最新刊期
卷 36 ， 期 6 ， 2023
- 摘要：Copolymerization of olefin and polar monomer to produce functionalized polyolefin is a straightforwardpathway; however, challenges exist, which thus becomes a hot but difficult project in the area of olefin polymerizationover two decades. Late transition metal catalysts are of advantages on preparing functionalized polyolefin,and nickel and palladium catalysts including diimine, salicylaldiminato, and phosphine-sulfonato ligands haveemerged. In contrast, phosphine-phenolate nickel catalysts have attracted much less attention. However, in recentfive years, phosphine-phenolate nickel catalysts have been corroborated to be a greatly promising catalystsystem on fundamental and industrial studies. Herein, in this review key phosphine-phenolate nickel catalystsare summarized, and significant advances in phosphine-phenolate nickel catalyzed ethylene polymerization, copolymerizationof ethylene with polar monomers, and copolymerization of propylene with polar monomers arediscussed over the past five years. Advantages of phosphine-phenolate nickel catalysts are thus summarized.Moreover, perspectives on polar monomer, catalyst structure, stereoselective copolymerization of propylene andpolar monomer, mechanism of polymerization reaction, and comprehensive property of functionalized polyolefinare provided.关键词：Functionalized polyolefin;Phosphine-phenolate ligand;Nickel catalyst;Olefin polymerization;Polar monomer
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发布时间：2023-04-11 - 摘要：Polyamide (PA) is one of the most widely used engineering-plastics. Different typs of PAs have distinct variations in properties, such as processability, heat-resistance and water adsorption. In order to further improve the comprehensive performance of polyamide materials and reduce costs, melt blending is the most basic method. Under the influence of high temperature and mechanical force field during melt blending, the amide bond is opened and rearranged to undergo an exchange reaction, and the homopolymer is first converted into a copolymer, resulting in changes in the polymer chain structure, crystalline structure and higher-level aggregation structure. The strength, modulus, toughness, thermal deformation, moisture absorption and other properties of the material change to meet the needs of specific application scenarios. This paper summarizes the transamidation of PA blending, including characterization techniques, the available research systems, accelerating, and restriction process. The transamidation of polyamide with other polymers, such as polyester and polyurethane is also briefly discussed. Finally, the design and preparation of polymer materials based on transamidation and dynamic chemistry principle are prospected.关键词：Polyamide;Blending;Transamidation;Ester-amide exchange
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发布时间：2023-04-11 - 摘要：The development of the next generation of high-security and high-energy-density energy systems is the key to the further vigorous development of the new energy industry. Among them, the replacement of flammable and explosive liquid batteries with solid-state batteries is a very promising work. Among solid-state electrolytes, polymer electrolytes have been widely studied due to their high safety, viscoelasticity, and good interfacial compatibility. However, its ionic conductivity is still low at room temperature, and a certain battery performance needs to be achieved at high temperature. Therefore, while improving the ionic conductivity of polymer electrolytes at room temperature, it is necessary to further study and improve the interface between the electrolyte/electrode and reduce the interface impedance. Based on the advantages and disadvantages of solid-state polymers, the properties and ion transport mechanisms of different solid-state polymer electrolytes are reviewed, and the latest research progress and development direction of solid-state polymers are prospected.关键词：Solid-state battery;Polymer electrolyte;Ion transport;Electrochemical performance
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发布时间：2023-04-11 - 摘要：Polyethylene (PE) is a kind of widely used polymer materials, however, the mechanical properties of polyethylene is insufficient. In order to satisfy the use of polyethylene requirement, plant fiber is used to enhance PE, which can replace the traditional plastic to become a lightweight and high strength materials. In this paper, the main factors affecting the tensile strength and flexural and other strength properties of plant fiber/PE are reviewed. The improvement direction of plant fiber reinforced PE is summarized.关键词：Polyethylene;Plant fiber;Reinforced modification;Composite materials
