最新刊期
卷 37 ， 期 2 ， 2024
- 摘要：With the rapid development of fuel cells, the balance between the improvement of performance and lifetime, and the reduction of the cost of the whole system become a bottleneck problem which restricts its application. As the key component of fuel cell, proton exchange membrane ensures the operation of the whole system. Polybenzimidazole (PBI) based high temperature proton exchange membrane (PEM) can greatly enhance the impurity tolerance of fuel cell and simplify its hydrothermal management, which reduce the cost. Therefore, it is an ideal Nafion alternative material. However, traditional PBI based PEM is easy to loss phosphoric acid during the operation and after acid loading, the mechanical strength decreases, resulting in the attenuation of battery performance. Aiming at the problems of PBI based proton exchange membrane, this paper reviews different methods that researchers attempted from various angles, hoping to summarize the general strategies that can be used for reference in the follow-up research.关键词：Polybenizimidazole;Porton exchange membrane;High-temperature fuel cell
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发布时间：2024-01-25 - 摘要：With the rapid development of the global petrochemical industry, the shortages of water resources and the growth of industrial wastewater have greatly hindered the sustainable development of the society and environment. Oily wastewater is one of the largest proportions and also one of the most difficult types to treat. Membrane separation is currently one of the most effective methods for treating oily wastewater. At present, some or all of the mainstream oil and water separation membranes in the market use non-renewable and non-degradable raw materials, causing secondary pollution to the environment. Biomass-based oil-water separation membrane with biomass material as the main raw material has attracted great attention for its green, sustainable, efficient and degradable advantages. In this paper, the sources and types of biomass, the corresponding preparation and modification methods, the status of application research and the main problems of biomass based oil-water separation membrane were discussed, and the development of biomass based oil-water separation membrane in the future is prospected.关键词：Biomass-based;Oil-water separation membrane;Renewable;Green;Biodegradable
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发布时间：2024-01-25 - 摘要：Natural polymer hydrogels with a highly hydrated three-dimensional polymer network structure show unique adhesion properties that are highly efficient in controlling bleeding and reducing secondary infections. Moreover, they are biocompatible and biodegradable, making them an ideal material for medical adhesives. In recent years, in view of the increasingly stringent requirements for underwater wet viscosity and biodegradability in the research and development of medical adhesives, new adhesion materials with water resistance, biological safety and shape controllability have become a hot spot and difficult point in research. The adhesion of natural organisms to various substrates is mainly dependent on their composition or structure, and biomimetic use of natural polymeric hydrogel materials, which can combine excellent tissue adhesion, haemostasis and bacteriostatic properties and shape controllability, is an effective strategy to address these issues. This paper outlines the adhesion mechanisms of two types of bionic natural polymeric hydrogel materials, discusses the compositional properties of mussel, barnacle and oyster and the structural characteristics of saltwater fish and extracellular matrix as well as the adhesion mechanism in a targeted manner, and introduces the research progress of the corresponding bionic natural polymeric hydrogel materials in tissue healing, wound hemostasis and drug delivery. Finally, the future directions of bionic natural polymer hydrogels are presented and the suggestions are provided.关键词：Medical adhesive;Bionic design;Hydrogel;Natural polymer
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发布时间：2024-01-25 - 摘要：The solid-liquid transition of many materials can be realized by heating through the traditional thermal method. The solid-liquid transition is a valuable property of the material. The liquefied material can be used to prepare objects of various shapes through molds. Compared with thermal-induced solid-liquid transition, photo-induced solid-liquid transition has higher spatial and temporal resolution, and can be irradiated precisely on the part that needs to be liquefied in a non-contact manner, which makes photo-induced solid-liquid transition materials have great potential application in the field of functional materials. This paper introduces the research progress of organic small molecules, polymers and other materials for photo-induced solid-liquid transition, discusses the transition mechanism and design principles, and introduces the potential application of photo-induced solid-liquid transition materials in reusable adhesives, photoactuators, and self-healing materials.关键词：Photo-induced solid-liquid transition;Azobenzene;Photo-responsive;Research progress
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发布时间：2024-01-25 - 摘要：Melt blowing (MB) is a nonwoven fabrication process in which polymer melt is blown by high-temperature and high-speed air to form micro-nano fibers. Over the past decades, a considerable amount of theoretical and experimental research has been conducted on the mechanisms of fiber dynamics during MB. Although some studies involving air flow field distribution, fiber thinning mechanism, and die improvement have been summarized by recently published review articles, the evolution of the theoretical equations and improvements in the mechanism experiments are rarely mentioned. Therefore, this work presents a comprehensive overview of the research on fiber dynamics in high-temperature and high-speed air. The evolution of the fiber formation and fibrous web formation models were analyzed. In addition, online and offline experiments used to demonstrate fiber formation and fibrous web mechanisms also are reviewed in our work. The fundamental studies reviewed in this paper contributed noteworthy findings in controlling the fiber and web uniformity, improving MB instrument and process, thereby enhancing the MB product quality.关键词：Melt blowing;Micron fiber;Nonwoven;Airflow;Fibrous web
