Abstract
Morphological changes of unsaturated polyester/polyvinylacetate semi-IPN were studied while the phase separation and the cure reaction occurred in a competing fashion. The light scattering and thermal analysis techniques were used to investigate the phase separation rates and mechanical properties resultantly induced by molecular diffusion of thermoplastic polymer during the curing process of thermosetting polymer. The reaction activation energy was calculated by using Flynn-Wall method and the semi-IPN structure exhibited various phase-separation morphological characteristics. When PVAc composition was 10 wt%, the phase separation was not observed during the curing reaction, but the phase separation occurred in a similar fashion to nucleation and growth(NG) mechanism at room temperature. On the other hand, when PVAc composition was over 11.65 wt%, the phase separation was generated in the middle of the curing process. Consequently, the phase separation seemed to influence the curing reaction rate, which was also supported by the changing activation energy with conversion and PVAc composition. Finally, the total scattered intensity was measured at various temperature, and subsequently the diffusion rates of phase separation R(${\beta}m$) were evaluated.
불포화폴리에스터/폴리비닐아세테이트 semi-IPN의 경화과정 중 경화속도와 상분리 확산속도의 상호관계 속에서 형성되는 상분리 모폴로지를 광산란 및 열분석 장치를 이용하여 연구하였다. 열경화성 고분자의 경화과정 중 열가소성 고분자의 확산에 기인한 물성의 변화를 측정하였고, 상분리를 수반하는 경화과정에서의 활성화에너지의 변화를 Flynn-Wall method를 이용하여 구하였다. 반응에 의하여 나타나는 상분리현상은 경화과정 중 다양한 상분리 거동을 나타내게 되는데, 폴리비닐아세테이트가 10 wt%일 경우에는 반응도중에 상분리가 일어나지 않고 냉각 후 상온에서 nucleation & growth 거동과 유사한 형태로 상분리가 발생하였고, 11.65 wt% 이상에서는 반응도중 spinodal decomposition으로 사료되는 상분리가 발생하였다. 또한 상분리현상이 경화속도에 영향을 미친 것을 활성화에너지의 변화거동으로부터 확인하였으며, 온도변화에 따라 총산란량을 측정하였고 이로부터 확산에 의한 상분리 속도 R(${\beta}_m$)를 비교하였다.
