橡胶中简单剪切与纯剪切的关系

 研究了简单剪切与纯剪切的关系，得出了：（１）简单剪切可看成纯剪切加转动，转动角θ有；（２）若简单剪切椭圆的长轴与坐标轴Ｘ的夹角为φ，相应的纯剪椭圆长袖与坐标轴ｙ的夹角为β０，则φ＝β０；（３）橡胶在双向拉伸时剪应变γ的一般表达式为，对简单剪切而言即为     

剪切速率对Fe-Al-Mg-MMH/钠质蒙脱土悬浮体触变性的影响

研究了测定条件对Fe-Al-Mg型混合金属氢氧化物（简称MMH）/钠质蒙脱土（简 称MT）混合悬浮体及纯MT体系触变性的影响，主要考察了高速剪切分散后，剪切速 率（D_L）对粘度（η）～时间（t）变化趋势的影响。发现纯的MT体系和MMH/MT质 量比（R）为0.013的Fe-Al-Mg-MMH/MT体系在所研究的D_L下（10，170，511和1 022 s~(-1)）都呈现为正触变性，D_L不影响触变性类型。R = 0.051的体系，低 D_L时（10和170 s~(-1)）呈现复合触变性，高D_L时（511和1 022 s~(-1)）呈现 正触变性；R = 0.091的体系在低D_L时（10和170 s~(-1)）呈现负触变性，在高 D_L时（511和1 022 s~(-1)）呈现复合触变性。D_L增加，各体系η逐渐降低。对 D_L影响触变性的机理进行了深入探讨。     

剪切速率对Fe-Al-Mg-MMH/钠质蒙脱土悬浮体触变性的影响

研究了测定条件对Fe-Al-Mg型混合金属氢氧化物（简称MMH）/钠质蒙脱土（简 称MT）混合悬浮体及纯MT体系触变性的影响，主要考察了高速剪切分散后，剪切速 率（D_L）对粘度（η）～时间（t）变化趋势的影响。发现纯的MT体系和MMH/MT质 量比（R）为0.013的Fe-Al-Mg-MMH/MT体系在所研究的D_L下（10，170，511和1 022 s~(-1)）都呈现为正触变性，D_L不影响触变性类型。R = 0.051的体系，低 D_L时（10和170 s~(-1)）呈现复合触变性，高D_L时（511和1 022 s~(-1)）呈现 正触变性；R = 0.091的体系在低D_L时（10和170 s~(-1)）呈现负触变性，在高 D_L时（511和1 022 s~(-1)）呈现复合触变性。D_L增加，各体系η逐渐降低。对 D_L影响触变性的机理进行了深入探讨。     

金刚石格点上自回避行走高分子链的构象熵

计算了链长Ｎ为１０－１９的金刚石格点上自加避行走高分子链的构象熵Ｓ和平均ｇ态个数〈Ｗｇ〉。发现Ｓ和〈Ｗｇ〉均与Ｎ成线性关系，每键构象β和ｇ态密度μ都随参数к（к＝кＢＴ／ε）的变化而变化，参数к是温度，键构象能ε有关的量。β随参数к的变化可划分三个区域，（１）│к│≥２．０，β的值几乎与к的大小无关，几乎接近于β的极值；（２）０．１６〈│к│〈２．０，β的变化非常明显；（３）│к│≤０．１６，β的     

剪切对玻璃珠填充聚丙烯结晶行为的影响

应用Linkam CSS450剪切仪、广角X射线衍射仪(WAXD)和小角X射线散射仪(SAXS)等研究了剪切对玻璃珠填充聚丙烯结晶行为的影响, 结果表明, 与纯聚丙烯相比, 填加玻璃珠的聚丙烯体系中, 玻璃珠起到成核剂的作用, 不利于β晶的生成. 玻璃珠直径较小(4 μm)时, 剪切对聚丙烯β晶的生成影响较小; 当玻璃珠直径增加到35 μm时, 剪切速率为20 s-1左右最有利于β晶生成; 剪切速率和玻璃珠直径的增加, 有利于聚丙烯片晶的取向, 而且玻璃珠含量越高, 片晶的取向程度越大.     

