Vitrification and crystallization of poly(butylene-2,6-naphthalate)

• Poly(butylene-2,6-naphthalate) (PBN) was apparently vitrified when cooling rate was larger than 6000 K/s.
• Cooling rate larger than 30,000 K/s prevented not only crystallization but also nucleation.
• Heating rate faster than 7000 K/s prevented cold crystallization from glassy state.
• Mesophase formation and crystallization have been observed on the less severe cooling and heating conditions.

The differential fast scanning calorimetry (DFSC) technique has been successfully applied to study the vitrification and crystallization of poly(butylene-2,6-naphthalate) (PBN). The cooling rate larger than 6000 K/s could make the PBN vitrify and the cooling rate larger than 30,000 K/s reduced effectively the development of the active nuclei. The critical cooling rate of 30,000 K/s is three times as large as that of the recently reported poly(ϵ-caprolactone) (PCL)'s. Namely, it turned out that PBN is a hard-to-vitrify polymer. The heating rate faster than 7000 K/s could prevent the cold crystallization from the proper glassy state. In the less severe cooling and heating rates than 30,000 K/s and 7000 K/s, respectively, a variety of structure formations, such as the nucleation, the mesophase formation, the crystallization and their multiple melting behaviors, have been observed.