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Polymers parameter

This chapter is the narrowest in scope of any chapter in this book. In it we discuss a single experimental procedure and its interpretation. It is appropriate to examine light scattering in considerable detail, since the theory underlying this method is relatively unfamiliar to students and the interpretation yields information concerning a variety of polymer parameters. [Pg.659]

Polymer parameters, catalysts and, 26 534 Polymer particle growth... [Pg.736]

This equation illustrates that KQC depends on the solute parameters Kow, V, and 6. Since molar volume and log KQW are positively correlated (log KQW = 0.49 + 0.020V 21), KQC could be expressed as a function of the solute parameters and 6, and polymer parameter <5p. [Pg.199]

Although many of the proposed applications for these gels requires that they operate under an applied pressure or generate some kind of mechanical force, a detailed understanding of these relationships does not currently exist. There is data available on the effect of the load on the rate of work and stroke, or generated force vs time, for example, but this is often presented on an empirical basis. Furthermore, much of the work has been carried out under conditions where the stimulus is rate-limiting, rather than the polymer network [66, 67], The development of a mathematical description of these phenomena using independently obtainable polymer parameters is needed. [Pg.88]

Polymer Parameter of Mechanochemical Synthesis Electric Conductivity a ohm l cm l... [Pg.106]

The polyanion-polycation complex (symplex) formation process is a phenomenon that had long been known on an empirical base from the mutual precipitation of proteins [150]. The internal structure and the properties of the resulting complexes are strongly influenced by the nature of the polymeric components and the system conditions. The polymer parameters include the molar mass, the... [Pg.171]

We show elsewhere (10) that sorption and transport expressions derived from eqs. (1) and (5) represent experimental sorption and transport data well. Nevertheless, the calculations are cumbersome and require additional polymer parameters. These disadvantages might hinder the broad use of these expressions thus, we will base our following discussions on the simplified expressions, eqs. (4) and (9), exclusively. [Pg.121]

The Molding Area in Injection Molding (a) Discuss the dependence of each of the curves making up the molding area in Fig. 13.6 on polymer parameters such as Tg, Tm, m(T), n, k, m(P), and Tm(P), and thermal degradation, (b) Apply the preceding ideas to three polymers—PVC, nylon, and HDPE—whose properties appear in Appendix A. [Pg.822]

Fig. 1. Weight fraction Wn of backbone polymer with n branches for most probable molar mass distribution of the mother polymer parameter is the average number of branches in one mother molecule, Nt. The points in the curves denote Wn at n = 0,1,... 8... Fig. 1. Weight fraction Wn of backbone polymer with n branches for most probable molar mass distribution of the mother polymer parameter is the average number of branches in one mother molecule, Nt. The points in the curves denote Wn at n = 0,1,... 8...
Figure 45a-c shows an adaptation of the developed model to uniaxial stress-strain data of a pre-conditioned S-SBR-sample filled with 40 phr N220. The fits are obtained for the third stretching cycles at various prestrains by referring to Eqs. (38), (44), and (47) with different but constant strain amplification factors X=Xmax for every pre-strain. For illustrating the fitting procedure, the adaptation is performed in three steps. Since the evaluation of the nominal stress contribution of the strained filler clusters by the integral in Eq. (47) requires the nominal stress aR>1 of the rubber matrix, this quantity is developed in the first step shown in Fig. 45a. It is obtained by demanding an intersection of the simulated curves according to Eqs. (38) and (44) with the measured ones at maximum strain of each strain cycle, where all fragile filler clusters are broken and hence the stress contribution of the strained filler clusters vanishes. The adapted polymer parameters are Gc=0.176 MPa and neITe= 100, independent of pre-strain. According to the considerations at the end of Sect. 5.2.2, the tube constraint modulus is kept fixed at the value Ge=0.2 MPa, which is determined by the plateau modulus Gn° 0.4 MPa [174, 175] of the uncross-linked S-SBR-melt (Ge=l/2GN°). The adapted amplification factors Xmax for the different pre-strains ( max=l> 1-5, 2, 2.5, 3) are listed in the insert of Fig. 45a. Figure 45a-c shows an adaptation of the developed model to uniaxial stress-strain data of a pre-conditioned S-SBR-sample filled with 40 phr N220. The fits are obtained for the third stretching cycles at various prestrains by referring to Eqs. (38), (44), and (47) with different but constant strain amplification factors X=Xmax for every pre-strain. For illustrating the fitting procedure, the adaptation is performed in three steps. Since the evaluation of the nominal stress contribution of the strained filler clusters by the integral in Eq. (47) requires the nominal stress aR>1 of the rubber matrix, this quantity is developed in the first step shown in Fig. 45a. It is obtained by demanding an intersection of the simulated curves according to Eqs. (38) and (44) with the measured ones at maximum strain of each strain cycle, where all fragile filler clusters are broken and hence the stress contribution of the strained filler clusters vanishes. The adapted polymer parameters are Gc=0.176 MPa and neITe= 100, independent of pre-strain. According to the considerations at the end of Sect. 5.2.2, the tube constraint modulus is kept fixed at the value Ge=0.2 MPa, which is determined by the plateau modulus Gn° 0.4 MPa [174, 175] of the uncross-linked S-SBR-melt (Ge=l/2GN°). The adapted amplification factors Xmax for the different pre-strains ( max=l> 1-5, 2, 2.5, 3) are listed in the insert of Fig. 45a.
Fig. 45 a Uniaxial stress-strain data (symbols) of S-SBR samples filled with 40 phr N220 at various pre-strains emax and simulation curves (lines) of the polymer contribution according to Eqs. (38) and (44). The set of polymer parameters is found as Gc=0.176 MPa, Ge=0.2 MPa, and njTe= 100. b Stress contributions of the strained filler clusters for the different pre-strains (upper part), obtained by subtracting the polymer contributions from the experimental stress-strain data of a. The solid lines are adaptations with the integral term of Eq. (47) and the cluster size distribution Eq. (37), shown... [Pg.72]

