Scientific and Technological Frontiers and Academic Review World Scientific Research and Development Research Status and Prospects of Microfiber Reinforced Polymer Composite Materials for Sand Concrete Research Zhang Yi, Xu Jiarui X (Materials Science Research Institute, School of Chemical and Chemical Engineering, Sun Yat-Sen University, Polymer Composite Materials and Functions Key Laboratory of Materials, Ministry of Education, Guangzhou 510275, China) â€œSummary of the research status, existing problems and future development prospects of materials in this field at home and abroad.
Sub-composite refers to a kind of composite system whose fibrous reinforcement phase is different from common fiber-reinforced composites. At present, the most thoroughly studied and most representative and practical ones are "Molecular Composites" and "In-Situ Composites". The most fundamental driving force for the study of microfibre reinforced polymer composites is the obvious synergistic effect between the rigid hardened rod reinforced phase and the flexible matrix, and it is expected to obtain structurally or functionally-higher polymer materials with better properties, and therefore the application prospects are attractive. people. The realization of this concept will help improve the polymer materials* project team of the Natural Science Foundation of Guangdong Province (20003038), the Guangdong Provincial Department of Education's Excellent Talents Training Fund (Q02014) and the Young Teacher Startup Fund Support Project of Sun Yat-sen University.
The world's science and technology research and development frontiers and academic reviews of the anti-aging, thermal stability 4, toughness. Since the thermal decomposition temperature of these materials is lower than their melting temperature, they can only be processed by the solution method. The superior performance of PPBT molecularly strong composites, people have been dedicated to the optimization of its processing technology. This method has been successfully used to prepare aromatic copolymers with PPTA hard segments (p*50 soft segment (3,4-oxidiphenylene*terephthalamide). The blends of amide and PPBT have been found to have a tensile modulus of 143 GPa for PPBT/PPOT * 50 (30/70) fibers and are in line with the linear relationship between complete orientation of PPBT and matrix molecules. The low-molecular-weight PPBT blend system is in line with the Halpin's phase transformation process and the tensile properties of the molded sample. It is found that the PPOT-based system is far from a thermodynamically stable state, so it is in the heat treatment process. Phase separation is still unavoidable, and other systems that are also considered to be "molecular composites", such as hard-rod polymers and benzocyclobutene systems, cannot maintain homogenous blending at all. In spite of this, there are some reports that the results of their research have resulted in the processing of molecularly strong composite materials.
In addition to the above two methods, there is a third method of preparation, which is to prepare homogeneous films, fibers and sheets by a rapid precipitation method.
If a PP-TA/amorphous nylon blend system is desired to reinforce common polymer fibers with a rigid component, compared with the conventional nylon 6 blend system containing 30% PP-TA, the material obtained by the spinning process has molecules. Strong results, tensile modulus can be increased by more than 3 times, while the flexibility of the fiber is better. A homogeneous molecular composite made from PPBO and 2 6* bis 4*benzocyclobutene benzo(1,2*d:5,4*d*)bisoxazole, with fewer soft chains added The segment can increase the compressive strength of PPBO fiber by 18%, while the modulus remains around 210GPa. However, the heat treatment process still results in phase separation.
In addition to the preparation of PPTA or its derivatives and composites of different flexible polymers such as aliphatic polyamides, fiber blend technology frontiers and academic reviews worldwide scientific research and development, the homogeneous blending system is basically used. â€œThe method of emulation* was used to prepare molecular composites of aromatic-fatty polyamides using a simple method of polycondensation. It was found that the mechanical properties of nylon 6 were significantly improved, and the modulus was increased by about three times. The tensile strength is increased by about two times, and for the homogeneous blending system, the strong effect can be obtained by using the blending system of Halpin Dragon;Charlet et al., and the second is to uniformly mix the monomers of the flexible substrate and the rigid polymer before performing the blending. Respective polymerization reactions: 23. Isomerization of isoimides to diimides under thermal initiation to obtain a series of polyaryl sulfones, polysulfones, and with end bis-ethylene isoimides Thermoplastic resins reported a novel method for the synthesis of polyimide molecular composites by direct in-situ polymerization of rigid monomers in solution in matrix polymers.This method is significantly superior to simple solutions. The polymerization method is favorable for obtaining homogenous mixing of monomers.Based on this method, a series of high-performance composite materials, such as acrylonitrile butadiene copolymer, polyamic acid and vinyl pyridine-styrene copolymer, have been prepared. The characterization of transparent films obtained by solution casting shows that the mechanical properties of the materials, especially the tensile modulus and strength, are greatly improved, and a strong interaction can be formed between the matrix polymer and the in-situ formed polyimide. At that time, the strong effect is even more pronounced.
Ogata et al. prepared a molecular composite of polyamidoine with nylon 6 and an epoxy resin by in situ molding. The hard rod prepolymer was polymerized in a reactive matrix prepolymer, and the matrix was then placed in a mold. In the formation, can be uniform photo material. When discussing with microscopic mechanical equations suitable for chopped fibers, it was found that 20% of polyazomethine was also added, and the tensile modulus of the three-component system was increased by 71% compared with the binary system composed of pure epoxy resin. The simulation of the molecular model gives a good explanation, but it cannot be calculated quantitatively.
