With the rapid development of polymer science and technology, society's requirements for polymer materials are getting higher and higher. Single polymer materials are often difficult to meet this requirement. It is necessary to modify the polymer materials by alloying, blending, and compounding (abc) to maximize the properties of the respective components and to impart a single material. Good quality not available. The research and development of high-performance composite materials has become an important part of contemporary high technology, and an important development trend of polymer materials. It is facing high specific strength, high specific modulus, high toughness, high temperature resistance, corrosion resistance and resistance. Wear and other multi-directional development. Among them, the toughened and enhanced polymer composite materials have become the hotspot of engineering plastics modification research.
However, from the material science point of view, strength and toughness are two particularly important but contradictory mechanical properties of structural materials. The problem of simultaneous reinforcement and toughening of materials has always been one of the important problems to be solved in polymer materials science. .
In general, the filling of rigid particles into a polymer matrix can effectively improve the strength, stiffness and dimensional stability of the material, but at the same time easily lead to an increase in brittleness of the polymer. The use of elastomers to toughen thermoplastics, while toughening, but the material stiffness, strength, temperature and other indicators have been greatly reduced. A polymer/elastomer/filler three-phase composite formed by mechanically blending rigid particles and rubber at the same time can balance the rigidity and toughness of the material within a certain range, but cannot simultaneously obtain high-strength and high-performance polymer materials. . Therefore, since the 1980s, a new modification method for toughening polymers with non-elastomeric (rigid particles) has been proposed.
Funded by the National Natural Science Foundation of China, the laboratory first carried out basic and applied basic research on polymer inelastic toughening in China. After years of efforts, we replaced rubber toughened polymer composites with inorganic rigid particles. A systematic and in-depth study on its toughening mechanism has made breakthrough progress. In theory, it is clarified that in addition to the particle size and particle size distribution of the filler, the inorganic rigid particle toughening polymer must propose a new structural form of its interfacial phase structure, that is, it is well embedded around the uniformly dispersed rigid particles. The interface is combined with a certain thickness of the flexible interface phase, so that when the material is subjected to damage, it can induce the silver streaks, terminate the crack expansion, and induce the shear yielding of the matrix under certain morphological conditions, thereby dissipating a large amount of impact energy.
However, the above-mentioned interfacial phase structures are formed during the reactive extrusion process, the material properties are unstable, the operation cycle is long, and it is difficult to control, so it is difficult to industrialize the high-rigidity and high-toughness polymer composite materials developed by the laboratory. In the production stage, for this reason, under the support of the national “863†project, the idea of ​​strengthening the toughened filler masterbatch to prepare high-performance composite materials was proposed, and under the guidance of this idea, the enhanced toughening filling for polypropylene was successfully developed. Masterbatch and toughener masterbatch for nylon modification.
The development of reinforced and toughened filler masterbatch involves a large number of edge disciplines: interface molecular design, physicochemical modification of filler and polymer surface, surface property characterization, interface compatibilizer synthesis, interfacial interaction, rheological behavior, filler dispersion speed And the degree of dispersion, polymer crystallization behavior, material mechanical properties, and strengthening and toughening mechanism are therefore very complicated and very meaningful. After studying the relationship between the surface properties of inorganic particles, the microstructure of dispersed phases and the mechanical properties of materials, we summarized four basic principles for the preparation of high-performance polymer composites for strengthening and toughening filler masterbatch and creatively solved the inorganic The key technical problems of uniform particle dispersion and interfacial bonding are contradictory. Through the use of high-efficiency interface modifiers and the application of reactive extrusion processing methods, a small amount of rubber in-situ infiltration and coating of inorganic rigid particles are realized. A novel toughened filler masterbatch of a novel polymer/inorganic particle "shell-core" structure with monodisperse inorganic particles as the core and a small amount of elastomer as the shell.
The reinforced and toughened filler masterbatch has the following characteristics:
1. The addition of the filler masterbatch not only can significantly improve the processing rheological properties of the polymer, but also can be quickly and uniformly dispersed in the polymer matrix. Therefore, the process of compounding the filler masterbatch with the polymer is simplified from secondary processing to once. Processing is possible.
2. The addition of the filler masterbatch increases the modulus and toughness of the polymer composite at the same time, that is, the modulus and toughness of the material exceed the values ​​of the polymer itself, and a composite material that is both tough and rigid is obtained.
The reinforcing and toughening effect of the filler masterbatch on polypropylene:
Mechanical properties of modified polypropylene material filled with masterbatch (content 40% by weight)
Homopolymer pp masterbatch filled homopolymer pp copolymer pp masterbatch filled copolymer pp
Notched impact strength (j/m) 2080-90150300-400
Tensile strength (mpa) 3025-302520-25
Bending strength (mpa) 3540-503030-36
Flexural modulus (gpa) 1.02.0~2.50.81.5-2.0
In the numerous existing filler masterbatch products and research reports at home and abroad, there have been no reports of highly dispersed and simultaneously enhanced filler masterbatch of toughened polymer materials. Its successful development has contributed to the improvement of the interface model of inorganic rigid particle reinforced and toughened polymer, the improvement of composite interface design and control level, and the upgrading of China's large variety of general plastics to engineering plastics and engineering plastics. Performance development opens up new avenues to broaden new fields for the application of polymer materials and create their social and economic benefits.
At present, the reinforced and toughened filler masterbatch can be used to modify polypropylene and polyethylene plastics, and at the same time improve the rigidity and toughness of the materials, and broaden their application range, such as modified polyolefin materials can be applied to automotive and automotive parts. , household appliances, electric toolbox, etc.
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Candle originated in the original era of the torch. Primitive man fat or wax like on bark or wood, tied together, made for the lighting of the torch. At about third Century BC the beeswax candles may be seen today. In the west, there is a period of time, the temple in beekeeping to self-made wax, this is mainly because the Catholic church that Mila is a symbol of a virgin conception, so the beeswax as pure light, dedicated to the altar of the church. From the existing literature, beeswax in our country have roughly same time with the west, Japan is in the Nara period (710 to 784 years) in our country was introduced into the candle of, and compared to modern candle, ancient candles have many shortcomings. The Tang Dynasty poet Li Shangyin, "when he cut a total of west window candle" of the poem
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