共查询到20条相似文献,搜索用时 62 毫秒
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在水溶液中,以氰乙基三乙氧基硅烷(CTES)为前驱体,氨水为催化剂,通过一步法合成聚氰基倍半硅氧烷(PCSQ)微球,并通过进一步酸化实现了氰基到羧基的转化.通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、热重(TG)分析对所得微球的形貌、有机功能基及热性能进行了表征,研究表明CTES的用量与催化剂氨水的浓度对PCSQ微球的形貌和粒径有着重要影响,当去离子水为30 mL、CTES为1mL、氨水为1 mL时,可以制备出平均粒径在600 nm、高度单分散的PCSQ微球.将所制备的PCSQ微球分散在30%硫酸溶液中,65℃搅拌24 h可以将微球上负载的氰基水解酸化为羧基. 相似文献
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聚氯乙烯/梯形聚苯基倍半硅氧烷共混物的相结构及流变性能 总被引:2,自引:0,他引:2
由单螺杆挤出机制备了 PVC PPSQ(10 0 0、95 5、90 10、85 15、80 2 0 )机械共混物。通过扫描电镜 (SEM)观察了该共混物的相结构 ,富 PPSQ相形成的球状颗粒较均匀地分散于 PVC的连续相中。PVC PPSQ共混物的流动温度 (Tf)均低于纯 PVC的 Tf,而它们的玻璃化转变温度 (Tg)略高于纯 PVC的 Tg,随 PPSQ含量的增加 ,PVC PP SQ共混物的 Tf移向低温 ,更易塑化。经 PPSQ改性后的 PVC的表观粘度随温度变化敏感性增加。加入少量 PPSQ后 ,可有效地改善 PVC的流动性。 相似文献
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用溶液浇注法制备了具有不同质量配比的高分子量,低分子量梯形聚苯基倍半硅氧烷与聚甲基丙烯酸甲酯的共混物。用扭辫分析技术研究了不同分子量PPSQ与PMMQ间的相容性及热历史对其相容性的影响。 相似文献
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:由单螺杆挤出机制备了聚氯乙烯 (PVC) /梯形聚苯基倍半硅氧烷 (PPSQ) (10 0 / 0、95 / 5、90 / 10、85 / 15、80 / 2 0 )机械共混物。通过扫描电镜 (SEM)观察了该共混物的相结构 ,富 PPSQ相形成的球状颗粒较均匀地分散于 PVC的连续相中。 PVC/ PPSQ共混物的流动温度 (Tf)均低于纯 PVC的 Tf,而它们的玻璃化转变温度 (Tg)略高于纯 PVC的 Tg,随 PPSQ含量的增加 ,PVC/ PPSQ共混物的 Tf 移向低温 ,更易塑化。经 PPSQ改性后的 PVC的表观粘度随温度变化敏感性增加。加入少量 PPSQ后 ,可有效地改善 PVC的流动性 相似文献
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一种聚苯基甲基硅氧烷改性环氧树脂耐高温防腐蚀涂料的制备研究 总被引:8,自引:0,他引:8
采用苯基三甲氧基硅烷和苯基甲基二甲氧基硅烷水解合成了聚苯基甲基硅氧烷(PS),然后改性E-20环氧树脂,通过环氧值、红外光谱分析表明,有机硅接枝了环氧树脂且环氧基保持不变。用DSC、TGA分析了有机硅含量对改性树脂固化体系耐热性能的影响,当m(E-20)∶m(PS)=100∶25时,化学改性树脂固化体系的耐热性能明显提高。以此改性树脂为基料,采用适宜的固化剂,添加适当的颜料、功能填料、助剂等制备耐高温防腐蚀涂料。结果表明,该涂料不仅具有优异的常规涂膜性能,同时还具有优异的耐高温及防腐蚀性能。 相似文献
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Fundamentals of controlled/“living” radical polymerization are given together with a discussion of selected initiating/catalytic systems which provide structural, compositional, and functionality control during radical polymerization. Four systems which enable the synthesis of polymers with low polydispersities (Mw/Mn< 1.2), relatively high molecular weights (Mn>10 000), and high degrees of functionality are: nitroxide-mediated polymerization of styrene and styrene copolymers; organometallic compounds used for polymerization of acrylates; atom transfer radical polymerization of various monomers; and the degenerative transfer process. Also important in this field are new structural features and potential applications of controlled radical polymerization. 相似文献
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《Journal of Experimental Nanoscience》2013,8(4):426-439
In our research, the preparation processes of Pd nanoparticles (Pd NPs) with different methods by adding a certain amount of silver nitrate, iron chloride or sodium iodide are presented in order to control their size and morphology. Various sizes and shapes of Pd NPs are observed by alcohol reduction. The results show the size and morphology control of Pd NPs with chemical reductions of Pd salts by ethanol and ethylene glycol (EG) that have very different reduction processes. The modified polyol method with the gradual addition of Pd and polyvinylpyrollidone precursors in EG at 160°C has led to control their size and morphology in the 10?nm range using 0.02?M AgNO3. It is observed that the Pd nanorod is also formed. The main factors that will control the shapes of Pd NPs have been presented to explain their growth and formation mechanisms in a control process. 相似文献
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É. T. Bruk-Levinson M. L. German M. A. Geller G. V. Gritskevich 《Journal of Engineering Physics and Thermophysics》1991,61(2):946-948
