Small‐angle x‐ray and light scattering studies of the morphology of blends of poly(ϵ‐caprolactone) with poly(vinyl chloride)

Abstract

Solvent‐cast films of blends of poly(ϵ‐caprolactone) (PCL) with poly(vinyl chloride) (PVC) were examined by low‐angle x‐ray scattering and by small‐angle light scattering. X‐ray scattering from crystalline compositions were analyzed using the Tsvankin–Buchanan technique and led to values of the repeat period of the lamellar structure and the thickness of the crystalline and amorphous layers. With increasing content of PVC, the amorphous layer thickness increased sufficiently to accommodate the PVC, leading to values of the linear crystallinity consistent with macroscopic measurements by density and DSC techniques up to about 50% PVC by weight. Above this concentration, the lamellar structure no longer appeared to be volume filling. At high concentration of PCL, the polymer consisted of volume‐filling spherulites containing the lamellar substructure. Spherulite sizes were measured by light scattering and absolute light scattering intensities were consistent with calculations based upon the degree of crystallinity and anisotropy of the spherulites. Compositions containing more than 60% PVC were amorphous. Low‐angle x‐ray scattering was interpreted in terms of the Debye–Bueche theory which leads to values for a correlation distance lc and the mean‐square electron density fluctuation 〈η2〉 (which was also obtained from the invariant). By the method of Porod, the correlation distances were resolved into persistence lengths within the two phases, which were determined as a function of composition. The fluctuation 〈η2〉 was analyzed in terms of a two‐phase model to show that its value was somewhat larger than would be obtained if the phases were composed of the pure components. It was not possible to uniquely determine their compositions. The data were consistent with the existence of a transition zone of the order of 30 Å thick between phases.

Miscibility and spherulite growth kinetics in the poly(ethylene oxide)/poly(benzyl methacrylate) system

“…For example, the crystallization of a crystallizing poly(-caprolactone) in miscible blends with poly(vinyl chloride) significantly can be disturbed (de- pressed), presumably by favorable molecular/segmental polar interactions. 21 For weak intersegmental interactions, the effect on suppressing the crystallization tendency of PEO was likely small. The figure shows that the relationship was largely linear up to the 50/50 composition, suggesting minimal disruption of PEO crystallization by PBzMA.…”

PEO/CHCl3. Crystallinity of the Polymer and Vapor Pressure of the Solvent. Equilibrium and Nonequilibrium Phenomena

“…Furthermore such systems offer an opportunity to learn more about the occurrence of nonequilibrium phenomena in mixtures containing crystallizable components. The freezing in of intermediate states during the 16.04.03 approach of equilibria is well documented for polymer blends of semi-crystalline and amorphous components in general [1][2][3][4][5][6][7][8][9][10][11][12][13] and with PEO as one component in particular [14][15][16][17][18][19] . Analogous investigations for the considerably less viscous solutions of such polymers (which should therefore be less prone to non-equilibria phenomena) are to our knowledge lacking.…”

Crystallization of Block Copolymers IV. Molecular Weight Dependence of the Morphology Formed in ε-Caprolactone–Butadiene Diblock Copolymers

“…31 Figure 7 shows the Mw dependence of le and la, where both le and la increase with M w, though la is much larger than le. The large value of la suggests the insertion of PB blocks between PCL lamellae.…”