Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Model polymer generation

The vector field entirely and uniquely determines the stream lines and their properties. As we focus our attention on the mesoscopic properties of stream lines, assuming that they can resemble a polymer-like amorphous packing of chain backbones, we have to consider in greater detail their intrinsic properties. As shown in the next section, Santos and Suter [98] elaborated a model for generating packing structures of Porod-Kratky chains. [Pg.61]

We mentioned the main models for generation, transfer, and recombination of the charge carriers in polymers. Very often, these models are interwoven. For example, the photogeneration can be considered in the frame of the exciton model and transport in the frame of the hopping one. The concrete nature of the impurity centers, deep and shallow traps, intermediate neutral and charged states are specific for different types of polymers. We will try to take into account these perculiarities for different classes of the macro-molecules materials in the next sections. [Pg.11]

The inadequacy of the so-called mathematical models led to a second class of distribution functions, which incorporated the specific conformational transitions available to a particular polymer system. These models, the so-called diamond or tetrahedral-lattice models, were generated by considering a three- or four-... [Pg.80]

Polyisobutene or polyisobutylene, CAS 9003-27-4, with the model formula [-CH2C(CH3)2-]n is another common polymer, which is used in practice mainly for sealants and adhesives and in various copolymers. Polyisobutylene copolymer with a small amount of isoprene is used as a synthetic rubber, the added isoprene making the material vulcanizable. The polymer is typically obtained by cationic polymerization using, for example, BF3 or AICI3 as catalysts. The thermal decomposition of the polymer generates various fragments [76,119-123]. The heating between 288° C and 425° C... [Pg.222]

Simple, exact models [51] consist of simple lattice polymers or heteropolymers where each amino acid in the hypothetical protein is represented by a bead occupying a single lattice point. Because of their simplicity, these models have generated considerable attention [57,58]. [Pg.208]

New model polymers were randomly generated and reacted until the predetermined Monte Carlo sample size was reached. The quantities of all products at each time were added to the sum recorded from all previous polymers. Afterward, the weight yield in g/giignin of each product of interest was calculated at each time step by multiplying its cumulative product sum by the ratio of its molecular weight and the cumulative molecular weight of all the model polymers reacted. The results were organized as product yield versus isothermal batch reaction time. [Pg.251]

Ihlefeld CM, Qu Z (2008) A dielectric electroactive polymer generator-actuator model modeling, identification, and dynamic simulation. Proc SPIE 6927 69270R... [Pg.55]

The first SCF result that we discuss here is shown in Fig. 7. In this case, bd has been varied from 0 to 1.5, with steps of 0.5, for the case that the lengths of the two chains is varied under the constraint that the sum of the two is fixed to 200. The most simple system is found for Nb=Nd = 100 and Xwi = 0. In this case, we have a spherical homodisperse, athermal brush. For this situation, the (dimensionless) segment potential is simply given by u r) = ln[l - (ps(r)] [73]. In short, within a freely jointed chain model, we generate all possible conformations of the polymer chains with the constraint that the first segment is positioned at r = 6 (next to the surface). Depending on the positions visited by, e.g. a conformation c, we can exactly enumerate the potential felt by this conformation Mc. The statistical weight of... [Pg.175]

Sigillo et al. (1997) used several experimental methods for the measurement of interfacial tension of a model polymer blend. Common to all methods presented here are two main points. The first is that a is obtained from experiments where the shape of the interface between the liquids is directly observed by means of optical microscopy techniques. The second point is that the interface geometry is controlled by a balance between the interfacial force and the viscous stresses generated by some flow applied to the system. Measurements have been carried out on a model polymer blend, whose constituents are a polyisobutylene and a polydimethylsiloxane, both transparent and liquid at room temperature. When compared with each other, the values of interfacial tension obtained from the different methods show a good quantitative agreement. Excellent agreement is also found with results for the same system previously published in the literature. [Pg.482]

A computational algorithm for generating and modeling polymer particles for our simulations was developed to construct particles that are as similar as possible to the experimentally created polymer particles. We have examined a variety of PE nano-scale particles, allowing the systematic study of size-dependent physical properties of these particles [214]. The models have been well tested and shown to provide realistic representation of the structure and vibrational spectroscopy of a number of polymer systems harmonic/Morse potentials for the bond stretches, harmonic potential for bending between two bonds, a truncated... [Pg.50]

Development of controlled radical polymerization techniques has stimulated basic research on radical chemistry in conventional radical polymerizations. Information on the effect of chain lengths on propagating radicals, chain-transfer reactions to polymers, and penultimate unit effects has been obtained from ESR observation of model radicals generated from radical precursors prepared by ATRP. Previously, it has been extremely difficult, even impossible, to obtain such information from ESR spectra during conventional radical polymerizations. The ESR study of radical polymerizations has made remarkable progress as a result of the combination of study of radicals formed as a result of various kinds of controlled radical polymerization techniques. [Pg.129]

The C Is and O Is peaks of model polymers [poly (bisphenol A carbonate) and poly (ethylene terephtalate)] have been recorded with two different spectrometers for which the 0/C concentration ratio was determined in a different way (a) ESC A 3 Mkll spectrometer from Vacuum Generators, Mg, use of Wagner empirical sensitivity factors and (b) SSX KXV206 spectrometer, monochromatized AIku, sensitivity factors determined from cross seclions and considering IMFP... [Pg.241]

A computer model of polymer photo-oxidation has been developed [878]. This model can generate realistic concentration versus time profiles of the chemical species formed during photo-oxidation of hydrocarbon polymers using, as input data, a set of elementary reactions with corresponding rate constants and initial conditions. A numerical integration procedure on the... [Pg.594]


See other pages where Model polymer generation is mentioned: [Pg.243]    [Pg.250]    [Pg.243]    [Pg.250]    [Pg.445]    [Pg.403]    [Pg.62]    [Pg.95]    [Pg.202]    [Pg.1317]    [Pg.236]    [Pg.65]    [Pg.86]    [Pg.627]    [Pg.247]    [Pg.150]    [Pg.482]    [Pg.405]    [Pg.58]    [Pg.152]    [Pg.387]    [Pg.429]    [Pg.254]    [Pg.98]    [Pg.108]    [Pg.198]    [Pg.342]    [Pg.198]    [Pg.471]    [Pg.197]    [Pg.351]    [Pg.1]    [Pg.1317]    [Pg.282]    [Pg.202]    [Pg.51]    [Pg.668]   
See also in sourсe #XX -- [ Pg.243 , Pg.245 ]




SEARCH



Generating models

Model Generator

Model generation

Polymers generation

© 2024 chempedia.info