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发布时间：2023-04-11 - 摘要：Hydroxyl value titration is a chemical analysis method that calculates the molecular weight by quantifying the terminal hydroxyl value in the diol based on the chemical nature of the hydroxyl groups. Polyurethanes are usually obtained from polyols and polyisocyanates through a polyaddition reaction between hydroxyl groups (—OH)and isocyanate groups (—NCO), and the ratio between them is particularly important in the process of producing polyurethanes. Therefore, it is necessary to accurately calculate the hydroxyl value of used polyols. Due to the high viscosity and poor water solubility of polycarbonate diol (PCDL) synthesized from epoxides and CO2 directly, we used an improved hydroxyl value titration strategy (acetic anhydride-methylimidazole-dimethylformamide method) to measure the hydroxyl value of commmercial and synthesized PCDL. The effects of various factors in the process of titration on hydroxyl value were discussed in detail. Compared with the industrial standard method, this optimized method can reduce the amount of samples and chemical reagents, moreover, the acylation reaction can be completed in a 45 ℃ water bath for only 20 min, which saved the test time and thus improved the efficiency.关键词：CO2 based polymer;Polycarbonate polyols;Hydroxyl titration;Acetic anhydride-methylimidazoledimethyl formamide method
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发布时间：2023-04-11 - 摘要：Acoustic wave propagation from external solution into a hydrogel can generate acoustic radiation stress due to acoustic momentum transfer between the two media, which may result in the large deformation of the hydrogel. To analyze the large deformation behavior of photo-thermal sensitive hydrogel under coupling acoustophoto-mechanical-thermo effect, an acousto-photo-mechanical-thermo constitutive model was established through the variational methods. Considering a specified case of photo-thermal sensitive hydrogel with uniaxial constraint, and that the condition of acoustic match was satisfied, the effects of ultrasonic intensity, light intensity and temperature on swelling properties of hydrogel had been analyzed systematically. The results show that the higher the uniaxial pre-stretching value is, the higher the equilibrium swelling ratio of the hydrogel is. The equilibrium swelling ratio of the hydrogel increases linearly with the rise of ultrasonic intensity, but decreases first and then increases with the temperature, and there is a minimum. The temperature at which the equilibrium swelling ratio reaches its minimum increases with the increase of pre-stretching and ultrasonic intensity, but decreases with the increase of light intensity. Once the environment temperature above the critical temperature, the change of pre-stretching and ultrasonic intensity has little effect on the swelling behavior of the hydrogel, but the change of light intensity still has a certain effect on the swelling behavior of the hydrogel.关键词：Photo-thermal sensitive hydrogel;Ultrasonic;Acoustic radiation stress;Large deformation
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发布时间：2023-04-11 - 摘要：The cellulose-based acrylate (CA) was prepared under heterogeneous conditions using cotton as the support material and acryloyl chloride as an intermediate; the cellulose-based solid-solid phase change fibers (solid-solid phase change fibers, SSPCFs) with controlled hydrophobicity were then grafted with hydrophobic octadecyl acrylate (A18), hydrophilic polyethylene glycol monomethyl ether methacrylate (OEGMA) and their copolymers by free radical polymerisation using benzoyl peroxide (BPO) as initiator. The structural and thermal properties of the SSPCFs were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and X-ray diffraction (XRD); the morphology of the graft copolymers was investigated by morphological stability tests at different temperatures; finally, the hydrophobicity of the phase change fibers was investigated by water contact angle tests. The results show that: A18 and OEGMA were successfully grafted onto the cellulose surface to prepare solid-solid phase change materials with certain energy storage properties; the initial decomposition temperatures of the five CA-g-P(A18-co-OEGMA) copolymers were among 348-368 ℃, all of which were higher than the initial decomposition temperature of CA, increasing the thermal stability of the cellulose-based products; The water contact angle of the graft copolymers decreased gradually with increasing OEGMA content, showing a progressive hydrophilic state. The controlled hydrophobicity of the CA-g-P(A18-co-OEGMA) copolymer was illustrated; at the same time the latent heat of fusion of its graft copolymer gradually decreased; the phase change fibers maintained good morphological stability at 70 ℃, indicating the successful preparation of morphologically stable cellulose-based SSPCFs.关键词：Cellulose;Octadecyl acrylate;Polyethylene glycol monomethyl ether methacrylate;Hydrophobic controllable phase change fibers
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发布时间：2023-04-11 - 摘要：A series of supramolecular polymers based on hydrogen bonds with different structures were synthesized through the reaction between 1,12-diaminododecane (DDA) and acrylic acid (AA), and then compounded with carboxyl nitrile rubber (XNBR) and other processing agents. After the sample being vulcanized, supramolecular polymers were formed in situ in the rubber matrix, thus sulfur crosslinked XNBR with high strength and toughness was prepared. The results showed that the tensile strength, modulus and toughness of the materials were improved by incorporating different supramolecular polymers. Specially, when the supramolecular polymer synthesized with the molar ratio of DDA to AA of 1∶3 was added to XNBR, the tensile strength and fracture energy of the material were 2.1 and 2.7 times that of the blank sample, respectively.This is because the fact that hydrogen bond, as a weak bond, will break prior to covalent bond when the material is under tension, which will dissipate a lot of energy in this process, thus improving the tensile strength and toughness of the material. In addition, the mechanism of energy dissipation and the time dependence of hydrogen bond fracture were further proven by cyclic tensile test and variable speed tensile test.关键词：XNBR;Supramolecular polymer;Hydrogen bond;Strengthen;Toughen
