X射线光电子能谱技术在高分子材料摩擦化学研究中的应用

X射线光电子能谱技术(XPS)是材料表面分析的重要手段,其近年的快速发展促进了表面化学领域研究的深入.高分子及其复合材料在摩擦学性能方面具有普遍的优势,通过XPS对高分子及其复合材料摩擦表面的分析,可以确定摩擦过程的化学变化,并对改进材料的摩擦学性能起到理论的指导作用.作者主要介绍XPS技术的基本原理,及其在高分子与复合材料摩擦学性能研究中的应用.     

镁盐晶须填充材料的研究进展和应用前景

介绍了镁盐晶须填充材料在复合材料、塑料、金属铸造等行业的应用,对当前国内外镁盐晶须的合成研究发展现状进行了简要评述,结合作者对硼酸镁晶须的研究结果,指出了当前研究中存在的一些问题和不足。     

硼酸镁晶须增强材料的制备和应用

介绍了硼酸镁晶须增强材料在塑料、金属、合金及复合材料等行业的应用,并对当前硼酸镁晶须的制备方法进行了分析和评述。结合作者等对硼酸镁晶须的研究结果,指出了当前研究中存在的缺点和不足。采用改进的制备工艺能够获得长度为30μm,长径比达30~50的硼酸镁晶须。     

高聚物固体减摩材料研究进展

评述了近年来部分固体减摩、抗磨材料的种类及其应用，总结了现阶段在摩擦学研究领域中所取得了主要进展和成果。介绍了摩擦学领域中具有发展前途的几种新技术、新方法。     

水润滑下稀土处理碳纤维填充聚四氟乙烯复合材料摩擦学性能

分别用氧化法、稀土处理法、氧化后稀土处理法对碳纤维进行表面处理，然后开展拉伸试验来对不同方法处理的碳纤维填充聚四氟乙烯复合材料进行界面粘着研究，并在UMT-2MT型摩擦磨损试验机上对水润滑条件下聚四氟乙烯复合材料摩擦学性能进行研究，使用扫描电镜对磨损表面进行观察，研究结果表明稀土处理方法在提高复合材料摩擦学性能上优于氧化方法，稀土处理碳纤维填充的聚四氟乙烯复合材料优良的摩擦学性能来自于碳纤雏增强体与聚四氟乙烯基体间强的界面粘着力。     

含聚苯胺类锂离子电池复合电极材料研究进展

聚苯胺是目前研究最为广泛的导电高分子材料之一,具有特殊的电学、光学性能,在电子工业、信息工程、国防工程等的应用开发进行了深入研究。聚苯胺经掺杂后可形成P型和N型导电态,这种掺杂机制使得聚苯胺的掺杂和脱掺杂完全可逆,而掺杂度受pH值和电位等因素的影响,且电化学活性同比传统锂电极材料在充放电过程中具有更优异的可逆性能,因此有关在设计聚苯胺参与锂电池电极复合材料的研究也越来越受到重视。本文综述了不同结构聚苯胺锂离子电池复合材料的制备方法,并着重介绍了聚苯胺基复合材料锂离子电池等领域研究的电化学性能,最后展望了聚苯胺基复合材料的应用前景。     

成型方式对不同木塑复合体系的性能影响研究

以木粉为填充材料,以PE(聚乙烯)、PP(聚丙烯)为塑料基体,分别采用混炼-模压工艺和挤出-注塑工艺制备木塑复合材料,对比研究不同复合材料的力学性能、热性能以及流变性。结果表明,混炼-模压工艺制备的PE基复合材料综合性能较优,而挤出-注塑工艺制备的PP基复合材料综合性能较优,且在PE塑料系列中,HDPE(高密度聚乙烯)基复合材料综合力学性能最好,LLDPE(线性低密度聚乙烯)基复合材料的冲击韧性最好,但其综合力学性能较差。     

纳米复合材料固定化酶的研究进展

载体材料的选择对固定化酶的性能有着至关重要的影响。纳米复合材料不仅具有纳米尺寸的特性,而且可以克服单一材料的不足,在固定化酶领域引起了广泛关注。本文就目前在固定化酶领域使用的纳米复合载体分类进行了系统的阐述,重点介绍了目前在固定化酶研究领域运用较为广泛的硅基纳米复合材料、碳基纳米复合材料和纳米纤维复合材料等材料的制备方法及不同材料对酶学性能的影响,并对这些纳米复合材料固定化酶发展前景进行了展望。     

