DENSITIES AND DERIVED THERMODYNAMIC PROPERTIES OF THE BINARY SYSTEMS OF BENZENE WITH BUTYL METHACRYLATE,ALLYL METHACRYLATE,METHACRYLIC ACID,AND VINYL ACETATE AT 298.15 K

Densities of the binary systems of benzene with butyl methacrylate, allyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess molar volumes are positive for the four binaries studied.     

FISCHER-TROPSCH SYNTHESIS: IMPACT OF PRETREATMENT OF ULTRAFINE IRON OXIDE UPON CATALYST STRUCTURE AND SELECTIVITY

ABSTRACT

The present study has shown that activation of a high surface area Fe₂O₃ catalyst in CO in a CSTR using tetralin as solvent results in an activity that is three times that of the material that is activated in H₂ or directly in the syngas. Independent of the catalyst activation, similar methane and CO₂ selectivities are obtained. This suggests that the active catalytic phase is the same for the three pretreatments. Since the particle size estimated by XRD shows a variation within 30%, the difference among the activities of the differently activated catalysts can be attributed to differences in the concentration of active sites on the catalyst surface rather than the extent of the surface.     

肉制品中氯化物含量测定——对氯化银沉淀排除方法的探讨

本文论述了应用佛尔哈德法测定肉制品中氯化物的含量,详细阐述了原理、试剂、步骤及其测定注意事项。主要阐述了氯化银沉淀对滴定终点判定的三种干扰排除方法：方法1、加入有机溶剂硝基汞;方法2、加入邻苯二甲酸二丁酯包裹氯化银沉淀;方法3、氯化银沉淀过滤,并通过实验数据比较这三种方法对实验结果的影响。结果表明三种方法均可行,但是有机溶剂毒性较强,氯化银沉淀过滤的方法实验过程较安全。考虑到准确、安全、经济三方面的因素,建议使用方法3。     

在线基体消除-离子色谱法测定甲醇汽油中的无机阴离子

建立一种在线消除基体、直接进样测定甲醇汽油中无机阴离子的离子色谱(IC)方法。样品经90%(V/V)甲醇溶解、稀释后直接进样,通过在线基体消除和预富集,采用IonPac AS23(250×4mm)分析柱分离,淋洗液为4.5mmol/L Na2CO3-0.8mmol/L NaHCO3,流速1.2 mL/min,采用Dionex DS6电导检测器检测,外标法定量。Cl-和SO42-的线性范围分别为0.05～5.0 mg/L,0.5～10 mg/L,相关系数分别为0.9998和0.9999,加标回收率为92.5%～96.7%,相对标准偏差RSD(n=8)<2.0%,检出限(以信噪比S/N=3计)分别为0.02 mg/L,0.08 mg/L。该方法用于甲醇汽油中无机阴离子的测定,结果令人满意。     

复掺矿渣微粉与粉煤灰配制尾矿砂混凝土及其应用

分别以30％、40％、50％和60％的铁矿尾矿细砂取代天然砂,并复掺矿渣微粉和粉煤灰,配制了C20、C30和C40预拌混凝土,试验研究了混凝土和易性、强度和抗氯离子渗透性等性能.结果表明,以30％、40％和50％铁矿尾矿细砂取代天然砂的各强度等级混凝土和易性均能满足要求;在60％取代率时,混凝土和易性较差,但强度仍能满足要求;50％取代率时,混凝土抗氯离子渗透能力与基准混凝土相当.     

地下工程混凝土的体积稳定性研究

研究了粉煤灰、矿粉、纤维素纤维、PVA纤维及其混杂掺入对混凝土体积稳定性的影响.结果表明,粉煤灰、矿粉均能有效提高混凝土的抗氯离子扩散性能,两者复掺更有利于氯离子扩散系数的降低,单掺矿粉较单掺粉煤灰好.掺入不同品种纤维的混凝土收缩率随时间而变化,时间越长各品种纤维混凝土的收缩率减小,在抑制混凝土长期抗裂方面,PVA纤维的作用效果最好.     

