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 In this paper, further simplifications are suggested for the twofraction method based on the solubility function and the treatment of fractionation data by using Tung functipn which were proposed by the present authors in previous publications.The evaluation of the distribution parameters for a fraction from two intrinsic viscosity measurements in a good solvent and in a θsolvent is shown to be not practical, because the required precision is not attainable in ordinary measurements. A new approximation is... In this paper, further simplifications are suggested for the twofraction method based on the solubility function and the treatment of fractionation data by using Tung functipn which were proposed by the present authors in previous publications.The evaluation of the distribution parameters for a fraction from two intrinsic viscosity measurements in a good solvent and in a θsolvent is shown to be not practical, because the required precision is not attainable in ordinary measurements. A new approximation is suggested by taking the phase separation parameter Q to be equal to the volume ratio R of the concentrated and dilute phases. Then, the distribution parameters for the twofraction method can be readily evaluated. Actual calculations show that the distribution parameters thus calculated is not very sensitive to the value of Q taken, and therefore this approximation is justified as a tentative simplification of the twofraction method for the determination of molecular weight distributions.In the treatment of ordinary fractionation data by means of Tung function, all fractions except the first and the last ones can be approximated by a straight line for the integral distribution curve. The line passes through the points M(1 = 1/2) = Mη, M(1 = 0) = 1/2Mη which corresponds roughly to a straight line with equal slope as the Tung function at M1/2 with b = 2.73.0. This leads to a considerable saving in computation but very slight difference to the result.The suggested simplifications have been applied to a sample of PMMA. The integral distribution curve obtained by the suggested method are closer to the actual one obtained by sedmentation rate method than the usual SchulzDinlinger treatment.  本文对作者等以前提出的应用溶度函数的简易分级法,和应用董履和函数处理沉淀分级数据作了进一步的简化和考验。用在良溶剂和θ溶剂中测定两个特性粘数值来决定 级分的分布参数,在一般的实验条件下不可能达到所要求的精确度,因此改用分相参数Q=R的近似来决定简易分级法中两个级分的分布参数,实际的计算说明Q的取值可以有相当大的变化范围而对结果的影响不大,这样对简易分级法提供了一个简便的权宜办法。对应用董履和函数计算普通分级法的分级数据时,除第一级分和最后级分外,其他各级分的累积分布均可采用直綫近似,此直綫通过M(I=1/2)=(?)_η,M(I=0)=1/2(?)_η两点,可以简省计算,而对结果的影响极小。本文中对一个聚甲基丙烯酸甲酯试样的两种分级数据进行计算的结果,说明上面两种方法都比习惯应用的SchulzDinlinger法计算结果更接近于用沉降速度法测定的分子量分布。  This paper discusses some important problems of the design of blasting in dam con struction by directional explosion. The planning of explosive charges is first mentioned.The effect of blasting order on the shape and height of piling is then discussed,and some principles for the deter mination of rational order of blasting are outlined: 1.If the slopes of the two opposite river banks are unequal,but the quantities of materials to be projected from them to the dam are equal,then the flatter bank should be blasted... This paper discusses some important problems of the design of blasting in dam con struction by directional explosion. The planning of explosive charges is first mentioned.The effect of blasting order on the shape and height of piling is then discussed,and some principles for the deter mination of rational order of blasting are outlined: 1.If the slopes of the two opposite river banks are unequal,but the quantities of materials to be projected from them to the dam are equal,then the flatter bank should be blasted earlier than the other. 2.If equal quantities of materials are projected from the two opposite banks of equal slopes,then they should be blasted simultaneously. 