Poly lamellar thickness

The scaling of the lamellar thickness with degree of polymerization of the crystalline and amorphous blocks was investigated for PEO-poly(ferf-butyl methacrylate) (PEO-PtBMA) diblocks using DSC and SAXS by Unger et al. (1991). The non-equilibrium exponents obtained immediately after bulk crystallization were found to be different to those from equilibrium results extrapolated... 

Figure 10-13. The melting temperature dependence of the reciprocal lamellar thickness Ijd of lamellae for poly(trifluorochloroethylene). The lamellar thickness was measured as the inter-lamellar distance by small-angle X-ray analysis, and thus contains both the crystalline component and the amorphous surface layer (after J. D. Hoffman from data of P. H. Geil and J. J. Weeks).

Lame lias of crystalline phase of the surface layer of poly olefin blends studied are thicker than present in the surface layer of their components, what suggests co crystallization of ethylene monomer unit from EPDM. Linear LDPE facilitates the phenomenon, especially when takes place in amorphous elastomer matrix. Branched plastomer re crystallizes to the same lamellar thickness, no matter the structure of elastomer matrix. 

Figure 9.16 (a) Deflection and (b) height images of a flat stack of lamellae of semicrystalline poly(lactic acid) by AFM. (c, d) Details of determination of the lamellar thickness [35]. (See color insert.)... 

Recent experiments (211) have shown that the lamellar thickness of poly(ethylene), PE, on oriented isotactic poly(propylene), changes from 16 to 39 nm upon annealing. This thickening is attributed to dimensional matching and secondary nucleation with the requirement (212) that the PE crystal(s) are thiimer than the PP dimension along the chain-row matching direction. However, no detailed kinetic measurements were reported on the rate of epitaxial growth here, or elsewhere in the literature. 

In view of the use of a similar repeating unit, tetramethylenecarboxyl, Seebach s approach should be included here. He incorporated oligomers and polymers of 3-hydroxybutanoic acid (3-HB) into planar bilayers and observed single-channel currents. It is known that poly(3-HB) forms lamellar crystallites with thickness in the range of 40 to 60 A when crystallized from dilute solutions. Therefore it is assumed that poly(3-HB) forms lamellar crystallites with a thickness of ca. 50 A. 

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