COMPATIBILITY OF COMPONENTS IN POLYOLEFINS - ETHYLENE-VINYL ALCOHOL COPOLYMER SYSTEMS

To develop composite materials based on mixtures of polymers incompatible or partially compatible from the point of view of thermodynamics, it is necessary to study the mutual solubility of the components, This is due to the fact that there may be a layer of a certain length and thickness at the interface, which is formed due to the segmental solubility of the components of the polymer mixture. This is due to the significant influence of the phase structure and characteristics of the interphase boundary of the entire complex of operational and technological characteristics of polymer mixtures. The mutual diffusion of components of polymer systems polyolefin/ethylene copolymer with vinyl alcohol (SEVC) has been studied by laser microinterferometry. It has been established that when components are combined above the melting temperatures of polymers, all systems are characterized by a phase boundary and lack of areas of partial compatibility. The absence of mutual diffusion of the components is indicated by the fact that the interferograms do not show an S-shaped curvature of the interference fringes. Even an increase in temperature above 250 °C does not lead to an improvement in the mutual solubility of the components. At high temperatures, due to temperature changes in the refractive index of the components, a decrease in the density of interference fringes is observed. Lowering the temperature of the experiment below the crystallization temperature of the component leads to uniform crystal formation over the entire observation area up to the phase boundary, which also confirms the absence of any mutual diffusion in the system. However, studies of polymer mixtures using the DSC method have shown a slight decrease in the melting point of the SEVC phase, indicating a slight diffusive penetration of segments of the second component into the epitaxial layers of the SEVC phase structure and their misorientation. The diffusion mechanism of the near-surface mixing of the components of the studied polymer pairs is confirmed by studies of the delamination resistance of duplicated systems formed at different temperatures and contact times.