最新刊期
卷 35 ， 期 5 ， 2022
- 摘要：Poly (4-methyl-1-pentene) is a kind of membrane material with excellent properties such as low density and high permeability. This paper reviews the research progress of PMP membranes in recent years from two aspects of preparation methods and applications prospects, focusing on the principles and influencing factors of the main preparation methods of PMP membranes which include thermally induced phase separation (TIPS) method, melt stretching method, solvent evaporation method and so on. The applications of PMP membranes in the fields of extracorporeal membrane oxygenation, membrane contactor, pervaporation and gas separation are reviewed. Finally, the challenges faced by PMP membranes are discussed and prospected.关键词：Poly(4-methyl-1-pentene);Thermally induced phase separation;Melt stretching;Solvent evaporation;Extracorporeal membrane oxygenation
- 20
- |
- 18
- |
- 1
发布时间：2022-09-09 - 摘要：The different physical states of plant fiber/polymer composites have a certain influence on the processing and properties of the composites. The advantages and disadvantages of powder fibers, chopped fibers and continuous fibers with different physical states in reinforced polymers and their applications in 3D printing are reviewed. The 3D printing of plant fiber/polymer was compared with traditional extrusion and injection molding, and the advantages and disadvantages of different processing methods were analyzed.At the same time, the future research directions of plant fiber/polymer composites with different physical states are analyzed and prospected.关键词：Plant fiber;Polymer;3D printing;Physical state
- 17
- |
- 14
- |
- 1
发布时间：2022-09-09 - 摘要：Cellulose is one of the most abundant natural polymer materials on earth, which can be divided into two types: plant cellulose and bacterial cellulose. Bacterial cellulose has higher purity and better performance than plant cellulose. As a natural renewable polymer material, bacterial cellulose has attracted much attention in recent years due to its porous nano network structure, high degree of polymerization, high purity, high crystallinity, excellent mechanical properties and biocompatibility. This review will introduce the main methods of preparation of bacterial cellulose, summarize several modification methods of bacterial cellulose, and introduce some latest applications of bacterial cellulose with examples. Hope this article can provide reference for related research.关键词：Bacterial cellulose;Preparation;Modification;Application
- 12
- |
- 16
- |
- 3
发布时间：2022-09-09 - 摘要：With the development of science and technology, the utilization of fossil fuels is increasing rapidly. At the same time, it also brings many environmental problems. For example, a large amount of CO2 intensifies the greenhouse effect and global warming. Therefore, the separation, recovery and reuse of CO2 are of great significance to environmental protection. Membrane separation technology has the advantages of no phase change, simple operation, low energy consumption etc. and has good advantages in solving gas separation, recovery and reuse. Comparing different polymer materials, polyimide is a mature and commercialized polymer material with good mechanical properties, heat resistance, chemical corrosion resistance etc., so it is widely used in the field of gas separation. The research status of the influence of polyimide gas separation membrane structure on gas permeability at home and abroad is summarized, the latest research progress of polyimide gas separation membrane containing fluorine atom, sulfonyl group, PIM structure and other structures is introduced in detail, and the preparation of high-performance polyimide gas separation membrane in the future is prospected.关键词：Polyimide;Separation coefficient;Transmittance;Permeability;Monomer structure;Polymer structure
- 15
- |
- 20
- |
- 1
发布时间：2022-09-09 - 摘要：With the rapid economic development and the continuous depletion of petroleum resources, more and more attention has been paid to converse the renewable resources into useful polymers or compounds. Bio-based furan polymers, not only having rich reserves of monomers, but also creating excellent ecological benefits, can be applied in many fields such as green packaging materials, conductive materials, self-healing materials and so on. The great application potential makes their synthesis researches being concentrated. Thus, based on different monomers and synthetic methods, e.g., polycondensation, metal-catalyzed coupling reaction, oxidative coupling polymerization, polymerization based on non-furan materials, and Diels-Alder reaction, the synthesis and application of polyfurans and their derivatives in the past decade (especially in the last 5 years) are summarized. In addition, a brief evaluation of each method is discussed in combination of the mechanical property and function of the products. In the future, performance optimization and function expansion are still the vital development directions for the design and synthesis of furan polymers.关键词：Bio-based furan polymers;Synthetic methods;Polycondensation;Metal-catalyzed coupling reaction;Oxidative coupling polymerization;Diels-Alder reaction;Application
