Average contour length

At this point a third intermediate approach deserves mentioning. It is due to Allegra [43] who proposed that polymer crystallization is controlled by a metastable equilibrium distribution of intramolecular clusters, the so-called bundles , forming in the liquid phase. These subsequently aggregate to the side surfaces of the crystals, driven by van der Waals interactions. The lamellar thickness is determined by the average contour length of the loops within the bundles. Although the model can... 

Ln is the number average contour length from the EM data... 

Figure 2. Contour length distributions obtained from electron micrographs of samples A, B, C and D (Fig. 1). The displacement along the y -axis of the contour length distributions corresponds to the reported Mw for each sample. The weight average contour length for each distribution is marked with an arrow.

We can assert outright that a semi-crystalline network in a continuous state of equilibrium might be satisfactorily described by a representative chain of average contour length and average crystallization. This is, after all, the same assumption that is invariably applied to amorphous networks. The results in this instance are exactly the same as those presented herein. 

Fig. 8. Tensile strength, aj, craze initiation stress, and stress at start of rapid craze development, vs average contour length between molecular entanglement points, for PSAN samples of varying AN content...

The average contour length (L) of the primitive path (the centre of the confining tube, see Fig. 7.10) is the product of the entanglement strand length a and the average number of entanglement strands per chain N/N. ... 

Here, Eq. (9.3) was used for the average contour length of the tube. The reptation time Trep is predicted to be proportional to the cube of the molar mass. The experimentally measured scaling exponent is higher than 3 ... 

At t = Teg, the tube stress resides over the whole tube length — the average contour length of the primitive chain L (Eqs. (8.3) and (8.51)). From Eq. (9.2) we have... 

The amplified tension caused by adsorption of side chains can lead to the scission of covalent bonds in the backbone once it exceeds their strength. We have shown that the C-C bonds in poly(2-hydroxyethyl methacrylate) backbone with long poly(n-butyl acrylate) (PBA) side chains mptured spontaneously uprm adsorption onto an aqueous substrate (Fig. 9) [126]. The kinetics of backbone scission was followed by monitoring the average contour length by AFM as a... 

The difference between and is more pronounced with d-PBT sample, and is b ieved to represent the effects of heterogeneity caused by molecular association. The result gin20/2 = 135 ys at infinite dilution is attributed to the unassociated species such that the molecular friction coefficient is given by HO/ng = 70.7 nm (the solvent viscosity rig is 9 mPa s at 25 ). For rodlike chains, the weight average contour length Lyj is given by ... 

Table 1 Light scattering results of the copolymacromonomers in DMF, and AFM results (weight and number-average contour lengths, L and Ln) of the samples spincast from CHCI3 solution onto mica...

This force acts to constrain the lateral motion of the chains (tube constraints) and the average contour length of the tube coincides with the equilibrium tube length... 

The number of hairpins in a nematic main-chain polymer is given by UIH, where L is the average contour length of the chain and 2H its dimension parallel to n. SANS of both polyesters [35] and polyethers [21] gives similar results the polymer chains are confined in very long (2/7 20-35 nm), thin (R 0.8-... 

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