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Epitaxial crystallization of linear polymers

Epitaxial crystallization of PE may be considered as a rather academic concern. It is indeed so for most linear PEs produced for example by Ziegler-Natta catalysis, which crystallize fast, as they have high nucleation and growth rates. However, modem PEs, such as the linear low density ones (LLDPE), have much reduced growth rates. It is therefore of technological interest to develop nucleating agents that are efficient for this class of polymers. [Pg.243]

Later structural data, already described in detail in earlier reviews, led to quite opposite interpretations [11-13,17]. They revealed that indeed interaction of PE with the substrates follows some strict epitaxy rules. The crux of the analysis lies in two features (1) use of electron diffraction, often of thin, composite bilayers (substrate and polymer), which helps see the interface more clearly, and (2) use of several different substrates with a range of periodicities susceptible to match the PE interchain distances. [Pg.243]

Similar investigations performed with polyamides are comparatively less telling. Indeed, the hydrogen-bonded sheets are a strong structural feature that does not leave much leeway for diverse epitaxial crystallizations. So far, the only contact plane observed in epitaxial crystallization of polyamides is indeed the hydrogen-bonded sheet [16]. This in turn implies that substrates with a periodicity close to 0.48 to 0.5 nm are most appropriate (provided of course that their compatibility with polyamides is sufficient). In this respect also, investigation of epitaxial crystallization of polyamides teaches us less than that of PE. However, further research is needed to investigate if some less standard crystal modifications of polyamides, such as the 7 form of polyamide 6, can be produced by epitaxial crystallization. [Pg.244]

Among many more linear polymers, poly(ethylene terephthalate) (PET) is of particular relevance since its maximum crystal growth rate is slow. The enhanced crystallization of PET has been, and still is, a topic of technological relevance. Following extended work by Legras, Mercier, and Nield [21], the impact of chemical nucleation (as opposed to epitaxial, i.e., physical interactions) has been widely publicized and is indeed [Pg.244]


Thierry, A. Epitaxial crystallization (of linear polymers). In Polymeric Materials Encyclopedia, Vol. 3, Salamone, J.C., ed. CRC Press, Boca Raton, FL, 1996, pp. 2167-2179. [Pg.262]


See other pages where Epitaxial crystallization of linear polymers is mentioned: [Pg.239]    [Pg.243]   
See also in sourсe #XX -- [ Pg.243 , Pg.252 ]




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