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81.
首先合成并表征了一种新的阻燃剂-次磷酸铈(CHP);然后采用熔融共混的方法制备了玻璃纤维(GF)增强聚对苯二甲酸乙二醇酯(PET)/CHP(PET/GF/CHP)复合材料;探讨了CHP对PET/GF复合材料热稳定性和燃烧性能的影响。材料的热稳定性是由热失重分析(TGA)进行表征的,燃烧性能是通过氧指数(LOI)、垂直燃烧(UL-94)以及锥形量热仪进行测试的,炭渣形貌由扫描电子显微镜(SEM)进行表征。结果表明:CHP的引入保持了PET/GF的热稳定性。含有15wt%CHP的PET/GF材料(PET/GF/CHP15),其LOI为30%,且能达到UL-94V-0级别。此外,与PET/GF相比,PET/GF/CHP15热释放速率峰值和热释放总量分别下降了67%和27%。SEM分析表明CHP的加入使得材料在燃烧后有大量致密的炭渣覆盖在玻璃纤维的表面,这些炭渣不仅降低了玻璃纤维的导热性,而且切断了可燃物质的传送通道,从而提高了材料的阻燃性能。 相似文献
82.
钙钛矿型复合氧化物用于汽车尾气催化净化的研究进展(一) 总被引:12,自引:0,他引:12
综述了钙钛矿型汽车催化剂的研究进展.和过渡金属简单氧化物相比,钙钛矿型复合氧化物(ABO3)在热稳定性、化学稳定性和结构稳定性方面具有一定的优越性,因而表现出更高的催化活性.在满足容限因子的条件下,有多种元素可以形成钙钛矿结构的化合物.通常,B位离子决定了钙钛矿型化合物的催化活性,A位离子是影响化合物结构和B位离子价态的重要因素.当A位离子或B位离子被不同价态的离子取代时,通过形成氧离子空穴或者形成混合价态来保持化合物的电中性.氧空穴的形成或B位离子价态的变化使得化合物具有更高的活性.贵金属和钙钛矿型化合物结合,不仅可以有效防止贵金属的烧结,同时也提高了钙钛矿型化合物的催化活性. 相似文献
83.
Bioabsorbable soy protein plastic composites: Effect of polyphosphate fillers on water absorption and mechanical properties 总被引:7,自引:0,他引:7
The use of synthetic and natural bioabsorbable plastics has been severely limited due to their low stiffness and strength
properties as well as their strong tendency to absorb moisture. This research focused on the development of bioabsorbable
polyphosphate filler/soy protein plastic composites with enhanced stiffness, strength, and water resistance. Bioabsorbable
polyphosphate fillers, biodegradable soy protein isolate, plasticizer, and adhesion promoter were homogenized and compression-molded.
Physical, mechanical, and water absorption testing was performed on the molded specimens. Results showed improvements in stiffness,
strength, and water resistance with increasing polyphosphate filler content up to 20% by weight. Application of a coupling
agent produced further mechanical property enhancements and a dramatic improvement in water resistance, interpreted by an
interfacial chemical bonding model. Examination of the fracture surfaces of the materials revealed that the addition of the
polyphosphate fillers changed the failure mode from brittle to pseudo-ductile. These results suggest that these materials
are suitable for many load-bearing applications in both humid and dry environments where current soy protein plastics are
not usable. 相似文献
84.
环境友好新型聚乳酸复合材料的研究及应用 总被引:1,自引:0,他引:1
聚乳酸(PLA)复合材料是一类重要的环境友好新型可降解材料。该材料通常是以PLA高分子为基体,以无机钙质成分(如羟基磷灰石、磷酸钙、珊瑚、珍珠层)、碳纤维、生物活性成分、有机物等为增强材料复合而成。概述了近年来国内外通过共聚、共混、复合等改性方法获得PLA复合材料的研究进展;论述了PLA复合材料的制备方法、生物相容性、力学性能、开发现状及应用等;指出使用新型的复合工艺、采用超细的无机粒子或纳米增强材料或加入特殊填料,同时开发新型增强物质是PLA复合材料的发展趋势;展望了PLA复合材料的应用前景。 相似文献
85.
Environmentally friendly composite materials can be prepared using wood fibers and/or various types of agro-derived fibers as reinforcements. In this study, agro-residues such as wheat straw and corn stem filled polypropylene were prepared and their suitability was investigated as a reinforcing filler in thermoplastics and as an alternative to the wood flour filled plastics. Effect of compounding techniques, compatibilizer and fungal treatment of agro-residues on the mechanical properties of the composites were evaluated. It was found that high shear compounding of wheat straw fibers exhibited similar properties to that produced by the milled wheat straw. This may be due to the extensive fiber breakage occurred during the high shear compounding that results in a similar aspect ratio to that of milled straw. Compatibilizer is needed for improving the strength properties of the agro-residue filled PP composites. Fungal treatment of milled wheat straw did not show much improvement in the strength properties of the composites. Comparison of mechanical properties of the agro-residue filled PP with that of the wood flour and the old newsprint filled PP showed the suitability of the agro-residues as alternative filler for thermoplastics. 相似文献
86.
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88.
本文就近年来对负载型汽车尾气催化剂的研究进展进行综述,侧重说明其组成配方,性能的影响因素,及相关的结构研究。讨论了催化剂制备工艺,添加剂的作用,催化剂种类,催化剂失活原因和表征方法 相似文献
89.
Ming GE Changsheng GUO Xingwang ZHU Lili MA Wei HU Yuqiu WANG Zhenan HAN 《Frontiers of Environmental Science & Engineering》2009,3(3):271
ZnO/TiO2 composites were synthesized by using the solvothermal method and ultrasonic precipitation followed by heat treatment in order to investigate their photocatalytic degradation of methyl orange (MO) in aqueous suspension under UV irradiation. The composition and surface structure of the catalyst were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM). The degradation efficiencies of MO at various pH values were obtained. The highest degradation efficiencies were obtained before 30min and after 60min at pH 11.0 and pH 2.0, respectively. A sample analysis was conducted using liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry. Six intermediates were found during the photocatalytic degradation process of quinonoid MO. The degradation pathway of quinonoid MO was also proposed. 相似文献
90.
本文针对汽车振动环境的特殊性,分析了其对汽车电子装置的主要影响;进一步介绍了几种主要的振动试验方法,并结合汽车电子装置相关标准对振动试验进行了探讨. 相似文献