用拟二元方法研究iPP-DBP-DPP三元体系的热致相分离热力学

采用拟二元方法研究等规聚丙烯(iPP)-邻苯二甲酸二丁酯(DBP)-邻苯二甲酸二辛酯(DOP)三元聚合物溶液的热致相分离热力学，得出了拟二元相图的数学关联方法．采用光学显微镜法测定浊点温度，采用差式扫描量热法(DSC)测定熔点、动态结晶温度．利用浊点测定数据回归聚合物一共溶剂的交互作用参数X的表达式，X是共溶剂配比和温度的函数，以此为基础计算的拟二元相图与实验数据吻合较好．发现共溶剂中DBP份数增加，相分离类型由单纯固液分相形式转变为液液分相、固液分相依次发生形式，共溶剂配比能调控拟二元相图结构．研究表明，只需测定一个较低冷却速率下几种共溶剂配比的拟二元溶液的浊点温度、分别测定几个冷却速率下iPP-DOP二元溶液的动态结晶温度即可掌握该三元溶液热致相分离热力学的全部信息．其可用来指导制膜过程，并能准确预测形成的膜结构形貌．     

浊点滴定法研究PAN-DMSO-H2O体系的相行为

采用浊点滴定法研究了聚丙烯腈-二甲基亚砜-水（PAN—DMSO—H2O）三元体系的浊点组成及其相分离行为。结果表明：当PAN—DMSO—H2O三元体系达到相分离时,浊点曲线上各点成分有一定线性关系。根据该线性关系推导了高聚合物浓度的浊点成分,获得不同温度下的PAN—DMSO—H2O三元相图。浊点滴定法测定体系浊点组成,精度高,相对平均偏差小。     

稀释剂对TIPS法等规聚丙烯中空纤维微孔膜孔径及其连通性的影响

热致相分离（TIPS）法制备等规聚丙烯（iPP）中空纤维微孔膜,邻苯二甲酸二丁酯（DBP）与邻苯二甲酸二辛酯（DOP）的混合溶剂作为制膜稀释剂。干/湿氮气流量法测定了α（稀释剂中DBP的质量分数）和β（铸膜液中聚合物的质量分数）对膜样品的平均孔径及其分布的影响,并采用膜孔曲折因子定量表达膜孔连通性。发现全部膜样品均体现窄孔径分布特征。对于相同的β, α增加导致平均孔径及膜孔连通性下降。α=0.20时,β增加,膜的平均孔径先增加后降低,膜孔曲折因子稍下降; α=0.35或0.50时,β增加,膜的平均孔径降低,膜孔曲折因子下降。膜孔连通性体现了膜内部的拓扑结构,共溶剂组成和铸膜液固含量能够调节iPP中空纤维微孔膜的孔径及其连通性。     

超高分子量聚乙烯微孔材料微观结构形成机理的研究 (I)相分离过程对微观结构的影响

超高分子量聚乙烯（ＵＨＭＷＰＥ）微孔材料是以ＵＨＭＷＰＥ为聚合物基体的一种新型功能性材料,利用这种材料能够实现非均相分离、过滤及离子通透等多种单元操作过程,可广泛地应用于化工、医药、能源等领域［１］。针对ＵＨＭＷＰＥ物料的特殊性能,采用热致相分离方法［２］（ＴＩＰＳ）进行微孔材料的成型。ＴＩＰＳ过程涉及到聚合物－溶剂二元体系,因此对ＴＩＰＳ的二元体系热力学过程进行了研究。同时,二元体系的相分离过程对微观结构有很大影响。结合ＵＨＭＷＰＥ－石蜡油二元体系相图可以知道,该二元体系的相分离由两种不同的相分离过程组成———固液相分离和液液相分离,研究了两种分离过程对最终微观结构的影响。     

二溴苯三元物系固液平衡测定与正规溶液模型

采用差示扫描量热法,通过对一系列"拟二元"物系固液平衡数据的测定,得到了邻二溴苯、间二溴苯和对二溴苯三元物系的固液平衡数据.实验结果表明本物系为简单低共熔型,其低共熔摩尔分数组成和温度分别为:邻二溴苯(x1) 间二溴苯(x2) 对二溴苯(x3),x1=0.4259,x2=0.5345,x3=0.0396,Tcu=238.5 K.文中绘制出了其相应的低共熔三元固液平衡相图,并采用正规溶液模型,利用二元溶液的三个相互作用参数对实验数据进行了关联,温度均方根偏差仅为1.32 K,说明正规溶液模型适用于上述弱极性异构体三元物系固液平衡的计算.     

