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排序方式: 共有5149条查询结果,搜索用时 15 毫秒
1.
Di Bao Fei Xu Yexiang Cui Sicheng Yuan Xiguang Zhang Yanji Zhu Yueyang Gao Huaiyuan Wang 《应用聚合物科学杂志》2021,138(41):51218
High loadings of fillers are usually needed to achieve high-thermal conductivity (TC) of polymer-based composites, which inevitably sacrifices processability and meanwhile causes high-cost. Therefore, it is of great significance to achieve high-TC composites under low-filler loading. Here, a novel p-phenylenediamine (PPD) modified expanded graphite (EG-PPD)/epoxy (EP) composite with high TC and low-filler content was successfully prepared via pre-dispersion and vacuum assisted mixing strategy. With the improved interfacial compatibility between EG and EP by PPD, the prepared EG-PPD/EP composite exhibited excellent thermal management performance, resulting in the TC of which reached 4.00 W·m−1·K−1 with only 10 wt% (5.59 vol%) of EG-PPD, which is approximately 19 times higher than that of pure EP. Meantime, the interface thermal resistance of EG-PPD/EP composite between EG-PPD and EP is reduced by 33% compared with EG/EP composite. This composite with excellent TC property is expected to be used in thermal management field. 相似文献
2.
In this work, Bis-(3-triethoxysilylpropyl) tetrasulphane was employed for surface modification of silica, ferrite and kenaf fiber filled natural rubber composites using aqueous solvent deposition, dry blending and integral blend methods. The efficiency of each method and the preferred modification method for improving the mechanical performance of natural rubber composites was assessed. The appearance of the Fourier transform infrared spectroscopy peak around 1088 cm−1 for all types of fillers provided evidence that silane interaction had occurred between the fillers and rubber and the formation of siloxane linkages were quantitatively determined by the crosslink density measurement. The surface treatment by dry method for silica and ferrite fillers showed significant improvement of tensile performance at approximately 67% and 34% compared to those with untreated fillers. For kenaf fiber-filled rubber composites, the surface treatment by aqueous solvent deposition showed the highest tensile improvement of 59% compared to the dry blending and integral blend method. 相似文献
3.
Yun Liao Bing Cao Li Liu Xiandong Wu Sheng Guo Changhui Mi Kaiwen Li Meng Wang 《应用聚合物科学杂志》2021,138(15):50179
Two kinds of bio-based polyurethane coatings for controlled-release urea were prepared by in-situ polymerization used castor oil and liquefied starch as raw materials, respectively. Scanning electron microscopy (SEM) showed that the section morphology of castor oil based polyurethane (Castor-PU) coating was uniform and dense, and that of liquefied starch based polyurethane (Starch-PU) coating had certain proportion of microporous. Infrared spectroscopy (IR) showed that the two coatings had typical urethane characteristic structure, but the difference was that the Starch-PU had obvious unreacted isocyanate structure. Differential scanning calorimetry (DSC) showed that the glass transition temperature of the two coatings was around 58°C, but the Castor-PU had a crystallization domain with obvious crystallization melting peak at 130°C. Thermogravimetric analysis (TG) showed that the thermal stability of Castor-PU was significantly higher than that of Starch-PU. The controlled-release property test showed that when the coating ratio was 2.8%, the nutrient release longevity of urea coated with Castor-PU was 49 days and that of urea coated with Starch-PU was 14 days. The reasons for the poor controlled-release performance of Starch-PU were analyzed, which probably caused by concentrated sulfuric acid and hydrophilic dispersant added in the liquefied starch. 相似文献
4.
Recently, the successful synthesis of wafer-scale single-crystal graphene, hexagonal boron nitride (hBN), and MoS2 on transition metal surfaces with step edges boosted the research interests in synthesizing wafer-scale 2D single crystals on high-index substrate surfaces. Here, using hBN growth on high-index Cu surfaces as an example, a systematic theoretical study to understand the epitaxial growth of 2D materials on various high-index surfaces is performed. It is revealed that hBN orientation on a high-index surface is highly dependent on the alignment of the step edges of the surface as well as the surface roughness. On an ideal high-index surface, well-aligned hBN islands can be easily achieved, whereas curved step edges on a rough surface can lead to the alignment of hBN along with different directions. This study shows that high-index surfaces with a large step density are robust for templating the epitaxial growth of 2D single crystals due to their large tolerance for surface roughness and provides a general guideline for the epitaxial growth of various 2D single crystals. 相似文献
5.
Ingrid R. Marques Camila Silveira Monique J. L. Leite Artur M. Piacentini Cristiano Binder Marta E. R. Dotto Alan Ambrosi Marco Di Luccio Cristiane da Costa 《应用聚合物科学杂志》2021,138(24):50558
The modification of the surface characteristics after treatment with plasma in polymeric materials, such as the aging phenomenon, calls the attention of research in the area of nonthermal plasma technology. In this work, a direct treatment with dielectric-barrier discharge plasma was used on the surfaces of ultrafiltration membranes. The measurements of the contact angle with water, attenuated total reflectance accessory, zeta potential, atomic force microscopy and scanning electron microscopy-MEV were performed on the surfaces to verify changes after plasma treatment and to understand the occurrence and timing of the plasma aging effect. In the analysis of the membrane performance, hydraulic permeation and protein retention tests were performed. The results showed an improvement in wettability and hydrophilic properties in the post-treated membranes. The study of reversibility/aging of the post-plasma surface is important for research that deals with the modification of polymeric membranes. Changes in surface morphology, topography and wettability of the membranes were observed up to seven days after treatment, with a tendency to return to the initial characteristics of the membranes. 相似文献
6.
