今日更新:Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 2 篇,Composites Science and Technology 2 篇
Methodology to Establish a Forming Process Window for Thermoset Aligned Discontinuous Fiber Composites
Loren J. Tomlin, Thomas A. Cender, Steven Sauerbrunn, Suresh G. Advani
doi:10.1016/j.compositesa.2024.108064
为热固性排列不连续纤维复合材料建立成型工艺窗口的方法学
Highly aligned discontinuous fiber composites have been pursued with the goal of achieving high performance properties with the formability of short fiber composites. The feedstock consists of a highly aligned discontinuous fiber preform which can be combined with thermoplastic or thermoset resins to create prepreg that can extend in the fiber direction. With this added benefit of lamina extensibility in the fiber direction, a methodology is needed to determine the degradation of material quality with applied forming strain. A framework is established to define a forming process window which sets the optimal process conditions—temperature and strain rate—for maintaining lamina uniformity after deformation. Digital image correlation was used to measure strain uniformity for samples stretched in uniaxial tension at constant temperature and strain rate. The experimental results show that forming strain rate should increase with increasing process temperature. The process window established in this work will be used to ensure that material uniformity can be optimized in manufacturing trials and other material characterization evaluations.
高度对齐的非连续纤维复合材料的目标是在短纤维复合材料可成型性的基础上实现高性能特性。这种原料由高度对齐的非连续纤维预型件组成,可与热塑性或热固性树脂结合,制成可在纤维方向延伸的预浸料。有了纤维方向层状延伸性这一附加优势,就需要一种方法来确定材料质量随施加成型应变而下降的情况。我们建立了一个框架来定义成型工艺窗口,该窗口设定了最佳工艺条件--温度和应变率,以保持变形后的薄片均匀性。使用数字图像相关技术测量了在恒定温度和应变率下单轴拉伸样品的应变均匀性。实验结果表明,成型应变率应随着加工温度的升高而增加。这项工作中建立的工艺窗口将用于确保在制造试验和其他材料表征评估中优化材料的均匀性。
A metal-based microencapsulated phase change material (MEPCM) with high thermal conductivity, electrical insulation and flame retardancy and its application in epoxy resin
Yuanyuan Chen, Chenwu Shi, Xiaojie Guo, Chunyao Qing, Deqiu Zou
doi:10.1016/j.compositesa.2024.108081
具有高导热性、电绝缘性和阻燃性的金属基微胶囊相变材料 (MEPCM) 及其在环氧树脂中的应用
Using the “double-layer coating, sacrificial inner layer” method, MEPCM with a thermal expansion void was prepared by encapsulating Sn particles into a magnesium hydroxide shell. The results showed that MEPCM exhibited better thermal reliability than those without a thermal expansion void. More importantly, the Sn was selected as the core material that MEPCM was enabled to have large volume latent heat (425.2 J/cm3) and high thermal conductivity (10.06 W/m·K), and magnesium hydroxide was chosen as the shell material that MEPCM was given great heat absorption ability (260 J/g), excellent electrical insulation performance and flame retardancy. By adding 20 vol% MEPCM to EP, the thermal conductivity of the composite improved 164.9%. The volume resistivity of EP/MEPCM was 2.1×1012 Ω·cm. The pHRR and THR of EP/MEPCM composite were only 471.64 kW/m2 and 12.95 m2, respectively. The existence of MEPCM enhanced the thermal conductivity, electrical insulation performance and flame retardancy of EP.
采用 "双层涂层,牺牲内层 "的方法,将锡颗粒封装到氢氧化镁外壳中,制备出了具有热膨胀空隙的 MEPCM。结果表明,与没有热膨胀空隙的 MEPCM 相比,MEPCM 具有更好的热可靠性。更重要的是,选择锡作为核心材料,可使 MEPCM 具有较大的体积潜热(425.2 J/cm3)和较高的热导率(10.06 W/m-K);选择氢氧化镁作为外壳材料,可使 MEPCM 具有较强的吸热能力(260 J/g)、优异的电绝缘性能和阻燃性。在 EP 中加入 20 Vol% 的 MEPCM 后,复合材料的导热率提高了 164.9%。EP/MEPCM 的体积电阻率为 2.1×1012 Ω-cm。EP/MEPCM 复合材料的 pHRR 和 THR 分别仅为 471.64 kW/m2 和 12.95 m2。MEPCM 的存在提高了 EP 的导热性、电绝缘性能和阻燃性。
End-of-Life wind turbine blades: Review on recycling strategies
Francesca Spini, Paolo Bettini
doi:10.1016/j.compositesb.2024.111290
报废风力涡轮机叶片:回收战略回顾
The review focuses on End-of-Life (EoL) strategies, with a primary emphasis on recycling techniques, to manage fiber reinforced thermoset polymer waste from decommissioned wind turbine blades. Wind energy has recently become one of the most important sources of electricity. Over the next few years, further growth is expected, leading to increasing amounts of EoL waste, and especially composite waste, which is difficult to recycle. Glass fiber reinforced polymer (GFRP) is the predominant composite material used in blades. However, the increasing size of next-generation wind turbine blades is also driving the adoption of carbon fiber reinforced polymer (CFRP). GFRP is often recycled through cement kiln process or mechanically due to its low-cost. Thus, research is needed on cost-effective methods that can recover valuable glass fibers. On the other hand, CFRP is a high-value material, justifying the use of high-cost recycling approaches compared to virgin fiber production.
