The synthesis of poly(ester amide) copolymers (PBTA) based on poly(butylene terephthalate) (PBT) and nylon-4,T with the diamide of butanediamine and dimethyl terephthelate (N,N′-bis(p-carbomethoxybenzoyl)butanediamine) has been carried out. Different melt and solid state condensation reactors were used. The polycondensation of PBT and PBTA with 20–25 mol% of amide units (PBTA20/PBTA25) was carried out in the melt at 255–265°C under high vacuum. The inherent viscosity ηinh, the amino and carboxylic acid endgroup concentrations and the melting temperature (Tm) were determined. The influence of diamide purity and concentration of Ti catalyst (0.02–0.28 mol%) was studied. The concentration of Ti catalyst had little effect. The purity of the diamide had an effect on ηinh but also on Tm. Postcondensation in the solid phase, 20°-30°C below Tm, was most effective after short melt polymerization times.
- Polybutylene terephthalate