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发布时间：2023-04-11 - 摘要：Styrene (ST)/1,3-pentadiene (PD) can undergo anionic polymerization to synthesize a special alternating sequence copolymer (SP) with BuLi as initiator. Interestingly, the multi-block copolymer based on this unique alternating sequence has great application value in the fields of high impact resistant, high transparent and toughened resin and so on. Furthermore, the polarity-modification of unsaturated polyolefin materials is of great research significance, for example, improving the compatibility and heat/weather resistance as well as transparent characteristics. In this paper, m-CPBA was used as the epoxidation reagent to study the epoxidation modification of SP. The effects of reaction temperature, solvent, SP molecular weight and epoxidation reagent on the epoxidation reaction were investigated in detail. The resultant epoxidation product (eSP) was characterized by proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectrometry (FTIR). In addition, the quantitative analysis method of eSP with different epoxidation degrees was well established, and the optimal reaction conditions were determined through orthogonal experiments: tetrahydrofuran (THF)/cyclohexane (CH) as solvent, T =343 K, n(C=C)/n(m-CPBA)=1∶1.25, t=60 min, which can realize the complete epoxidation of SP. Finally, Tgs of eSPs with different epoxidation degrees were analyzed by differential scanning calorimeter (DSC), which proved that epoxidation could significantly improve the polarity of products and the service temperature of polyolefins.关键词：1,3-Pentadiene;Styrene;Anionic polymerization;Alternating sequence;m-Chloroperoxide benzoic acid;Epoxidation
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发布时间：2023-04-11 - 摘要：The teaching of crystalline polymers is one of the most important parts in the syllabus of polymer physics, including massive concepts and theories of polymer crystallization. Tie molecules, as the essential part of crystalline polymers, are not only the link of polymer crystallites, but also the key which helps to understand the structure and property of crystalline polymers. In this work, the crystal models of polymers and the structure-property relationship of crystalline polymers are elaborated, focusing on the effects associated with the tie molecules. In this way, it is much easier for students to understand the structures as well as the corresponding properties of crystalline polymers. Reading literature and recapitulating the recent advances in the field of crystalline polymers are also encouraged to improve the students’ ability of independent thinking.关键词：Polymer physics;Crystalline polymers;Tie molecules
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发布时间：2023-04-11 - 摘要：In order to cultivate high-quality comprehensive talents in line with the needs of the new era, and to create a series of first-class general education courses about polymer, this paper focuses on analyzing the problems existing in the traditional polymer general education course, and puts forward reform ideas in the aspects of teaching contents, teaching methods and assessment methods, etc. In addition, during the teaching practice of Polymer and Human Life, we reconstructed the curriculum framework suitable for interdisciplinary students, built appropriate knowledge modules, explored the inquiry-based small class teaching methods imported from realistic scenarios, and based on which promoted the entire assessment system. The teaching reform strategy had achieved ideal results and could be extended to the construction of general education and public courses for other majors.关键词：Realistic scenarios;Polymer;General education courses;Inquiry-based small class teaching
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发布时间：2023-04-11 - 摘要：Based on engineering education professional certification and the integration of science and education, the scientific achievements are used in the experiment and practical teaching in order to improve the students’ abilities to solve complex engineering problems. Under the guidance of this concept, some exploratory experiments were added into Polymer Physics Experiment, in the teaching process of polymer materials and engineering majors for Liaocheng University. According to the experimental results of the team, an essay is finished. In team-work essay, students must discuss the effect of functional fillers on the performance of polymer composites, such as softening point, mechanical properties and crystallization. The logical assessment of experimental score can be formed by the integration of laboratory report, team-work essay and semester examination.关键词：Polymer Physics Experiment;Engineering education professional certification;Integration of science and education;Teaching reform
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发布时间：2023-04-11
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