Table 4 Material parameters obtained from adaptations of the model to uniaxial stress-strain data of four S-SBR samples filled with 40 and 60 phr N220 (C40, C60) and silica (S40, S60), respectively. Further polymer parameters are given as Ge=0.2 MPa and ne/Te= 100, independent of sample type... Table 4 Material parameters obtained from adaptations of the model to uniaxial stress-strain data of four S-SBR samples filled with 40 and 60 phr N220 (C40, C60) and silica (S40, S60), respectively. Further polymer parameters are given as Ge=0.2 MPa and ne/Te= 100, independent of sample type...
TABLE 3-3. Typical Polymer Parameters of Cellulose and Hydroxyethyl Cellulose Compared with Polyvinyl Acetate"... [Pg.58]

Rapid accumulation of the missing data on termination is documented by well-founded theoretical studies, leading to the solution of the complicated problems connected with the consequences of termination and transfer on the molecular mass distribution by means of graphical analysis [147, 148], Equilibrium polymerization with reversible transfer has also aroused the interest of theorists [149] even though it appears that this kind of transfer in particular has only a small efect on the resulting polymer parameters. [Pg.438]

The van Krevelen method should be used in those cases where the deviation with GCVOL is over 6% (polyisobutylene, polyvinyl propionate) and for those polymers for which the GCVOL group parameters are not available. The density of polymers is important in many calculations. Several of the free-volume activity coefficient models discussed in Section 16.4 require the densities of polymers (and solvents) as input. We will see then that certain models are quite sensitive to the values of the densities employed. Moreover, polymer density data are often employed in equations of polymers for obtaining the pure polymer parameters. [Pg.687]

Table 2.8 Pure polymer parameters and binary parameters for the different ternary solutions considered... Table 2.8 Pure polymer parameters and binary parameters for the different ternary solutions considered...
Many such theories concentrate on the determination, by different mathematical approaches and different physicochemical approximations, of the degree of conversion and hence of the advancement of polymerization at the point of gel formation and on the calculation of basic polymer parameters derived from the determination of the gel point. Two main approaches are used statistical methods and kinetic methods. Combinations of the two have also been presented [1]. [Pg.187]

The selection was based on measures of the goodness of fit the standard deviation (a), the correlation coefficient squared (r ), and the coefficient of determination (Q). It is noteworthy that the range of variables selected is much wider than that experienced by a single polymer. Parameters for the goodness of fit for Eqs. (6.43) and (6.44) are listed in Table 6.2. Similarly, the scaled CED and S = S(T, P) were approximated by... [Pg.248]