食品接触塑料材料中有害重金属迁移量测定方法综述

塑料在食品接触材料中占有重要地位,通过介绍食品接触塑料材料中重金属危害及来源,总结食品接触塑料材料中有害重金属安全限量,并对目前食品接触塑料材料中有害重金属的迁移测定方法进行综述。开发食品接触材料快速检测方法是今后研究的方向。     

纳米复合材料固定化酶的研究进展

载体材料的选择对固定化酶的性能有着至关重要的影响。纳米复合材料不仅具有纳米尺寸的特性,而且可以克服单一材料的不足,在固定化酶领域引起了广泛关注。本文就目前在固定化酶领域使用的纳米复合载体分类进行了系统的阐述,重点介绍了目前在固定化酶研究领域运用较为广泛的硅基纳米复合材料、碳基纳米复合材料和纳米纤维复合材料等材料的制备方法及不同材料对酶学性能的影响,并对这些纳米复合材料固定化酶发展前景进行了展望。     

Exceptionally Plastic/Elastic Organic Crystals of a Naphthalidenimine-Boron Complex Show Flexible Optical Waveguide Properties

The design of molecular compounds that exhibit flexibility is an emerging area of research. Although a fair amount of success has been achieved in the design of plastic or elastic crystals, realizing multidimensional plastic and elastic bending remains challenging. We report herein a naphthalidenimine–boron complex that showed size-dependent dual mechanical bending behavior whereas its parent Schiff base was brittle. Detailed crystallographic and spectroscopic analysis revealed the importance of boron in imparting the interesting mechanical properties. Furthermore, the luminescence of the molecule was turned-on subsequent to boron complexation, thereby allowing it to be explored for multimode optical waveguide applications. Our in-depth study of the size-dependent plastic and elastic bending of the crystals thus provides important insights in molecular engineering and could act as a platform for the development of future smart flexible materials for optoelectronic applications.     

Bibliometric analysis and an overview of the application of the non-precious materials for pyrolysis reaction of plastic waste

Huge plastic consumption and depletion of fossil fuels are at the top of the world's environmental and energy challenges. The scientific community has tackled these issues through different approaches. Catalytic pyrolysis of plastic wastes to valuable products has been proved as a sustainable route which fits with the circular economy aspects. The design of catalytic materials is the central factor for performing the catalytic conversion of plastic wastes. This review aims to conduct a Bibliometric analysis of the pyrolysis of plastic wastes and non-precious-based catalysts by mapping research studies over the last fifty years. The analysis was developed via VOSviewer and RStudio tools. It showed the historical progress regarding plastic waste pyrolysis to produce valuable products and chemicals worldwide. The research shows that the top five countries with the highest citations and publications in this field were Spain, China, England, the USA and India. The Journal of Analytical and Applied Pyrolysis had the most comprehensive coverage of plastic waste. The relationship between the catalyst and the mechanism of plastic waste can influence the production yield and selectivity. The research gap and underrepresented research topics were identified, and previous research studies on developing non-precious-based catalysts that were most relevant to the current topic were reviewed and discussed. The challenges and perspectives on catalyst preparation and development for material complexity were critically discussed. Challenges of previous studies and directions for future research were provided. This report might guide the reader to take a general look at plastic waste valorization by pyrolysis and easily understand the main challenges.     

Sn-Pb-RE钎料的塑性变形抗力研究

利用拉伸实验方法研究了室温下Ｓｎ－Ｐｂ－ＲＥ钎料的塑性变形抗力。钎料的变形抗力随稀土含量的增加而提高。稀土垢加入使钎料组织均匀细化，导致位垒硬化和多滑移硬化作用增强。同时，稀土存在晶界偏聚，牵制了晶界的运动，因此提高了钎料的变形抗力。     

Photodegradable plastics: end-of-life design principles

Abstract

Photochemically degradable polymers and plastics are reviewed with an emphasis on the environmental and molecular factors that control the onset of degradation and the rate of degradation. A number of principles are beginning to emerge for the design of viable photochemically degradable plastics. Among the principles discussed are those relating to the effects of chromophores, initiators, antioxidants, temperature, oxygen diffusion into the plastic, polymer crystallinity, tensile and compressive stress, and the absorbed light intensity on the plastic. To obtain a plastic with a controlled lifetime and a specific rate of degradation, many of these parameters can be controlled or adjusted in the design stage of the plastic.     

