Delayed Phase Inversion Research Articles

Mechanical properties of ethylene-vinyl acetate/polystyrene blends studied byin situ polymerization

This study examined ethylene–vinyl acetate (EVA)-toughened polystyrene (PS). EVA is well-known to be incompatible with PS; thus, the PS graft to the EVA backbone (EVA-g-PS) was used as a compatibilizer and provided good adhesion at the interface of PS and EVA. In addition, the mechanical properties and impact resistance of the PS matrix were obviously improved by EVA-g-PS and by EVA itself. Meanwhile, differential scanning calorimetry results showed that the grafted PS chain influenced the crystallization of EVA; for example, the melting temperature, the crystallization temperature, and the percentage crystallinity related to EVA were reduced. Moreover, the addition of 10% EVA increased the impact strength by a factor of five but reduced the modulus by the same factor. Additionally, a lower number-average molecular weight EVA delayed phase inversion and resulted in poor mechanical properties. A fracture surface photograph revealed that the major mechanism of EVA-toughened PS was craze and local matrix deformation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 699–705, 2003

Morphological Change in Drop Structure with Time for Abnormal Polymer/Water/Surfactant Dispersions

The morphological variation of complex drops of oil/water/oil (O/W/O) in unstable polymer/water/surfactant systems was investigated. A new, but simple, technique was developed to measure the internal phase ratio of multiple drops. The morphology change occurred because of inclusion of oil droplets into the dispersed water drops which contained water-soluble surfactant. The variation in morphology can lead to a delayed phase inversion if a substantial variation in the effective volume fraction of the dispersed phase occurs. The time sequence of the morphology change of complex drops is as follows: In the early stage of stirring, most water drops that are formed contain no internal oil droplets but some contain large internal oil droplets. As time proceeds, the relative size of the internal oil droplets to that of surrounding water drops is appreciably reduced, while the water drops become richer in the continuous phase. The progressive increase in the internal phase ratio of the dispersed phase will conti...

Delayed phase inversion in stirred liquid—liquid dispersions

Delayed phase inversion in stirred liquid—liquid dispersions