According to Flory-Huggins theory, both the location and size of the different regions depend on the Flory-Huggins binary interaction parameters, which are parameters that characterize the interaction between pairs of compounds. Thus, we have the solvent-polymer parameter (X23), the nonsolvent-Polymer (X13), and solvent-nonsolvent (Xi2)- The subscripts, as shown also in the figure, refer to the nonsolvent, solvent, and polymer. ... [Pg.349]

It is possible that equilibrium morphology is not obtained because the movement of the polymer chains is not fast enough to reach that equilibrium within the time-frame of the reaction this is kinetic control of morphology. The kinetic parameters influence the rate of formation of a certain morphology [27, 28], which is basically determined by the interfacial tensions [29]. The parameters of importance are the rate of formation of the polymer (parameters are propagation rate coefficient, and the local monomer and radical concentrations) and the rate of diffusion of the polymer chains (parameters are viscosity in the locus of polymerization, molar mass and topology of the polymer chain). Both the rate of formation and the rate of diffusion of a polymer chain are, for example, affected by the mode of addition of the monomer and initiator. An increased rate of addition of the monomer will lead to a lower instantaneous conversion and thus a lower viscosity in the particle, which in turn increases the rates of diffusion and leads to different morphologies. [Pg.8]

Another special polymer parameter comes from the hierarchy of interactions. The energy Ei of a covalent bond between two neighboring monomers in a chain is normally about 5 eV 0.8 10 J. This is much... [Pg.148]

Table 11.3 Influence of different processing parameters during reactive extrusion polymerization on the resulting molecular polymer parameters... Table 11.3 Influence of different processing parameters during reactive extrusion polymerization on the resulting molecular polymer parameters...
Soon after the report of the McCullough method, the Rieke method (Scheme 2.2B) was published (Chen and Rieke, 1992). In this method, the stcuting material is changed to 2,5-dibromo-3-alkylthiophenes 34, which reacts with Rieke zinc at low temperature to yield a mixture of two isomeric organozinc intermediates 35 and 36 in a ratio of 90 10 directly. The intermediates are polymerized in the presence of Ni(dppe)Cl2. The yield of P3ATs 33 is increased to 75%, and the polymer parameters (Mn = 24,000-34,000, PDI = 1.4) are maintained in a comparison to McCullough method. [Pg.16]

We synthesised different model polyesters and also oligomeric esters with specific structures to study the correlation between biodegiadability and the polymer-parameters responsible for the biological susceptibility. Polyesters are a suitable substance class for such investigations, because they can easily be synthesised in the lab, are potentially biodegradable due to their hydrolyzable ester bonds and they are of practical relevance, because most of the biodegradable plastics currently on the market are based on polyesters. A substantial part of our investigations is the detailed analysis of the structures of complex polyesters (e.g. copolyesters). [Pg.304]

Using the Hansen approach, the solubility of any polymer in solvents (with known Hansen s parameters of polymer and solvents) can be predicted. The determination of polymer parameters requires evaluation of solubility in a great number of solvents with known values of Hansen parameters. Arbitrary criteria of determination are used because Hansen made no attempts of precise calculations of thermodynamic parameters. [Pg.113]

Equation (9) is predicated on the assuraiptions that both networks are continuous in space, network II swells network I, and that the swelling agent then swells both networks. The several PS/PS IPN s under consideration constitute an excellent model system with which to examine.fundamental polymer parameters. Questions of interest in the field of IPN s relate to the relative continuity of networks I and II and their consequent relative contribution to physical properties and the extent of formation of physical crosslinks or actual chemical bonds between the two networks. The reader will note that if equation (9) is obeyed exactly, the implicit assumptions require that both networks be mutually dissolved in one another and yet remain chemically independent. Then the only features of importance are the crosslink densities and the proportions of each network. [Pg.173]


See other pages where Polymers parameter is mentioned: [Pg.155]    [Pg.528]    [Pg.65]    [Pg.24]    [Pg.1209]    [Pg.53]    [Pg.396]    [Pg.143]    [Pg.401]    [Pg.401]    [Pg.461]    [Pg.260]    [Pg.401]    [Pg.401]    [Pg.256]    [Pg.96]    [Pg.117]    [Pg.42]    [Pg.215]    [Pg.351]    [Pg.198]   
See also in sourсe #XX -- [ Pg.155 , Pg.156 , Pg.157 ]




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