Ultrasonic methods for characterizing polymeric materials

Article Abstract:

Ultrasonic methods for characterizing polymeric materials are discussed. These classical methods are making a comeback and can also be used for polymer process monitoring. Some experimental results of using a shear wave reflection technique, vs that with longitudinal waves, in isothermal film formation from aqueous dispersions, isothermal crystallization in semicrystalline polymers, and temperature-dependent investigations near the glass transition in amorphous polymer films are presented. Examples for applying longitudinal ultrasonic wave techniques to characterize viscoelastic behavior in dispersions and inline monitoring in the extrusion process are given.

Germany, Methods, Ultrasonics, Control, Chemistry, Chemical process control, Extrusion process, Extruding

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SEC(super.3): a new tool for the polymer chemist

Article Abstract:

An improved version of size-exclusion chromatography (SEC(super.3)) can be a new tool for the polymer chemist and helpful in development of polyesters and nylons according to a research chemist at DuPont Central Research and Development (Wilmington, DE). The technology gives ability to measure molecular weigh distribution far more accurately than in the past. Researchers can better correlate physical properties to molecular structure. SEC column packings are nonpolar. Where packings are polar, as in HFIP solvent, universal calibration is not a viable option. Topics include existing methods, three dimensions, and branching measurements.

Statistical Data Included, Analysis, Halocarbons, Polymer industry, E.I. du Pont de Nemours and Co., Gel permeation chromatography, Nylon, Polyesters

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Functional polyolefins

Article Abstract:

Small-molecule chemistry is being studied. The molecules can be used to modify polyolefins, acting as implanted hooks in the starting preformed polymer. Reactivity of a functional group in a polymer chain may or may not be the same as in a small molecule. Reactivity of a group may be influenced or controlled by the neighboring groups, type/conformation of the polymer backbone or its morphology and crystallinity, and solubility or miscibility of the reactant and catalyst phases. Topics include poly (IB-PMS) Friedel-Crafts chemistry, polymers with terminal double bonds, and fullerene-grafted hydrocarbon polymers.

Polyolefins, Chemical bonds

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