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发布时间：2024-01-25 - 摘要：Efficient, energy-saving and environment-friendly rubber reclaiming method is of significance to realize the green and sustainable development of rubber industry. The selection of de-crosslinking chemical agents is the key for waste rubber reclamation. The reclamation mechanism of rubber was introduced. And six types of de-crosslinking agents were categorized according to the mechanism: free radical, nucleophile, phase transfer catalysis, olefin metathesis, catalysis and oxidation. The mechanism and research progress of various agents were reviewed. Subsequently, the shortcomings of their application technology were also discussed. Finally, the challenges and future development of waste rubber recycling were recommended.关键词：Waste rubber;Reclamation;De-crosslinking agents;Reclaiming methods
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发布时间：2024-01-25 - 摘要：Warping deformation of plastic parts is one of the common quality defects in injection molding, attracting many scholars and engineering practitioners to put forward endless optimization ideas. From the perspective of industrial mass production, this paper systematically introduces optimization ideas of plastic parts in different stages which are divided into drawing stage, trial production stage and final mass production stage. Firstly, the optimization ideas of warping deformation of thin-walled plastic parts and irregular plastic parts are introduced, and the application of new die temperature technology in the optimization of warping deformation of plastic parts as well as the current research of predeformation technology is summarized and described, and the solution of die temperature technology combined with artificial intelligence algorithm can have a more long-term development in the future. It is indicated that there are some limitations to optimizing the warping deformation of plastic parts by using post-process shaping method. Finally, it is summarized that the new application of molding technology in the optimization of plastic parts warpage deformation and low warpage specification materials. Based on the current industry research foundation, it is proposed that co-simulation technology and online detection technology are the future research direction and technology development trend to solve the warpage deformation of plastic parts.关键词：Injection molding;Deformation;Optimization;Development
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发布时间：2024-01-25 - 摘要：α-CD/PMPEGA-2000 supramolecular hydrogel was fabricated by mixing 7 wt% α-cyclodextrin (α-CD) aqueous solution with 5 wt% methoxy polyethylene glycol (2000) methacrylate homopolymer (PMPEGA-2000) aqueous solution. The necessary condition for the formation of the hydrogel was that the volume ratio of the two aqueous solution should not be less than 1.5:1. When the volume ratio was 2:1, a hydrogel with the highest viscosity can be obtained. The scanning electron microscopy results confirmed that there exist three-dimensional network structures in the hydrogel. The results of thermogravimetric analysis and X-ray powder diffraction analysis indicated that the formation of the hydroygel was based on the host-guest recognition between α-CD and PMPEGA-2000. The results of optical microrheological analysis showed that the macroscopic rheological performance establishment process of the hydrogel was actually a process of an increasing in the number of host-guest recognition crosslinking points, thereby constantly enhancing the strength of the network structure. The process started at 8′36″ after the mixing of α-CD aqueous solution and PMPEGA-2000 aqueous solution, and was basically completed at 64′00″. The entire process took about 55′24″.关键词：Supramolecular hydrogel;Three-dimensional network structure;Host-guest recognition;Micro-rheology;Macro-rheological performance
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发布时间：2024-01-25 - 摘要：The crosslinking structure and homogenization stress of natural rubber (NR) were studied by using zinc 1,5-pentyldithiocarbamate (ZPDC) as accelerator. It was found that the crosslinking bond of the vulcanizate of accelerator ZPDC combined with NR was mainly polysulfide bond. Compared with the similar accelerator zinc dibutyldithiocarbamate (BZ), it had a higher content of polysulfide bond, which gave the rubber a better homogenizing stress effect, mainly in the significant improvement of tear resistance. In addition, through the analysis of the vulcanization process and mechanical properties of the NR compound accelerator ZPDC, the results show that the suitable vulcanization temperature conditions are 120–130 ℃, the amount of 1.5–2.0 phr, and the vulcanizate shows the best homogenization stress effect.关键词：Natural rubber;Homogenization force effect;Crosslinking structure;Tear resistance
