聚氨酯弹性体的电致伸缩效应

电致伸缩是指在外电场作用下电介质所产生的与场强二次方成正比的应变。近年来对聚氨酯电致伸缩性能的研究发现，聚氨酯弹性体综合了压电聚合物与传统的锆钛酸铅(PZT)压电陶瓷片的优点，具有很好的应用前景，本文简单介绍了聚氨酯的电致伸缩效应。     

Y2O3改性的MgO—ZrO2共析陶瓷

共析ＭｇＯ－ＺｒＯ２陶瓷添加Ｙ２Ｏ３可以获得高温热稳定性和较佳的力学性能，添加２％Ｙ２Ｏ３时断裂韧性为７．６ＭＰａ．ｍ＾１／２，弯曲强度为６１８ＭＰａ，用透射电子显微镜详细研究和讨论了上述材料的时效显微组织和韧化的原因。     

New anion exchanger organic–inorganic hybrid materials and membranes from a copolymerof glycidylmethacrylate and γ‐methacryloxypropyl trimethoxy silane

Organic–inorganic hybrid materials and mem branes were prepared through coating on Teflon plate or dip‐coating on microporous alumina substrates with the solution of glycidylmethacrylate (GMA) and γ‐methacryloxypropyl trimethoxy silane (γ‐MPS) copolymer, followed by ring‐opening of the GMA moiety with trimethylamine hydrochloric and sol–gel reaction of the γ‐MPS moiety. Composition of the GMA and γ‐MPS copolymer was varied by changing the feed ratio of GMA to γ‐MPS during the copolymerization. So the thermal stability, hydrophilicity, electrical properties, etc. of the hybrid materials and membranes were varied. Results showed that as the γ‐MPS amount increased in the copolymer, T_d (the temperature on thermogram at 5% weight loss) value of the hybrid materials and water contact angle of the hybrid membrane generally increased, while the anion exchange capacity, water uptake (W_R) and pure water flux decreased. The charge transition point of the hybrid membranes deduced from their streaming potential behavior decreased from pH > 12 to pH = 7–8 as the γ‐MPS amount increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3580–3589, 2006     

4′-甲基2腈基联苯的合成

以邻氨基苯甲酸为起始原料,经重氮化、芳基化、取代和脱水等步骤合成药物中间体4′-甲基-2-腈基联苯.通过正交实验得到芳基化反应较佳条件为:10mol/L氢氧化钠15mL,甲苯30mL,反应温度5℃,反应时间5h,产物4′-甲基-2-联苯羧酸的产率为59.4%. 考察了脱水剂种类,脱水反应较佳的实验条件为氯化亚砜15mL,4′-甲基-2-联苯酰胺2.6g,反应8h,产物4′-甲基-2-腈基联苯的产率为67.7%.     

Exothermic effect in the process of electron‐beam curing of epoxy resins

Temperature measurements have been performed in the process of electron‐beam curing of EB‐I and EB‐II epoxy resin systems. The influence of initiator content, resin type, and dose rate on the temperature of the systems was studied. Transverse and longitudinal temperatures of samples in the glass vessel were also analyzed. The nature of temperature curves varied with the different epoxy resin systems in the steel mold, but did not change with different contents of the initiator. At the same time, the heat had no effect on the gel fraction of epoxy resin systems. The temperature curve was greatly affected by the dose rate, and its peak value, peak width, and plateau value also increased with it. The transverse temperature of EB‐II glass vessel samples increased as the radiation dose increased and, in the same sample, the temperature reduced as the distance between the radiation center and the test point increased. The longitudinal temperature of EB‐I and EB‐II resin systems in a glass vessel decreased as the radiation depth increased. As the radiation dose increased, the temperature of the EB‐I resin system increased simultaneously, while that of the EB‐II resin system initially increased and then kept constant when the dose reached a certain value. The temperatures of these two resin systems decreased rapidly when the radiation process stopped. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2217–2222, 2004     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

Creep and Stress Rupture Behavior of an Advanced Silicon Nitride: Part I, Experimental Observations

Cylindrical buttuohead specimens of an advanced silicon nitride were tested in uniaxial tension at temperatures between 1422 and 1673 K. In the range 1477 to 1673 K, creep deformation was reliably measured using high-temperature contact probe extensometry. Extensive scanning and transmission electron microscopy has revealed the formation of lenticular cavities at two-grain junctions at all temperatures (1422–1673 K) and extensive triple-junction cavitation occurring at the higher temperatures (1644–1673 K). Cavitation is believed to be part of the net creep process. The stress rupture data show stratification of the Monkman–Grant lines with respect to temperature. Failure strain increased with increase in rupture time or temperature, or decrease in stress. Fractography showed that final failure occurred by subcritical crack growth in all specimens.     

Dynamic viscoelasticity of low‐density polyethylene/in‐situ‐grafted carbon black composite

The study on the dynamic viscoelastic properties of grafted carbon black (g‐CB) filled low‐density polyethylene (LDPE) was carried out. Because of formation of CB networking, the characteristic modulus plateau and loss tangent arc appears. Addition of grafting monomer like butyl acrylate (BA) and acroleic acid (AA) enhances the interaction between particles and matrix due to accelerated formation of micronetworking in the composites induced by forming branch chains of AA and BA with multiunit. The decrease of the temperature corresponding to α_c mechanical relaxation together with AA (BA) addition given by the position of loss tangent (tan δ) peak for LDPE is owed to the formation of long‐chain polymer grafted between CB and the matrix, which facilitates the slip of the lamella of LDPE. The influence of maleic anhydride (MA) on enhancing interaction between LDPE and CB is not so pronounced, as compared with AA and BA because of no formation of long chain between CB particle and polymer matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4127–4132, 2006     

The effect of waste oil-cracking catalyst on the compressive strength of cement pastes and mortars

Epcat, one of the spent fluid catalytic cracking (FCC) catalysts from oil-cracking refineries, shows pozzolanic activity. In this study, pastes and mortars with Epcat were prepared and cured, and their compressive strengths after 3, 7 and 28 curing days were measured. The water/binder (W/B) ratios were 0.2, 0.25 and 0.3, and the replacement levels of cement by Epcat were 0, 5, 10 and 15 wt.%. Proper amount of superplasticizer was added into each mix to ensure similar workability.The results indicate that the presence of Epcat would increase the compressive strength of mortars substantially, but increase the compressive strength of the related pastes only slightly. Epcat mortars with W/B=0.25 show more strength-enhancing effect than those with W/B=0.3, and this effect increases with the catalyst content. Therefore, the mix (W/B=0.25) incorporated 15% Epcat exhibits the greatest compressive strength (92.3 MPa). For mortars with W/B=0.2, the strength-enhancing effect occurs only for those containing 5% catalyst; this effect becomes unclear when mixes containing 10% Epcat or more because high dosage of superplasticizer was added in obtaining proper workability and that affects the strength development. The improvement in the mechanical properties of mortars is attributed to the increase in the hydrated cement paste itself and, more importantly, improved bonds between the cement paste and aggregate.     

旋风分离器内颗粒运动规律的数值模拟

采用单颗粒动力学模型计算了旋风分离器内颗粒的运动轨迹。计算结果表明：进入旋风分离器的颗粒绝大多数在环形空间内就被甩向器壁；从入口上部进入的部分较小颗粒由于局部二次流作用而上升形成顶灰环；还有少量颗粒进入下部分离空间。在下部分离空间内，有灰斗返气夹带上来的颗粒，处于内旋流的颗粒则有可能随上升气流而逃逸，所以一定的分离空间高度有利用颗粒的二次再分离。