摘要:

The interfacial tension between molten, high molecular weight samples of polycarbonate and poly(methyl methacrylate) was measured using the imbedded fiber retraction (IFR) technique. A value of 1.44 ± 0.16 dyn/cm was measured at 240 °C. This value was obtained on commercial resins with zero‐shear bulk viscosities and at a temperature typically encountered in the processing of blends and/or composites. Refinements to the IFR method were implemented which reduced the experimentation time. Consequently, measurements of the interfacial tension can now be routinely obtained in several hours for materials with zero‐shear bulk viscosities on the order of 104Pa s.

ISSN:0148-6055    

DOI:10.1122/1.550212

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

We present the results of a dynamic Monte Carlo simulation of macromolecules in a dilute solution subjected to plane Poiseuille flow in a channel between impenetrable walls, in two dimensions. The polymer dimensions parallel and perpendicular to the flow direction and the polymer distribution in the flow channel are calculated as a function of the distance from the walls and the difference with previous work on self‐avoiding chains in simple‐shear flow is discussed. In agreement with our previous analysis of the simple‐shear flow case we find that Poiseuille flows also produce narrowing of wall‐depletion layers.

ISSN:0148-6055    

DOI:10.1122/1.550252

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

A comprehensive experimental study of the pressure drop vs flow rate relationship was carried out using a variety of Newtonian as well as non‐Newtonian liquids in circular cross‐section tubes having a radius that varied sinusoidally with axial distance. The goal of this work was to verify or refute the existence of viscoelastic effects in this Lagrangian unsteady flow field under conditions of low Reynolds numbers and large Weissenberg numbers. Highly elastic and rheologically well‐characterized polyacrylamide solutions having zero‐shear viscosities as large as 140 Pa s were utilized for this purpose; some of the fluids were shear thinning while others were not. Clear elastic effects were observed at high enough Weissenberg numbers.

ISSN:0148-6055    

DOI:10.1122/1.550213

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

An attachment for a standard torsional rheometer based on the sliding plate geometry is described which can measure the dynamic shear rheological properties of small samples with total volume on the order of 5–25 μl. The overall error is found to be 1.86% in measuring the dynamic viscosity and 4.04% in the storage modulus when compared to data collected with standard geometries for three fluids: a Brookfield oil, a high density polyethylene melt, and a paint base. It is found that there is an optimum gap between the sliding plates and surface tension can influence the results particularly for the lower viscosity Brookfield oil. This  attachment is most useful for fluids which can degrade with repeated moulding, as must be done when preparing samples for the standard attachments, and may be used to determine various shear properties of suspensions including: large amplitude true dynamic shear properties, yield stress, and time‐dependent viscosity.

ISSN:0148-6055    

DOI:10.1122/1.550214

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

Hydrated glutenin was studied using mechanical spectrometry and differential scanning calorimetry (DSC). Small amplitude oscillatory measurements showed, as a function of temperature, that hydrated glutenin between 4% and 14% moisture content showed glass transition temperatures between 132 and 22 °C. Over the same moisture range, glutenin samples had glass transitions temperatures between 110 and 21 °C as measured by DSC. Both techniques showed that the glass transition temperature of glutenin shifted to lower temperatures with increasing moisture content. Linear approximations of the glass transition temperatures obtained by DSC vs moisture content showed a depression of about 9 °C/wt. %. Both methods showed that glutenin was very sensitive to the plasticizing effect of water in the moisture range studied and appears to be an amorphous, water plasticizable polymer.

ISSN:0148-6055    

DOI:10.1122/1.550255

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

Plane Poiseuille flow of viscoelastic liquids of the memory integral type driven by a quasiperiodic pressure gradient, pulsating around a nonzero mean, is investigated. A regular perturbation in terms of a dimensionless amplitude parameter is used. Kernel independent flow enhancement effects are predicted and closed form formulas are given for mass transport rates. Resonance effects are shown to take place. Additional mean flows, independent of the mean pressure gradient, may exist if the frequencies of the superposed waves satisfy certain relationships. An algorithm to determine the constitutive parameters is presented.

ISSN:0148-6055    

DOI:10.1122/1.550215

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.550216

出版商:The Society of Rheology    

年代:1991

数据来源: AIP