Isothermal crystallization of sulfonated poly(ethylene terephthalate) ionomer crystal nucleation and growth parameters

Isothermal crystallization of a ionic random copolyster (K-X/SPET) based on poly(ethylcne terephthalate) (PET) was analysed in detail over a compositional range from pure PET to a copolymer containing 10.1 mol % of potassium neutralized sulfonated PET. In measurements differential scanning calorimetry (DSC) was used. A significant influence of the ionic groups on crystal nuclcation and growth was stated. Under isothermal conditions, the nuclcation parameters (width of a critical nuclcus and free energy of forming a critical nucleus) are slightly dependent on the co-unit content. The crystal growth in the ionic copolycsters occurs from the melt by chain folding with trc values comparable to that of the corresponding nonionic homopolymer.