最新刊期
卷 37 ， 期 3 ， 2024
- 摘要：Main-chain liquid crystalline polymer (MCLCPs) possess excellent performance due to its readily orientable molecular chain, making it irreplaceable in fields such as aerospace and electronics. Specifically, aromatic polyesteramides (APEAs) address the issues of processing at high temperatures required by both single aromatic polyesters and aromatic polyamides, the excessive rigidity caused by hydrogen bonding between characteristic groups of aromatic polyamides, and susceptibility to water absorption. However, despite the plethora of studies on APEAs’ molecular chain structures and synthesis methods, there remains a lack of systematic overview. Based on the order of ester and amide bond formation, the synthesis is categorized into two distinct approaches: one-step condensation method that simultaneously generates bonds, resulting in random chain structures; and two-step condensation method that sequentially produces bonds, yielding ordered sequences. Moreover, the suitability of various monomer structures affects the polymerization methods and conditions, and hence, an assessment of the factors influencing the polymerization reaction is presented. Building upon this foundation, the relationship between main-chain structure and properties is comprehensively reviewed, and future development directions are proposed to provide guidance and references for the synthesis of novel APEAs.关键词：Main-chain liquid crystalline polymers;Aromatic polyesteramides;Condensation methods1002|1148|0更新时间：2024-02-06
- 摘要：Gene therapy, a revolutionary treatment method, has opened up a new way of thinking in the treatment of cancer. The most critical problem of gene therapy is the realization of nucleic acid drugs targeting tumor tissues and precise treatment. Direct delivery of nucleic acid drugs has the problems of nuclease degradation and metabolism, negative charge rejection on cell membrane and poor stability, so nucleic acid drugs need the assistance of the carrier. Successful carrier delivery can not only enrich nucleic acid drugs in tumor areas, but also play the role of drug controlled release. Natural polysaccharide is non-toxic, biocompatibe, elasy to modify, and has immunomodulatory, anti-tumor, anti-inflammatory and other biological activities. This review summarizes the structural characteristics of the five most representative polysaccharides and their applications in nucleic acid drug delivery, and then describes the common nanoscale carrier forms of polysaccharides, which lays a foundation for the construction of a new nucleic acid delivery system based on natural polysaccharides and its application in immunoantitumor therapy.关键词：Gene therapy;Nucleic acid drugs;Natural polysaccharides;Durg delivery system633|1564|1更新时间：2024-02-06
- 摘要：Dielectric elastomer (DE), as a new type of electroactive material, will become one of the materials for modern generator technology implementation because of its large deformation, light mass, and high energy density. This paper first outlines the working principle of DE material as a power generation mode, then describes the classification, and material optimization, and then introduces its application according to its tensile structure.关键词：Dielectric elastomer;Dielectric elastomer generator;Energy harvesting755|1205|1更新时间：2024-02-06
- 摘要：Due to the excellent properties of high temperature resistance, corrosion resistance, high hardness, light weight, fatigue resistance and so on, poly(ether ether ketone) (PEEK) is widely used in machinery manufacturing, aerospace and some other crucial applications instead of metals. With the development of science and technology, PEEK has already been used for precision manufacturing machinery and constructing complex structures. However, traditional injection molding cannot meet the needs for fabricating micro-precision and high-strength parts, which may limit the further development and application of PEEK. Nevertheless, the combination of PEEK and the fast-growing 3D printing techniques provides a novel thought for the development of its manufacture and application. Among the 3D printing techniques, fused deposition modeling (FDM) has been highlighted in fabricating PEEK depend on its unique advantages. But limited by the manufacturing method, the process parameters of FDM-printed PEEK have not formed a unified standard yet. Therefore, this work summarized researches about the effect of process parameters on the mechanical properties and crystallinity of FDM-printed PEEK in recent years, concluded the optimized process parameters of FDM printed PEEK, and finally provided a prospection in its development.关键词：Poly(ether ether ketone) (PEEK);Fused deposition modeling (FDM);Process parameters;Mechanical properties977|1324|1更新时间：2024-02-06
