摘要:

Polymers are generally extremely multi-component materials. Performance of a product is often dictated by the individual concentrations of their wide variety of different molecules. We conventionally consider the importance of molecular weight distribution (i.e. concentration of each molecular weight present) and attempt to characterize it via one or two averages (a number (Mn) and/or a weight average (Mn)) for correlation with performance properties. However, most industrial polymers are copolymers or branched polymers or both. Even “simple” linear copolymers often contain molecules which differ from each other by at least three properties: molecular weight, composition and sequence length. [Sequence length here refers to the number of one type of repeating chemical unit in a row within a macromolecule before other types are encountered.] Three simultaneous property distributions are then present. Branched polymers contain the added complication of different branch lengths and/or “density of branching per molecule”. Despite the potential importance of all of these distributions, with the exception of molecular weight distribution, at most one average value can readily be measured to characterize each (e.g. average composition, average sequence length, average branch length). Also, as will be discussed later, molecular welght distribution measurements of such polymers are highly uncertain.

ISSN:1542-2119    

DOI:10.1080/03602548208066015

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The field of membrane technology is currently undergoing a rapid expansion of the areas of both research and industrial separation techniques. Developments in membrane technology have been guided by the need to develop relatively simple but highly selective separation techniques that are economically at tractive when compared to other separation processes. An area of current interestis the use of liquid membranes to separate species or to control mass transfer rates. Liquid membranes can be manipulated to selectively separate as pecific solute from a mixture, and even to extract a solute against its concentration gradient by coupling its flux to the flux of another solute or by coupling to another external force across the membrane such as an electrical field.

ISSN:1542-2119    

DOI:10.1080/03602548208066016

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The existence of surface charges on living cells was recognized very early by Jurgensen in 1860 when he reported a migration of erythrocytes toward the anode(1). Since then, numerous attempts at qualitatively or quantitatively describing these charges have been made, which are now generally accepted as arising from the carboxyls of sialic acid residues(2). But because of serious theoretical and practical limitations of previous designs, these surface charges are not often measured.

ISSN:1542-2119    

DOI:10.1080/03602548208066017

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

ULTRAFILTRATION MEMBRANES AND APPLICATIONS Anthony R. Cooper, Ed. Plenum Press, New York, 1980; hardbound, 707 pages, $75.00

ISSN:1542-2119    

DOI:10.1080/03602548208066018

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:1542-2119    

DOI:10.1080/03602548208066019

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1542-2119    

DOI:10.1080/03602548208066014

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor