最新刊期
卷 32 ， 期 7 ， 2019
- 摘要：Polylactic acid (PLA) has good biodegradability and biocompatibility, and is widely used in many fields. Modifying PLA by direct melt polycondensation (DMP) is an environmental and efficient way to prepare high-performance PLA, which has potential industrial application value. In this paper, the research progress on the modification of PLA by DMP at home and abroad since 2010 has been reviewed from the aspects of modifying substances, catalyst types and polymerization ways in DMP. It is also pointed out that the research direction of industrial application based on sustainable development is worthy of attention in the future.关键词：Polylactic acid;Modification;Direct melt polycondensation;Solid state polycondensation
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发布时间：2022-09-02 - 摘要：Thermosensitive hydrogels can respond to the change of temperature and attract much attention in practical applications. Among them, poly (N-isopropylacrylamide) (PNIPAM) is one of the most widely studied and applied thermosensitive hydrogels because of its good thermosensitivity, simple preparation and easy modification. In recent years, with the further development of research, especially the progress of chemical modification and functionalization technology, a variety of novel PNIPAM thermosensitive hydrogels with excellent response performance have emerged. The depth and breadth of their applications have been expanded and updated,which are more close to the actual needs. So PNIPAM thermosensitive hydrogels have broad prospects in the fields of biomedicine,chemical industry and so on. In this article, the principle of thermosensitivity and main preparation methods of PNIPAM hydrogels are introduced. The application situation and development trend of PNIPAM hydrogels in drug release, cell scaffold,sensor analysis and material separation are discussed. The existing problems and development prospects of PNIPAM hydrogels are analyzed and prospected. This review could provide a reference for the further development of PNIPAM thermosensitive hydrogels.关键词：Poly(N-isopropylacrylamide);Hydrogel;Thermosensitive
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发布时间：2022-09-02 - 摘要：A series of air stable 8-arylimine-5, 6, 7-trihydroquinoline palladium complexes (LPdCl2, Pd1-Pd3) and methylpalladium chloride complexes (LPdClMe,Pd4-Pd6) was synthesized and fully characterized by 1H/13 C NMR spectroscopy and FT-IR spectroscopy as well as elemental analysis. The crystal structure of the complex Pd1 indicates that it possessed distorted square coordination geometry around the palladium. In the presence of boron salt, the complex Pd4-Pd6 showed good efficiency for the polymerization of methacrylate with high monomer conversion, producing polymethylacrylates with high molecular weights and narrow distribution. The parameters of solvent, temperature and polymerization time greatly affected the catalytic performance.关键词：N^N Bidentate;Dichloride palladium complexes;Methyl chloride palladium complexes;Methylacrylate polymerization
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发布时间：2022-09-02 - 摘要：Vacuum treatment was used to coagulate natural latex. The effects of vacuum on physical and chemical properties, mechanical properties, thermal stability, crosslink density and processing properties of vacuum coagulated natural rubber (NR) were investigated, and compared with acid-coagulated natural rubber. The results show that the nitrogen content of vacuum coagulated NR is lower than that of acid coagulated NR. The nitrogen content gradually decreases with the increase of vacuum degree. The initial plastic value (P0) and plastic retention rate (PRI) of vacuum coagulated NR are higher than those of acid coagulated NR. The ash content and Mooney viscosity are not much different. The mechanical properties of vacuum solidified NR are better than acid solidificatied NR, and the tensile strength of vulcanizate increases slightly with the increase of vacuum. As the degree of vacuum increases, the tensile strength of vulcanizates rises slowly. The vulcanization characteristics and thermal stability of NR are not much difference. The crosslinking density of vacuum solidified NR is larger than that of acid solidification, and its processing performance is better than that of acid-solidified rubber. In the range of vacuum, the comprehensive performance of NR is good when vacuum is —0.95MPa.关键词：Nature rubber;Vacuum;Coagulation;Properties
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发布时间：2022-09-02 - 摘要：A hydrophobic associating copolymer (SPAMA) emulsion was synthesized by using sodium 2-acrylamido-alkyl sulfonate (SADS) as hydrophobic monomer, acrylamide (AM) and acrylic acid (AA) as raw materials through the inverse microemulsion polymerization. The surface activity of SADS was determined by the surface tension method. The particle size distribution and rheology properties of the SPAMA emulsion were characterized by the Dynamic light scattering(DLS) and dynamic rheometer, respectively. The critical micelle concentration (CMC) of SADS is 0. 25g • L-1 at 25℃, and the surface tension is 25. 42mN • m-1. The average particle size of the SPAMA emulsion is 68.06nm, and the polydispersity coefficient is 0. 055. According to the rheological test results, SPAMA aqueous solution is a pseudoplastic fluid and its critical associating concentration (c *) is 1.62g • L-1. The SPAMA is a typical viscoelastic fluid based on the viscoelasticity tests. The value of storage modulus (G′) is larger than loss modulus (G″). SPAMA displays obvious elastic characteristics.关键词：Inverse microemulsion;Surface active monomer;Hydrophobic association;Rheological behavior;Viscoelasticity
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发布时间：2022-09-02 - 摘要：The nylon 612/6 copolymer was synthesized by melt polymerization using a 5L polymerizer. The effects of different mass fractions of caprolactam (CPL) on the mechanical properties of nylon 612/6 copolymer were investigated. The reasons for the influence of CPL addition on the mechanical properties of nylon 612/6 copolymer were determined by end group titration, section moisture content and X-ray diffraction(XRD)test. The mass fraction of CPL was determined to be 15% nylon 612/6 copolymer can obtain better mechanical properties. Compared with nylon 612: the notched impact strength is improved by 113%; the elongation at break is increased by 127%; the tensile strength is decreased by 8%; the bending strength is decreased by 28%; and the isothermal crystallization behavior of nylon 612 and nylon 612/6 with a mass fraction of 15% CPL was analyzed by Avrami equation. The Avrami index n was between 2.02~2.53 and 2.23~2.38, respectively. Isothermal crystallization process of nylon 612 and nylon 612/6 copolymers is secondary nucleation. After nucleation, it grows along the crystal nucleus in two dimensions. At the same time, the Arrhenius equation is used to determine the isothermal crystallization activation energy ΔE was —756.38kJ/mol and —115.09kJ/mol, respectively.关键词：Nylon 612;Nylon 612/6;Mechanical properties;Isothermal crystallization kinetics
