wash time over 1500 min, suggesting its great potential in wearable PTM. 相似文献
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以聚乳酸(PLA)为基体,分别采用粘胶纤维与Lyocell纤维这2种典型的再生纤维素纤维为增强纤维,通过熔融共混和注塑成型制备了再生纤维素纤维/PLA复合材料,并对这2种复合材料的性能进行了比较研究。结果表明,采用粘胶纤维或Lyocell纤维增强均可有效提高PLA复合材料的结晶度、力学性能和维卡软化温度。粘胶纤维的锯齿形截面有利于其与PLA基体的结合,因此粘胶纤维/PLA复合材料具有略高的冲击强度及拉伸强度。Lyocell纤维增强更有利于复合材料结晶度的提高,使得Lyocell/PLA复合材料具有更高的弹性模量和维卡软化温度。 相似文献
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构建多孔碳化硅纳米线(SiCNWs)网络并控制化学气相渗透(CVI)过程,可设计并获得轻质、高强度和低导热率SiC复合材料。首先将SiCNWs和聚乙烯醇(PVA)混合,制备具有最佳体积分数(15.6%)和均匀孔隙结构的SiCNWs网络;通过控制CVI参数获得具有小而均匀孔隙结构的SiCNWs增强多孔SiC(SiCNWs/SiC)陶瓷基复合材料。SiC基体形貌受沉积参数(如温度和反应气体浓度)的影响,从球状颗粒向六棱锥颗粒形状转变。SiCNWs/SiC陶瓷基复合材料的孔隙率为38.9%时,强度达到(194.3±21.3) MPa,导热系数为(1.9 ± 0.1) W/(m∙K),显示出增韧效果,并具有低导热系数。 相似文献
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A Bioinspired Interface Design for Improving the Strength and Electrical Conductivity of Graphene‐Based Fibers
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Tao Ma Huai‐Ling Gao Huai‐Ping Cong Hong‐Bin Yao Liang Wu Zi‐You Yu Si‐Ming Chen Shu‐Hong Yu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(15)
Graphene‐based fibers (GBFs) are attractive for next‐generation wearable electronics due to their potentially high mechanical strength, superior flexibility, and excellent electrical and thermal conductivity. Many efforts have been devoted to improving these properties of GBFs in the past few years. However, fabricating GBFs with high strength and electrical conductivity simultaneously remains as a great challenge. Herein, inspired by nacre‐like multilevel structural design, an interface‐reinforced method is developed to improve both the mechanical property and electrical conductivity of the GBFs by introducing polydopamine‐derived N‐doped carbon species as resistance enhancers, binding agents, and conductive connection “bridges.” Remarkably, both the tensile strength and electrical conductivity of the obtained GBFs are significantly improved to ≈724 MPa and ≈6.6 × 104 S m?1, respectively, demonstrating great superiority compared to previously reported similar GBFs. These outstanding integrated performances of the GBFs provide it with great application potential in the fields of flexible and wearable microdevices such as sensors, actuators, supercapacitors, and batteries. 相似文献
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Single Carbon Fibers with a Macroscopic‐Thickness, 3D Highly Porous Carbon Nanotube Coating
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Mingchu Zou Wenqi Zhao Huaisheng Wu Hui Zhang Wenjing Xu Liusi Yang Shiting Wu Yunsong Wang Yijun Chen Lu Xu Anyuan Cao 《Advanced materials (Deerfield Beach, Fla.)》2018,30(13)