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发布时间：2024-01-25 - 摘要：A series of polyester polyurethanes (PU) with different molar ratios of urethane/urea were synthesized by using polyester diol XCP-2000PM (PM) as the soft segment. The influence of urethane/urea on the surface energy of polyester polyurethane film and the adhesion work between bioriented stretching polyester film (BOPET) and PU were studied by contact angle test. The influence of urethane/urea molar ratio on adhesion fastness before and after boiling was studied when by bonded with BOPET, and its heat resistance was also studied. The results showed that with the change of urethane/urea, the overall changes of surface energy and adhesion work were small. The surface energy was mainly nonpolar Lifshitz-Vander Waals γ LW, and the adhesion work was mainly nonpolar work WLWBi . The acid-base contribution of the two was small, but PU-P1 and PU-N1 showed relatively strong acidic effect. There were some differences between the actually tested adhesion fastness and the theoretical surface energy and adhesion work. When the urethane/urea was 10/90, the adhesion work of PU-P1 and PU-N1 were relatively low, and the actual adhesion fastness was elatively good due to the acid-base effect in the surface energy and better wettability and spreadability; The adhesion work of PU-B1 was the largest, and its actual adhesion fastness was the smallest due to its larger apparent viscosity. When the urethane/urea was 40/60, the adhesion fastness were relatively best, which were consistent with the theoretical adhesion work and surface energy. After the coating samples were boiled for 30 min, the adhesion fastness decreased to a certain extent, while PU-N and PU-E could maintain good adhesion fastness, while PU-B decreased significantly. With the increase of urethane/urea, the initial thermal decomposition temperature T5% and Tmax of polyurethane generally showed a downward trend, and the T5% of PU-B was the highest, while the T5% of PU-P was the lowest.关键词：Urethane/Urea;Polyester polyurethane;Contact angle;Surface properties;Adhesion fastness
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发布时间：2024-01-25 - 摘要：Traditional hydrogels have the disadvantages of poor mechanical properties and machinability. In this study, aryl-reinforced MXene-poly(acrylic acid)-amorphous calcium carbonate (ANF/MXene-PAA-ACC) composite hydrogels were prepared, and the related mechanical and physical properties were studied. Firstly, two-dimensional MXene monolayer nanosheets were prepared by the method of lithium fluoride and hydrochloric acid etching combing with ultrasonic stripping process. Then, it was added into PAA-ACC composite hydrogel. In order to improve the mechanical properties of MXene-PAA-ACC hydrogel, ANF/MXene-PAA-ACC composite hydrogel was prepared by adding aryl fiber. The appearance, mechanical properties, self-healing and adhesion properties of the ANF/MXene-PAA-ACC composite hydrogels were characterized and tested by scanning electron microscopy and universal mechanical testing machine. The results showed that compared with PAA-ACC hydrogels, the machinability, mechanical properties, adhesion and self-repair performance of ANF/MXene-PAA-ACC hydrogels were all improved.关键词：MXene;Poly(acrylic acid)-amorphous calcium carbonate hydrogel;Aramid fiber
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发布时间：2024-01-25 - 摘要：The cohesion energy density describes the magnitude of intermolecular forces, which is one of the most fundamental concepts in polymer physics. The physical properties of polymers are closely related to the cohesion energy density. In undergraduate polymer physics teaching, polyethylene, due to its high crystallinity, was often described as the only exceptional case of the rule that "the density of cohesion energy is used to determine the macroscopic use of the material". It is highly desired to prepare completely amorphous polyethylene at room temperature. In this paper, an α-diimine nickel catalyst (NiB) was used to catalyze the pressurized polymerization of ethylene to successfully synthesize amorphous polyethylene (Mw: 2.01×105 g/mol, PDI: 1.80, Branches: 107/1000C, Tg: −63.1 ℃, ρ: 0.856 g/cm3) at room temperature. The maximum characteristic viscosity method was used to measure the cohesive energy density of polyethylene as 259 J/cm3, which was very close to the value estimated by the group contribution method. The amorphous polyethylene exhibited a rubbery macroscopic behavior at room temperature. As a result, the correlation between the measured cohesion energy density (< 300 J/cm3) and the rubbery macroscopic behavior is not exceptional but follow the general rule.关键词：Polymer physics;Cohesion energy density;Amorphous polyethylene
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发布时间：2024-01-25 - 摘要：The thermodynamics of polymer phase separation constitutes a crucial topic in polymer physics, and the associated parameters pertaining to the critical point of the phase diagram, namely,
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发布时间：2024-01-25 - 摘要：The reverse thinking experiment solves practical problems by independently and comprehen-sively applying various basic knowledge, promoting the close integration of theoretical knowledge and practice, and is conducive to cultivating students’ engineering practice ability and scientific exploration spirit. The reverse thinking experiment Composition and Content Analysis of Polymer Composites was designed and implemented in this paper. The experiment consists of several parts, including experimental scheme design, sample testing, data analysis, etc. The experimental scheme is perfect and can be implemented. The results of the experiment show that the application of the reverse thinking has greatly mobilized the students’ exploration spirit, stimulated the students’ ability to solve practical problems by comprehensively using the relevant knowledge of multiple professional basic courses, which played an important role in cultivating students’ engineering practice ability and scientific research spirit. The reverse thinking experiment meets the urgent needs of the current society for polymer materials professionals. It lays a good foundation for students to go to work and further study. At the same time, this experiment provides a good reference for other majors to design reverse thinking experiments.关键词：Reverse thinking;Comprehensive;Professional experiments;Design;Practice
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发布时间：2024-01-25
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