- 17
- |
- 19
- |
- 0
发布时间：2022-09-09 - 摘要：1-Butene and 2-butene are important raw materials for organic synthesis, which can be selectively catalyzed by metal catalysts to catalyze the dimerization of ethylene into butene. Catalysts for selective dimerization of ethylene to butene usually include nickel catalyst system, vanadium catalyst system, tungsten catalyst system, iron or cobalt catalyst system, tantalum catalyst system and titanium catalyst system. In recent years, nickel-based catalysts have made great progress in the selective dimerization of ethylene. This paper reviews the selective dimerization of ethylene catalyzed by nickel-based catalysts in recent years. It mainly summarizes [NN], [NO], [NP] and other homogeneous nickel catalysts, and also summarizes the research progress of heterogeneous or supported nickel catalysts catalyzing the selective dimerization of ethylene.关键词：1-Butene;2-Butene;Ethylene;Selective dimerization;Nickel catalyst
- 14
- |
- 17
- |
- 0
发布时间：2022-09-09 - 摘要：Chromocene supported by silica is a traditional industrial ethylene polymerization catalyst that does not require aluminum alkyl cocatalyst, however, its initiating mechanism for ethylene polymerization remains unclear up to now. The feasibility of metallacycle and oxachromacycle mechanisms suggested in literatures, as well as the chroma-Cpcycle mechanism which was firstly proposed in this work were systematically investigated by DFT method. It was found that chain initiation could be achieved with a relatively low barrier (ca. 24.9kcal/mol) in the metallacycle mechanism, which was consistent with the experiment results. However, because of the large steric effect of the metallacycle, the subsequent propagation would be very slow due to the high insertion barrier (ca. 31kcal/mol). For the oxachromacycle mechanism, both the initiation and insertion barriers were very high, and the bonding between Cr and silica support would be impaired by C2H4 insertion, which made this mechanism nearly impossible. With respect to the chroma-Cp-cycle mechanism, the energy for cyclopentadienyl slippage to weaken its coordination with Cr center is very high, making the initiation barrier as high as 37.3kcal/mol, which contradicted with the fast initiation nature of S-9 catalyst. Nevertheless, the low barrier (ca. 20kcal/mol) for insertion ensured a fast propagation, which was in agreement with experimental observations. In this work, molecular simulation methods are used to study three possible initiation mechanisms including metallacycle mechanism, oxachromacycle mechanism and chroma-Cp-cycle mechanism for S-9 catalyst, which gave a relatively deep understanding on this catalyst under a molecular level.关键词：S-9 Catalyst;Polyethylene;Density functional theory;Polymerization mechanism;Spin cross
- 13
- |
- 17
- |
- 0
发布时间：2022-09-09 - 摘要：Oral administration has the advantages of convenience, safety, and strong patient dependence which is an ideal route of administration. However, protein drugs are easily degraded by gastric acid and protease during oral administration resulting in low bioavailability. In this paper, a drug carrier was designed for oral administration of protein drugs, which solved the problem that protein drugs were easily inactivated in the gastrointestinal tract. Glucose oxidase nanocapsules were prepared by in-situ free radical polymerization on the surface of the protein using glucose oxidase as a protein drug model, and the nanocapsules were grounded into powder and encapsulated in the capsul after dried at low temperature. Hypromellose was used as a raw material to prepare hypromellose acetate succinate, which was used as an enteric coating material to coat the above-mentioned capsules to obtain enteric capsules. By simulating the environment in the gastrointestinal tract, in vitro release experiments and activity tests were performed. The results showed that the enteric-coated capsule did not dissolve within 2h under the environment of gastric juice, and the glucose oxidase in the capsule maintained high activity. Under the environment of intestinal juice, the enteric-coated capsule was dissolved and the activity of the glucose oxidase encapsulated by the nanocapsules was significantly higher than that of free glucose oxidase. The above experimental results proved that the drug-carrying system could solve the problem that oral protein drugs were easily decomposed by gastric acid and protease in the gastrointestinal tract and became inactivated.关键词：Protein drugs;Oral administration;Nanocapsules;Hypromellose succinate;Protein activity
