Elongational rheology of polymer melts and solutions

Elongational rheological properties of polymer melts and solutions may be measured using nonlubricated flow characteristics through a semihyperbolic converging die. The effects of body forces related to developing orientation in the fluid during converging extensional flow are so strong that the shearing contribution become negligible in comparison, eliminating the need for lubrication to achieve an essentially pure elongational flow. The effective elongational viscosities of polypropylene melts and lyocell solutions correlated with shear-flow determinations were used to estimate the enthalpy and entropy changes as function of processing conditions. The flow of lyocell solutions through a converging die had, as a result, not only phase separation and cellulose crystallization, but also microfibers formation and high orientation. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2357–2367, 1998     

Elongational rheology of polyethylene melts

Effective elongational viscosities were measured for high‐ and low‐density polyethylene samples using a capillary rheometer fitted with semihyperbolic dies. These dies establish a purely elongational flow field at constant elongational strain rate. The effective elongational viscosities were evaluated under the influence of the process strain rate, Hencky strain, and temperature. Enthalpy and entropy changes associated with the orientation development of semihyperbolic‐processed melts were also estimated. The results showed that elongational viscosities were primarily affected by differences in the weight‐average molecular weight rather than in the degree of branching. This effect was process‐strain‐rate‐ as well as temperature‐dependent. An investigation of the melt‐pressure relaxation and the associated first decay time constants revealed that with increasing strain rate the molecular field of the melt asymptotically gained orientation in approaching a limit. As a result of this behavior, molecular uniqueness became much less distinct at high process strain rates, apparently yielding to orientation development and the associated restructuring of the melt's molecular morphology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2170–2184, 2001     

丁苯嵌段共聚物结构与性能研究

以苯乙烯（St）、丁二烯（Bd）为单体,正丁基锂为引发剂,通过阴离子聚合合成了丙烯腈-丁二烯-苯乙烯（ABS）改性用丁苯嵌段共聚物（LBS）。探讨了聚合温度、加料工艺对产品分子结构及性能的影响规律。详细分析了相对分子质量及其分布、结合St质量分数、分子结构参数、St序列分布与产品性能的关系,探讨了影响产品生胶门尼粘度（MV）的关键因素。合成出了可用于连续本体ABS改性的LBS新产品,并进行了连续本体ABS改性性能评价实验。     

丁苯嵌段共聚物溶液粘度影响因素探讨

从聚合物的分子量、合成方法、聚合配方、聚合物的微观结构、单体反应浓度等方面探讨了聚合物溶液粘度的影响因素。     

Effect of composition of added random copolymer on the phase behavior of block copolymer

Blends of styrene-butadiene diblock copolymer (S-B, 52 wt% styrene content) and styrene-butadiene random copolymer (SBR) of various styrene compositions were studied by small-angle X-ray scattering, light scattering, and transmission electron microscopy. The composition of random copolymer plays an important role in the solubilization of SBR in S-B. The order-disorder transition temperature, T_ODT, decreases linearly with the addition of SBR. T_ODT decreases as the symmetry in SBR composition increases and shows the highest value in the case of homopolymers. Asymmetric butadiene-rich SBR dissolves mostly into PB microdomain of S-B to increase lamella microdomain spacing, D, and its addition makes the overall microdomains of S and B in the mixture more asymmetrical. Symmetric SBR is localized into the interface of S-B microdomain to reduce unfavorable S-B contact at the interface. The phase diagram for S-B containing asymmetric SBR shows a succession of mixed mesophases of different morphologies from lamellae and cylinder to disordered liquid phases, whereas the phase diagram containing symmetric SBR shows two homogeneous phases and one region of two-phase coexistence, where macroscopically separated phases coexist together.     

氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物研究进展

概述了氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)国内外生产状况,介绍了SEBS生产工艺技术及其加氢催化剂的开发进展,提出应加强SEBS的改性及应用技术开发,在国内尽快实现SEBS的规模化工业生产。     

PBT-PTMG嵌段共聚酯的研究

对以对苯二甲酸二甲酯、1,4-丁二醇和四氢呋喃聚醚二元醇为原料,钛酸四丁酯为催化剂制备PBT—PTMG嵌段共聚酯的工艺方法进行了研究。制备了软硬段比不同的PBT—PTMG嵌段共聚酯切片,并对其性能进行了表征。其结果显示,PBT—PTMG嵌段共聚酯的密度和硬度都随PBT含量的增大而增大,吸水率随聚醚含量增大而增大;调节PBT-PTMG嵌段共聚酯的组成可以得到具有不同力学性能的产物,且具有良好韧性。     

纤维素溶液吹膜过程中拉伸黏度的测定

通过非等温吹塑薄膜挤出实验研究了纤维素的NMMO(N-甲基吗啉-N-氧化物，亦称N-甲基氧化吗啉)溶液在不同工艺条件下的拉伸流动行为。讨论和推导了挤出过程中的理论数学模型，测定了纤维素溶液在加工过程中膜泡半径和膜厚随加工方向的变化，并对沿加工方向上拉伸速率和表观拉伸黏度的变化进行了探讨。研究表明：质量份数为9％的纤维素溶液在加工过程中拉伸黏度受拉伸速率与温度的综合影响，沿加工方向呈现先微降，再渐升的趋势；在加工过程中随着牵引速度和膜泡内外压力差(△P)的增大，膜泡的厚度变小，拉伸速率变大，拉伸黏度变小。     

Theoretical study on morphology of ABCD 4-miktoarm star block copolymer

A real-space implementation of the self-consistent field theory (SCFT) has been used to study the morphologies of ABCD 4-miktoarm star block copolymers. For the sake of numerical tractability, the morphologies and the phase diagrams of ABCD 4-miktoarm star block copolymers are investigated in two dimensions (2D) by varying the volume fractions of the blocks and the interaction parameters. Many interesting and complex morphologies occur and compared with ABCD linear block copolymers; ABCD 4-miktoarm star block copolymers have more regular disciplines. We found that systems with similar components have similar morphologies and at the weaker segregation, the minority components always cannot separate from the other blocks and they easily dissolve to form one phase with other block(s), but with the increase of the segregation degree (large ), the ordered phases can be well separated. With the help of our computational prediction, experimental researchers can work more purposefully and efficiently.     

用AB嵌段共聚物型分散剂制备色浆

利用以受控自由基聚合技术合成的AB嵌段共聚物型分散剂P12制备了PG7和PR112的色浆,与聚氨酯型分散剂P63进行了性能对比。结果表明,P12制得的色浆平均粒径小于1μm,属于纳米级别;色浆通用型强,在丙烯酸、环氧、聚氨酯、醇酸、硝基等体系中都有较好的相容性,在同等条件下,不影响体系光泽,且可提显著高着色力。     

苯乙烯-异戊二烯-苯乙烯(SIS)嵌段共聚物的镍系催化加氢

Ni(naph) 2 /Al(i-Bu) 3 常温、常压催化SIS加氢的研究结果表明 ,反应只发生在PIp中的不饱和双键上 ,苯环不参与加氢反应 ;实验条件下 ,PIp中的 3,4-链节、1,4-链节具有相同的加氢活性 ;在 5 0℃、0 .1MPa氢压、1.90× 10 -4 mol/g·SIS的Ni用量、Al与Ni的摩尔比为 5时 ,SIS的加氢度可达92 .6 %;陈化后的催化剂显示出较高的加氢活性。     

嵌段共聚物的合成及其组装行为

嵌段共聚物在选择性溶剂中可逆缔合形成以不溶性链段为核 ,溶解性链段为壳的胶束。广泛用作表面活性剂、增溶剂、药物载体和纳米材料等。综述了嵌段共聚物的合成方法 ,着重分析了浓度、温度、嵌段长度、溶剂、添加物及电荷等因素对嵌段共聚物在选择性溶剂中组装行为的影响及其形成机理。展望了嵌段共聚物组装行为的应用前景     

Miscibility studies on blends of Kraton block copolymer and asphalt

Miscibility phase behavior in blends of SBS copolymers (Kraton 1101) and asphalt has been investigated through establishment of thermodynamic phase diagrams. The observed phase diagram of the SBS/asphalt blend is an upper critical solution temperature (UCST) type with a maximum at about 20% copolymer and around 200 °C. The study on kinetics of phase decomposition has been carried out by means of time resolved light scattering at the 6/94 Kraton 1101/asphalt composition. Time-evolution of structure factor has been analyzed in the context of temporal scaling laws. The growth regime is seemingly dominated by the late stage of phase decomposition where the hydrodynamic effect is dominant. As typical for a deep off-critical quench, the cessation of domain growth occurs presumably through physical pinning.     

