| 초록 |
It is well kwon that poly(vinyl chloride) (PVC) can form thermoreversible gels in a large number of solvents. One of the remarkable characteristics of PVC gels is that the addition of a high lever of the plasticizer to PVC still allows the system to remain a useful degree of mechanical strength and elasticity. This surprising property has been difficult to explain why a mainly atactic polymer like PVC can from gels exhibiting very high elastic modulus. However, the mechanism of gel formation and the structure of PVC thermoreversible gels have still not been fully elucidated. In this work, the structure and physical properties of PVC gels prepared from the solution of dibutyl phthalate(DBP) and butyl benzoate(BB) are investigated. The influence of solvent type on the mechanical responses was investigated by dynamic viscoelastic measurements as a function of temperature and aging time. In the case of PVC/DBP aged gels, transition phenomenon appeared close to 60℃, which can not be observed in PVC/BB gels. This transition was considered to be associated with polymer-solvent complex, which might result from electrostatic interactions between the polarized C=O bonds of the diester and polarized H-C-Cl bond of PVC. Also, FT-IR, DSC, and SAXS experiments on either diester or monoester gels will be reported and discussed together with the dynamic mechanical behavior. Finally, the structure of PVC gels will be fully elucidated. |
