不同剂型液体农药的密度测定方法研究

介绍了液体农药4种密度测定方法及其特点,选择水剂、悬浮剂、可分散油悬浮剂样品进行密度测定,比较不同测定方法的差异,分析了液体农药密度测定的适宜方法。     

黑火药真密度测定方法的比较分析

测定黑火药的真密度。所述测定方法比现在用的水银法较好，可替代水银法，同时不污染环境。     

用回归分析法确定水泥企业生产矿渣粉的指标

0引言近年来,湖南省水泥市场价格低迷,而矿渣粉的销售则行情见涨。作为水泥企业,能否利用现有的水泥磨生产矿渣粉?生产各级别的矿渣粉应达到多少比表面积?生产哪个级别的矿渣粉比较合算?带着问题,我部门开展了一系列矿渣粉试验,试验项目包括新渣与陈渣的密度、比表面积、活性指     

测定水泥密度的方法

1 仪器 容量瓶和滴定管是测定水泥密度的主要仪器(见图1).容量瓶的容积量程为120～125cm3,带有长约10cm,直径约1cm的细颈,细颈上的刻度读数精确至0.1cm3;滴定管的量程为0～4cm3和100～122cm3,内径约为1cm,刻度读数精确至0.1cm3.     

水泥密度测定误差对水泥比表面积测定结果的影响

根据透气法测定水泥比表面积的原理可知,空气透过具有确定的空隙率和厚度的粉末料层时,所受到的阻力与粉末料的比表面积相关。粉末料的比表面积越大,则空气透过时的阻力越大,一定量的空气透过时所用的时间越长。理论推导与试验数据表明：在相同试验条件下,     

介绍一种简便的DNA胶回收方法

目前DNA的回收方法主要有柱回收法、玻璃奶回收法等，这些方法回收效率较低，难以保证DNA的回收率及纯度。我们介绍一种简单经济适用，而且回收率较高的方法，并与传统的回收方法进行了比较。     

一种简便方法评价空气净化产品除氨率性能

通过搭建装置,模拟《QB/T 2761-2006室内空气净化产品净化效果测定方法》,测定被动式空气净化产品的除氨效果。该装置由氨气发生装置、除氨装置和氨气收集装置组成。实验时在氨气发生装置中加入5.0 mL浓度为25%的浓氨水作为氨源,用滤纸作为样品载体,取3.0 g样品加于滤纸上,通过附有样品的滤纸吸收氨气后,采集剩余氨气并使用酸碱滴定法测定被吸收氨气量,通过计算空白样品和待测样品吸收氨气量的差异,从而得到样品除氨率。分析测试4个不同样品,结果稳定性良好且与行标方法接近。该方法具有设备简单,占地面积小,氨含量测定时不需要用到有毒有害物质,分析结果准确等特点。     

一种水泥强度快速测定方法的初探

水泥28 d强度值是确定水泥强度等级和砼质量等级的依据。水泥生产质量控制和砼施工质量控制都要求能快速估测出水泥28 d强度值。经长期摸索,作者发现沸煮后雷氏夹内水泥净浆圆柱体的强度与水泥28 d抗压强度存在良好的相关性,据此建立了相应的快速测定水泥28 d强度值的公式:R28=4.72+0.8928 Rj。该经验公式通过实例应用,证明其预测结果与实际强度值很接近,可以用于水泥生产控制和砼施工质量控制。     

GB/T8074《水泥比表面积测定方法(勃氏法)》2007年修订版的介绍

1标准修订的目的和意义GB/T8074—1987《水泥比表面积测定方法(勃氏法)》实施已有20年了,许多水泥厂生产的水泥和以前相比要细很多,在测定过程中有时会出现捣器压不到底的现象,改变空隙率又不知道改变多少比较合适。因此国家标准化管理委员会委托我院进行修订。现将标准修订情况介绍如下。     

