Phase structure and compatibility studies in poly(ethylene oxide)/poly(methyl methacrylate) blends

Abstract

Morphology, crystallinity, and melting behaviour of solution-cast films of poly(ethy1ene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of composition, using optical and scanning electron microscopy, differential scanning calorimetry, and dilatometry. Up to a content of about 40 wt.40 of PMMA the blend films are completely filled with PEO spherulites, no separated domains of PMMA being observed. This observation suggests, in agreement with small angle X-ray scattering analysis, that for such compositions the PMMA molecules are incorporated in interlamellar regions of PEO spherulites. Blends with higher content of PMMA show islands of crystalline PEO within a matrix of PMMA; large amorphous regions coexist with not well developed PEO spherulites. Addition of PMMA strongly increases the nucleation density for PEO crystals. The solubility parameters 6 of PEO and PMMA were calculated from specific volume values as a function of temperature. It was found that at temperatures higher than that of PEO melting the difference 6(PEO) -G(PMMA) is very low suggesting that the two polymers are compatible in the melt. Compatibility of PEO and PMMA was also predicted by using a theoretical approach which allows to calculate the free energy of mixing as a function of composition and temperature.

Casting solvent effect on crystallization behavior and morphology of poly(ethylene oxide)/poly(methyl methacrylate)

“…The scales of optical micrographs were all the same. The results were similar to those reported by Martuscelli et al 28 The blends used in ref. 28 were also cast from chloroform.…”

“…Such unusual behavior of glass transition was reported in the literature. 4,28,29 Alfonso and Russell proposed that the reason for this unusual behavior was that the T g observed was not the true T g of the blend but rather a relaxation associated with the crystal/amorphous interface. 4 The true T g would be close to the melting point of PEO crystal.…”

“…The experimental value of T g of neat PEO was reported to be in the range Ϫ45 to Ϫ60°C in the literature. 3,6,7,[21][22][23][24][25][26][27][28] The solid line in Figure 3 represented the T g values of the blends estimated from the Fox equation,…”

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

“…Topics have been covered ranging from the effects of casting solvents, crystal/spherulite morphology, crystallization, thermal behavior and oxidation, and interaction parameters to IR vibrational spectroscopy and NMR studies on PEO/PMMA. [1][2][3][4][5][6][7][8][9][10][11][12] PEO contains an ether group in the main chain, whereas PMMA possesses a carboxyl group in its pendant position. No specific interactions such as hydrogen bondings may be expected between these two polymers.…”

Blends of polycarbonate and acrylic polymers: Crystallization of polycarbonate

“…We have postulated that the surface is a two-dimensional representation of what happens in the bulk. This hypothesis has been put forward by others 18,53 who analyzed the spherulitic structure at the surface of thin films by SEM.…”