- 11
- |
- 12
- |
- 0
发布时间：2022-09-09 - 摘要：In some glassy polymers, the transport behavior of solvent molecules exhibits non-Fickian diffusion features which are different from the classical Fick's law, and this process is usually accompanied by swelling and large deformation of the material. In this paper, the characteristics of non-Fickian solvent diffusion and swelling deformation of gels are investigated by using a two-phase hysteresis method, which is analogous to the theory of non-Fourier effect in heat conduction analysis. In other words, two controlling parameters related to solvent concentration are introduced to describe the material properties during the glassy transition process. The governing equations for describing diffusion and swelling of different material systems, namely one-dimensional gel rod and a two-dimensional gel plate, are numerically solved by the finite difference method. Our obtained results show that the concentration distribution of solvent molecules in these two polymers is significantly different from that under the case of Fick diffusion. There is a sharp boundary between the swollen part and the non-swollen part, and its moving speed is approximately a constant. At meantime, the theoretical predictions are in good agreement with the existing experimental results, which further verifies the validity and ability of the two-phase hysteresis method to characterize the kinetics of Non-Fickian diffusion.关键词：Polymer;Non-Fickian diffusion;Swelling;Large deformation;Relaxation time
- 11
- |
- 13
- |
- 0
发布时间：2022-09-09 - 摘要：Thermoplastic polyurethane elastomer (TPU) with high impact strength was prepared by sequential thiolene and thiol-isocyanate click reactions. The structures and properties of thiol-ene-isocyanate based TPU ternary crosslinking networks were proven by using FT-IR, refraction, tensile, impact strength and hardness tests, DSC, DMA and TGA. The increased crosslinking density and decreased rigidity of the polymer networks, compared with the thiolisocyanate based dual networks, resulted in relatively better impact strength. When the molar ratios of C=C/NCO were 50/50 and 30/70, the notched impact strength were 24.28 and 18.57kJ/cm2. Compared to those without toughening, the impact strength was increased by 92.2% and 47.0%, respectively. In addition, different structures of thiols, isocyanates and the molar ratio of C=C/NCO also influenced the optical, mechanical and thermal properties, which showed that the TPU with different properties can be designed by controlling the polymerization components and potentially used as optoelectronic materials or dental materials.关键词：Thiol-ene-isocyanate;TPU;Dual cured by UV irradiation and heat;Impact strength
- 14
- |
- 17
- |
- 0
发布时间：2022-09-09 - 摘要：Based on the consideration of the normalization about COVID-19, the position of the bilingual course of Polymer Chemistry is reoriented. The new course design starts from the comprehensive course teaching and training, and ends to the comprehensive development of teachers and students' abilities. Online and offline teaching and learning are carried out in order to adapt to the new social needs. Firstly, Teaching-related issues, such as teachers’ self-improvement, educational methodologies, the reorganization and optimization of teaching content, the expansion of teaching theories, the design of interaction between teachers and students, and the arrangement of after-school review system, etc., have been carried out to strengthen students’ overlaid learning. Secondly, students' self-improvement issues, such as the comparison learning, the competition learning, the initiative learning, the comprehensive learning and the innovative learning, etc., have been carried out to facilitate their systematic learning. The redesigned course can improve students' overall abilities (learning efficiency, self-study ability, induction and summary ability) and let teachers master students' learning trends in real time and solve students' learning difficulties immediately.关键词：Curriculum orientation;Comprehensive education;Co-frequency teaching through online and offline;Comprehensive improvement of teachers and students' ability
- 15
- |
- 18
- |
- 0