- 摘要：Vitrimers are booming in macromolecule research field because of the combination of the plasticity of thermoplastic materials and the permanent properties of thermosetting materials. The dynamic viscoelastic and rheological behaviors of these materials can be studied in-depth by dynamic mechanics analysis, contributing to establishing the relationships between vitrimer structures, such as crosslinking networks and dynamic bonds, and material properties. In this short review, applications of dynamic mechanical analysis in the detection of the dynamic viscoelasticity, cross-linking network structures, rheological behavior, expansion and shape memory behavior of vitrimers are summarized, providing a reference for the structural design, performance characterization and processing applications of such materials.关键词：Dynamic mechanical analysis;Vitrimers;Dynamic Viscoelasticity;Rheological behavior;Shape memory1062|2215|2更新时间：2024-02-06
- 摘要：The blends of poly(butylene adipate-co-terephthalate) (PBAT)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) were prepared by melt-compounding. The effects of P34HB content (0 wt%,5 wt%, 10 wt%, 15 wt%, 20 wt%) on the melt flowability, tensile properties, thermal behavior and interfacial morphology of the blends were investigated. The mechanical properties and barrier properties of the blown films were also studied. The results indicated that the incorporation of P34HB increased the melt flowability of PBAT, improved the right-angle tear strength, puncture strength and oxygen barrier property of blown films. When the weight content of P34HB is 5 wt%, the blend exhibited the highest comprehensive performance, PBAT and P34HB showed good compatibility, the blend displayed excellent mechanical properties for both injection samples and blown films, and the film demonstrated the highest tensile and puncture strength, showing promising application prospects for package and agriculture film.关键词：Poly(butylene adipate-co-terephthalate);Biodegradable material;Mechanical property;Barrier property;Poly(3-hydroxybutyrate-co-4-hydroxybutyrate577|586|0更新时间：2024-02-06
- 摘要：Multi-rib comb shaped parts have a complex structure with multiple ribs and hollow cavities, and traditional injection molding is difficult to achieve good molding results. Therefore, gas-assisted injection molding is usually used as the manufacturing process. However, gas assisted forming under complex structures will produce gas finger defects, seriously restricting the quality of part forming. Taking the calf support of a multi-rib comb shaped part as the research object, aiming at the gas finger defect of the part, based on the analysis of the structural design of the product and the molding technology, the formation mechanism of gas finger defect was analyzed theoretically. Based on Moldflow software, the finite element model of calf support was established to analyze the formation mechanism of gas finger. Based on the principle of thinning wall thickness, the wall thickness of the main body and the wall thickness of ribs were improved, and the scheme of reducing glue in the crater was proposed. The results show that with the thickness of the main body and the wall thickness of ribs decrease, the gas fingering is improved. The use of volcanic crater glue reduction scheme can avoid large-scale thinning while eliminating gas fingering defects. The test mold has verified that local thinning can accelerate the cooling of parts, form an effective freezing layer, and thus eliminate gas fingering defects.关键词：Multi-rib comb shaped part;Gas-assisted injection molding;Gas fingering defect;Quantitative analysis of gas fingering;Defect control409|601|0更新时间：2024-02-06
- 摘要：In this work, the working roles of stretching temperature (Ts) on impacting the microstructure characteristics of oriented isotactic polypropylene (iPP) were surveyed in depth by a combination of two-dimentional wide-angle/small-angle X-ray scattering, differential scanning calorimetry, dynamic mechanical analysis, etc. The results show that the initial spherulitic morphology transformed into the fibrillar crystal morphology after experiencing hot-stretching process, and that the crystalline fibrils consist of the altermative stacks of highly orentied lamellae and amorphous layers. A Ts-dominant crystallization enhancement was found as that: crystallinity and mean lamellar thickness increased monotonously as elevating Ts. Meanwhile, as the Ts increases, the physical properties of the crystalline phase begin to diverge significantly from those of the amorphous phase, resulting in opposite trends for chain relaxation in the two phases. Two fractions of lamellae with different thicknesses (melt point) are newly formed during the hot stretching process. The lamellae with higher melt point are arisen from the melt-recrystallization mechansim, while the occurrence of low-melt point lamellae obeys the strain-induced crystallization mechanism. This work provides a new understanding into the rule of structural manipulation of semicrystalline polymers during stretch processing.关键词：Isotactic polypropylene;Stretching temperature;Lamellae;Crystallinity;Melt point513|1403|2更新时间：2024-02-06