壳聚糖浓溶液流变性质研究──零剪切粘度的测定和外推

用落球法测定了不同溶剂体系和浓度的壳聚糖浓溶液的零剪切粘度η０，用ＲＰＸ－７０５多功能流变仪同轴圆筒方法测定了各浓溶液的粘度随剪切速率的变化关系，并用Ｐｅｒｒｒ、Ｃｒｏｓｓ和Ｂａｌｌａｕｆｆ方法进行了求η０的外推．将外推结果与落球法结果进行了比较，认为Ｃｒｏｓｓ方法的结果与实际测得结果更接近，可以代替落球法，这样可以简单地得到壳聚糖浓溶液η０的信息．     

低剪切速率下聚乙二醇／KCl／蒙脱土分散体系的剪切稠化现象

用Hakke RS75流变仪研究了聚乙二醇（PEG）／KCl/蒙脱土分散体系的流变性 。结果发现，当KCl和聚乙二醇浓度在一定范围内时，体系随剪切速率增加，表现 出剪切稀释－剪切稠化－剪切稀释的复杂结构变化，并且剪切稠化发生在低剪切速 率区。KCl浓度继续增加，剪切稠化逐渐减弱。TME表明，蒙脱土分散体系中加入 KCl使得蒙脱土颗粒聚集，而聚乙二醇导致经微絮凝；二者同时加入，体系形成细 枝条状的空间稳定结构。     

杯芳烃涂层厚度剪切模式声波传感器对苯甲醚的主-客识别

实验考察了６种合成的杯芳烃化合物涂层的厚度剪切模式（ＴＳＭ）声波传感器对３０多种有机蒸气的频移响应情况，发现３７，３８，３９，４０，４１，４２－六（乙氧基羰基甲氧基）杯［６］芳烃对苯甲醚分子具有灵敏的主－客识别功能。当涂载量为４３μｇ时，传感器的线性响应范围可达０．０１６～２５．４０６ｍｇ／Ｌ，灵敏度为４３．８Ｈｚ／（ｍｇ·Ｌ－１）（３０℃±０．５℃），检测下限可达０．００７ｍｇ／Ｌ。传感器具有重现性和稳定性好、响应较快的优点，羧酸和含苯环类化合物对传感器有一定干扰，而湿度不干扰。将该传感器用于苯甲醚样品的测定，测量精度与气相色谱法相当，回收率为９７．５２％～１０４．３７％。     

铁,钴,镍的反相高效液相色谱分离和测定

１引言建立了用反相高效液相色谱同时测定铁、钴、镍的分析方法并对Ｍｅｎ＋－二硫腙（ＤＺ）体系的色谱行为进行了探索。较之萃取进样更快速、简便。测定条件为：Ｓｈｉｍ－ＰａｃｋＣＬＣ－ＯＤＳ（φ６×１５０ｍｍ，５μｍ）；流动相：甲醇：水：三氯甲烷（含１％三乙胺）（８０：１０：１０）；流速１ｍＬ／ｍｉｎ；柱温３５℃；检测波长２５４ｎ。线性范围０．０１－２．０ｍｇ／Ｌ；相关系数ｒ＝０．９９９ｌ～０．９９９８；检测限为０．００２３～０．００５０ｍｇ／Ｌ；相对标准偏差为１．８％－２．７％；回收率为９６％－１０４…     

反相高效液相色谱法同时测定苦豆子及其制剂中苦参碱和氧化苦参碱

建立了用反相高效液相色谱法测定苦豆子及其制剂中苦参碱和氧化苦参碱的方法。色谱条件：ＯＤＳ柱，甲醇－水－三乙胺，φ（甲醇）＝０．５５，φ（三乙胺）＝０．０００２为流动相，紫外检测波长２１５ｍｍ。为苦豆子及共制剂的质量评价提供了一种方法     

