Thermal properties and crystallization kinetics of poly(butylene suberate)

Abstract

In this work, we synthesized poly(butylene suberate) (PBSub) with a weight average molecular weight of 3.64 × 104 g/mol from the monomers of butanediol and suberic acid via a two-step melt polycondensation method. The basic thermal behaviors, overall isothermal melt crystallization kinetics, crystal structure, spherulitic morphology and growth, thermal stability, and hydrolytic degradation of PBSub were systematically investigated for the first time. PBSub has a low glass transition temperature of about −61 °C, a melting point of 55.2 °C, and an equilibrium melting point of 61.4 °C. The overall isothermal melt crystallization kinetics of PBSub was investigated at different crystallization temperature values and analyzed by the Avrami equation. PBSub has an average Avrami exponent value of about 3, suggesting that the crystallization mechanism of PBSub may correspond to three-dimensional truncated sphere growth with athermal nucleation. An obvious spherulitic morphology was observed for PBSub, and the spherulitic growth rates decrease with increasing crystallization temperature. PBSub exhibits a crystallization regime II to regime III transition on the basis of the secondary nucleation theory. The crystal structure study reveals that PBSub is highly crystalline, presenting strong diffraction peaks and a great crystallinity of about 55%. The thermogravimetric analysis study demonstrates that PBSub has both a high decomposition temperature at 5 wt% weight loss of about 377 °C and a high temperature at the maximum degradation rate of about 421 °C, suggesting its good thermal stability. PBSub may undergo a hydrolytic degradation, which may be of interest for its end use as a degradable material in some special application fields.