Although the structure of the polymer chain is different, the interactions between the groups (electron interaction, hydrogen bonding) provide the necessary impetus to improve the miscibility. In the blending system with rigid chain rods and flexible matrix, the weak dipole-dipole interaction force is not enough to overcome the trend of phase separation. Therefore, the introduction of strong hydrogen-bond interactions between the molecular chains has become the study of An important direction.
Imide and polyester amide blend systems, where the polyimide molecule is seen as a strong molecule with a hard rod structure. The mechanical properties and intermolecular interactions of the homophasic blends, such as fully aromatic polyamides and polyamideimides, have been studied. The result is that strong hydrogen bonding interactions are beneficial to improve the miscibility of the blends.
When studying polyimide systems, there is no absolute link between the hardness of a molecule and the viscosity of a material. Because of the strong intermolecular interactions, steric effects, and large molecular segments, polyimide derivatives tend to have high glass transition temperatures. Therefore, some so-called rigid polyimide polymers are actually composed of flexible molecular chains having different degrees of rigidity, and the molecular chains have similar intermolecular interactions. This property greatly enhances its processability, and its excellent overall performance has attracted people's interest in research.
Garlund et al. The study shows that the material with less than 30% hard bar does not phase separate, and the mechanical properties are greatly improved. The tensile strength increases from 28 MPa to 191 GPa, and the tensile modulus increases from 1.06 GPa to 7.55 Gpa. The mechanical property data conforms to Halpin. *Tsai relationship.
Recent studies on graft copolyamides have also been reported, namely the direct grafting of flexible nylon 6 segments to the rigid aromatic polyamide backbone benzene ring or spiro compounds M. Takayanagi, Japanese technology frontiers and academic review world science and technology Research and Development Frontiers in Science and Technology and Academic Review Yi197410â€•) Female, Ph.D., Institute of Materials Science, Sun Yat-sen University, lecturer. Mainly engaged in the synthesis of polymers containing aromatic structure and the study of the structure and properties of polymer multiphase composite materials (Editor: Zhang Hao) Foreign news starved tumors Starved to death, several new biotech companies in the United States have used this principle to develop new anti-cancer drugs. Recently, good news has been circulating in clinical trials. Some of these drugs have been proven to prolong the lives of cancer patients. This has inspired the industrial and academic communities in the United States engaged in cancer research.
At the 69th American Clinical Oncology Annual Meeting in Chicago, USA, oncologists from around the world reported their latest research achievements, the most notable of which was the starving tumor anti-cancer therapy study. Made a breakthrough. The two new anticancer drugs have good and stable efficacy in human trials and are expected to be approved for listing by the U.S. Food and Drug Administration within the year. The United States Genetic Technology Research Institute has conducted clinical tests on its experimental anti-cancer drug Avastin and found that it can reduce tumors in half of patients with colon cancer by more than half, and can extend the average life span of patients by 5 Months. "Erbitux*" developed by Im-Clone Biotechnologies, USA, combined with chemotherapy, reduced tumors in patients with a quarter of advanced colon cancer by more than half. Another new drug for the treatment of lung cancer, "Iressa", has been shown to inhibit colon cancer.
Currently in the medical field in the United States, the field of research on the use of "starved tumors" technology to treat cancer is very popular. At present, more than 10 experimental drugs have been approved for human testing.
Comparable to the model of anti-cancer drugs in the United States. The drug was developed 15 years ago by the American Genetics Research Institute and is the first type of "starved tumor" anticancer drug approved for human experiments in the United States. However, the testing of this drug has suffered setbacks. Last year, researchers had conducted anti-breast cancer tests on the drug. The results showed that the drug did not prolong the lives of breast cancer patients. In addition, in the anti-colon cancer 1000-person trial of the drug, there were 6 cases of intestinal perforation, which almost caused the experiment to soak.
At the same time, â€œErbitux*'s road to development was not easy. The drug was applied for marketing in 2001 but was rejected by the US Food and Drug Administration because of the remaining doubts about the efficacy of the drug.â€ But analysts According to a recent human experiment, the drug has reached the market standard in terms of both safety and efficacy. Therefore, the Food and Drug Administration is expected to release the drug during the year.
Dr. Ruanping Wang, senior engineer at PRA Biotechnology Test Company of the United States, told reporters that â€œLove Do Not Stop,â€ â€œAi Wei She,â€ and â€œErbitux* represent the world's most advanced levels of anti-cancer drugs. They are eradicating tumor cells at the same time. It does not harm healthy cells and is therefore superior to ordinary chemotherapy, and Dr. Wang believes that breakthroughs in anti-cancer research will allow investors to increase investment in this area, which in turn will promote cancer research in the United States. The further development of Handan (Xinhua News Agency for this publication) 77 pages
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