23MHz核磁测定聚乙烯密度的影响因素

采用聚乙烯标准试样,将用密度梯度柱法测试的密度值与在共振频率为23 MHz的核磁共振波谱仪(简称23 MHz核磁)上测得的核磁共振时域信号建立标准曲线。以此标准曲线为准,在23 MHz核磁上研究了温度、试样量、预热时间、添加剂对聚乙烯密度的影响。结果表明:23 MHz核磁的核磁管恒温温度对聚乙烯密度的影响最大;适宜的试样量为4.0～5.5 g;在干浴恒温器中预热60 min后的密度值基本稳定;粒料测定结果的整体离散程度小于粉料。     

原油压缩系数实验与关联

采用Ruska高压PVT装置,测定了9个油田油样的压缩系数,其温度与压力范围分别为308—338 K,0.6—6.6 MPa。并测得了各油样4个温度下的密度值。实验发现,原油压缩系数随温度的升高而增加,随压力的升高而降低。并建立了温度、压力和密度函数的原油压缩系数关联式,其对404个数据点的平均误差为2.96%。该式可用于预测不同条件下的原油压缩系数计算,方便原油输送的计量与管道的设计。     

沉积温度对碳/碳复合材料密度均匀性的影响

采用快速化学液相气化渗透法制备了二维碳／碳复合材料。用Leica定量金相分析仪及Archimedes排水法测定了不同沉积温度制备的样品沿径向的孔隙率及密度分布，同时用扫描电子显微镜观察了样品的低倍形貌及孔隙率分布。实验结果表明：定量金相观察计算得到的孔隙率值略大于排水法测得的孔隙率值；当沉积温度≤1200℃，随着沉积温度的升高，沉积得到的材料残留孔隙率降低，密度升高，样品沿径向密度分布比较均匀，基本上不存在密度梯度或分布不均匀现象。沉积温度为1250℃时，孔隙分布也比较均匀，但样品内残留孔隙较多且大。     

聚烯烃树脂熔体密度的测定

通过测量树脂熔体体积流动速经和活塞规定距离所需时间，分别测定各类树脂的熔体密度结果与文献值一致，用试验测得熔体密度值，可以得到准确的熔体质量流动速度。     

胺的密度的模拟研究

运用分子动力学模拟方法研究了氨、甲胺、三甲胺体系的密度。首先模拟与文献相同的温度和压力下的三甲胺密度,模拟值与文献实验值吻合得很好,于是预测了宽广的温度和压力范围内氨、甲胺、三甲胺体系的密度。     

液态烃球罐储量计算方法探讨

液态烃球罐储量计算,通常是根据储罐内液态烃的体积、密度加上计量温度下液态烃的体积温度修正系数,即VCF值(以下简称VCF值),其中,液态烃的VCF值与计量温度、密度有关。本文主要探讨液态烃VCF值的计算并运用计算机语言实现精确快速计算的方法。     

纯CO2体系扩散性质的分子动力学模拟

使用基于COMPASS力场的分子动力学（MD）模拟方法计算了CO2在气相、液相以及超临界区的自扩散系数。计算结果表明温度对扩散系数的影响在密度较低时比较明显,随着密度的升高温度的影响逐渐减弱;密度较高时密度的影响对扩散系数起主导作用。通过研究温度和密度对扩散系数的影响规律,提出了预测CO2自扩散系数的新方程,该方程与模拟值和文献试验值吻合良好。     

不同温度下铵梯油炸药中TNT的准确测定

提出了在岩石粉状铵梯油炸药组分分析中，试验温度对TNT测定的影响，从而间接地影响复合油相含量的确定值。通过绘制不同温度下TNT工作曲线．证明随着温度的升高，曲线的斜率减小。因此，平常室温下测得的吸光度值，必须校准到制作工作曲线相对应温度下的吸光度值，才能测得准确的TNT含量。     

