Fundamental Research On Synthetic Rubber Production With Supercritical Fluid

为超临界流体在合成橡胶生产中的应用奠定了基础。本文的研究主题是：1）用超临界流体脱除聚合物溶液中的溶剂和未反应单体; 2）在超临界流体中进行溶液聚合，本工作中使用的超临界流体是超临界CO_2，因为它的临界温度为31 ℃，可以在室温下操作，并且可以通过减压容易地除去它本身。聚丁二烯用作聚合物样品，正己烷用作溶剂。在40 ℃、150 Mpa的萃取条件下，超临界CO2萃取聚合物溶液中的正己烷，在S/F = 100时，正己烷的浓度可降至1wt%以下。用色谱法测定了无限稀状态下超临界CO_2在聚合物中的分配平衡系数 ...更多信息 设备.平衡系数是评价聚合物产品中残留溶剂不可缺少的参数。在压力8- 20 MPa、温度80- 140 ℃的范围内，用自制的三个填料塔进行了实验，得到了重量分配系数在1-2范围内，并随温度和压力的增加而增加。用一个既适用于CO_2又适用于聚合物的状态方程对数据进行关联，并根据实验数据确定了方程参数。利用优化后的参数，可以预测在较宽的溶剂浓度范围内的分配平衡，设计超临界CO_2生产聚合物的脱溶剂工艺。作为首次尝试，以偶氮二异丁腈（AIBN）为引发剂，在70 ℃、0.1，8，15和20 MPa下，通过改变4种反应时间，进行了苯乙烯在超临界CO_2中的自由基聚合。通过称量所产生的聚合物来测定单体转化率。转化率数据表明，在0.1.8MPa下的聚合反应与苯乙烯本体聚合和有机溶剂中的聚合反应非常相似，而在15和20 MPa下的反应速率较慢，这可能是由于CO2在反应溶液中起稀释剂的作用。从分子量来看，由于高分子量聚合物在CO2中的溶解度小，聚合过程中发生了聚合物沉淀。用文献中提出的有机溶剂的速率常数数据进行模拟计算，部分地证实了上述讨论。反应体系的相行为是阐明超临界流体中聚合反应机理的关键。少

This work was conduted as a fundamutl study of applying supercritical fluid to synthetic rubber production processes. The researchtopicsare followings ; 1) removal of solventand unreactedmonomer from polymer solution with supercriticalfluid , 2) solution polymerizationin supercriticalfluid.The supercriticalfluid usedin this work is supercritical CO2 sinceit allows for us to operate around room temperature due to its critical temperatureof 31C and to removeitself easily via decreasingpressure.Desolvation experimentwas performedwith a supercriticalextraction apparatus. Polybutadiene was used as a polymer sample and n-hexane as a solvent. The extractionat 40C and 150 Mpa revealed that supercritical CO2 can removefairly amount of n-hexane and reduce the concentration of n-hexanein polymersolution upto 1wt % at S/F of 100. Partition equilibrium coefficient between supercritical CO2 and polymer has been measured at infinitely dilute state via chromatography technique with a new experimental … More apparatus. The equilibirum coefficient was indispensableto evaluate the remaing solvent in polymer products. Experiments were carried out with three packed columnspreparedin this study in the pressure range of 8-20Mpa and at temperatures of 80-140C.The obtained data showed that the weight baed partition coefficientsare in the range of 1-2 and increased with temperature and pressure. An equation of state which can be applied to both CO2 anf polymer, was used for correlation the data, and its equation paraneters were determined with the experimentaldata. With the optimized parameterswe can predictthe partition equilibria in the wide range of solvent concentration in polymer solution and design the desol vation process in polymer Production with supercritical CO2.As a firstattempt, radical polymerization of stirenein supercritical CO2 was conducted with AIBN as an initiator at 70C and 0.1,8,15 and 20 Mpa by varying the 4 reaction time. The monomer conversion was determinedby weighing the produced polymer. The conversiondata suggested that the polymerizationat 0.1,8Mpa is quite similar to bulk polymerization of stireneand that in organic solvent while the reaction ratesat 15 and 20 Mpa are slow, which may be attributableto CO2 playing a role as a dilutantin the reactionsolution. Accordingto the molecularweight, the polymer pricipitation took place in the course of polymerzation because of small solubility of high molecaular weightpolymer into CO2. This discussion was partly supportedby the simulation results with the literaturedata for rate constantspropsed for or ganic solvents. It should be noted that the phase behavior of reaction systemis key to elucidate the mechanism of polymerization in supercritical fluids. Less