振荡剪切场下PS/PVME共混物的相分离动力学研究——相分离的依时性及应力响应

利用自制的激光散射流变仪研究了聚苯乙烯/聚甲基乙烯基醚(PS/PVME)(重量比30/70)二元共混物在振荡剪切场下的相分离动力学过程.在特定的振荡频率和应变振幅条件下,共混物的相分离具有显著的周期特性和各向异性.在同一个振荡相位角条件下,相分离在早期符合经典的Cahn-Hilliard线性理论.在相分离过程中,流动方向上的特征波数qxm表现出明显的受迫振荡特征而涡流方向上的qzm却没有;同时,两个方向上的特征波数qm平均值都未随时间发生变化,说明特定振荡频率和应变振幅的振荡剪切对特定尺寸的浓度涨落具有选择作用.研究还发现,体系的应力响应可以反映出相分离的阶段性过程,例如当相分离早期结束时,表征弹性的第一法向应力差出现了峰值.     

KINETIC MODEL FOR DIFFUSION-CONTROLLED INTERMOLECULAR REACTION OF HOMOGENOUS POLYMER UNDER STEADY SHEAR

The kinetic model for diffusion-controlled intermolecular reaction of homogenous polymer under steady shear was theoretically studied. The classic formalism and the concept of conformation ellipsoids were integrated to get a new equation, which directly correlates the rate constant with shear rate. It was found that the rate constant is not monotonic with shear rate. The scale of rate constant is N^-1.5 （N is the length of chains）, which is in consistent with de Gennes＇s result.     

STUDY ON INTERMITTENT SHEAR FLOW AND RELAXATION BEHAVIOR OF THERMOTROPIC LIQUID CRYSTALLINE POLYMER

Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation after cessation of shear flow was used to study the rheological behavior and internal structure of thermotropic liquid crystalline polymer (TLCP). There are two kinds of intermittent shear flow: all start-up flows are in the same direction (intermittent flow forward: IFF) and start-up flows change their directions alternately (intermittent flow reversal: IFR). The results show that the stress of start-up flow of IFF and IFR in the test process is not superposed, indicating different changes of internal structure of thermotropic LCP (TLCP). Two main factors affect structure changes in the experimental time scale. One relates to long-term texture relaxation process, the other is an interchain reaction that becomes important after 30 min. The two factors raise the stress of IFF, but express complex effects for the stress of IFR. The latter factor becomes very important at long time annealing process. The relaxation behavior was also studied by the application of wide range relaxation spectrum calculated from the combined dynamic modulus, which gave three characteristic relaxation times (0.3, 10 and 600 s) ascribable to the relaxations of less-phase orientation, domain orientation, and domain deformation, respectively. The result also shows that the domain coalescence (texture relaxation), a long relaxation time, is a much slow process and lasts beyond 2400 s of the test time.     

剪切历史对尼龙熔体结晶行为的影响

采用差示扫描量热法研究了原始聚酰胺材料在经历不同的预剪切过程或应用不同设备进行剪切后其结晶行为的变化,结果表明,原始样品经过预剪切后,结晶温度升高5～10℃,半结晶时间降低到原始样品的一半.当聚酰胺材料经历很低的剪切时其结晶温度就有很大的提高,进一步提高剪切强度,结晶温度的增加趋势变缓.偏光显微镜观察表明有剪切历史的样品,球晶尺寸减小.作为对此,聚烯烃和聚酯材料的结晶对剪切历史不敏感,剪切与非剪切样品的结晶行为基本相同,据此推测聚酰胺分子间氢键可能是这种剪切记忆效应产生的原因.     

The complex shear modulus of polymeric and small-molecule liquids

The complex shear moduli of some ordinary liquids and their dependence on the shear deformation angle have been measured by the resonance method at a frequency of 73.5 kHz. From the results obtained, it is concluded that liquids exhibit a low-frequency shear elasticity—a property unknown before—which is associated with collective interactions of liquid molecules.     

