Dynamic light scattering experiments on thermoreversible pregels from chemically modified PVC

Abstract

 Dynamic light-scattering experiments have been performed on solutions of poly(vinyl chloride) (PVC) and chemically modified PVC (HPVC) in diethyl oxalate (DEO). Hydrodynamic sizes of the clusters in the solution were measured as a function of temperature, concentration and quenching temperature.

The higher the starting concentration of the PVC and HPVC solutions the larger the size of the aggregates formed. However, clusters formed by pure PVC are smaller than those formed by modified PVC. Aggregate sizes decrease with increasing temperature whereby a change in the cluster melting process is observed at 55 °C. Successive dilution of highly concentrated aggregate solutions causes reduction of the cluster size until a critical dilution concentration is reached below which no further reduction in size occurs. The lower the temperature at which the solutions are quenched the larger the clusters which are formed.

We believe that all results can be interpreted using a model developed by Guenet [1–4] which describes the molecular structure of PVC/DEO gels and pregels.