3.If the quantity of materials projected from one bank is much greater than that from the other,then the forth bank should be blasted earlier. According to the characteristics and requirements of dam construction,a formula considering the slope effect of ground surface is given for evaluating the weight of ex plosive charges.And,in order to obtain a rather uniform velocity distribution of the thrown material over the region between charges,a formula for determination of the spacing of the explosive charges is also obtained. Based on the theory of ballistics,with the consideration of all factors,such as para meters of explosive charge,air resistance and slope of free surface etc.,another formula for calculating the maximum distance of projectiles is given as follows: L_(max)=(A_i~2)/(gW~(2m)F(s))sin2(α—)con~(2m)+(3sin(α))/(2cos)W. With the same consideration,a method for calculating the piling of projected materials is also presented. Finally,a general idea of how to choose the best scheme of blasting is briefly des cribed.  本文就定向爆破筑坝时爆破设计计算的主要问题进行了初步探讨.文中,首先讨论了药包规划方法和爆破程序对坝体堆高和成型的影响,并概括出确定合理爆破程序的几点原则.其次,根据定向爆破筑坝的特点和要求,认为药包间距计算应以药包间被爆岩石具有均匀初速度分布为前提,装药量的计算应考虑到斜坡的影响,并给出了相应的计算式.此外,用弹道理论法在考虑了爆破参数、空气阻力和地面坡度影响等所有因素的情况下,导出了最大抛距计算式和堆积计算方法.最后,扼要地讨论了有关最优方案的选择问题.  We have investigated the decomposition of lauroyl peroxide, 1 in benzene at 30℃, 40℃ and 50℃ and followed the reaction iodometrically. With an initial concentration of 1 between 0.1 to 0.2M and at temperature of 30℃ or 40℃, a firstorder plot could be obtained, but the slope increased with the increase of initial concentration (Fig. 1) indicating that some induced decomposition was involved. When the decomposition was carried out at 50℃, a firstorder plot could be obtained only when the initial concentration... We have investigated the decomposition of lauroyl peroxide, 1 in benzene at 30℃, 40℃ and 50℃ and followed the reaction iodometrically. With an initial concentration of 1 between 0.1 to 0.2M and at temperature of 30℃ or 40℃, a firstorder plot could be obtained, but the slope increased with the increase of initial concentration (Fig. 1) indicating that some induced decomposition was involved. When the decomposition was carried out at 50℃, a firstorder plot could be obtained only when the initial concentration was below 0.04 M, but deviation became apparent with higher initial concentrations (Fig. 1, 2). A kinetic analysis of the data from the experiment at 50℃ gave the results which fit well with a first plus three halves order kinetics (Fig. 3). The firstorder rate constant k_1 for spontaneous decomposition was found to be 0.0115 hr~(1), and the rate constant k_1 for induced decomposition 0.014 mol~(1/2)·1~(1/2).hr~(1).dα/dt=k_1+k_ia~(3/2) (1)When 1 was decomposed in benzene to which the radical scavenger "galvinoxyl" 2 was added, and the progress of reaction monitored by optical density measurements at 434 nm as described by Williams et al, the results showed a firstorder reaction with respect to 1 and a zeroorder reaction with respect to 2 (Fig. 4). It can be seen from Figure 4 that the straight lines are all nearly parallel with about equal slope, irrespective of the molar ratio between 1 and 2 being changed from 7 to 207, a thirtyfold variation. This means that, in the presence of 2, the induced decomposition was suppressed.From the above results, on the assumption that two radicals were produced from the decomposition of one molcoulo of 1 and that these radicals could be scavenged entirely by 2, the firstorder rate constant k_1 was calculated to be 0.0057 hr~(1), which was just about half the value as determined from iodometric measurements as given above. This implies that only one half of the radicals produced from the decomposition of 1 was scavenged by 2.The carbon dioxide evolved from the decomposition of 1 in benzene in the absence of 2 amounted to about 87％ of the theoretical value. But when 2 was added to the reaction mixture, the amount of carbon dioxide dropped to about 50％.The above results could be interpreted by the following mechanism. In accordance with the general view, the decomposition of 1 proceeded by the fission of O—O bond, followed by the decarboxylation of the resulting RCOO· radicals, producing R· and CO_2.