ESBS嵌段共聚物的制备及反应机理研究

利用甲酸和过氧化氢原位生成的过氧甲酸对苯乙烯-丁二烯-苯乙烯（SBS）嵌段共聚物进行环氧化,制备了环氧化SBS（ESBS）。采用FT—IR、GPC、TGA和MFR对ESBS进行了表征,分析了环氧化反应机理。结果表明,在环氧化反应过程中,SBS分子链上聚丁二烯链段1,4-结构中C=C双键的反应活性要大于1,2-结构中C=C双键的反应活性。当反应时间较长时,ESBS会发生环氧基开环副反应。在SBS的环氧化反应初期,会有部分分子链发生断裂生成小分子产物,反应后期会发生环氧基或C=C双键引发的分子间偶联反应,容易形成交联不溶物。     

用于包覆丙烯腈-丁二烯-苯乙烯共聚物的苯乙烯嵌段共聚物热塑性弹性体的制备与性能

以苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)为基体,白油为增塑剂,热塑性聚氨酯(TPU)为极性改性剂,SEBS接枝马来酸酐(SEBS-g-MAH)为相容剂,利用双螺杆挤出机共混挤出制备了用于包覆丙烯腈-丁二烯-苯乙烯共聚物(ABS)的包覆料,考察了填料种类和TPU、白油及SEBS-g-MAH的用量对包覆料物理机械性能、黏结性能及微观相态的影响。结果表明,随着TPU用量的增加,SEBS包覆料的邵尔A硬度、拉伸强度和扯断伸长率均提高,且对ABS的剥离强度增大,综合考虑,TPU最佳用量为50份;在碳酸钙、滑石、云母和高岭土4种填料中,碳酸钙填充的SEBS包覆料对ABS的剥离强度最佳,滑石的效果最差;随着白油用量的增加,SEBS包覆料对ABS的剥离强度减小;加入SEBS-g-MAH后,SEBS包覆料的相界面不明显,趋向于形成连续相结构;随着SEBS-g-MAH用量的增加,包覆料对ABS的剥离强度先增大后减小,当SEBS-g-MAH用量为5份时,剥离强度达到最大值(2.5 k N/m)。     

无规共聚聚丙烯管材专用料的研制开发

通过对进口无规共聚聚丙烯（PP-R）产品的分析研究,在引进装置上成功生产出PP-R管材专用料的基础树脂;经测试检验,树脂性能达到国外同类产品水平。     

傅立叶变换红外光谱法快速测定乙丙共聚物中的乙烯含量

研究了用傅立叶变换红外光谱法测定乙丙共聚物中乙烯含量的方法。建立了傅立叶红外光谱法快速测定乙丙共聚物中乙烯含量的标准工作曲线,对其准确性和精密度进行了评价。结果表明,测定样品的最大相对误差为2.82%,重复测定同一样片的相对标准偏差为0.48%,方法的准确性和精密度良好。该方法适用于乙烯质量分数为0%~33%的乙丙无规共聚物和嵌段共聚物的测定,并且已在生产中得到很好的应用。     

丁苯嵌段共聚物的偶联反应研究

以正丁基锂为引发剂、环己烷为溶剂、四氢呋喃为活性添加剂和结构调节剂,研究了用苯甲酯为偶联剂合成ＳＢＳ的规律。结果表明,用苯甲酸苯酯作偶联剂,其偶联效率（ＣＥ）可达９６％;偶联反应最快在３０ｓ内完成;偶联反应温度、ＳＢ段相对分子质量和聚合物溶液浓度对偶联反应无明显影响;当四氢呋喃／正丁基锂（ＴＨＦ／Ｌｉ）（摩尔,下同）值不大于０．５时,ＣＥ与苯甲酸苯酯偶联剂／正丁基锂（ＢｚＯＰｈ／Ｌｉ,摩尔比）值无     

SB共聚物的技术进展

综述了单乙烯基芳烃-共轭二烯烃共聚物及其聚合工艺的技术进展,基于高分子链中渐变嵌段的数量与位置,讨论了这类共聚物的物理和机械性能与其高分子链结构的相关性,介绍了近年开发的此类共聚物新产品的性能与应用领域。