John R. Martin

Mechanical Properties of Polymers: The Influence of Molecular Weight and Molecular Weight Distribution

Abstract The molecular weight and molecular weight distribution of a polymer can markedly affect its mechanical properties. While this has been recognized for a long time, quantitative studies have been relatively difficult to perform for a number of reasons. A major problem has been the characterization of the complete molecular weight distribution curve by fractionation methods because fraction collection and the determination of the various molecular weight averages of polymers is time consuming. Additionally, measurement of the number-average molecular weight, [Mbar]n, by classical osmometry procedure is often unreliable.

Determination of Viscosity of Food Systems

Viscosity is an important physical property of food systems. It is related to flow properties of fluids which in turn control manufacturing operations in many cases. This chapter describes a variety of methods for determining viscosities of liquids and gases as a function of temperature, pressure and shear. As only fluids are considered, viscoelastic measurements, normal stress effects and elongational flow are excluded. The various theories of viscosity and the interpretation of flow characteristics of suspensions have been reviewed in Chapter II and elsewhere [1–3] and are therefore also omitted.

Cost-Efficiency Comparisons of Some Polymer Fractionation Techniques

Abstract An expression to permit comparison of various techniques of polymer fractionation in terms of both fractionation efficiency and cost is proposed. Comparisons are made for large-scale gel permeation chromatography at elevated and ambient temperatures, large-scale Baker-Williams fractionation, and narrow distribution unfractionated polymers prepared by anionic polymerization.