(RCOO)→2RCOO·→2R·+2CO_2 (2) When the decomposition was conducted at 50℃ in the presence of 2, only about one half of the RCOO· radicals decarboxylated and the resulting radicals partly reacted within the cage (c), through disproportionation, recombination etc., and partly diffused into solution to become "free" radicals (d). Thus the free radicals, which were scavenged by 2, would consist at least part of the RCOO· radicals formed. These sequences may be formulated as follows:However, a more tempting and also more tentative interpretation could be put forward as an alternative. Thus when 1 was decomposed in benzene at 50℃, a simultaneous breakage of O—O bond and R—COO linkage took place with the formation of R., CO_2 and RCOO· in one step. Again about one half of the radicals reacted within the cage and the remaining half diffused into solution with the same results. This mechanism may be depicted by the following scheme: However, our results are different from Ward's. Ward et al. studied the decomposition of 1 in odichlorobenzene at 112℃ with 2iodopropane as the scavenging agent and found that no net polarization was observed in the CIDNP spectra for the products. They conclude that the decarboxylation of C_(11)H_(23)COO· must be a very fast process with a life<10~(10) sec. and cannot be scavenged.Since the experiments by Ward et al. was conducted at 112℃, the extensive decarboxylation of the RCOO· was not surprising. We did the decomposition experiment at 50℃ and it might be that, in the presence of 2, only about one half of the RCOO· radicals decarbexylated under these conditions. The fact that approximately 50％ of the theoretical amount of carbon dioxide liberated supported this contention.In order to ascertain whether the decomposition of 1 undergoes by a stepwise sequence or it may proceed by a concerted mechanism involving the simultaneous breaking of O—O and R—COO bonds, a detailed study of the decomposition products is necessary. Work along this line is being planned.Finally, it should be mentioned that Bawn and Halford have reported early a kinetic study of the decomposition of 1 with DPPH as the scavenging agent. On the assumption that 1 decomposed into two RCOO· radicals and DPPH could capture these radicals with a 100％ efficiency, these authors obtained a value of 0.0078 hr~(1) for k_1 at 50℃, which is lower than what we have found (0.0115 hr~(1)) from iodometric determination and somewhat higher than the value (0:0057 hr~(1)) which we have found by scavenging experiments. In view of the report by Shine et al. that DPPH could cause an induced decomposition of acyl peroxide, it appears that the value reported by Bawn et al. may be a little uncertain.  进行了过氧化月桂酰(1)在脱氧的苯中的分解动力学研究,当起始浓度0.1～0.2克分子·升~(1),温度30℃、40℃时,1不是严格地按一级反应分解的。在50℃下起始浓度0.04～0.34克分子·升~(1)时,实验结果符合一级加二分之三级的反应规律:(da/dt)=k_1a+k_1a~(3/2)。求出的自发分解速率常数k_1=0.0115小时~(1),诱导分解速率常数k_1=0.014克分子~(1.2)·升~(1/2)·小时~(1)。研究了50℃时有自由基捕获剂galvinoxyl(2)的动力学试验,根据光密度变化测定分解反应,知1为一级,2为零级,诱导分解受到抑制。假定1的初级分解生成两个自由基,且可被2完全捕获,则计算出来的分解速率常数为0.00570小时~(1),恰好为碘量法测定1的自发分解速率常数的一半;同时,根据有2存在下测出1分解产生的二氧化碳量,约为理论值(假定一个1分子分解产生两个二氧化碳分子)的一半的事实,推论1在50℃的苯中的初级分解可能有如下两种过程: (RCOO)_2→2RCOO·→R··OCOR+CO_2 或者(RCOO)_2→R·CO_2·OCOR→R··OCOR+CO... 进行了过氧化月桂酰(1)在脱氧的苯中的分解动力学研究,当起始浓度0.1～0.2克分子·升~(1),温度30℃、40℃时,1不是严格地按一级反应分解的。在50℃下起始浓度0.04～0.34克分子·升~(1)时,实验结果符合一级加二分之三级的反应规律:(da/dt)=k_1a+k_1a~(3/2)。求出的自发分解速率常数k_1=0.0115小时~(1),诱导分解速率常数k_1=0.014克分子~(1.2)·升~(1/2)·小时~(1)。研究了50℃时有自由基捕获剂galvinoxyl(2)的动力学试验,根据光密度变化测定分解反应,知1为一级,2为零级,诱导分解受到抑制。假定1的初级分解生成两个自由基,且可被2完全捕获,则计算出来的分解速率常数为0.00570小时~(1),恰好为碘量法测定1的自发分解速率常数的一半;同时,根据有2存在下测出1分解产生的二氧化碳量,约为理论值(假定一个1分子分解产生两个二氧化碳分子)的一半的事实,推论1在50℃的苯中的初级分解可能有如下两种过程: (RCOO)_2→2RCOO·→R··OCOR+CO_2 或者(RCOO)_2→R·CO_2·OCOR→R··OCOR+CO_2生成的R·和RCOO·一部分在笼内反应(歧化、再结合等);一部分扩散到溶剂中,当有2存在时,为2所捕获。   << 更多相关文摘 
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