电流变液在平行平板剪切下的动态响应

建立了用于测试电流变液在两平行平板间剪切时对外加高压阶跃电场的剪切应力响应的实验测试系统.此系统对剪切应力变化的时间分辨率可以达到10 μs量级.利用此系统对基于沸石和硅油的电流变液的极化和退极化过程,电流变液在不同外加电场强度和不同剪切速率条件下的剪切应力上升和撤去电场时剪切应力的下降过程进行了研究.研究发现电流变液的剪切速率越高,其响应时间越短,随着外加电场的升高,响应时间略有增加.此实验结果与其他现有相关研究结果比较吻合.     

不同介电常数悬浮颗粒的电流变液固态结构

讨论了两种不同介电常数的固体颗粒不同配比时,对电流变液固态结构的影响.计算结果表明,颗粒的介电常数及配比变化时电流变液的固态结构没有变化,只影响其能量大小;而且发现在低介电常数颗粒的电流变液中加入少许高介电常数颗粒会引起体系能量的显著下降,从而增加了电流变液的稳定性和剪切应力.     

外电场与微波交互作用下 BaTiO3 电流变液的透射特征

分别考虑了微波传播方向与电流变液颗粒链相垂直和平行的情况,对BaTiO3电流变液微波透射行为进行了实验研究.发现BaTiO3电流变液微波透射率可由外电场调控.在垂直的情形,当流体浓度较低时,透射率随电场强度增加而减小,并且随浓度增加电场调节微波透射率的变化幅度增加.浓度超过一定值时,透射率随电场出现由减小向增加的改变,存在透射率的极小点.在平行的情形,发现透射率随电场强度增加而减小.另外透射率随电场强度变化具有延时性,对于给定浓度的情形,电场强度增加延时性明显减小.     

PBT／PC共混体系流变性能与形态结构研究

采用毛细管流交仪测定了ＰＢＴ／ＰＣ共混物的表观粘度、剪切应力，观察了不同共混物组成和不同温度下共混物的流变行为，并借助扫描电镜对共混物和微观形态结构进行分析。结果表明：ＰＢＴ／ＰＣ熔体共混物的流变行为接近假塑性流体．温度对共混物的流变行为影响很大，共混物的熔体粘度在ＰＢＴ／ＰＣ为９０／１０和６０／４０时呈双极值．共混物为两相结构，ＰＣ含量为４－５０％时呈两互锁结构。     

蒙脱土/二氧化钛复合颗粒电流变液材料的制备及其性能

利用溶胶-凝胶法制备了一种新型的蒙脱土/二氧化钛(MMT/TiO_2)复合电流变 颗粒材料，FT-IR，XRD，SEM分析表明TiO_2以纳米晶的形态包覆于蒙脱土表面。电 流变性能测试表明，MMT/TiO_2复合颗粒的电流变效应比纯蒙脱土电流变液有显著 提高，当颗粒体积分数为25%，直流电场强度为3kV/mm时，TiO_2质量分数为22.7% 的MMT/TiO_2复合颗粒电流变液的静态屈服应力达8.3kPa，此值约为纯蒙脱土电流 变液的4倍。同时发现TiO_2包覆量对电流变效应有重要影响。     

应力引发官能化EPDM/HDPE及其对PA66/EPDM/HDPE 共混物相形态和力学性能的影响

通过提高双螺杆挤出机螺杆转速的方法,研究了熔融挤出过程中高剪切应力对马来酸酐(MAH)官能化三元乙丙橡胶(EPDM)与高密度聚乙烯(HDPE)共混物的接枝率、熔体流动速率及凝胶含量的影响.随着双螺杆挤出机螺杆转速的增加,强烈的机械剪切应力引发EPDM/HDPE共混物大分子链的断链反应形成大分子自由基,从而引发接枝反应制...     

丙烯腈接枝改性聚氨酯溶液的流变行为

合成了具有不同支链长度和分布的丙烯腈接枝改性聚醚聚氨酯。对其流变行为的研究表明，体系表现出剪切应力变稀的非牛顿性流体特征。丙烯腈支链的和长度、分布状况以及测试温度等都对体系的变性产生影响。流体粘流活化能结果说明，支链亦影响了聚氨酯粘度对温度的依赖性。同时，聚氨酯的聚合反应条件也会改变体系的流变行为。     

水溶性β-环糊精聚合物的交联度对3-羟基-2-萘甲酸荧光性质及电流变性能的影响

用改进的Renard方法控制合成了6种不同交联度的水溶性β-环糊精聚合物.以3-羟基-2-萘甲酸为荧光探针,考察了聚合物交联度对形成超分子配合物的稳定性及荧光性质的影响,发现生成常数和相对荧光强度均随交联度的增长呈上升趋势,并发现其相对荧光强度的增量与对应的交联度存在线性关系.用β-环糊精聚合物及其与3-羟基-2-萘甲酸构筑的超分子配合物分别与二甲基硅油配制了电流变液,流变学性能测试发现这些聚合物电流变液均有很好的电流变活性,其中,单纯聚合物电流变液的屈服应力随交联度的增加呈上升趋势,而超分子配合物电流变液则表现出更高的电流变活性,但当交联度太大时,其屈服应力甚至低于对应的聚合物,并随交联度的增加呈先增加后降低的趋势;介电性能测试发现,交联度对电流变液介电常数和体积电导率的影响均出现了与电流变液效应相类似的趋势.     