发布时间：2022-09-09 - 摘要：Glass transition, as a common phenomenon of polymer, is a key content in polymer physics teaching. A comprehensive explanation of the nature of glass transition is helpful for students to deepen their understanding of polymer structure, properties of polymer materials and statistics of polymer chain motion. Aiming at the deficiency of the concept of glass transition temperature of amorphous polymer mainly based on differential scanning calorimetry (DSC), this paper discussed the application of Fourier transform infrared spectroscopy (FTIR) and two-dimensional correlation spectroscopy to explain the glass transition temperature and the analysis of teaching effectiveness. From the actual teaching effectiveness, the application of FTIR to determine the glass transition temperature of polymer can not only cultivate students' exploration spirit, but also make students understand new research methods and broaden their scientific vision.关键词：Polymer;The glass transition;FTIR;Two-dimensional correlation spectroscopy
- 17
- |
- 21
- |
- 0
发布时间：2022-09-09 -
Exploration on the Case Teaching Method of
Polymer Chemistry Based on the Hyperbranched Polysiloxane摘要：Hyperbranched polysiloxane is a new type of hyperbranched polymer, which has the advantages of hyperbranched polymer and siloxane, thus it is a typical case in the teaching of polymer chemistry. This paper takes hyperbranched polysiloxane as the teaching object, discusses monomer selection, raw material ratio, polymerization process control and other aspects, and focuses on gradual polymerization, polycondensation reaction, gel point prediction and other related knowledge points. On this basis, the relationship between the structure and properties of polymers and the preparation method of novel hyperbranched polymers are extended. Through course design, students are organized to study this course by combining online preview, traditional teaching, classroom discussion and offline learning. Furthermore, the students' learning interest and subjective initiative are stimulated. The teaching effect and teaching quality are also discussed and explored.关键词：Polymer chemistry;Hyperbranched polysiloxane;Teaching experience;Exploration of teaching- 14
- |
- 21
- |
- 0
发布时间：2022-09-09 - 摘要：Talent cultivation quality is the foundation of survival and development for universities and majors. Nowadays, more and more colleges are eager to promote the first-class undergraduate major construction and to improve the talent cultivation quality by using specialty construction. Talent cultivation plan is of great importance to talent cultivation quality. It is an effectual way to regulate the talent cultivation process and to improve the talent cultivation quality by using the concept and methods of engineering education accreditation. In this work, the detailed approaches and procedures of revising talent cultivation plan (2019 version) were introduced by taking polymer materials and engineering specialty of Wuhan Institute of Technology for an example. The talent cultivation plan of polymer materials and engineering specialty (2019 version) was revised by taking three steps which included the analysis of the relationship between the development characteristics and the position of universities, regulations of revision and estimation and the opening methods for talent cultivation plan. It will serve as reference and guidance for cultivating talents to meet the requirement of the development for regional economy for similar specialties of local colleges.关键词：Engineering education accreditation;Speciality construction;Talent cultivation plan;Polymer material and engineering
- 17
- |
- 18
- |
- 0
发布时间：2022-09-09 - 摘要：Engineering education accreditation is not only an important means and tool to improve the quality of higher education in China, but also an efficient method for majors to enhance the quality of talent cultivating. Professional curriculum system is the key link of undergraduate talent training and the core element of realizing the goal of professional training. Firstly, this paper analyzes the necessity of engineering education accreditation for engineering majors in universities. Secondly, some principles for professional curriculum are summarized. Finally, through the investigation of the professional curriculum setting of seventeen universities that have passed the engineering education accreditation, this study provides some suggestions on the professional curriculum setting in the talent training of polymer major. It offers some important reference for the development of talent training plan of polymer materials and engineering.关键词：Engineering education accreditation;Polymer materials and engineering major;Cultivation scheme;Major curriculum setting
- 17
- |
- 17
- |
- 1
发布时间：2022-09-09
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0