- 摘要：Crystal-crystal II-I transformation and crystal form regulation of isotactic polybutene-1 (PB) determined its molding period and properties. Study on crystal-crystal II-I transformation of PB has always been the research hot issue. As the typical crystalline/crystalline polymer blends, the aggregation structures and thus the crystal-crystal transformation of PB in the PB/polypropylene (PP) blends are influenced greatly by PP content and crystallization temperature. In this work, the effects of PP content on the nucleation and transformation rate of PB form I were studied. The crystallization morphology of PB/PP blends and crystal structure of PB form II were studied by wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS) and polarizing microscopy (POM). The influence of PP content on the PB form II-I transition was in situ observed. It was found that the nucleation of PB form I and form II-I transition rate increased with the increase in PP content when ≤20 wt% PP was blended. While the nucleation of PB form I and form II-I transition rate decreased gradually with the increase in PP content when more than 25 wt% PP was blended. The nucleation of PB form I, PB form II-I transition rate and transition degree in PB/PP (80/20) blend reached the highest. The influencing mechanism of PP component on PB form II-I transition was discussed.关键词：Polybutene-1;Polypropylene;Blending;Lamellar thickness;Crystal transformation812|604|0更新时间：2024-02-06
- 摘要：Polyester catalysts are mainly antimony-based compounds for a long time, which have potential heavy-metal hazards. To develop an efficient and environmentally friendly polycondensation catalyst, firstly, a comparative catalytic study of the novel two-dimensional material Ti3C2Tx MXene and the representative antimony-based catalyst Sb2O3 was conducted. The results showed that Ti3C2Tx MXene exhibited significant catalytic activity for the condensation of polyethylene 2,5-furandicarboxylate (PEF) with intrinsic viscosity up to 0.74 dL/g. Secondly, the thermal properties and crystallization kinetics of PEF prepared by both catalysts were investigated using differential scanning calorimetry (DSC). Ti3C2Tx MXene with the heterogeneous nanosheet structure was confirmed as a nucleating agent to enhance the crystallization rate of PEF. Finally, the mechanical investigation showed that the catalyst type did not affect the mechanical properties of PEF, indicating the good compatibility of Ti3C2Tx MXene with PEF. In summary, this work showed that Ti3C2Tx MXene is an efficient catalyst/nucleating agent for PEF.关键词：2,5-Furandicarboxylic acid;Polyesters;MXene;Catalytic synthesis;Crystallization property301|304|0更新时间：2024-02-06
- 摘要：Hierarchical interfacial tissues (such as the tendon-bone interface, bone-cartilage interface, etc.) play an extremely important role in maintaining the development and function of organs. The tendon-bone interface is one of the most typical interfacial tissues. Therefore, in this study, gelatin, poly(vinyl alcohol) (PVA) and hydroxyapatite (HAp) were mixed together, and the coating technology combined with freezing-thawing method was used to prepare the hierarchical integrated scaffold. The scaffold consisted of three regions: (i) the upper layer is an unmineralized area to facilitate the integration of the scaffold into the tendon; (ii) the intermediate layer is a zone with gradients of mineral composition and mechanical properties to facilitate stress transfer between tendon and bone; (iii) the lower layer is a mineralized area with high mechanical properties which promotes the integration of scaffolds and bones. The structure and properties of the scaffold were characterized by infrared spectroscopy, mechanical properties testing, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The result showed that the PVA scaffold can be obtained by physical crosslinking using freeze-thaw cycle technology, and the mechanical tensile test results of mineral content-mechanics, freeze-thaw cycles-mechanics showed that the mechanical properties of the scaffold from the top to the bottom gradually increase. SEM was used to observe the overall microstructure of the material. The layers of the material fused perfectly, which formed an integrated scaffold with hierarchical structure. Finally, the mineral content of the scaffold was analyzed by EDS. The results showed that the mineral content of the scaffold increased gradually from the upper layer to the lower layer in a gradient manner. This kind of biomimetic scaffold will have great application prospect in interface tissue engineering.关键词：Poly(vinyl alcohol);Physical crosslinking;Hierarchical structure;Freezing-thawing method;Interfacial tissues473|771|0更新时间：2024-02-06
