作者：
H. Henning WinterUniversity of Massachusetts
Department of Chemical Engineering and Department of Polymer Science and Engineering 159 Goessmann Laboratory Amherst MA 01003 USA
Recent advances in rheometer design and rheology theory have led to an abundance of rheological information, both experimental and theoretical. In response to this wonderful opportunity, many of the world's leadin...
Recent advances in rheometer design and rheology theory have led to an abundance of rheological information, both experimental and theoretical. In response to this wonderful opportunity, many of the world's leading rheologists began to share their expert software codes with the wider community of materials researchers and practitioners. This became possible through “Rheo‐Hub”, a central computer platform from which the user interrogates rheological expert codes (”engines”) and rheological data by comparing, merging, and funneling these into further interrogations and explorations. In this virtual environment, results are returned to the computer screen as visuals so that the visual intelligence of the user gets involved in the cognition process. Rheological explorations may be repeated in different ways (using different expert codes for answering the same research question) and viewed from different graphical viewpoints. This creates the multi‐scale and multi‐expertise workspace that is needed to support quantitative rheological explorations and to prepare for discovery. The virtual environment technology will be presented and examples will be shown. Rheo‐Hub's strengths are data analysis, integration of experimental results with theoretically predicted rheology, visuals for communicating results, and introduction of a rheological data standard.
Conductive polymers (polypyrrole, polyaniline, poly3, 4-ethylene-dioxythiophene)/fibers (silk, poly-acrylonitrile) composites were fabricated successfully by in-situ chemical oxidation polymerization. The surfaces of ...
详细信息
Conductive polymers (polypyrrole, polyaniline, poly3, 4-ethylene-dioxythiophene)/fibers (silk, poly-acrylonitrile) composites were fabricated successfully by in-situ chemical oxidation polymerization. The surfaces of silk and polyacrylonitrile fibers were covered entirely and uniformly by conductive polymers. These novel composite fibers exhibited different conductivity in the range of 10-1-10-3 S/cm, and still possessed former fibrillar morphologies and strength properties. In addition, improved thermal stability of composite fibers was also observed.
In attempts to modify the degradation characteristics of polylactic acid (PLA) the addition of selected low molecular weight (MW) ionic liquids, at concentrations up to 5 wt%, are shown to result in enhanced thermal a...
详细信息
ISBN:
(纸本)9781605603209
In attempts to modify the degradation characteristics of polylactic acid (PLA) the addition of selected low molecular weight (MW) ionic liquids, at concentrations up to 5 wt%, are shown to result in enhanced thermal and hydrolytic degradation rates accompanied by plasticization and lubrication. Thermal degradation was studied via mass changes, MW changes by gel-permeation chromatography and viscosity changes, whereas hydrolytic degradation was followed by MW changes, scanning electron microscopy, solution pH and acid number changes and visual observations. The different effects of the two ionic liquids are explained in terms of their different chemical structures and interactions with the polymer.
Despite its technological significance, the rheological behavior of polymer melts in equibiaxial elongational flow is largely unexplored and, consequently, is inadequately understood. The simple reason for this is tha...
Despite its technological significance, the rheological behavior of polymer melts in equibiaxial elongational flow is largely unexplored and, consequently, is inadequately understood. The simple reason for this is that methods for generating equibiaxial elongational deformations are either very complicated or not reliable. The most widely accepted method for generating rheologically controlled equibiaxial elongational flow is the rotating clamp method, or MultiAxiale Dehnung (MAD), developed by Meissner. However, the extremely complicated nature of the MAD rheometer has resulted in a relatively limited set of experimental data. A promising method that has been used with some success is known as Lubricated Squeezing Flow (LSF), where a polymer melt is squeezed between lubricated surfaces. Unfortunately, uncontrolled lubricant thinning limits the LSF technique to rather modest strain levels. Here we report the first direct comparisons of data obtained with the LSF and MAD techniques. We find that the data obtained using LSF deviate from the MAD data at Hencky strains of less than one, and display behavior that could easily be mistaken for strain hardening. For the past few years, we have been developing a modified LSF technique that involves the continuous injection of lubricant through porous metal plates. We report the first measurements of transient equibiaxial elongational viscosity obtained using the modified LSF technique and make comparisons with data from the MAD rheometer.
暂无评论