Carbon fiber (CF) grafted with a layer of carbon nanotubes (CNTs) plays an important role in composite materials and other fields; to date, the applications of CNTs@CF multiscale fibers are severely hindered by the limited amount of CNTs grafted on individual CFs and the weak interfacial binding force. Here, monolithic CNTs@CF fibers consisting of a 3D highly porous CNT sponge layer with macroscopic‐thickness (up to several millimeters), which is directly grown on a single CF, are fabricated. Mechanical tests reveal high sponge–CF interfacial strength owing to the presence of a thin transitional layer, which completely inhibits the CF slippage from the matrix upon fracture in CNTs@CF fiber–epoxy composites. The porous conductive CNTs@CF hybrid fibers also act as a template for introducing active materials (pseudopolymers and oxides), and a solid‐state fiber‐shaped supercapacitor and a fiber‐type lithium‐ion battery with high performances are demonstrated. These CNTs@CF fibers with macroscopic CNT layer thickness have many potential applications in areas such as hierarchically reinforced composites and flexible energy‐storage textiles. 相似文献
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聚甲基丙烯酸甲酯/二氧化硅(PMMA/Si O_2)复合材料可以通过简便的单体浇铸、本体聚合方法制备,二氧化硅用硅烷偶联剂3-(异丁烯酰氧)丙基三甲氧基硅烷(γ-MPS)进行表面修饰,并用红外光谱表征其甲苯抽提后的组成。当加入量为11.76%时,PMMA/Si O_2复合材料的导热率达到0.23 W/(m·K),比基体PMMA提高了27.78%。用PMMA红外光谱的侧甲基弯曲振动峰(δCH3)与羰基(νC=O)的伸缩振动峰比值可以表示PMMA大分子的偶合终止与歧化终止的比例,随着二氧化硅含量的增加,歧化终止比例升高,从而使PMMA/Si O_2复合材料的热稳定性提高,与热重分析结果一致。 相似文献
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Mg对La2Ce2O7的掺杂可提高其热膨胀系数、降低其热导率, 从而改善其作为热障涂层材料的性能。采用溶胶-凝胶法制备了(La1-xMgx)2Ce2O7-x系列组成样品。X射线测试表明: 当 0≤x≤0.4时, 所有(La1-xMgx)2Ce2O7-x 样品均与La2Ce2O7具有相同的缺陷萤石结构, 且晶胞参数随x的增大而递减; 当x?0.4时, 样品中出现MgO的峰。在组成相同的情况下, 样品(La1-xMgx)2Ce2O7-x (0≤x≤0.4)的热膨胀系数随温度升高而增大, 而热导率随温度升高而降低。在相同温度下, 不同组成样品(La1-xMgx)2Ce2O7-x (0≤x≤0.4)的热膨胀系数随x的增大而增大; 而样品的热导率则随Mg掺杂量的增加呈先增大后减小的趋势。在此基础上, 探讨了Mg掺杂对La2Ce2O7的物相、晶胞参数、热膨胀系数以及热导率的影响机理。 相似文献
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激光裂解聚合物先驱体在金属表面制备性能优异的陶瓷涂层,解决了金属本身存在的耐磨防腐蚀性能不足的问题,已成为一种行之有效的方法。采用激光裂解含二茂铁的聚硅氧烷制备了SiOC(Fe)陶瓷涂层,采用电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱(XPS),分析了激光裂解含二茂铁的聚硅氧烷生成物的组成与结构,并初步研究了其裂解机理。结果表明:在激光作用下,含二茂铁的聚硅氧烷在激光裂解过程中会发生非平衡态的自由基化学反应,生成的陶瓷涂层主要由晶态的SiC、Fe_3C,非晶态的SiO_2、Fe_2O_3、Fe_3O_4以及C单质、C_6H_(18)OSi_2等物质组成,由二茂铁激光裂解生成的Fe_2O_3、Fe_3O_4、Fe_3C相对制备的陶瓷涂层孔隙具有填补作用。二茂铁质量分数越大,陶瓷涂层表面越平整致密,孔隙越少。 相似文献
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用高速混合-平板热压法制备了70%木纤维含量的木纤维-聚乳酸(WF-PLA)复合材料,研究了不同聚乳酸(PLA)对WF-PLA复合材料的耐水性、弯曲强度和弯曲模量、PLA分子量及热性能的影响。结果表明,PLA与木纤维复合后,弯曲模量明显增加,复合材料中PLA分子量和熔融温度明显下降;PLA性能对WF-PLA复合材料性能影响显著,WF-PLA复合材料中PLA分子量随PLA原料分子量下降而下降,高分子量PLA制备的WF-PLA复合材料耐水性更好,弯曲强度和弯曲模量更高;在PLA改性时,应避免引起PLA分子量下降。 相似文献
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Graphene Fibers: Mussel‐Inspired Defect Engineering of Graphene Liquid Crystalline Fibers for Synergistic Enhancement of Mechanical Strength and Electrical Conductivity (Adv. Mater. 40/2018)
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In Ho Kim Taeyeong Yun Jae‐Eun Kim Hayoung Yu Suchithra Padmajan Sasikala Kyung Eun Lee Sung Hwan Koo Hoseong Hwang Hong Ju Jung Jeong Young Park Hyeon Su Jeong Sang Ouk Kim 《Advanced materials (Deerfield Beach, Fla.)》2018,30(40)