Colin Robert Witiwat Best Thitasiri Dimitrios Mamalis Zakareya Elmo Hussein Muhammad Waqas Dipa Ray Norbert Radacsi Vasileios Koutsos 《应用聚合物科学杂志》2021,138(5):49749
The through-thickness conductivity of carbon fiber reinforced polymer (CFRP) composite was increased by incorporating multiwalled carbon nanotubes in the interlaminar region. Carbon nanotubes (CNTs) were dispersed in a polyethylenimine (PEI) binder, which was then coated onto the carbon fiber fabric. Standard vacuum-assisted resin infusion process was applied to fabricate the composite laminates. This modification technique aims to enhance the electrical conductivity in through-thickness direction for the purpose of nondestructive testing, damage detection, and electromagnetic interference shielding. CNT concentrations ranging from 0 to 0.75 wt% were used and compared to pristine CFRP samples (reference). The through-thickness conductivity of the CFRP exhibited an improvement of up to 781% by adopting this technique. However, the dispersion of CNT in PEI led to a viscosity increase and poor wetting properties which resulted in the formation of voids/defects, poor adhesion (as shown in scanning electron micrographs) and the deterioration of the mechanical properties as manifested by interlaminar shear strength and dynamic mechanical analysis measurements. 相似文献
7.
Andreas S. Katsigiannis Danny L. Bayliss James L. Walsh 《Comprehensive Reviews in Food Science and Food Safety》2022,21(2):1086-1124
Food safety is the primary goal for food and drink manufacturers. Cleaning and disinfection practices applied to the processing environment are vital to maintain this safety; yet, current approaches can incur costly downtime and the potential for microorganisms to grow and establish, if not effectively removed. For that reason, manufacturers are seeking nonthermal, online, and continuous disinfection processes to control the microbial levels within the processing environment. One such emerging technique, with great potential, is cold atmospheric pressure plasma (CAP). This review presents the latest advances and challenges associated with CAP-based technologies for the decontamination of surfaces and equipment found within the food-processing environment. It provides a detailed overview of the technology and a comprehensive analysis of the many CAP-based antimicrobial studies on food-contact surfaces and materials. As CAP is considered an emerging technique, many of the recent studies are still in the preliminary stages, with results obtained under widely different conditions. This lack of cohesive information and an inability to directly compare CAP systems has greatly impeded technological development. The review further explores the challenge of scaling CAP technology to meet industry needs, considering aspects such as regulatory constraints, environmental credentials, and cost of use. Finally, a discussion is presented on the future outlook for CAP technology in this area, identifying key challenges that must be addressed to promote industry uptake. 相似文献
8.
库岸滑坡是一种常见地质灾害,如果无法及时预测而出现下滑,则滑坡入库后很可能诱发涌浪,危及河道交通或附近水利设施安全。以弯曲型河道滑坡入库诱发涌浪为研究对象,基于Flow-3D模拟弯曲河道型库岸滑坡涌浪传播过程及其与下游水利设施——大坝相互作用。为了检验水工物理模型试验的有效性和精度,在相关库岸滑坡涌浪研究基础上构建了三维滑坡涌浪数值模型。研究表明:三维数值模拟和水工物理模型试验结果吻合较好,主要体现在涌浪水面高度变化和传播过程。同时,分析不同水深和下滑坡角条件下大坝和滑坡涌浪相互作用过程,得出最危险的水深条件和入射角度,通过工程实例验证分析得出最大动水头小于涌浪高度水头且沿水深有一定程度的折减,则采用最大涌浪爬高水位静力方法计算分析坝体应力,其结果偏安全。 相似文献
9.
Owing to its high degree of crystallinity and orientation, the surface of aramid fiber is smooth, causing its low bonding strength with polymer matrix. This has restricted the application of aramid fiber in reinforced polymer materials. Effective methods are by introducing functional groups through surface modification and by increasing its surface roughness thereby greatly improving its bonding strength with the polymer. In this work, molecular dynamics (MD) simulation study fiber functionalized with hydroxyl (OH), carboxyl (COOH), and the silane coupling agent as nanofillers for polymer nanocomposites. The interfacial characteristics and the mechanical behavior of polymer nanocomposites are investigated. The results show that the functionalization can enhance the interfacial shear stress and tensile strength. The functional group not only provides a stronger interface, but also provides additional mechanical interlocking effect, which effectively improves load-bearing transmission capacity. The analysis of the micro-mechanism from the energy level also provides new insights for the functionalized design of nanocomposites. 相似文献
10.
Application-specific optical glass properties are achieved by utilizing complex material compositions. This can be problematic in reactive plasma-assisted deterministic surface processing since a non-volatile surface layer may form depending on the glass composition, which affects the etch rate and thereby the local etching depth. In this investigation, a model algorithm is proposed to tackle some restrictions in applying fluorine-based plasma jet as etching tool utilized for freeform surface machining of optics made of complex glass composition, like borosilicate crown glass (e.g., N-BK7®). In this regard, firstly an analytical model is proposed for estimating the depth-dependent etch rate function. Subsequently, a recursive simulation algorithm is introduced for convolving the derived depth-dependent etch rate function with the given dwell time matrix to simulate a deterministic freeform generation process. By the proposed simulation algorithm, the impeding influence of the residual layer on the reduction of etching depth is computed prior to a real experiment in order to scale the local dwell time to ensure the targeted local removal. Finally, the simulated freeform shape is compared with the corresponding result of an etching experiment to validate the feasibility of the proposed approach. 相似文献