Effect of shear history on the steady shear flow behavior of a thermotropic liquid-crystalline polymer

The steady shear stress (σ) and first normal stress difference (N₁) of a thermotropic liquid-crystalline polyester, poly[(phenylsulfonyl)-p-phenylene 1,10-decamethylene-bis(4-oxybenzoate)] (PSHQ10), in both the isotropic and nematic regions were measured as a function of shear rate (γ), using a cone-and-plate rheometer. For the study, PSHQ10 was synthesized via solution polymerization in our laboratory. The PSHQ10 was found to have (a) the weight-average molecular weight of 45,000 relative to polystyrene standards and a polydispersity index of 2, (b) a glass transition temperature of 88°C, (c) a melting point of 115°C, and (d) a nematic-to-isotropic transition temperature of 175°C. For the measurements of σ and N₁ in the nematic region of PSHQ10, its initial conditions for the startup of shear flow was controlled by (a) first heating an as-cast specimen to 190°C, (b) shearing there at γ = 0.085 s^?1 for about 5 min, and then (c) cooling slowly down to a predetermined temperature (130, 140, 150, 160, or 171°C) in the nematic region. For each γ chosen, after start-up of shear flow, we waited for a sufficiently long time until both the shear stress and first normal stress difference leveled off, giving rise to steady-state values of σ and N₁. Emphasis was placed on investigating the effect of shear history on σ and N₁ of PSHQ10 in the nematic region. For this, the following experiments were conducted: (a) a fresh specimen was sheared continuously by increasing the γ stepwise, and (b) a presheared specimen was further sheared continuously by increasing the γ stepwise. We have found that fresh specimens exhibited ‘shear-thinning’ behavior over the entire range of γ (0.008?0.27 s^?1) tested, whereas the presheared specimens exhibited both zero-shear viscosities and shear-thinning behavior. When using fresh specimens, we found that N₁ was positive over the entire range of γ (0.008–0.27 s^?1) tested. However, when using presheared specimens we found that (a) at very low γ, N₁ initially was negative and then became positive as shearing continued, and (b) at higher γ, N₁ was positive over the entire duration of shearing. © 1994 John Wiley & Sons, Inc.     

Effect of shear on human insulin in zinc suspension

Human insulin in zinc suspension was used as a model protein to test the effect of shear on the settling rate of proteins, a possible inference for protein denaturation. The rate of settling was determined directly in a spectropho-tometer. Shear effects are important in retaining the activity of proteins and are present in bubble, foam, and droplet protein fractionation processes. A sim pletest, such as that conducted here, mayeven be useful for monitoring changes in protein structure caused by commercial shipping of the protein. The settling ratefor insulin was continously monitored in theoriginal bottle by spectrophotometric absorbance changes as a function of time. A settling curve was determined following each shear experiment, which included shaking the “worked” insulin solution in a vortex mixer for different lengths of time. It was determined, when comparing long shaking times with short ones, that the initial settling rate was less for the long-term shaking of the insulin samples and greater for the short-term shaking. The secondary effects of light and heat, along with shaking, a pparently did not produce differences from shaking alone.     

Light Scattering Experiments on Shear Induced Structures of Micellar Solutions

The formation of shear induced structures (SIS) of a mixed micellar solution of tetradecyldimethylaminoxide and sodium dodecylsulfate is studied by light scattering experiments under shear (rheo-optical method). In the shear rate- as well as in the time-dependent measurements we found an aggregation process taking part in the SIS formation. Below the critical shear rate for the occurrence of SIS, the shear rate dependent experiments show an increased scattering intensity, indicating micellar associates. Above the critical shear rate, we found structures oriented in the direction of flow. The time dependent measurements show that the SIS formation can be regarded as a process which can be divided into three stages: induction—aggregation—orientation. After the aggregation, we found a temporal process in which the orientation increases to reach complete orientation in the direction of flow.