Morphological variations in PMMA-modified epoxy mixtures by PEO addition

Water Sorption of Interpenetrating Polymer Network Hydrogels Composed of Poly(Ethylene Oxide) and Poly(Methyl Methacrylate)

Anomalous water sorption behavior has been observed in interpenetrating polymer network (IPN) hydrogels composed of poly (ethylene oxide) and poly (methyl methacrylate). The water sorption of IPN hydrogels was investigated gravimetrically by dynamic vapor sorption at a relative humidity of 95%, and the collective diffusion coefficients determined at 25, 35 and 45° C. With increasing temperature the vapor sorption behavior, was affected more by the density of the water vapor than by the hydrophilic properties of the IPN hydrogels. The apparent activation energy was independent on the composition of the IPN hydrogels, with a value of 1.31∼1.90 kJ mol -1. However; the equilibrium water content was dependent on the temperature, decreasing as the temperature increased. The IPN hydrogels exhibited a relatively high equilibrium water contents, in the range 13∼68%.

Morphological Characterization and Mechanical Behavior of Poly(styrene-co-acrylonitrile)-modified Epoxy Matrices

The phase-separation behavior and mechanical properties-morphology relationships of a bifunctional epoxy resin cured with an aromatic diaminic hardener and modified with several quantities of poly(styrene-co-acrylonitrile) (SAN) were investigated by thermal and microscopic analysis and by other techniques. Atomic force microscopy (AFM) revealed that all cured epoxy/SAN blends presented a two-phase structure, each composition giving a different morphology. The influence of cure temperature on phase separation and gelation was studied by solvent extraction and optical microscopy (OM). Flexural and compression behavior as well as fracture toughness results are presented as a function of the amount of copolymer. The toughening effect of adding SAN is greatly dependent on morphological features of the blends. The activation volume for plastic deformation, Vs has been calculated from stress-strain compression curves for both unmodified and 10 wt% SAN-modified epoxy mixtures.