这篇综述主要介绍报废(EoL)策略,重点是回收技术,以管理退役风力涡轮机叶片产生的纤维增强热固性聚合物废物。风能最近已成为最重要的电力来源之一。在未来几年内,预计风能将进一步增长,从而产生越来越多的 EoL 废物,尤其是难以回收利用的复合材料废物。玻璃纤维增强聚合物(GFRP)是叶片中使用的主要复合材料。然而,下一代风力涡轮机叶片尺寸的不断增大也推动了碳纤维增强聚合物(CFRP)的采用。由于成本低廉,GFRP 通常通过水泥窑工艺或机械方法进行回收。因此,需要研究可回收有价值玻璃纤维的经济有效的方法。另一方面,CFRP 是一种高价值材料,与原始纤维生产相比,有理由使用高成本回收方法。
Study on HAZ extension characteristics during laser ablation of CFRP based on dimensional analysis
Han Liang, Shusen Zhao, Haijun Yu, Lu Jiang, Zhiyan Zhang, Xuechun Lin
doi:10.1016/j.compositesb.2024.111295
基于尺寸分析的 CFRP 激光烧蚀过程中 HAZ 拉伸特性研究
Heat affected zone (HAZ) is one of the key factors in evaluating quality in laser processing of carbon fiber reinforced polymer (CFRP). To achieve a systematic and quantitative description of continuous wave (CW) and pulsed wave (PW) laser ablation of CFRP, dimensional analysis was applied to establish the HAZ extension models. The HAZ morphology and fracture microstructure were characterized, and the characteristics of the ablation plume and gas diffusion were observed. The HAZ extension models show good prediction effect on HAZ and the key dimensionless numbers that determine the HAZ are found. Relating the dimensionless numbers to the HAZ extension characteristics provides a quantitative optimization direction for avoiding excessive ablation. Differences in the heat accumulation process of CW laser and PW laser ablation are concluded, which lead to complex comprehensive effect among the parameters. The resulting differences in the effects of CW and PW laser parameters on the HAZ are comparatively studied. PW laser ablation under the parameters of high repetitive frequency and low scanning speed is found to exhibit the properties of CW laser in the HAZ extension characteristics including size and morphology.
热影响区(HAZ)是评估碳纤维增强聚合物(CFRP)激光加工质量的关键因素之一。为了系统、定量地描述连续波(CW)和脉冲波(PW)激光烧蚀碳纤维增强聚合物的过程,应用尺寸分析法建立了热影响区扩展模型。对 HAZ 形态和断口微观结构进行了表征,并观察了烧蚀羽流和气体扩散的特征。HAZ扩展模型对HAZ显示出良好的预测效果,并找到了决定HAZ的关键无量纲数。将无量纲数与热影响区扩展特征联系起来,为避免过度烧蚀提供了定量优化方向。总结出 CW 激光和 PW 激光烧蚀的热积累过程存在差异,从而导致参数之间产生复杂的综合效应。比较研究了 CW 和 PW 激光参数对 HAZ 影响的差异。结果发现,在高重复频率和低扫描速度的参数下,PW 激光烧蚀在 HAZ 的扩展特征(包括尺寸和形态)方面具有 CW 激光的特性。
Electrostatically self-assembled three-dimensional conductive network for highly sensitive and reliable skin-like strain sensor
Shengkai Li, Jian Tang, Yudong Liu, Jing Hua, Jinhui Liu
doi:10.1016/j.compscitech.2024.110493
静电自组装三维导电网络,用于制造高灵敏度、高可靠性的类肤应变传感器
In recent years, flexible strain sensors have garnered significant attention in industrial manufacturing and daily life. Sensitivity and reliability are two crucial characteristics of flexible strain sensors in practical applications, and they depend on the development of the sensor's internal conductive network. However, the aggregation phenomenon of conductive fillers in the elastic matrix has a serious impact on the construction of a developed conductive network. In this work, we have designed electropositive amino-functionalized carbon nanotubes (CNTs-p) based on the electrostatic self-assembly of electronegative MXene in the aqueous phase. Compared to the use of surfactants, the electrical modulation of carbon nanotubes through chemical bonding modification is more robust and the electrostatic self-assembly with MXene is more stable. CNTs-p and MXene were self-assembled by electrostatic attraction in butyl latex and uniformly dispersed in the latex. Following demulsification, the polymer composite film (MXene&CNTs-p/IIR) with a three-dimensional conductive network was obtained. The skin-like strain sensor, which utilizes the conductive composite film, demonstrates high sensitivity (gauge factor (GF) = 35137 that is among the highest values for the reported strain sensor), remarkable reliability (The signal monitoring capability remains after 15000 cycles), and excellent responsiveness (62 ms). Additionally, the skin-like strain sensor boasts a wide detection range (0–431%) and unprecedented stability, enabling strain sensing functionality in a wide temperature range of -10—100 °C, as well as strong acid (pH = 1) and strong alkali (pH = 11) environment. The preparation of MXene&CNTs-p/IIR provides a safe, environmentally friendly and effective method for improving the sensitivity and reliability of flexible sensors in wearable intelligent electronics and health detection.
