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991.
992.
A novel intumescent flame retardant (IFR), containing ammonium polyphosphate (APP) and poly(hexamethylene terephthalamide)
(PA6T), was prepared for acrylonitrile–butadiene–styrene (ABS). Limiting oxygen index (LOI), vertical burning test (UL-94),
thermogravimetric analysis (TGA) were used to investigate the flammability property and thermal stability of the IFR/ABS systems.
It was found that the flame retardancy of the IFR/ABS systems was improved significantly. When the components of the IFR were
25% APP and 5% PA6T, the LOI value of IFR/ABS system reached to the maximum of 29, but only UL-94V-1 rating was passed. Thus,
Al(H2PO2)3 was incorporated into ABS/APP/PA6T system as a synergistic agent, it was found 2% addition of Al(H2PO2)3 caused PA6T/APP/PA6T/Al(H2PO2)3 (70/23.3/4.7/2) to pass V-0 rating of UL-94 test. Meanwhile, the TGA curves indicated that PA6T could be effective as a charring
agent and there was a synergistic reaction between PA6T and APP, which effectively promoted the char formation of IFR/ABS
composites. Moreover, the residual char obtained after the LOI test of the IFR/ABS was characterized by Fourier transform
infrared spectra (FTIR). Results indicated that P–O–C chemical bond was formed in the residual char, which could indicate
the cross-linking reaction between PA6T and APP could occur. Furthermore, scanning electron microscopy (SEM) was used to investigate
the morphology of the residual char formed in the LOI tests. It was revealed that both ABS/APP/PA6T (70/25/5) and PA6T/APP/PA6T/Al(H2PO2)3 (70/23.3/4.7/2) formed uniform and compact intumescent charred layers. 相似文献
993.
A new and efficient synthetic method of a liquid crystalline epoxy resin with biphenol and aromatic ester group 总被引:1,自引:0,他引:1
Yin-Ling Liu Zhi-Qi Cai Xiufang Wen Pihui Pi Dafeng Zheng Jiang Cheng Zhuoru Yang 《Polymer Bulletin》2011,67(1):57-66
This article describes a high efficient and economical method to synthesize a liquid crystalline epoxy resin (LCER) containing biphenol and aromatic ester group, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-(oxiran-2-ylmethoxy) benzoate) (4). First, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-hydroxybenzoate) (3) was prepared by direct esterification of 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol (2) with p-hydroxybenzoic acid (1) in the presence of a certain amount of p-toluene sulfonic acid (p-TSA) as catalyst. And then (4) was synthesized by the reaction of (3) with epichlorohydrin. The chemical structure, melting range, and liquid crystalline phase transition behavior of (4) were characterized by FT-IR, 1H-NMR, 13C-NMR, mass spectroscopy, differential scanning calorimetry (DSC), and polarized optical microscopy (POM). 相似文献
994.
输水管线大口径长距离钢顶管施工中,技术措施的正确运用对保证质量安全、降低施工风险具有重大意义.该文从青草沙严桥支线DN3600双线钢顶管施工实践出发,介绍大口径钢顶管施工工艺中的几个问题和采取的对策,以期与同行进行交流和探讨. 相似文献
995.
996.
997.
以丙烯酸(AA)、丙烯酸丁酯(BA)和甲基丙烯酸二甲胺乙酯(DM)为单体,合成了AA-BA-DM三元共聚物分散剂,研究了其对二氧化钛颜料的分散效果;讨论了分散剂黏度、分散剂用量对颜料分散体系的影响;同时考察了该共聚物分散剂对不同颜料的分散稳定性。结果表明,当n(AA):n(BA):n(DM)=1.25:1:0.15,引发剂占单体总质量的1%,链转移剂占单体总质量的4%,为聚合物分散剂的最佳合成条件,所得共聚物分散剂对二氧化钛分散效果最佳,分散力达97.5%,且分散剂的用量占颜料总质量的0.80%时分散效果较好。通过对酞菁绿、二氧化钛及铬红分散效果的考察,该分散剂对颜料酞菁绿的分散效果最好,二氧化钛次之,对铬红的分散效果较差。 相似文献
998.
999.
1000.
This work reports the development of a facile, one-step microwave heating method for the synthesis of graphene-supported Pd1Pt3 (Pd core/Pt shell) electrocatalysts. The structure and composition of the synthesized nanocomposites were characterized via transmission electron microscopy and atomic force microscopy as well as energy-dispersive X-ray, X-ray powder diffraction, FTIR, and Raman spectroscopies. Using voltammetry, the electrocatalytic characteristics of the graphene-supported Pd1Pt3 nanostructures were evaluated for the oxidation of methanol as a model reaction. The results show that the introduction of graphene increases the electrochemically active surface area of the Pd1Pt3 nanostructures. As compared to the unsupported Pd1Pt3 electrocatalyst, the graphene-supported Pd1Pt3 electrocatalyst exhibited 80% enhancement of the electrocatalytic specific mass current for the oxidation of methanol. This method may serve as a general, facile approach for the synthesis of graphene-supported bimetallic PtM electrocatalysts with increased utilization of the Pt metal, which is expected to have promising applications in fuel cells. 相似文献