INTERCHAIN PACKING

The CH2 density of our model can be easily calculated from the interchain packing density and the mean intrachain CH2 spacing. The former was obtained from the fit of the RDDF s, the latter can be extracted from the mean electronic density (Fig. 16). If we consider complete space filling of the model short range order regions, we finally get... 

It appears that the nature of the cooperativity that develops in aryl-aliphatic epoxy resin is similar to that encountered in bisphenol A polycarbonate a cooperativity directly involving the local interchain packing, which... 

When pending groups or antiplasticisers are present in the systems, they breakdown the local interchain packing and motions of the HPE units can occur without implying such a large number of crosslink points. 

An aspect ratio T=a/V1/3 has been introduced [213], characterizing an effective stiffness of the chain and reflecting an interchain packing ability. The real more linear (low x) olefinic copolymers are described as the more stiff chains (with large T and a), while the more branched polyolefines (high x) as the more flexible blend components (with small r and a). 

In the spectrum of the /3-form (Fig. 11.1(b)), each carbon resonance is a single peak. The chemical shifts of the methylene and methyl carbons in the /3-form are close to the low frequency part of each pair of the same resonances in the a-form, which were attributed to the B sites [3]. Figure 11.2(b) shows the interchain packing of the /3-form of i-PP. Unlike a-form packing, all 3i-helixes are separated with equal intervals (6.36 A) form the other chains. 

Figure 11.1(c) shows the smectic crystalline of i-PP. This spectrum is similar to that of the a-form. This suggests interchain packing in smectic crystalline is similar to that of /3-form. 

The details of the interchain packing determine whether there will be any crystalline phase at all, what the maximum possible crystallinity is, and what the rate of crystallization is under a given set of conditions [30]. It is, for example, entirely possible and very common for a polymer to be anticipated to have a very high Tm but to be completely amorphous because it has irregular chains which do not pack well in a crystalline lattice. For example, (a) the absence of stereoregularity makes crystalline packing impossible in atactic polymers with a vinyl-type... 

Figure 1.53. (a) Schematic drawing of the main chains and the interchain packing (b) projection of the PANI-DBSA unit cell on the (b, c) plane (c) projection of the PANI-DBSA unit cell on the (a, b) plane. Note that the hydrogen atoms have been omitted. (Reproduced from ref. 330 with kind permission. Copyright (1994) Elsevier Science Ltd, Kidlington 0X5 1GB, UK.)... 

Attempts to establish the details of the interchain packing and ciy stal structure through comparison of the calculated structure factors with the data in Figures la and lb are currently underway. However, some more general aspects of the structure can be inferred directly from the data. The coherence lengSis parallel and perpendicular to the chains (based on the narrowest lines at 20 10 and 19 , respectively) are comparable. From the Scherrer formula,... 

The similarities between the molecular structure of the emeraldine base and those of poly(p-phenylene sulfide),poly(p-phenylene oxide),and even poly(p-phenylene terephthalamide) suggest that a sinular interchain packing might be expect. Indeed, the two strongest equatorial peaks in Figurelb(at 20=19.5 and 20=22.8 ) correspond to the similar peaks observed in all three materials. 

Interchain conduction, 8-22 Interchain hole hopping, 9-24 Interchain hopping, 16-10 Interchain packing, 17-6, 17-8, 17-15, 17-29,... 

As an example of recent developments in the use of solid-state NMR to probe interchain packing relationships, the independent works of Schaefer and Suter deserve mention [79-84]. Polycarbonate (PC) is an industrially important... 

Chen, H.Y. et al. (2010) Silicon atom substitution enhances interchain packing in a thiophene-based polymer system. Adv. Mater, 22 (3), 371. 

The high cohesive energy density (H bonding) of PAs (Figure 4.2), which directs an efficient polymer interchain packing along with a rigid polymer backbone, results in poor processability and limits their applicability. 

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