Confined relaxation dynamics in long range ordered polyesters with comb-like architecture

The cooperative relaxation dynamics of methylene units in self-assembled amorphous alkyl nanodomains with typical dimensions in the range 5–20 Å is studied in a series of poly(1,4-phenylene-2,5-n-dialkyloxy terephthalate)s (PPAOTs) with C = 6–12 alkyl carbons per side chain. These comb-like polymers are long range ordered on the nanoscale since domains where main chains are stacked in a crystal-like manner alternate with alkyl nanodomains formed by aggregated side chains. Dynamic mechanical data for the investigated PPAOTs show polyethylene-like glass transitions α_PE which are similar to those for many other polymer series with comb-like architecture containing long alkyl side groups. Hence, self-assembled PPAOTs are excellent model systems for studies focusing on a detailed understanding of the influence of (i) alkyl nanodomain size, (ii) average volume per CH₂ unit and (iii) number of alkyl groups per interfacial area on the cooperative dynamics of methylene units seen as α_PE process. Structural parameters as obtained from X-ray diffraction experiments allow to deduce quantitative information about these influencing factors. The results are compared with those for regio-regular poly(3-alkyl thiophenes) with similar molecular architecture. The comparison shows that important features of the α_PE process within amorphous alkyl nanodomains are main chain independent even in case of long-range ordered polymers with quite different main chain packing. It is concluded that the alkyl nanodomain size is the most important factor determining the α_PE dynamics of the methylene units. Main chain dependent aspects like average volume per CH₂ unit and interfacial constraints do only weakly influence the relaxation behavior within the alkyl nanodomains.     

240t/h锅炉底部加热系统的研究与应用

主要介绍了底部加热技术在攀钢240 t/h锅炉的应用情况,通过锅炉点火升压时壁温差产生机理,引出了相关控制方法,并对底部加热方式与"煨炉"方式进行了经济性和应用效果的综合比较,说明了底部加热方式应用的优势,同时,提出了现底部加热系统安全应用的注意事项。     

Crystallization and thermal expansion behavior of lithium zinc silicate sealing glass

Effect of heat treatment schedule on the crystallization and thermal expansion behavior of a lithium zinc silicate glass system was investigated by differential scanning calorimeter (DSC), X-ray diffraction, and linear thermal expansion test. Two well-defined crystallization exothermic peaks were observed from the DSC trace. According to the apparent activation energies and avrami parameter values calculated from the two crystallization exothermal peaks, the first crystallization exothermal peak was attributed to a combining surface and internal crystallization behavior, while the second one was found to be internal crystallization. Additionally, the phase evolution and the thermal expansion behavior with increasing heat treatment temperature were found to be closely related. Interestingly, it was found in comparison with previous reports that addition of CaO varies the phase composition of the resulting glass–ceramic in an opposite way to K₂O and the deep rooted reason has been discussed which may cast light on the modulation of properties of glass–ceramic involved crystalline phase of quartz or cristobalite. At last, average thermal expansion coefficient of 7.99–15.38×10⁻⁶ K⁻¹ in the temperature range of 25–400 °C has been obtained with different heat treatment schedules.     

The Internal Pressure Test in Experiment and Simulation—Influence of the Wall Thickness Variation and the Change of the Packaging Behavior after the Impact of Standard Liquids