相转化法聚合物/溶剂/非溶剂铸膜体系的热力学计算

计算了相转化法铸膜体系中常见的典型三元相图,分析了聚合物与溶剂之间、聚合物与非溶剂之间、溶剂与非溶剂之间的相互作用参数对聚合物/溶剂/非溶剂铸膜液体系相图的影响,以及体系温度和聚合物摩尔体积对聚合物/溶剂/非溶剂铸膜液体系相图的影响。根据溶剂-非溶剂汽液平衡数据和溶解度参数得到了溶剂-非溶剂、溶剂与聚合物以及非溶剂与聚合物之间的Flory-Huggins相互作用参数,从而获得了几种常见铸膜液体系的相图。同时,利用聚合物/溶剂/非溶剂铸膜液体系的相图数据对热力学模型的参数进行了优化,取得了与实验结果较一致的计算结果。     

4-羟基苯甲醛及其溴代物三元固液平衡

采用差热扫描量热法,通过对一系列“拟二元”物系固液平衡的测定,得到了4-羟基苯甲醛、3-溴-4-羟基苯甲醛和3,5-二溴-4-羟基苯甲醛物系的三元固液平衡数据,实验结果表明本物系为简单低共熔型,其低共熔摩尔组成和温度分别为：3,5-二溴-4-羟基苯甲醛（x₁）＋3-溴-4-羟基苯甲醛（x₂）＋4-羟基苯甲醛（x₃）,x₁=0.2445,x₂=0.3883,x₃=0.3672,T_eu＝338.5 K。同时绘制出相应三元相图,并采用Ott方程对实验数据进行了很好的关联;根据Wilson方程由二元溶液的相互作用参数,对本物系进行计算,关于温度的标准偏差为0.97 K,计算值和实验值符合良好,说明Wilson方程能较好地描述文中三元固液平衡体系。     

PVDF-PVP-DMAc-H2O铸膜液体系中浓相固化过程研究

研究了PVDF-PVP-DMAc-H2O体系的聚合物溶液固化的机理和速度.对PVDF聚合物凝胶进行了差示扫描量热实验和粉末衍射实验,表明聚合物溶液转变成凝胶固化是由结晶导致的物理可逆过程,结晶性液固分相按照成核-长大机理发生.通过落球实验测定了聚合物溶液体系从具有流动性的液态转换成凝胶态的过程,实验发现在凝胶点处从流动态转换成凝胶固态的过程大致需要2.5～4 min.光透射曲线法测定了成膜时的相分离速度, 结果表明成膜过程中,在凝胶分相后约1min出现了液液分相. 可见从开始发生液液分相到最后浓相固化、膜形态固定之间大致还有1.5～3 min的时间,这段时间是聚合物浓、稀相间的结构发生变化并最终固化定型的关键阶段.     

LiNO_3-NaNO_3-KNO_3三元熔盐材料的设计及热稳定性研究

采用共形离子溶液模型(conformalionic solution model, CIS)在二元熔盐体系相图的基础上,对三元熔盐体系LiNO_3-NaNO_3-KNO_3进行了相图计算,得到该三元体系最低共熔点为117.7℃,相应的摩尔分数组成分别为x(LiNO_3)=0.375,x(NaNO_3)=0.075,x(KNO_3)=0.550。按照热力学最低共熔点计算结果,采用熔融法制备了三元硝酸熔盐,通过DSC和TG实验测定其最低共熔点为118.3℃,这与计算得到的结果 (117.7℃)基本一致。TG测试结果表明当温度低于587.2℃时,该三元熔盐体系较为稳定,其工作温度范围为118.3～587.2℃,该三元硝酸熔盐适合在太阳能热发电中作为高温传热蓄热材料使用。     

聚丙烯腈原丝的凝固成形与相分离研究进展

以热力学相图为工具,探讨了聚丙烯睛(PAN)原丝凝固成形过程。从相图中原丝凝固成形的不同途径和相应的织态结构可以知道,原液体系以旋节方式分相是最佳的热力学路径。原丝凝固成形可以看作是浓度致变相分离(CIPS)和热致变相分离(TIPS)两种相分离形式的组合,通过后者得到高性能原丝要容易实现得多。可以根据相图来优化纺丝工艺条件,通过调节凝固浴浓度、纺丝液浓度、初始纺丝温度以及淬火深度.削弱CIPS过程在凝固成形中的作用,使凝固成彤尽可能多的以TIPS方式通过旋节线和双节线的交界处进行,以得到具有理想结构的优质的PAN原丝。     

Formation of microporous membrane of isotactic polypropylene in dibutyl phthalate‐soybean oil via thermally induced phase separation

Isotactic polypropylene (iPP) microporous membranes were prepared via the thermally induced phase separation (TIPS) process with the diluents being dibutyl phthalate (DBP) and soybean oil mixture. By changing the weight ratio of DBP to soybean oil systematically, it was determined experimentally that the cloud‐point curves were influenced to a great extent, while the crystallization curves showed much less dependence on the diluents composition. Scanning electron microscopy (SEM) showed that the resulting membrane morphologies changed significantly by varying the composition of the diluents, i.e., by changing the interaction parameter and other characteristics of diluents, the interwoven or celluar structure can be fabricated successfully at a fixed polymer concentration under the same cooling conditions. Different growth rates of iPP spherulite were obtained in the diluents with different composition. It is shown that the spherulites growth rates may be also attributed to the great variations of the final microporous morphology to a certain extent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

热致相分离法iPP中空纤维微空膜结构与性能--稀释剂的作用

Isotactic polypropylene （iPP） hollow fiber microporous membranes were prepared using thermally induced phase separation （TIPS） method. Di-n-butyl phthalate （DBP）, dioctyl phthalate （DOP）, and the mixed solvent were used as diluents. The effect of α （DOP mass fraction in diluent） on the morphology and performance of the hollow fiber was investigated. With increasing α, the morphology of the resulting hollow fiber changes from typical cellular structure to mixed structure, and then to typical particulate structure. As a result, the permeability of the hollow fiber increases sharply, and the mechanical properties of the hollow fiber decrease obviously. It is suggested that the morphology and performances of iPP hollow fiber microporous membrane can be controlled via adjusting the compatibility between iPP and diluent.     