- 摘要：The relationship between the number-average degree of polymerization and polymerization mechanism is the key content of polymerization reaction engineering analysis, and is also one of the difficulties of the course “Fundamentals of Polymerization Reaction Engineering”. The understanding of the effect of operation and polymerization mechanism on the number-average degree of polymerization will help students to master the polymerization mechanism, process, product characteristics, and the analysis of similar engineering problems. Here, the relationship between the number-average degree of polymerization and the conversion is analyzed in light of the lack of a detailed derivation process. The effect of chain transfer reactions on the relationship between the number-average degree of polymerization and the conversion is mainly discussed in two cases of short and long active chain life, and a detailed derivation process is given to provide a reference for teaching and help students to deepen their understanding and grasp. The aim is to provide a reference for teaching, to help students to deepen their understanding, and to enhance their learning interests.关键词：Polymer reaction engineering;Number-average degree of polymerization;Polymerization mechanism410|880|0更新时间：2024-02-06
- 摘要：The construction of “new engineering” is a major strategic deployment and a new explorationof the talent training mode under the new situation, which is of great significance to promote the reform and development of national higher education. Focusing on cultivating high-level composite talents in composite materials and engineering that meet the national strategy and the needs of new industry development, the teaching team began to establish the “production practice” course in 2016. As the main practical course of the major, combining “composite materials+X” industry-education integration interdisciplinary talent training mode, with multi-party collaborative practice and innovation ability training platforms, and the course is deeply optimized in terms of teaching methods, teaching methods, and teaching content. In 2019, this major was selected as the first national first-class undergraduate major construction site for composite materials and engineering. In 2021, the major successfully passed the engineering education professional certification. Consequently, the engineering practice and innovation ability of students have been significantly improved, and the employment rate for 6 consecutive years (2017–2022) reached 100%, and the further education rate increased to 82% in 2022. The exploration and practice of the “production practice” course in the construction process became more and more perfection, providing a useful guidence for the construction of relevant new engineering professional talent training system.关键词：Production practice;Composite materials;Course design;Teaching method288|542|0更新时间：2024-02-06
- 摘要：The development characteristics of the college dictate that teaching is informed by scientific research, thereby enhancing students’ capacity for scientific inquiry and their ability to tackle intricate engineering problems. The polymer materials and engineering major at Nanjing University of Posts and Telecommunications has developed a professional course curriculum centered on “design and information display applications of light-emitting conjugated polymers”. The teaching team has developed a virtual simulation system to facilitate students in previewing and conducting online rehearsals of experimental principles and the overall process. The course experiment is conducted through the method of “team design, student experimentation, and team discussion”. The relationship between the structure of electron donors and acceptors, molecular weight, and optical properties of conjugated polymers was investigated. The students’ understanding of polymerization kinetics, molecular weight testing, structure and photophysical properties of conjugated polymers, as well as optical imaging applications is enhanced through the interrelation and comparison between individual experiments. This work provides a concise overview of the initial advancements in course design pertaining to light-emitting conjugated polymers and their application in information display.关键词：Curriculum professional design and practice;Optical conjugated polymers;Information display application;Virtual simulation;Training of scientific thinking527|597|1更新时间：2024-02-06
- 摘要：Polymer Chemistry and Polymer Chemistry Experiments are both important foundation courses of vocational polymer material intelligent manufacturing technology major. The courses aimed at helping students understand the basic principles of polymer chemistry and set out and implement reasonable polymerization process. In order to solve the existing problems of these two courses, such as separated theory and practice courses, inadaptation of course design to student situation, single teaching method etc, project-based-teaching reform was carried out and “Theory-Real-Virtual” combined curriculum was constructed. With the main teaching line of “introduction to polymer, addition polymerization, condensation polymerization and chemical reaction of polymer” , the reconstruction of curriculum content, the improvement of teaching methods and the optimization of examination methods were conducted. Satisfactory teaching results had been achieved.关键词：Virtual simulation;Polymer chemistry;Project-based-teaching reform453|762|2更新时间：2024-02-06
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