Papers by Keyword: Immiscibility

Abstract: In this work, the effect of ethylene vinyl acetate (EVA) on the rheological and mechanical properties of low-density polyethylene (LDPE)-based greenhouse plastic films was explored. The rheological experiments showed that, for given PE and EVA, both complex viscosity and storage moduli of LDPE/EVA blends were not significantly affected when EVA content is less than 30%wt but increased with increasing EVA content thereafter. However, the mechanical results inconsistently showed that blown films with 10%wt EVA content gave the most superior mechanical properties compared to other blends. It was found that, at higher EVA contents, immiscibility between the LDPE and EVA phases occurred, resulting in much poorer mechanical performance.

Abstract: PLA/PCL and PLA/PCL/LTI blends were developed to improve the fracture properties of biodegradable PLA. LTI was blended to improve the miscibility of PLA and PCL. It was shown that the fracture toughness values were dramatically increased due to LTI addition. SEM results also exhibited that PCL spherulites decreases due to LTI addition and therefore, void formation is reduced and local stress concentration is suppressed, resulting in the improvement of the toughness values. The improved miscibility is also closely related to the enhancement of ductile deformation; as a result, the fracture toughness is increased.

Abstract: Attempts have been made to improve the impact resistance
of biodegradable thermoplastic polymer, PLA. A ductile biodegradable polymer, PCL, has been used to improve such property of PLA by using blending technique. Details of the impact fracture properties and mechanisms of PLA/PCL blends, however, have not fully been understood yet. Recently, it was also found that LTI can improve the immiscibility between PLA and PCL. In this study, PLA/PCL and PLA/PCL/LTI blends were prepared, and their impact fracture toughness values were measured
to assess the effect of PCL content and LTI addition on the impact resistance. Fracture mechanisms of the polymer blends were also characterized by scanning electron microscopy.

Abstract: Phase diagrams of mixed crystal systems exhibiting the cooperative Jahn–Teller effect are investigated. The competition of Jahn–Teller interaction with a) the preference energy of cation distribution over nonequivalent sublattices or b) stabilization energy of 3d-ion valence configuration is considered. The developed model enables to explain the nature of equilibrium and metastable states, the variety of phase diagrams and its special features in crystals with the competing interactions.