PVDF porous matrix with controlled microstructure prepared by TIPS process as polymer electrolyte for lithium ion battery

Poly(vinylidene fluoride) (PVDF) microporous matrix of polymer electrolyte for lithium ion battery was prepared via the thermally induced phase separation (TIPS) process using diluent mixture of dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). Since this method has only one parameter, namely the DBP/DEHP ratio in diluent mixture, the membrane microstructure is easily and conveniently controlled. With the assistance of a pseudo-binary temperature-DBP ratio phase diagram of the PVDF-diluent mixture system, the membrane formation mechanism for different microstructures of membranes was proposed. In addition to studying the different microstructures available in TIPS process, the relationship between performance of membrane, electrochemical property of polymer electrolyte and final microstructure has been investigated in this paper.     

合成硝基麝香溶液结晶分离研究

为了开发低共熔组成酮麝香、二甲苯麝香混合物溶液结晶新过程,计算得到酮麝香、二甲苯麝香、溶剂三元相图。在此基础上研究了麝香混合物溶液结晶分离方法,提出了轮流加入乙腈和庚烷从低共熔组成麝香混合物中,分级冷却结晶分离得到2种产品的过程。由三元相图得到理论产量并进行试验验证,结果表明加入乙腈一级结晶可得到纯度为97.5%的二甲苯麝香,加入庚烷二级结晶后酮麝香的纯度为98.1%。     

Effect of diluents on membrane formation via thermally induced phase separation

The effect of diluents on isotactic polypropylene (iPP) membrane formation via thermally induced phase separation was investigated. The diluents were methyl salicylate (MS), diphenyl ether (DPE), and diphenylmethane (DPM). The cloud-point curve was shifted to a lower temperature in the order iPP–MS, iPP–DPE, and iPP–DPM, whereas the crystallization temperature was not influenced so much by diluent type. Droplet-growth processes were investigated under two conditions: quenching the polymer solution at the desired temperature and cooling at a constant rate. Although droplet sizes were in the order iPP–MS, iPP–DPE, and iPP–DPM in both cases, the difference was more pronounced with the constant cooling rate condition. Scanning electron microscopy indicated that interconnected structures were obtained when the polymer solution was quenched in ice water. The effect of the diluents on these structures was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 169–177, 2001     

Effects of mixed diluent compositions on poly(vinylidene fluoride) membrane morphology in a thermally induced phase‐separation process

The effects of a mixed diluent (MD) composition [dibutyl phthalate/dioctyl phthalate (DOP)] on poly (vinylidene fluoride) (PVDF) membrane morphology were investigated with scanning electron microscopy, and a bicontinuous morphology could be obtained with MD in a thermally induced phase‐separation process. The reasons for the morphology formation were explained according to the effect of MD on the phase diagrams. In addition, the effects of the PVDF concentration on the membrane morphology were examined. For the system with less DOP, the large spherulite morphology was obvious under all investigated concentrations, whereas no large spherulite structure existed in the membrane as the DOP content increased to concentrations other than 20%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of ultrahigh‐molecular‐weight polyethylene membranes via a thermally induced phase‐separation method

Porous, flat membranes of ultrahigh‐molecular‐weight polyethylene were prepared as thermally resistant and solvent‐resistant membranes by the thermally induced phase‐separation method. Diphenyl ether and decalin were chosen as the diluents. The phase diagrams were drawn with the cloud‐point temperatures and the crystallization temperatures. According to the phase diagrams, scanning electron microscopy images, and porosities of the samples, the influential factors, including the polymer concentration, cooling rate, and viscosity, were investigated. Porous ultrahigh‐molecular‐weight polyethylene membranes with thermal and solvent resistance could be prepared with suitable diluents and cooling rates by the thermally induced phase‐separation method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Estimation of phase diagrams for copolymer‐diluent systems in thermally induced phase separation

The binary interaction model was introduced to estimate phase diagrams of copolymer‐diluent systems in thermally induced phase separation. The crystallization curves and cloud points of poly(ethylene‐co‐vinyl alcohol) (EVOH) with 1,4‐butanediol, EVOH/1,3‐propanediol, and EVOH/glycerol were calculated and compared with experimental value or literature data. Fair agreement was obtained. To confirm the importance of incorporating intramolecular interactions, calculations with and without the consideration of intramolecular interactions were performed and compared. It was found that better results can be obtained if intramolecular interaction was introduced. The reason for the small differences between the calculated value and the experimental data of the liquid–liquid phase separation is discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007