Polymer factors which influence

Much LC-MS work is carried out in a qualitative or semi-quantitative mode. Development of quantitative LC-MS procedures for polymer/additive analysis is gaining attention. When accurate quantitation is necessary, it is important to understand in depth the experimental factors which influence the quantitative response of the entire LC-MS system. These factors, which include solvent composition, solvent flow-rate, and the presence of co-eluting species, exert a major influence on analyte mass transport and ionisation efficiency. Analyte responses in MS procedures can be significantly affected by the nature of the organic modifier used in the RPLC... 

This paper will provide an overview of the polymerization processes and the properties of poly(dichlorophosphazene). This paper will also discuss the various factors which influence the properties of the poly(organophosphazenes) and show how these factors have resulted in a class of polymers with a wide range of properties, including several examples of current commercial importance. 

The characteristics of particulate filled polymers are determined by the properties of their components, composition, structure and interactions [2]. These four factors are equally important and their effects are interconnected. The specific surface area of the filler, for example, determines the size of the contact surface between the filler and the polymer, thus the amount of the interphase formed. Surface energetics influence structure, and also the effect of composition on properties, as well as the mode of deformation. A relevant discussion of adhesion and interaction in particulate filled polymers cannot be carried out without defining the role of all factors which influence the properties of the composite and the interrelation among them. 

Other factors which influence the properties of polymers can be illustrated by examining the bond energies or bond strengths and the ionic character of bonds based on Si as contrasted to similar ones based on C. 

Hi. The monomer polymerization route. Compared with the resin-functionalization route, the homo- and copolymerization of organotin-containing monomers permits one to influence the polymer resin structure to a greater extent. In principle, it is possible to prepare gel-type, macroporous, microporous or nonporous polymers. The pore structure, tin loading, solubility and other factors which influence the reactivity of the polymer-supported organotin reagents can be controlled by appropriate... 

Polymers are in general use because they provide good mechanical properties at reasonable cost. The elTicient application of macromolecules requires at least a basic understanding of the mechanical behavior of such materials and the factors which influence this behavior. 

Both intermolecular and intramolecular additions of carbon radicals to alkenes and alkynes continue to be a widely investigated method for carbon-carbon bond formation and has been the subject of a number of review articles. In particular, the inter- and intra-molecular additions of vinyl, heteroatomic and metal-centred radicals to alkynes have been reported and also the factors which influence the addition reactions of carbon radicals to unsaturated carbon-carbon bonds. The stereochemical outcome of such additions continues to attract interest. The generation and use of alkoxy radicals in both asymmetric cyclizations and skeletal rearrangements has been reviewed and the use of fi ee radical reactions in the stereoselective synthesis of a-amino acid derivatives has appeared in two reports." The stereochemical features and synthetic potential of the [1,2]-Wittig rearrangement has also been reviewed. In addition, a review of some recent applications of free radical chain reactions in organic and polymer synthesis has appeared. The effect of solvent upon the reactions of neutral fi ee radicals has also recently been reviewed. ... 

Period of Particle Formation. An important factor which influences the duration of the period of particle formation and hence the number of particles formed is the rate of growth of the particles. This rate in turn is strongly influenced by the solubility of the monomer in its polymer or rather the partition of monomor between polymer and aqueous phase. Table III lists approximate values of C, the conversion at which free monomer droplets disappear... 

There are many factors which influence Che activity and selectivity of an Immobilized metal complex, mass transfer of the substrate is but one. Additional factors are associated with Che chemical properties of the complex and include altered ligand environment about the complex (29.38) steric constraints imposed by the presence of the polymer structure in the vicinity of the attached complex (8,16,17,30,38) reduced activity due to thermodynamic exclusion of the reactant molecules from the solvent-swollen... 

As for batch processes, monomer partitioning is a factor which influences individual values of [M]p (and hence reaction kinetics) in all of the aforementioned types of semi-batch copolymerization. The approach to partitioning in the absence of monomer droplets which was put forward by German, Maxwell and co-workers (see Section 7.3.2.2) also is appropriate to monomer-starved semibatch processes. Assuming that thermodynamic equilibrium is established during addition of monomer, then all that is needed is to account for the changing masses of the unreacted monomers and polymer, as monomers are fed to the reaction vessel and removed from it through polymerization. 

The factors, which influence the permeability or mass transport, are the following chemical composition of the polymer matrix and its free volume. In fact, crystallinity, molecular orientation, and physical aging in turn influence the free volume of a polymer matrix. In addition, porosity and voids, like free volume, offer sites into which molecules can absorb and are far less of a barrier to transport than solid polymer. Temperature also affects permeability and diffusion properties of small molecules in polymers. With increased temperature, the mobility of molecular chains (in polymer) increases and thermal expansion leads to reduced density therefore, the free volume in the system will increase. External tensile stress applied is expected to increase free volume and open up internal voids or crazes, providing additional sites into which molecules can absorb. Of course, there may be unquantified internal residual stresses, arising from processing, present in the polymers. It is well established that the properties of materials... 

The radiation chemistry of polymers is an extremely rich field of study, both from an intellectual and a practical viewpoint. The very large body of research devoted to this field is testament to this fact. The overall outcome of this work is a clear understanding of the effect of radiation on this class of materials, and the factors which influence the rates of reaction and the product distribution. These include factors intrinsic to the polymers, and extrinsic factors more readily imder the control of the experimental scientist or engineer. These are summarized below. 

Recent advances in the development of drug dehvery research area have led to the need for the production of weU-defined and characterized nanoparticulates. Especially the particle size and size polydispersity are important factors which influence the distribution of the particles within the body and their interaction and uptake by hving cells [1 ]. Colloidal carriers such as liposomes, micelles, dendritic polymers, and nanoparticles are the most promising candidates in regards to the site-specific delivery and controlled dmg release. Core-shell particles with a liquid core have gained increased attention in the past years owing to their utilization as sub-p.m containers for the encap-... 

An understanding of the factors which influence cutaneous and percutaneous absorption, together with advances in polymer technology, have led to the possibility of providing optimal drug therapy for the treatment of systemic disorders — acute or chronic — by means of controlled, unattended administration of a drug to the skin surface, for prolonged, predetermined periods of time (5). ... 

The basic factors which influence polymer wear > are pressure, coefficient of friction, surface texture, sliding velocity, elastic modulus, strength and fatigue resistance. Surface energetics may affect polymer wear through the adhesional friction. Thus, a direct correlation between surface energetics and polymer wear is not apparent. 

PSAs that have got a high performance use the versatility of acrylate chemistry. The broad base of raw materials available and the versatility of the UV-crosslinking process are factors, which influence the design of acrylic polymers. The design parameters include the following aspects ... 

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