【作者】 刘赫扬；

【导师】 李伯耿； 曹堃；

【作者基本信息】 浙江大学 ， 化学工程与技术， 2007， 博士

【摘要】 本文以苯乙烯—N-苯基马来酰亚胺无规共聚物耐热树脂的自主开发和复杂反应挤出过程的优化设计为目标,实验研究了苯乙烯—马来酸酐共聚物（SMA）与苯胺的热酰亚胺化反应机理、动力学、反应挤出过程以及反应产物组成与热性能间的关系,建立了SMA酰亚胺化的微观动力学模型和宏观反应挤出过程模型。论文首先参考聚酰胺酸热环化反应,并通过SMA酰亚胺化产物的组成分析,确定了SMA与苯胺的热酰亚胺化反应机理为一个包含由SMA生成苯乙烯—N-苯基马来酰胺酸共聚物（SNPMA）的二级可逆开环反应以及由SNPMA生成苯乙烯—N-苯基马来酰亚胺共聚物（SNPMI）的一级不可逆分子内闭环反应在内的串联反应过程,其中第二步SNPMA闭环反应为控制步骤。系统研究了溶液反应体系中,反应温度、反应物浓度及胺酐比等因素对反应过程的影响,发现SMA与苯胺的热酰亚胺化反应速度大大低于小分子化合物马来酸酐与苯胺的反应速度,首次得到了适用于较宽温度和溶液浓度范围的动力学参数:k₁^solution=1.10×10⁴e^-27,100/RT(1·mol^-1·s^-1),k_-1^solution=7.82×10⁴e^-61,000/RT(s^-1),k₂^solution=9.49×10⁴e^-65,800/RT(s^-1)。利用热失重—傅立叶变换红外（TGA-FTIR）联用测试技术,研究了熔融反应体系下SMA与苯胺开环反应中间产物SNPMA的正反双向闭环反应,首次得到了熔融反应条件下SNPMA正反双向闭环反应的动力学参数:k_-1^melt=1.02×10⁵e^-60,200/RT(s^-1),k₂^melt=1.12×10⁵e^-70,200/RT(s^-1)。以SMA的直接熔融酰亚胺化反应挤出过程为对象,系统研究了挤出条件对反应过程的影响。实验结果显示,降低反应温度、提高胺酐比以及降低SMA喂料速度均有助于酰亚胺化反应的进行;而提高螺杆转速一方面会减少物料在挤出机内的停留时间,一方面能够强化传质,并且温度越高,体系粘度越低,螺杆转速对上述两个因素的影响就越大。结合不同操作条件下的实验现象及产物组成,推测SMA熔融酰亚胺化反应挤出过程中,由于挤出操作温度（＞210℃）高于苯胺的汽化温度（184℃）,以液体方式进料的苯胺在进入挤出机内后,一部分溶解在SMA熔体中并立即与其发生反应,另一部分则迅速汽化,充斥在螺槽与机筒的空隙中,并随着挤出过程的进行不断地进入SMA熔体参与反应。苯胺在挤出机内呈现气相和液相两种状态,因而该反应挤出过程为一非均相反应过程。由此建立了连续反应过程模型,通过模型参数回归进一步验证了上述机理的可信度。同时,首次提出了SMA熔融酰亚胺化反应挤出过程中的苯胺有效利用率概念。提高反应温度,能够提高苯胺的气相分压,降低苯胺在熔体中的初始液相分率,继而由于气液传递的限制导致苯胺的有效利用率降低。提高苯胺喂料速度也会导致苯胺有效利用率的降低。对比直接熔融反应挤出法,以部分酰亚胺化的SMA为前驱体,对其浓溶液反应挤出过程进行了分析,并建立了其连续反应过程模型。根据反应挤出过程中的实验现象及模型预测结果,推测该过程实际上更趋近于熔融反应挤出过程,其中浓溶液进入挤出机后,未反应的苯胺将会瞬间全部逸出,而反应过程中由于SNPMA逆向闭环生成的苯胺也几乎会完全从反应体系中逸出。系统研究了一系列具有不同组成的SMA酰亚胺化产物的玻璃化温度。实验结果显示,SMA、SNPMA及SNPMI的玻璃化温度符合SMA＜SNPMI＜SNPMA的关系,且所有样品的玻璃化温度均符合Fox方程。刚性基团的引入与氢键作用对于热性能的提高都能起到很重要的作用。考察了SMA、SNPMA及SNPMI的热稳定性。热失重分析结果显示,SNPMA在热失重过程中出现两次失重,其中主失重过程的最大分解温度与SMA的最大分解温度十分接近,这主要是由于SMA开环反应的可逆性而造成的。另外,SNPMI的热稳定性比SMA更为优异。以本文所用的SMA为例（MAh=16.63mol%）,其完全酰亚胺化产物的最大分解温度能提高约20℃。更多还原

【Abstract】 In this study,the independent development of the process for the manufacture of poly（styrene-co-N-phenyl-maleimide）（SNPMI）,a kind of heat-resistant resin,and the optimal design of the complex reactive extrusion process was focused on.Based on the experimental studies on the mechanism,the kinetics,the reactive extrusion process the thermal imidization of poly（styrene-co-maleic anhydride）（SMA）with aniline and the relationship of the thermal properties and the result polymer composition,a model for the micro kinetics and a model for the macro reactive extrusion process were developed.Based on the-references on the thermal imidization of poly（amide acid）and the polymer composition analysis,the thermal imidization mechanism of SMA with aniline was demonstrated to be a two-stage consecutive reaction（as shown in the scheme below）,in which a second-order reversible ring-opening reaction of SMA to produce poly（styrene-co-N-phenyl-maleamic acid）（SNPMA）and a first-order irreversible intrachain ring-closing reaction to form SNPMI were involved. Furthermore,the latter reaction is the controlling step.The effect of the reaction condition,such as the temperature,the solution concentration and the aniline to maleic anhydride ratio（ANL/MAh ratio）etc.,on the imidization rate in the solution reaction system was investigated.It was found that the imdization of SMA was much slower than the imidization of small maleic anhydride molecule.The kinetic parameters within broad reaction temperature range and wide SMA concentration range were determined as k₁^solution=1.10×10⁴e^{-27.100 RT}(1·mol^-1·s^-1), k_-1^solution=7.82×10⁴e^-61,000/RT(s^-1)and k₂^solution=9.49×10⁴e^-65,800/RT(s^-1).The competitive reactions of SNPMA to produce either SMA or SNPMI were investigated by using the TGA-FTIR integrated technology,and the kinetics parameters of the above two reactions in the melt state were determined as k_-1^melt=1.02×10⁵ e^-60,200/RT(s^-1)and k₂^melt=1.12×10⁵ e^-70,200/RT(s^-1).The reactive extrusion process for the direct imidization of the molten SMA was studied,and the influence of operation conditions on it was investigated.It was shown that reducing the temperature,increasing the ANL/MAh ratio or decreasing the SMA throughput helped raising the imidization reaction conversion.However,a higher screw speed led to a shorter fluid residence time in the extruder accompanied with the strenghened mass transfer,especially for the extrusion process with a higher extrusion temperature due to the lower viscosity.The mechanism of the reactive extrusion process for the direct imidization of the molten SMA.was deduced from the experimental phenomena and the product composition.In an extruder,the barrel temperature（>210℃）is much higher than the boiling point（184℃）of the aniline.Accordingly,most of the aniline is vaporized immediately after being fed into the extruder.The aniline in gas phase occupies the unfilled part of the extruder and only little can stay in the liquid phase.Then along with the consumption of the liquid aniline,the aniline in the gas phase will gradually liquidize and react immediately.On the basis of this heterogeneous reactive extrusion process mechanism,a continuous process model was developed.Meanwhile,the efficiency of aniline,a useful concept,was proposed to evaluate the reactive extrusion process.It was found that the vapor pressure increased and the initial aniline in liquid phase decreased when the temperature was raised,and then resulted in a drop of the efficiency of aniline for the gas-liquid mass transfer restriction.It was shown that a higher aniline throughput also led to a lower efficiency of aniline.As a comparison with the above direct reactive extrusion.The thick solution reactive extrusion process for the imidization of the partially amidized SMA was investigated and a continuous process model was developed also.According to the experimental fact and the prediction results of the process model,this thick solution reactive extrusion was considered as a reactive extrusion process in melt state,and both the unreacted aniline in the inlet feed and the aniline producted from the SNPMA-to-SMA reaction will escape. The glass transition temperatures（T_g）of the imidization products of SMA with various compositions were measured by DSC.It is found that the T_g data increase as: SMA<SNPMI<SNPMA,and the T_g of all the samples follows the Fox equation.It demonstrates that both the introduction of rigid phenyl rings and the presence of hydrogen-bonding interactions have great contribution on enhancement of the thermal properties.Finally,the thermal stabilities of SMA,SNPMA and SNPMI were also investigated.It was shown that a two-stage weight loss exsited during the thermogravity analysis of SNPMA,and the main weight loss of SNPMA was similar with the weight loss of SMA,which is caused by the from-SNPMA-to-SMA ring-closing reaction.Furthermore,the thermal stability of SNPMI is better than that of SMA.For example,in this study,the maximum decomposition temperature of SNPMI is 20℃higher than that of the corresponding SMA。更多还原