弹性体及无机粒子协同增韧PVC研究

利用甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物(MBS)、氯化聚乙烯(CPE)及碳酸钙(CaCO3)对聚氯乙烯(PVC)进行协同增韧改性.研究表明,固定MBS用量,随着CaCO3用量的增加,拉伸强度及冲击强度呈先上升后下降趋势,而硬度变化不大;固定CPE用量,随着CaCO3用量的增加,拉伸强度呈下降趋势,冲击强度呈上升趋势,而硬度基本保持不变.     

Ethyl silicate for surface treatment of concrete - Part II: Characteristics and performance

In this study, several aspects of the surface treatment of concrete with ethyl silicate were investigated. After the treatment, two different types of concrete (w/c 0.45 and 0.65) showed a dramatic decrease in capillary suction, chloride diffusion coefficient and carbonation depth. A penetration depth into the concrete of about 3-5 mm was assessed. Microstructural investigations showed evidence of a chemical interaction of the amorphous silica gel within the concrete forming calcium silica gel and a selective distribution of silica gel, which was mainly deposited in the small pores. In addition, the brightness and colour changes of the concrete surfaces after the treatment were analyzed quantitatively, finding limited differences, further decreasing over time. This last aspect is relevant for architectural applications of concrete, for example façades of residential buildings, where the architects may be interested in using the texture of concrete but are concerned by possible colour changes related to surface treatments application.     

Korrosionsinhibitoren für die Instandsetzung chloridverseuchter Stahlbetonbauten

Der Einsatz von Inhibitoren wird weltweit als technisch und wirtschaftlich interessante Alternative zur konventionellen Instandsetzung von Stahlbetonbauten betrachtet, da der Betonabtrag erheblich reduziert oder sogar ganz wegfallen kann. In diesem Aufsatz werden die Resultate von praxisnahen Laboruntersuchungen vorgestellt (aktive, d. h. laufende Bewehrungskorrosion, unterschiedliche Bewehrungsüberdeckung, unterschiedlicher Chloridgehalt im Untergrund bzw. im “Altbeton”, Makroelementwirkung). Keines der drei geprüften Systeme war in der Lage, die Korrosionsgeschwindigkeit zu reduzieren oder sogar zu stoppen. Corrosion Inhibitors for the Rehabilitation of Chloride Contaminated Reinforced Concrete Structures The use of inhibitors is considered worldwide as a technically and economically interesting alternative to the conventional repair of reinforced concrete structures since the removal of concrete can be considerably reduced or completely omitted. In this contribution the results of practical laboratory investigations are presented (active, e.g. ongoing corrosion, different concrete cover depths and chloride contents of the substrate or “old concrete”, macroelement effect). None of the three tested systems was able to reduce the corrosion rate or to stop the corrosion.     

Lebensdauerbemessung im Betonbau

Ein effizientes Lebenszyklusmanagement von Betonbauwerken erfordert die Dauerhaftigkeitsbemessung beim Neubau bzw. die Lebensdauerprognose für Bestandsbauten. Sie ermöglichen gleichermaßen eine wirtschaftliche wie auch eine nachhaltigkeitsbezogene Optimierung einer Konstruktion bzw. einzuleitender Erhaltungsmaßnahmen. Der vorliegende Beitrag behandelt schwerpunktmäßig die Dauerhaftigkeitsbemessung. Dabei werden weniger die Schadensmechanismen auf Bauteilebene beleuchtet als vielmehr die Methodik des Übergangs vom Bauteil zur Gesamtkonstruktion. Ebenfalls wird dargestellt, wie die Interaktion dauerhaftigkeitsrelevanter Einwirkungen modelliert werden kann und wie singuläre Risiken (z. B. Spannstahlkorrosion) in einer Gesamtbetrachtung berücksichtigt werden können. Service life design in concrete construction – From the deterioration process related to components to safety analysis of whole structures Relevant methods for the lifetime management of concrete structures are the design for durability relating to new structures and the lifetime prediction relating to existing structures. These methods allow to manage the entire lifetime of a concrete structure while avoiding cost‐intensive maintenance measures and corresponding downtimes. This paper focuses on the design for durability. Major emphasis is put on the presentation of methods to describe the behaviour of the concrete structure as a whole resulting from the integration of the deterioration effects on the member level. Based on the fact that different deterioration mechanisms occur in combination with each other, procedures for modelling interactions and singular risks (e. g. corrosion of tendons) are dealt with as well in this paper.