Effect of the temperature on the chemical healing of poly(ethylene terephthalate)

The effect of temperature on the chemical healing of poly(ethylene terephthalate) (PET) – healing as a result of chemical reactions between neighboring macromolecules located in the interface surface — was studied. The healing process was carried out in vacuum on pressed partially overlapped strips of commercial PET, previously annealed at 258°C, at temperatures between 140 and 250°C for 24 h. It is demonstrated that the fracture behavior of the welded samples depends strongly on the healing temperature T_h. At T_h > 200°C the strips break beyond the contact area, at 160 < T_h < 200°C debonding occurs, and at T_h < 160°C no bonding is observed. It is assumed that the bonding effect is mainly a result of chemical reactions (solid state postcondensation and transreactions) taking place during the healing procedure.