Polymeric properties

The other restriction of SynChropak size exclusion columns is a general one for silica-based supports, that of pH. The most harmful pH is that above 7.5 due to silica dissolution. The bonded phase of SynChropak GPC has some polymeric properties therefore, it is not removed rapidly from the silica at pH 2-3. The bonded phase of SynChropak CATSEC is polymeric and stable at pH 2-7.5. 

The decision to characterize polymerization processes, polymeric properties, and current efficiencies in any kinetic study as a function of... 

These facts are different demonstrations of the same event degradation reactions occur simultaneously with electropolymerization.49-59 These reactions had also been called overoxidation in the literature. The concept is well established in polymer science and consists of those reactions between the pristine polymer and the ambient that promote a deterioration of the original polymeric properties. The electrochemical consequence of a strong degradation is a passivation of the film through a decrease in the electrical conductivity that allows a lower current flow at the same potential than the pristine and nondegraded polymer film did. Passivation is also a well-established concept in the electrochemistry of oxide films or electropainting. 

Polythiophene electrogeneration on a rotating disc electrode. The water content influence on polymerization and on the polymeric properties. J. Electroanal Chem., 310, 219, 1991, Fig. 9. Copyright 1991. Reprinted with permission of Elsevier Science.)... 

A more drastic influence of subphase H concentration can be observed for the sulfolipid analog (8) (Figure 7.). At pH values from 2 up to 5,5 (8) forms two condensed phases, whereas at pH 12, where the nitrogen is deprotonated, there is only one phase present (35). This behavior has a considerable influence on the mono-layer polymerization properties of (8), which is discussed later in this chapter. 

At the same time, there are instances in which critical concentration determinations still do not offer the experimenter the opportunity to reach a definitive conclusion about important aspects of protomer-polymer interactions. The lack of agreement about the polymerization properties of the Tb GDP complex is an excellent example. Several investigators have claimed that the tubulin GDP complex can elongate microtubules (Carlier and Pantaloni, 1978 Karr et al, 1979b) others. 

Metallocenes have a transition metal sandwiched between two cyclopentadienyl rings. The cyclopentadienyl rings may not necessarily be parallel because of bridging. They may be further substituted to restrict access to the metal. The catalyst structure can be changed to make different polymeric properties. A typical example would be the zirconium metallocene shown below. 

Throughout the text we will relate polymer structure to the properties of the polymer. Polymer properties are related not only to the chemical nature of the polymer, but also to such factors as extent and distribution of crystallinity, distribution of polymer chain lengths, and nature and amount of additives, such as fillers, reinforcing agents, and plasticizers, to mention a few. These factors influence essentially all the polymeric properties to some extent including hardness, flammability, weatherability, chemical stability, biological response, comfort, flex life, moisture retention, appearance, dyeability, softening point, and electrical properties. 

St Pourcain CB, Griffin AC. Thermoreversible suptamolecular networks with polymeric properties. Macromolecules 1995 28 4116-4121. 

Hydrogen bonding interactions are important for the development of selfassembling supramolecular materials, which are defined as materials in which monomeric units are reversibly bound via secondary interactions to form polymer-like stmctures that exhibit polymeric properties in solution as well as in bulk (Bmnsveld et al. 2001). Rotello used hydrogen bond functional polymers to direct the formation of large vesicles (lUian et al. 2000), reversibly attach polymers on... 

Figure 5.1 Relation between chain length and select polymeric properties such as Tg, yield stress, and modulus.

TABLE 1. Polymerization Properties of Photochemically Prepared Using Resin Compositions Containing the Step 2 Product... 

Table 1. Melting and polymerization properties of isomeric ether-ketone bismaleimides...

Liu X, Howard KA, Dong M et al (2007) The influence of polymeric properties on chitosan/ siRNA nanoparticle formulation and gene silencing. Biomaterials 28(6) 1280—1288... 

The objectives of this paper are to discuss and present some examples of how polymer characterisation must be used in order to determine a range of important polymeric properties in recycled plastics. These properties in turn are used to define the quality of recycled plastics. 

Online separations are often based on spectroscopic identification of polymeric type, but seldom give any indications of polymeric properties (e.g. melt index, crystallinity, mechanical properties) or of the level of low molecular weight compounds. A complicating factor when trying to define properties of recycled plastics has to do with the word contamination . Depending on the context and also the person it may imply as vastly different things as dirt or low molecular weight compounds. 

Influence of Various Processes in the Recycling Plant on the Polymeric Properties... 

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