The effect of the wall thickness variation of blow‐moulded bodies made of high‐density polyethylene on an internal pressure test after prestoring the packaging with standard liquids was evaluated in experiments and simulations. The objects of the investigation were jerrycans used for the transportation and storage of dangerous goods. The wall thickness was determined using two alternative methods to the magnetostatic measurement. These alternative methods are used for research purpose to get a volumetric model of the jerrycan wall as a geometric model for the simulation. The comparison of the experiments and the simulations of the internal pressure test were performed using the digital image correlation method. The integral strain and deformation of the whole jerrycan was detected by measuring the total mass of the jerrycan being filled with water during the internal pressure test. This is a suitable alternative to the optical measurements of local deformation by the digital image correlation method. Prestorage at 40 °C without the influence of chemicals strengthens the jerrycan, whereas the swelling effect of butyl acetate and hydrocarbon mixture softens the jerrycan. The comparison with the experiment is necessary to verify the accuracy of the simulation. It shows that the deformation can be simulated more precisely by using the actual measured geometry. The weakening of the high‐density polyethylene caused by a hydrocarbon mixture can be simulated using the Arrhenius equation. The aim of the simulation was to discover whether it is possible to use specimens to predict the behaviour of a packaging both after the influence of standard liquids. Copyright © 2012 John Wiley & Sons, Ltd.     

谈装饰工程施工中各种砖的排砖方法

为了避免装饰工程施工中因排砖方法不正确影响工程观感效果,对外墙面砖、室内地板砖、卫生间地板砖的排砖方法进行阐述,以供装饰工程施工人员参考借鉴。     

水煤浆水冷壁气化技术及其应用

水煤浆水冷壁气化技术是在非熔渣-熔渣分级气化技术基础上进行的技术改进和创新开发的具有自主知识产权的煤气化新技术，采用该技术的工业装置于2011年8月在山西阳煤丰喜集团建成并成功投入运行。介绍了水煤浆水冷壁气化技术的概况、优势特点、工业装置运行情况及目前该技术产业化推广应用的最新进展。     

B2O3-free SiO2–Al2O3–SrO–La2O3–ZnO–TiO2 glass sealants for intermediate temperature solid oxide fuel cell applications

In this study, the chemical and thermal stabilities of eleven B₂O₃-free SiO₂–Al₂O₃–SrO–La₂O₃–ZnO–TiO₂ glasses were investigated, and the adhesion and sealing properties of the glasses with respect to Gd_0.2Ce_0.8O_2−δ (GDC) electrolyte and SUS 430 stainless steel (SUS430) were evaluated for use in intermediate temperature solid oxide fuel cells (ITSOFCs). It was found that the major crystallites formed in the glasses were initiated during the joining process at 950 °C, and only slight changes were observed in the intensity of crystallite peaks for the glasses subsequently soaked at 700 °C for 200 h. Experiments on the glass sandwiched with GDC electrolyte and SUS430 indicated that the SALSTi11 and SALSZT10 glasses provided good adhesion along the interfaces after heat treatment. According to the results of leakage test, the seals with the SALSTi11 and SALSZT10 glasses at 700 °C for a duration of 500 h showed good thermal stability with low leak rates of 0.007 and 0.003 sccm/cm at 0.5 psi, respectively. This property indicates a highly promising long-term thermal stability qualifying the sealing materials for ITSOFC applications.     

围水堵漏—混凝土排水管道接缝漏水处理的新方法

混凝土排水管道接缝漏水在施工过程中经常发生,接缝漏水引起的隐患不言而喻。笔者根据多年来的现场施工经验,摸索出一种全新的都漏方法——围水堵漏,经过多年来多个工程的实践检验,此方法确实能起到立竿见影的功效,有推广应用的价值。     

吊挂式全玻幕墙简易施工技术

通过采用卷扬机与自制钢架平台相结合施工工艺,解决吊挂式全玻幕墙施工条件受到限制,无法采用传统的吊车与专用大型玻璃吸盘方法进行吊装的难题。卷扬机与自制钢架平台相结合的施工技术适合于室内吊挂式全玻幕墙的安装,同样适合于室外吊挂式全玻幕墙安装,是一种较为经济实用的施工方法,为类似的吊挂式全玻幕墙的施工提供了技术指南。     

基坑支护工程三轴搅拌桩施工方案

郑州市某高层商业办公楼基坑采用1 000 mm厚"两墙合一"地下连续墙,墙内外侧各做一排Ф850@600三轴搅拌桩作为槽壁加固。施工中严格按流程实施并采取多项技术措施,保证了基坑支护的质量。