The article presents a method of solving the problem of controlled heating involving the reproduction of some regularity of heating the surface of an object. As an example the article presents the solution of the problem of controlled radiative heating of a steel cylinder, and the obtained calculation is compared with experimental data.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 61, No. 2, pp. 187–189, August, 1991. 相似文献
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In this work, FePt-Au heterostructured nanocrystals (HNCs) such as tadpole-, dumbbell-, bead-, and necklace-like nanostructures
were synthesized by a facile heteroepitaxial growth of Au NCs onto FePt nanorods (NRs). A study of the growth mechanism revealed
that the morphology control of the final products can be correlated with the adsorption sites of hydrogen onto the FePt NRs,
which can be manipulated by the amount of the forming gas (Ar/7% H2) added. Not only the optical characteristic and magnetic properties of the intrinsic materials were retained in the products,
but also the FePt-Au HNCs showed the tunable multifunctional properties resulted from the interactions between Au and FePt.
Moreover, for methanol oxidation, the FePt-Au HNCs exhibited enhanced catalytic activity and CO tolerance on the catalyst
surface compared to commercial Pt catalysts. It is worth noting that as multifunctional units, the FePt-Au HNCs also possess
a heterogeneous surface, which could potentially enable their site-specific functionalization for targeting or imaging purposes
in biomedical applications. More interestingly, the catalytic properties of the FePt-Au HNCs also endow this material with
application potentials in nanocatalysis.
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C. G. Speziale 《Acta Mechanica》2001,150(1-2):121-126
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Rogrio Pinto Mota Douglas Galvo Steven F. Durrant Mrio A. Bica De Moraes Socrates de Oliveira Dantas Mauricio Canto 《Thin solid films》1995,270(1-2):109-113
Thin films were deposited from hexamethyldisiloxane (HMDSO) in a glow discharge supplied with radiofrequency (rf) power. Actino-metric optical emission spectroscopy was used to follow trends in the plasma concentrations of the species SiH (414.2 nm), CH (431.4 nm), CO (520.0 nm), and H (656.3 nm) as a function of the applied rf power (range 5 to 35 W). Transmission infrared spectroscopy (IRS) was employed to characterize the molecular structure of the polymer, showing the presence of Si-H, Si-O-Si, Si-O-C and C-H groups. The deposition rate, determined by optical interferometry, ranged from 60 to 130 nm/min. Optical properties were determined from transmission ultra violet-visible spectroscopy (UVS) data. The absorption coefficient , the refractive index n, and the optical gap E04 of the polymer films were calculated as a function of the applied power. The refractive index at a photon energy of 1 eV varied from 1.45 to 1.55, depending on the rf power used for the deposition. The absorption coefficient showed an absorption edge similar to other non-crystalline materials, amorphous hydrogenated carbon, and semiconductors. For our samples, we define as an optical gap, the photon energy E04 corresponding to the energy at an absorption of 104 cm−1. The values of E04 decreased from 5.3 to 4.6 as the rf power was increased from 5 to 35 W. 相似文献
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合成了一种新的丁酸酰基取代对亚苯基二亚甲基二聚体,用化学气相沉积聚合法制备了聚丁酸酰基取代对亚苯基二亚甲基(PPX-COCH2CH2COOH)膜,采用FTIR、NMR的方法证实了其化学结构,采用元素分析方法测定苯环上丁酸酰基的取代程度为4.7%左右.对膜溶解性和抗化学氧化性能的研究表明,PPX-COCH2CH2COOH膜具有优异的耐溶剂性和抗化学氧化性能.丁酸酰基的引入使得薄膜的结晶度有所下降.含有丁酸酰基取代基的聚合物的热稳定性较好.PPX-COCH2CH2COOH膜可以和肝素等反应,甲苯胺蓝法测得肝素含量为15.8μg/cm2. 相似文献