相反转技术制备环氧树脂水基体系——相反转过程的流变行为研究

对高乳化剂浓度下的相反转发展过程的流变行为进行了应力扫描、动态频率扫描实验表征．结果表明，乳化剂浓度较高时，体系发生完全相反转；体系在相反转点前为Ｗ／Ｏ结构，其粘度几乎不随剪切应力的改变而改变，表现为牛顿流体行为；体系在相反转点后为Ｏ／Ｗ结构，具有很高的粘弹性，并且在较高剪切应力下表现为典型的假塑性．这是由于高分子水基微粒间通过其表面覆盖的表面活性剂与水形成氢键而产生了一种静态结构，此结构在较高剪切应力作用下破坏而导致假塑性．     

由聚苯胺粒子组成的电流变液的研究

由经碱处理的掺杂态聚苯胺（ＰＡｎ）制得高介电常数的半导体ＰＡｎ粒子，将其悬浮于电绝缘油可组成电流变液，讨论了电流变（ＥＲ）液的静态屈服应力（τ＿ｓ），电流密度等性能与ＰＡｎ的介电常数（ε＿ｐ），导电率（σ），体积分数和应用电场强度的关系。对导电率相同的ＰＡｎ粒子，用氨水处理的ＰＡｎ粒子ε＿ｐ较用ＮａＯＨ液处理的高，前者在σ足够低如σ≤１．０×１０￣（－７）／ｃｍ时，ＥＲ液的τ＿ｓ随偶极系数的平方（β￣２）的增大而呈现非线性增加；后者ＥＲ液的τ＿ｓ随β￣２的增大出现一最大值．结果表明：由聚苯胺粒子可组成高电流变活性的无水ＥＲ液．     

Surface and solution properties of polysiloxane–poly(methyl methacrylate) graft copolymer

A polysiloxane–poly(methyl methacrylate) (PMMA) graft copolymer was prepared by hydrosilylation reaction between a Si? H containing polysiloxane and an allyl-terminated PMMA. The obtained graft copolymer was blended with PMMA homopolymer. The addition of only 0.01 wt % of graft copolymer was sufficient to make PMMA surfaces hydrophobic. In acetone–cyclohexane mixed solvent, the graft copolymer formed a polymeric micelle by the aggregation of PMMA branches.     

含氟两亲接枝共聚物的制备及其结晶行为

采用大分子单体技术合成了一系列以聚乙二醇为支链、甲基丙烯酸六氟丁酯为主链的含氟两亲接枝共聚物(PHFMA-g-PSPEG)。用1HNMR和凝胶色谱(GPC)对制备的大分子单体和两亲接枝共聚物的结构进行了表征。利用示差扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(POM)测试技术对含氟两亲接枝共聚物的结晶行为进行了研究。DSC和XRD结果表明,随着共聚物中含氟链段质量分数的增加,其结晶温度(Tc)和结晶度(Xc)均降低,而结晶熔融温度(Tm)先减小后增加。POM发现,随着共聚物中含氟链段质量分数的增加,其结晶速度减慢,共聚物形成清晰球晶的能力减弱,当共聚物中含氟链段质量分数为57%时,含氟两亲接枝共聚物已不能形成清晰的球晶。     

Effect of graft copolymer on demixing of immiscible polymers in solution

The effect of graft copolymer on the demixing of solutions of two immiscible homopolymers and critical conditions for emulsion formation were studied. The graft copolymer used in the present work consists of one backbone poly(vinyl acetate) (PVAc) and one branch polystyrene (PS). PVAc and PS of various degrees of polymerization were used as immiscible homopolymers. The common solvent was benzene. When the concentration of homopolymer blend was not sufficiently higher than the critical concentration for demixing of the blend solution, no stable emulsion was formed, even when a considerable amount of graft copolymer was present, and the added graft copolymer merely reduced the demixing rate. However, as the blend concentration was increased, a stable emulsion could readily be obtained by addition of rather small amounts of graft copolymer. The radius of emulsion droplets was inversely proportional to the weight ratio of the graft copolymer to the dispersed component polymer, in accordance with the theoretical prediction. It was concluded that the emulsions were stabilized against coagulation by graft copolymer molecules fixed strongly as a monolayer on the interface of the emulsion.     

