最新刊期
卷 30 ， 期 10 ， 2017
- 摘要：Flow-induced polymer crystallization was seldom carried out under pressure because there is higher requirements for the experimental device than under pressure. However, not only flow field, but pressure is involved in real processing. So,authors'group performed studies on flow-induced crystallization of polymer under pressure using homemade device and found the flow-induced crystallization behaviors of polymers under pressure are notably different from those under normal pressure. For isotactic polypropylene (iPP), unique oriented sphere-shaped crystals could be formed under pressure and flow. In a short time (30min),the lamellae of iPP could quickly thicken and generated thick lamellae with a high melting temperature close to the equilibrium melting point (ca. 180℃). The reason is that the activity energy for lamellar thickening remarkably decreased under pressure and shear. Meanwhile, we also obtained the window to generate a large amount of β-iPP for the system of iPP mixed with β nucleating agent. For polylactic (PLA), the similar lamellae thickening phenomenon was also observed under flow and pressure. In addition, we obtained β-PLA directly from PLA melt under pressure and flow. These research results provide theoretic and experimental data for tailoring the morphology and structure of polymers in practical processing.关键词：Pressure;Flow field;Flow-induced crystallization;Morphology and structure
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发布时间：2022-09-06 - 摘要：Inspired by powder metallurgy,sintering molding method has been developed to processing polymers with extremetly high melt viscosity and low degradation temperature. The polymer sintering is generally carried out by powder melting and chain diffusion, and the sintering temperature is above the melting temperature of the polymers. In this review, sintering conditions and sintering mechanism involved in the sintering of polytetrafluoroethylene (PTFE) and ultra high molecular weight polyethylene (UHMWPE) are systematically introduced. Moreover, the application of the sintering technology in the fabrication of multifunctional materials are also discussed. Most importantly, in order to overcome the poor melt stability as well as serious degradation of stereocomplexed polylactide (SC-PLA) after complete melting, our research group proposed a novel low-temperature (lower than the melting temperature stereocomplex (SC) crystallite) sintering technology for SC-PLA. During the sintering process,the powdery SC-PLA particles are welded by the formation of new SC crystallite at the interface. The research progress are also highlighted.关键词：Sintering;Polylactide;Stereocomplex;Polytetrafluoroethylene;Ultra high molecular weight polyethylene
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发布时间：2022-09-06 - 摘要：The layered structures widely existing in natural world such as shells or trees, often bring excellent performances or special features. As the application of biomimetic science in polymer processing field, micro/nanolayer coextrusion technology offers a new method to fabricate alternating multilayer polymers with good physical properties. By virtue of the special design of the flow channels, the polymeric melt would experience an iterative layer-multiplying process and be imposed by multiple stresses,which provides an opportunity to tailor the morphology and microstructure of polymer materials. Additionally, the confined layer spaces generated by the alternating multilayer structure not only endows excellent mechanical, optical, electrical and barrier properties,but also supplies an ideal model for researching polymer crystallization. This paper presents a review of the recent progress of structural development and related properties of polymer materials in confined layer spaces.关键词：Micro/nanolayer coextrusion;Multiple stress;Confined crystallization;Structural development;Physical properties
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发布时间：2022-09-06 - 摘要：Different from conventional aerogel monoliths, aerogel microspheres are new kind of aerogel materials with unique structures. Aerogel microspheres has micron size and is composed of nanoscale materials with the aerogel-featured unique heat,sound, light, electrical properties as well as complex three-dimensional topology networks, which means they have a wide application potential in the fields such as biological medicine, environmental remediation, functional carrier, energy storage and conversion, etc. In recent years, the research progress of aerogel microspheres has been rapidly growing,however,there is rare review on aerogel microspheres. In this paper, based on the latest research progress in the fields of aerogel microspheres, we made a brief review on preparation methods, different types and applications in medicine, environment, energy fields of aerogel microspheres.关键词：Aerogel;Microsphere;Emulsion method;Spray
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发布时间：2022-09-06 - 摘要：The 3D printing of polymer materials, as an advanced and rapidly developed manufacturing technology, can fabricate polymer parts with very complicated shape and structure that can,t be achieved by traditional polymer processing technology. However, it is difficult to prepare the polymer devices with desired shapes and functions due to only few single component polymer materials suitable for 3D printing. This paper introduced our research work on 3D printing of polymer based micro/nano functional composites. By using organic-inorganic hybrid, solid state shear milling, ultrasonic irradiation, molecular complexation,etc.,a series of polymer-based micro/nano functional composites suitable for selective laser sintering (SLS) and fused deposition modeling (FDM) processing were successfully prepared. The SLS processing of functional polymer-based micro/nano composite powders and FDM processing of functional composite filaments were successfully realized. The low-dimensional construction, layer by layer superposition, free interface forming and complicated solid-liquid-solid phase transition in 3D printing process were investigated. The novel technique for spheroidization of polymer-based micro/nano powders was established, and the new directly melt-extruded FDM printer was invented. A lot of polymer parts with complicated geometric shapes and functions, such as PA11/BaTiO3 piezoelectric device, flexible PU/CNTs sensor,individualized mandible model, etc.,which can' t be manufactured by traditional polymer processing technology, were successfully fabricated by optimizing 3D printing process. This is a big breakthrough in manufacturing polymer parts with complicated shapes and functions that can' t be prepared by traditional polymer processing and the current 3D printing technologies.关键词：Polymer-based micro/nano functional composites;3D Printing;Selective laser sintering;Fused deposition modeling