一种简单实用的水位自控装置

水泥生产中要保证供水的连续性，就必须使水塔或水罐内的水位控制在一定范围内。我们自制出一种较简单实用的水位自动控制装置，其原理图如图1所示。1控制原理图中虚框内A、B分别为下水位和上水位探极，各由两块金属板制成，当被水淹没时，两金属板导通。设开始时水塔内无水，则下水位探极A不通，即A（11，17）断开，KA线圈失电，触点KA（13，15）闭合，当开关S（可用拉线开关）合上后，交流接触器KM得电吸合，水泵电机M起动。当水位淹没下水位探极A后，A（11，17）导通，但因上水位探极B不通，故KA保持原失电状态。当水位上升到淹没…     

A direct way to determine iPP density nucleation from DSC isothermal measurements

Summary In the present work, a large number of growth rate data for -phase isotactic polypropylene, taken from literature, have been described by the Lauritzen and Hoffmann equation. A general procedure to predict nuclei density by simple DSC measurements is described and applied successfully to a commercial iPP.     

碳纤维密度测量不确定度评定

采用氯化锌溶液配置密度梯度柱测定碳纤维密度,并评定其测量不确定度。结果表明:密度测量不确定度来源于密度梯度管内浮子间距、刻度读数精度、浮子密度校准精度和相邻两浮子密度差;减小密度梯度管配置时高低密度溶液密度差,可以有效降低测量不确定度。     

Ultrasonic velocity measurement for the determination of density in polyethylene

An ultrasonic immersion method is presented for the rapid and accurate measurement of longitudinal sound velocity (v) in polyethylene (PE). The method is based solely on the measurement of time delays and can be automated. The samples are the same press-molded plaques that are prepared for the standard-density (ρ) determination using a density-gradient column, Our measurements on a representative group of various types of PE with densities in the range 0.92 to 0.96 g/cm³ show without ambiguity that v is proportional to ρ. The degree of correlation is such that we come to suggest that the acoustic method be used for the characterization of density. We show that the accuracy is good and compares with that of the density-gradient column and we then conclude on the practical advantages of the ultrasonic method.     

热固性聚合物的交联密度测试方法研究进展

综述了热固性聚合物交联密度测定方法的研究进展,重点介绍了平衡溶胀法、应力-应变法、动态机械热分析法、流变法、核磁共振法5种常用方法。     

Parison swell—A new measurement method and the effect of molecular weight distribution for a high density polyethylene

The measurement of parison swell is difficult because swell is a time-dependent phenomenon and because, for a parison, two independent swell ratios must be determined. A new technique has been developed that makes use of a video camera focused on the end of the parison. Unlike previous techniques designed to measure time-dependent swell, no oil bath is required. The new technique was used to study the effect of molecular weight parameters on the parison swell of high density polyethylene. For a series of blends of two resins having significantly different weight-average molecular weights, the blends exhibited larger swell ratios than the base resins.     

A novel way for ethoxylation with basic catalysts

Ethoxylation of dodecyl alcohol catalyzed by alkali hydroxides are accelerated by adding complexing agents for the alkali ions. The rate of ethoxylation could be increased by crown ether and dodecyl alcohols of a higher degree of ethoxylation. The effect is more pronounced with the crown ether; thus, reactions not taking place under other circumstances could also be carried out. The complexing additives have no significant effect on the molar mass distribution, The reaction could also be accelerated by using more bulky organic cations (e.g., triethylbenzylammonium ion) instead of the alkali cation.     

A practical method for discriminating among mechanistic models

A method is presented for designing and analysing experiments for choosing the best mechanistic model among a set of more than one to describe a real-world relationship. The method is a personalistic Bayesian one which does not depend on linearization of the models or on any specific form of the error distributions. Examples illustrating different types of applications of the method are given     

实用的液氯充装报警装置

介绍了自制式液氯充装报警系统：利用光电控制器改造原有的液氯包装用衡器，进行充装上限报警。既满足了生产安全要求，也不影响衡器的精度和使用。