几种蒸气的计量方法及所选用的流量计

1　几种蒸气的计量方法11　饱和蒸气俗称的饱和蒸气实际上是指干饱和蒸气,其物理性质参数具有单值对应关系。在某一饱和蒸气温度下,有唯一压力、唯一密度与之对应。因而在蒸气压力较为稳定时,可采用温度、也可采用压力查表来确定密度值。但不能采用先设定密度值再用温度(或压力)修正的方法;当蒸气压力波动较大,尤其是大大小于设计值时,就要考虑对可膨胀性系数(指差压流量计)、流量系数等参数的修正。12　过热蒸气过热蒸气的密度与压力、温度均有关系。测量过热蒸气的流量,要求同时测量温度和压力,通过查表或回归公式得到密度值,进而计算出质…     

温度对低模数水玻璃碳化法制备白炭黑微观结构的影响

以低模数水玻璃为原料,通入φ(CO_2)=40%的混合气体在不同反应温度下制备白炭黑产品。测得不同反应温度下白炭黑产品的粒径、吸油值和比表面积。通过SEM、BET、FTIR、TG等表征手段探讨反应温度对白炭黑吸油值、比表面积及微观结构的影响,得到以下结论,随着温度从30℃上升到90℃,白炭黑的粒径逐渐增大,吸油值逐渐下降,比表面积逐渐增加。在30℃和50℃时,白炭黑的孔径分布为双峰,在70℃和90℃时,白炭黑的孔径分布为单峰。白炭黑表面羟基的密度也随温度的升高而降低。白炭黑表面羟基含量越大,比表面积也就越大,两者呈正相关关系。不同温度下白炭黑产品的孔径相差不大,但孔体积相差悬殊。这是由于不同温度下白炭黑的孔道数相差较大引起的。     

Frictional behavior of solid polymers on a metal surface at processing conditions

The frictional coefficients of three glassy polymers (polystyrene, polycarbonate, and polymethylmethacrylate) and three crystalline polymers (high density polyethylene, low density polyethylene and polypropylene) on a highly polished steel surface were measured at high temperatures, high pressures, and high speeds, all comparable to actual processing conditions. The frictional behavior of these polymers was found to depend on temperature, pressure-and speed in a very complicated manner. There appears to exist inter-relationships among the temperature, pressure and speed dependences of the frictional coefficients. The frictional coefficients of ductile, crystalline polymers as a function of temperature appear to undergo two distinct transitions: one associated with yielding and the other associated with melting. The frictional coefficients of glassy polymers go through only one transition, associated with the glass transition. The friction-generated heat at high pressures and high speeds can increase the sliding interface temperature of a polymer to values much greater than the metal surface temperature, and thus the polymer can start to melt (or plasticate) at metal surface temperatures appreciably below its thermodynamic melting (or glass transition) temperature.     

指数-6流体的自扩散系数的分子动力学模拟

Self-diffusion coefficients of exponential-six fluids are studied using equilibrium molecular dynamics simulation technique. Mean-square displacements and velocity autocorrelation functions are used to calculate self-diffusion coefficients through Einstein equation and Green-Kubo formula. It has been found that simulation results are in good agreement with experimental data for liquid argon which is taken as exponential-six fluid. The effects of density, temperature and steepness factor for repulsive part of exponential-six potential on self-diffusion coefficients are also investigated. The simulation results indicate that the self-diffusion coefficient of exponential-six fluid increases as temperature increases and density decreases. In addition, the larger self-diffusion coefficients are obtained as the steepness factor increases at the same temperature and density condition.     