Radiation-induced graft polymerization of acrylic acid onto fluorinated polymers. II. Graft copolymer–metal complexes obtained by radiation grafting onto poly(tetrafluoroethylene-ethylene) copolymer

A study has been made on the graft copolymers obtained by radiation-induced grafting of acrylic acid onto poly(tetrafluoroethylene-ethylene) (ET) films. The conversion of the graft copolymer into metal acrylate copolymer complex was carried out by treatment with different metal salts. Such a prepared graft copolymer–metal complex was confirmed by different methods: IR, UV spectrometry, degree of coloration, and x-ray fluorescence. Some selected properties of the graft copolymer–metal complexes such as electrical conductivity, swelling behavior, and mechanical properties were investigated. The influence of metal complexes in the graft copolymers was determined and compared with the grafted films. The possibility of the practical uses for such prepared graft copolymer–metal complexes was discussed and determined. It was assumed that such materials may be of great interest in the field of semiconducting materials in addition to their applicability as cation-exchange membranes. © 1993 John Wiley & Sons, Inc.     

Graft Copolymerization of Methyl Methacrylate on Poly(phenyl Vinyl Sulfide)

Graft copolymer of poly(phenyl vinyl sulfide) and methyl methacrylate was obtained. The isolation of graft copolymer was carried out by the fractional precipitation method. The isolated polymer was confirmed to be a graft copolymer by IR spectra and T determinations. Graft copolymerizations of poly(phenyl vinyl sulfide) with vinyl acetate, acrylonitrile, acrylamide, and acrylic acid were also carried out, but the separation of graft copolymer in these cases was difficult, and satisfactory results could not be obtained.     

Grafting acrylic acid monomer to poly-(vinyl alcohol) and methyl cellulose by ceric ion

A graft copolymer of acrylic acid on poly(vinyl alcohol) was prepared by use of the ceric ion–polyol redox system in aqueous medium. The graft copolymer obtained was water-soluble under the specified experimental conditions. The efficiency of grafting was determined by measuring carboxyl group content (as expected from acrylic acid unit) in the copolymer by applying the newly developed reverse dye-partition technique. The graft copolymer was also characterized by viscosity and solubility measurements. The effect of varying concentration of catalyst, monomer, and grafting time has also been determined.     

多功能高分子植物生长剂制备及其应用

高吸水树脂以其吸水性强、吸水速度快、保水能力强等优点。广泛用于农业、园林、卫生材料等方面[1～4] 。本文制备的高吸水树脂是以过硫酸钾为引发剂 ,淀粉为原料 ,使之接枝并适度交联。交联产物经醇解、脱水、干燥、粉碎即得吸水倍数大于 70 0倍的吸水树脂 ,并对主要影响因素进行正交优化 ,在最佳条件下制得的吸水树脂配以一定量有效微生物群 ,制得具有吸水、保水、促生长及可降解的多功能植物生长剂。1　实验部分1 1　主要试剂及仪器玉米淀粉 (市售 ,1 0 5℃下烘干 ,干燥保存 )、过硫酸钾 (ＣＰ)、丙烯酸 (ＣＰ ,用前减压蒸馏精制 )、Ｎ …     

具有血液相容性的嵌段聚酯-聚醚接枝共聚物的合成

本文研究了嵌段聚酯-聚醚膜经紫外光活化后,于水溶液中铈盐引发亲水性单体丙烯酰胺在其表面上接枝共聚合反应。同时对接枝物进行了证实和表征。并通过活体动物血液灌流实验表明,此接枝共聚物具有良好的血液相容性。     

Study of Intermacromolecular Complex Formation Between Acrylamide—Vinyl Alcohol Graft Copolymer and Poly[Methacrylic Acid]

Acrylamide‐vinyl alcohol (AAm/VA) graft copolymer was prepared and characterized. The interaction of the graft copolymer with poly‐(methacrylic acid) (PMAA) in water was studied by several experimental techniques, such as viscometry, potentiometry, conductometry, IR spectra, and transmittance measurements. PMAA was found to interact with the graft copolymer in two distinct steps. The relative complexation ability of PAAm and PVA with respect to PMAA does not change when these polymers are present as parts of a graft copolymer chain.     

HIPS／MA接技共聚物对HIPS／PA1010共混体系的增容

制备了高抗冲聚苯乙烯和马来酸酐的接枝共聚物，利用红外光谱，电子能谱和动态力学谱对产物的结构进行了表征，并通过滴定法测定了接枝物中马来酸酐的含量。结果表明马来酸酐接技到了高抗冲聚苯乙烯中顺丁橡胶的分子链上，接技率为４．７％。研究了该接枝共聚物对ＰＡ１０１０／ＨＩＰＳ共混物的增容作用。电镜照片显示，随着共聚物中接枝物含量的增加，分散相相区尺寸明显减小，说明增容效果显著。测定了共混体系的拉伸行为，研究了