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发布时间：2022-09-02 - 摘要：A potassium dichromate molecularly imprinted membrane was prepared on the surface of a gold electrode modified with chitosan by precipitation polymerization, the performance and effect of molecularly imprinted membrane were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), factors affecting the properties of sensor, such as optimal concentration, elution time and scanning liquid were investigated, the result showed that the sensor had a good selectivity to potassium bichromate. Under the optimized experiment conditions, the current response of the imprinted sensor had a good linear relationship with the concentration of potassium dichromatein in the range of 0 ~31× 10-3mg/L,the regression curve was y=25.02x — 0.0073, R2=0.9991, and the detection limit was 2.47×10-6 mg/L. The molecularly imprinted electrochemical sensor also had good stability and selectivity, at the same time, it was used to detect the potassium dichromate content in tea in the actual environment.关键词：Potassium bichromate;Gold electrode;Molecularly imprinted membrane
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发布时间：2022-09-02 - 摘要：Modern Research Techniques for Polymer is a required course for Polymer Materials and Engineering Specialty in application-oriented colleges, and is also a necessary and indispensable course to cultivate students' comprehensive analysis, practice and innovation abilities. Therefore, it plays a very important role in the training of application-oriented undergraduate talents in Polymer Materials and Engineering Specialty. In order to realize the training goal of application-oriented colleges, teaching method of theory in connection with practice, the introduction of video data and open experiments and the adjustment of final examination methods were adopted in the course of Modern Research Techniques for Polymer according to the characteristics of undergraduates in application-oriented colleges. After several years of teaching practice, the teaching method, which can not only suit the characteristics of application-oriented undergraduate students,but also improve students abilities of comprehensive analysis of problems, hands-on practice and innovation, was formed, so as to achieve the purpose of training new application-oriented undergraduate talents.关键词：Application-oriented colleges;Modern Research Techniques for Polymer;Teaching methods
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发布时间：2022-09-02 - 摘要：In the environment of talent cultivation for "new engineering course",an exploration for improving innovation ability of students during the polymer chemistry experiment teaching process is carried out, based on the implementation of bulk polymerization innovation experiment project. A complete student-oriented system for polymer chemistry experiment teaching practical innovation is formed. A series of acrylic resin will be synthesized by continuous bulk polymerization, and their structure and properties will be test. Based on these, students will learn how to combine theoretical knowledge with practical production and improve their ability to resolve the actual production problem. Finally, the function of student, teacher and company to the experiment is identified,and an investigation of the safeguard mechanism is also performed.关键词：Polymer chemistry experiment teaching;Ability training for practical innovation;Student-oriented;Bulk polymerization
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发布时间：2022-09-02 - 摘要：Polymer materials processing training is an important part of practice process in regular education, which can train students practical capability, safety production capacity, innovation capacity and vocational capability. Considering the relevant devices and software of Chizhou University and the circumstances of the periphery related polymer materials processing enterprise, and through the research analysis of the present situation of polymer materials processing training in recent years, a teaching model of polymer materials processing training was explored, which combined safety production training, simulation training and production training. Then, a double-qualified teacher team was cultivated. The explorations and achievements of this teaching training mode construction was introduced in this paper,which may provide useful experience and reference to the teaching model of polymer materials processing training in local universities.关键词：Integration of production and education;Polymer materials processing training;Teaching model;Practice teaching
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发布时间：2022-09-02 - 摘要：In view of the shortage of applied innovative training in polymer materials and engineering in Hunan institute of engineering, reform about practical curriculum system was conducted based on the guiding ideology of "laying the foundation, expanding the vision, expanding the quality and promoting the application", which is aim to train students' applied innovative ability. In this work, a new practical curriculum system was constructed to promote hierarchical and individualized teaching, a multi-directional and diversified practical teaching assessment mechanism was established to emphasize the learning process, and school-enterprise cooperation was motivated to expand practical teaching methods. What's more, a good atmosphere for cultivating innovative and entrepreneurial talents was created. The application of this new model in the practical teaching of polymer materials and engineering is beneficial to the cultivation of students' innovation and application ability. Based on the feedback and supervision of employers, the model has achieved good results.关键词：Applied innovative talents;Polymer materials and engineering;Practical course system
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发布时间：2022-09-02
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