固--固换热器传热特性研究

在自制的固—固套管式换热器中,以催化裂化催化剂为原料,对系统的循环特性、传热系数进行了实验研究。分析了床层密度、提升风量、床层温度、催化剂粒径等因素对传热过程的影响。实验结果表明,随着提升风量增加,表观气速增大,床层密度下降,传热系数下降;提高床层温度,减小催化剂的粒径,传热系数增加。     

液态甲醇的分子动力学模拟

应用分子动力学模拟方法系统地研究了温度为298、550和950K,密度为0.78g/cm3的液态甲醇的微观结构和动力学性质。研究发现,随着温度的增加,甲醇体系的径向分布函数的峰位整体左移,第一峰峰值下降,峰谷上升;自扩散系数随温度增加而增大。     

高炉炭砖的导热系数及其影响因素

对微孔、半石墨质和普通等级炭砖试样的导热系数与温度的关系做了回归分析,得到了导热系数和温度的关系表达式,由此,可以从室温导热系数预测高温导热系数。另外,还计算了导热系数与体积密度、显气孔率、透气度和原料等级之间的相关系数。结果表明,导热系数与透气度和原料等级有一定的相关关系,而与体积密度和显气孔率无关。     

Some thermodynamic and kinetic properties of the system PETG-CO2, and morphological characteristics of the CO2-blown PETG foams

The solubility of CO₂ in PETG, a glycol-modified PET, was measured at different temperatures and over a broad pressure range, and diffusion coefficients were derived at the corresponding conditions. The solubility of CO₂ is quits high. For example, almost 15 wt% CO₂ can be dissolved in PETG at 35°C and 6.0 MPa. Consequently, CO₂ is good blowing agent for PETG. Cellular foams in the density range of about 0.04 to 1.2 g/cm³ and diameters in the range of about 10 to 150 µm were produced. The foam density and the cell size were found to depend on the foaming temperature and time, with larger cells obtained at higher temperatures or when the sample was foamed for a longer time. The foam density decreased with an increase in the foaming temperature to about 90°C, beyond which the density tended to increase slightly due to the cell collapse or coalescence. The density reduction also depended on the pressure at which the polymer was saturated with CO₂; the higher the saturating pressure at a given temperature, the greater the density reduction.     

无定形PET中小分子扩散系数的分子动力学模拟

采用分子动力学模拟研究了相对分子质量在32～339范围内小分子在无定形PET中的扩散过程。基于Einstein关系式计算了扩散系数,讨论了模拟时间、密度对扩散系数的影响。结果表明：在较高的温度下,较短的模拟时间内就能观察到均方位移曲线的线性区;而在较低的温度下,需更长的模拟时间。扩散系数随密度增加而降低,聚合物密度越大,所需的模拟时间越长。通过比较扩散系数的计算值与实验值,发现两者的比值在一个数量级范围内,表明建立的聚合物模型可接受且能正确描述小分子在无定形PET中的扩散过程, 为获得迁移模型中关键参数——扩散系数提供了一种近似的计算方法。     

Molecular migration of low sorbing organic liquids into polymeric geomembranes

Laboratory test results of sorption/desorption for tetrahydrofuran, tetralin, 1,4-dioxan, methyl acetate, ethyl acetate and butyl acetate into high density polyethylene, linear low density polyethylene, very low density polyethylene and polypropylene geomembranes at 25, 50 and 70 °C are presented. Partition coefficients are calculated from the measured increase in the mass of geomembranes immersed in the liquid of interest, from the initial value until the mass becomes constant. From the initial linear portions of the sorption curves, the diffusion coefficients of liquids into the geomembranes are calculated using the Fick equation. From a temperature dependence of sorption, diffusion and permeation coefficients, the Arrhenius parameters are calculated for each of these processes. Results of the preliminary findings reported here might be useful in the applications of geomembranes in containment facilities. © 1999 Society of Chemical Industry     

Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol·L?1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.     

电解质溶液的分子热力学模型

本文以扰动理论为基础建立了含极性组分和电解质的混合物的状态方程.混合物的Helmholtz能由硬球、静电和吸引项三部分组成.对于无电解质的混合物,本状态方程还原成Hu等近期开发的方程.用Bromley、Meissner、pitzer、Chen和本文摸型对25个二元电解质水溶液(最高浓度达20mol/kg)298.15K时的离子平均活度系数进行了关联,本文模型的精度最高.另外,用298.15K回归出的参数对其它温度下的离子平均活度系数进行了预测,结果表明模型参数与温度的关系较小.