近年来,柔性应变传感器在工业制造和日常生活中备受关注。灵敏度和可靠性是柔性应变传感器在实际应用中的两个关键特性,而这两个特性取决于传感器内部导电网络的发展。然而,导电填料在弹性基体中的聚集现象严重影响了导电网络的构建。在这项工作中,我们基于电负性 MXene 在水相中的静电自组装,设计出了电正性氨基功能化碳纳米管(CNTs-p)。与使用表面活性剂相比,通过化学键修饰对碳纳米管进行电学调制的效果更强,与 MXene 的静电自组装也更稳定。CNTs-p 和 MXene 通过静电吸引在丁基胶乳中自组装,并均匀地分散在胶乳中。破乳后,得到了具有三维导电网络的聚合物复合薄膜(MXene&CNTs-p/IIR)。利用该导电复合薄膜制成的类肤应变传感器具有高灵敏度(测量系数 (GF) = 35137,是目前已报道的应变传感器中最高值之一)、卓越的可靠性(15000 次循环后仍能保持信号监测能力)和出色的响应速度(62 毫秒)。此外,这种类似皮肤的应变传感器还具有很宽的检测范围(0-431%)和前所未有的稳定性,可在 -10-100 °C 的宽温度范围以及强酸(pH = 1)和强碱(pH = 11)环境中实现应变传感功能。MXene&CNTs-p/IIR 的制备为提高可穿戴智能电子产品和健康检测领域柔性传感器的灵敏度和可靠性提供了一种安全、环保和有效的方法。
Construction of micro-nano hybrid structure based on carbon nanotube whisker and alumina for thermally conductive yet electrically insulating silicone rubber composites
Xiaowang Ji, Zhaoyu Lu, Junyan Wang, Neng Ye, Huan Zhang, Letian Zhou, Jingchao Li, Yonglai Lu
doi:10.1016/j.compscitech.2024.110495
构建基于碳纳米管晶须和氧化铝的微纳混合结构,用于导热和绝缘硅橡胶复合材料
High-performance electronics urgently need more effective thermally conductive rubber composites to solve interfacial heat transfer problems in the thermal management systems. Tiny amounts nanocarbon materials (NCM) can significantly improve the thermal conductivity of conventional ceramic-filled rubber composites, but the volume exclusion effect of micrometer ceramic fillers makes NCM highly susceptible to the formation of the conductive pathways, which inevitably leads to the substantial decrease in the volume resistivity of the materials, posing a safety hazard, such as short circuits, to electronic devices. Here, we report an electrostatic self-assembly method to prepare CNW@n-Al2O3 hybrids by loading nano-alumina (n-Al2O3) onto carbon nanotube whiskers (CNW) and co-filling them with micrometer alumina (m-Al2O3) to silicone rubber, constructing a micro-nano-multi-level hybrid network structure, which can fully utilize the high thermal conductivity while shielding the electrical conductivity of CNW. The resulting composite filled with 2 phr of CNW@n-Al2O3 exhibits a significantly enhanced thermal conductivity of 1.137 W/(m·K) and a high volume resistance of 1.323 × 109 Ω cm, and is proved to be used as an excellent thermal interface material to assist the heat dissipation of the microelectronic chip. This study provides a facile and effective strategy for the design of thermally conductive yet electrically insulating rubber composites filled with CNW, which shows a bright application prospect in the thermal management of high-performance electronic devices.
高性能电子产品迫切需要更有效的导热橡胶复合材料来解决热管理系统中的界面传热问题。微量纳米碳材料(NCM)可显著提高传统陶瓷填充橡胶复合材料的导热性能,但微米级陶瓷填料的体积排斥效应使 NCM 极易形成导电通路,从而不可避免地导致材料的体积电阻率大幅下降,给电子设备带来短路等安全隐患。在此,我们报告了一种制备 CNW@n-Al2O3 混合材料的静电自组装方法,即在碳纳米管晶须(CNW)上负载纳米氧化铝(n-Al2O3),并在硅橡胶中共同填充微米氧化铝(m-Al2O3),构建微纳多层次混合网络结构,从而在屏蔽 CNW 导电性的同时充分利用其高热传导性。填充了 2 phr 的 CNW@n-Al2O3 的复合材料的热导率显著提高,达到 1.137 W/(m-K),体积电阻高达 1.323 × 109 Ω cm,可用作优良的热界面材料,帮助微电子芯片散热。该研究为设计填充了氯化萘的导热绝缘橡胶复合材料提供了一种简便有效的策略,在高性能电子设备的热管理方面具有广阔的应用前景。