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发布时间：2022-09-06 - 摘要：The increasing application of polymeric materials in modern society requires a deep understanding on their aging behavior and underlying molecular mechanism. In this article,we reviewed the recent progress in the aging behavior of commodity polymeric materials both in the complicated natural weathering and artificial accelerated conditions. The aging behavior and underlying molecular mechanisms of several polymers under multiple and interplaying chemical and physical aging factors (such as UV light, temperature, stress and humidity) were discussed. Effective strategies for evaluating or predicting the service lifetime of polymers were described. Recent efforts in developing high efficient, anti-migration, multifunctional stabilizers (including graphene, reactive antioxidant, fumed SiO2-grafted antioxidant ) and novel stabilization theories/techniques were introduced.关键词：Polymeric materials;Degradation and stabilization;Complex conditions;Molecular mechanism;Lifetime prediction
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发布时间：2022-09-06 - 摘要：Polymer solar cells (PSCs) have attracted considerable attention due to their advantages of light-weight, flexibility, solution-processibility to produce low-cost and large-area devices. At present, the PSCs are still at the research stage in laboratory. The researches in this field still focus on further improving the performance and the stability. Developing new and high-performance materials is one of the most important approaches to continually improve the device performance of PSCs. Donor-Acceptor (D-A) copolymers have the merits of wide absorption range, tunable energy levels, strong intramolecular charge transfer via " push-pull" effect, which has become an important material design strategy in PSCs. Tremendous electron-rich and electron-deficit skeletons have been employed as donor and acceptor units to build D-A conjugated copolymers. Among them, naphthobisthiadiazole and its fused-ring acceptor units possess large rigid planar conjugations and strong electron-withdrawing features,which have been used to develop highly efficient polymer donor materials. In this review,we present an overall view of the recent progress of the naphthobisthiadiazole and its fused-ring acceptor units-based conjugated copolymer materials and their applications in PSCs.关键词：Naphthobisthiadiazole;D-A conjugated copolymers;Donor materials;Polymer solar cells;High efficiency
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发布时间：2022-09-06 - 摘要：Polyethersulfone has gained great attention due to its good thermal stability, oxidative stability, mechanical property and film-formation. Thus, polyethersulfone membrans are widely used in separation and purification fields, especially in blood purification. In this review,we summarize the adjustment of permeability of polyethersulfone membranes in past years, and the progress in modification of polyethersulfone membranes with hemocompatibility, antifouling, antibacterial property, cytocompatibility and multi-functions is also reviewed, especially for the research in our group. Finally, we give the future perspectives of polyethersulfone membranes for blood purification.关键词：Polyethersulfone membranes;Blood purification;Hemo-compatibility;Antifouling;Antibacterial property;Cytocompatibility
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发布时间：2022-09-06 - 摘要：Designing and constructing orderly micro/nanostructured conductive network is essential in the preparation of conductive polymer composites (CPC). The construction of efficient conductive network can simultaneously reduce the percolation threshold of CPC, and improve its conductivity and resistance response sensitivity. This article reviews different polymer processing methods for the construction of micro/nanostructured conductive network in CPC and its application in various sensors. These methods include double-percolation network method, isolated structural network method,aerogel template method, emulsion template method and 3D printing method, etc. Meanwhile,the future improvement directions of polymer processing methods for the development of next generation flexible sensors are proposed.关键词：Conductive polymer nanocomposites (CPC);Flexible sensors;Polymer processing;Conductive network construction;Micro/nanostructure
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发布时间：2022-09-06 - 摘要：Poly(lactic acid) (PLA) is one of the most applied synthesized degradable polymer materials and is hopeful to substitute polyolefine to be used in general plastic products. However, due to the particular viscoelastic responses resulting from the relaxation characteristic of PLA resin, the low melt strength of PLA causes the instability during processing, and the instability in size and properties of the products, which limits the development of PLA products. Moreover, PLA is usually amorphous after processing owing to its extremely slow crystallization rate in conventional processing conditions in extrusion and injection molding with high cooling rates. The extremely slow crystallization rate and low crystallinity of PLA result in poor processability and performance, which has become the bottleneck of PLA for large-scale commercial applications. Tailoring crystallization of PLA, including crystallinity and crystalline polymorphism, can achieve high performance of PLA. Based on the enhancement of processability of PLA, this paper gives a review on the controlling of melt viscoelasticity, crystallization rate and stereocomplex crystallization during processing of PLA.关键词：Poly(lactic acid);Melt viscoelasticity;Crystallization rate;Stereocomplex crystallization
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发布时间：2022-09-06 - 摘要：Both carbon nanotubes and graphene are typical carbon-based nanomaterials,whose nanoscale size imparts them excellent optical,electric, thermal and mechanical properties. However, both of them are difficult to be dissolved in common solvents due to the strong van der Waals interaction between individual tubes or sheets, which largely impedes their practical applications. In order to overcome such problems, polymers or small molecules are often used to modify these carbon-based materials to improve their solubility. Interestingly, stimuli-responsive polymers or small molecules can not only enhance their solubility, but also endow them with smart properties. This mini-review summarizes the recent progress in modification of carbon nanotubes and graphene using stimuli-responsive polymers or small molecules,and their smart properties as well as applications. The perspectives and future development of such nano carbon materials are outlooked to close the review.关键词：Carbon-based nanomaterials;Stimulus-responsiveness;Surface modification;Smart property
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发布时间：2022-09-06 - 摘要：Biodegradable polyurethanes have drawn large attentions in biomedical applications, especially, in drug delivery and tissue engineering scaffolds,due to their favorable biocompatibility,biodegradability,facile functionalization as well as tunable mechanical property. In this review, reports especially those from our lab about the structure, multi¬ functional design and biomedical applications of biodegradable polyurethanes are discussed. The prospect of biodegradable medical polyurethanes is expected.关键词：Polyurethane;Biodegradable;Biomedical application;Functional design
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发布时间：2022-09-06
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