Segments, lengths

Helfand and Tagami [75,76] introduced a model which considered the probability that a chain of polymer 1 has diffused a given distance into polymer 2 when the interactions are characterised by the Flory-Huggins interaction parameter x They predicted that at equilibrium the thickness , d c, of the interface would depend upon the interaction parameter and the mean statistical segment length, b, as follows ... 

Pi = Inlet pressure, psia P2 = Outlet pressure, psia D = Inside pipe diameter, inches L = Segment length, miles f = Friction factor, dimensionless... 

Airway region Cross- sectional area (cm) Equivalen t diameter (cm) Airway segment length (cm) 8 L/min 16 L/min 30 L/min... 

ATBN - amine terminated nitrile rubber X - Flory Huggins interaction parameter CPE - carboxylated polyethylene d - width at half height of the copolymer profile given by Kuhn statistical segment length DMAE - dimethyl amino ethanol r - interfacial tension reduction d - particle size reduction DSC - differential scanning calorimetry EMA - ethylene methyl acrylate copolymer ENR - epoxidized natural rubber EOR - ethylene olefin rubber EPDM - ethylene propylene diene monomer EPM - ethylene propylene monomer rubber EPR - ethylene propylene rubber EPR-g-SA - succinic anhydride grafted ethylene propylene rubber... 

In terms of structural control, block copolymers have considerable advantages over graft copolymers. The segment length and sequence are generally more easily controlled for block copolymers than for graft copolymers. 

When ACPC was condensed with hexamethylene diamine in the presence of two other acid chlorides (seb-acoyl or adipoyl chloride), poly(amide)s 6.6 and 6.10 with various numbers of azo groups per repeating unit (between 0.14 and 1.0, depending on the ratio of the acid chlorides used) could be obtained [35,36]. Thus, block copolymers with a controlled segment length of the poly-(amide) blocks were attainable. 

If the persistence length Ip is much larger than the mean chain diameter, d, Yamakawa and Fujii gave limiting values for ai = - ln(d/2Ip) and = 0.1382. Freire and Garcia de la Torre [122] have considered further these coefficients. The factor 2Ip appears rather than Ip simply because 2Ip is equivalent to the statistical Kuhn segment length... 

Miller J.A., Lin S.B., Hwang K.K.S., Wu K.S., Gibson P.E., and Cooper S.L. Properties of polyether-polyurethane block copolymers Effect of hard segment length distribution. Macromolecules, 18, 32, 1985. 

Here, b denotes the Kuhn s statistical segment length. The network is represented by a huge chain internally cross-linked at cross-linking points where it touches and at the surfaces of Mf filler particles. The point-like local cross-hnk constraints are easy to handle and can be represented by the term... 

Rat (hooded) 3 wk ad lib (W) Ocular 0.5 F (decreased retinal sensitivity, rhodopsin, and rod outer segment length) Fox and Rubinstein 1989 PbAc... 

Fox DA, Rubinstein SD. 1989. Age-related changes in retinal sensitivity, rhodopsin content and rod outer segment length in hooded rats following low-level lead exposure during development. Exp Eye Res 48 237-249. 

Comparing Eqs. (83), (84) and Eqs. (21), (22) it follows immediately that Rouse and Zimm relaxation result in completely different incoherent quasielastic scattering. These differences are revealed in the line shape of the dynamic structure factor or in the (3-parameter if Eq. (23) is applied, as well as in the structure and Q-dependence of the characteristic frequency. In the case of dominant hydrodynamic interaction, Q(Q) depends on the viscosity of the pure solvent, but on no molecular parameters and varies with the third power of Q, whereas with failing hydrodynamic interaction it is determined by the inverse of the friction per mean square segment length and varies with the fourth power of Q. 

Within the scaling concept the answer to the question, how physical properties alter with changes in scale, is of fundamental importance. For example, Fig. 37 shows two polymer chains which result from another altering of the scale (here, number of segments N) by a factor X = 2. Then the following transformation rules are valid for the monomer concentration c and the segment length /[5]... 

Fig. 37a, b. Two chains which result from each other by changing the segmental length scale by a factor X = 2. a initial chain b chain with altered scale. 

From experimental data we would like to visualize the segment length distributions - in order both to gain some imagination of the type71 of the distribution - and in order to understand the arrangement of the domains in the material. This visualization is achieved by computation of... 

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