Crack propagation in poly(2,6-dimethyl-1,4-phenylene oxide), polystyrene,and their blends

Cracks have been propagated in double-cantilever beam specimens of poly(2,6-dimethyl-1,4-phenylene oxide), polystyrene, and their blends. The plane-strain crack propagation energy varies with crack speed, distance from crack arrest following an instability, molecular weight, and blend composition. Auxiliary measurements of moduli, yield properties, and craze initiation resistances at crack tips were carried out together with microscopic studies of the crack-tip plastic zone. Fracture instabilities are rationalized in terms of the interplay of shear deformation with crazing in the crack-tip plastic zone. Negative deviations from ideal behavior in the crack propagation resistance of the blends are rationalized in terms of the concurrent negative deviation in crazing resistance which in turn is thought to be related to positive deviations in shear resistance and thus to negative volumes and heats of mixing.     

History of Engineering Thermoplastics

When engineers design high-performance precision products made from plastics, they demand that the plastic materials should approach or even surpass conventional structural materials, particularly in areas such as modulus, strength, creep resistance, lubricity, thermal expansion, high-temperature properties, heat aging, and high-frequency dielectric loss. In response to these demands, polymer chemists have developed a series of high-performance “engineering” thermoplastics offering a wide variety of choice in balance of important engineering properties. These include the fluoroplastics, aliphatic and aromatic polyethers, polyacetals, polysulfones, aromatic polyesters, and aliphatic and aromatic polyamides.     

Efficient Plastic Waste Recycling Using Polymer

This study explores the possible uses of polymers to facilitate the more efficient recycling of plastic waste. Recycling plastics has been singled out as one way to mitigate the damaging effects of plastic trash on the environment. However, traditional recycling methods can only go so far, therefore innovative approaches are needed. This research investigates how a variety of polymers may be able to improve recycling operations. The study simulates the recycling procedure and employs experimental analysis to compare the performance of various polymers. Results show that by selecting the right polymers, recycling plastic trash can be made much more efficient, cutting down on both waste and energy consumption. The results have important ramifications for the plastic waste recycling sector and point the way towards fruitful future study in this area.     

Recent advances in microbial fuel cell-based toxicity biosensors: Strategies for enhanced toxicity response

Microbial fuel cells (MFCs) have been extensively studied as self-powered toxicity biosensors; however, their applications are limited by the relatively poor toxicity responses. The toxicity responses are known to be related to the factors such as the resistance of species to toxicants, the bioavailability of toxicants and the type of sensing elements. Accordingly, some strategies have already been proposed to enhance the toxicity responses in the past several years, including the external resistance tuning, quorum sensing effect, shear stress control, nutrient level control, electrode material choice, sensing element choice, and cell configuration design. This work introduces and discusses these strategies, and the suggestion for future work is also provided finally.     

Foreign Body Reactions to Plastic Implants

There are three types of foreign body reactions to plastic implants: 1) reactions due to physical characteristics of the implant, 2) reactions due directly to chemical properties of the implant, and 3) immune reactions. Responses which vary with the physical properties of the implant are epithelial encapsulation of the plastic, epithelial keratinization in cutaneous implants, thickening of the connective tissue fibrous capsule, formation of ground substance, and the presence of giant cells. Responses related directly to chemical toxicity of the plastic are epithelial hypertrophy (with mild irritants), inhibition of epithelial growth (with more toxic irritants), connective tissue inflammation, accumulation of a cellular glycoproteins, and vacuolization of host tissue. Finally, reactions due to infection or the presence of other antigens are characterized by inhibition of epithelial growth, invasion of epithelium by leukocytes, and proliferation of inflammatory tissue with a large population of plasma and other round cells.

There is always a tissue response to a plastic implant, even when the material is chemically inert. However, with use of a suitable design and a chemically inert material, and with sterile conditions, plastic implants with only minimal host tissue response may be achieved. Infection, not physical (design) or chemical properties, remains the primary problem with current implantation procedures.