Non‐isothermal crystallization kinetic of recycled PET and its blends with PBT modified with epoxy‐based multifunctional chain extender

Abstract

A fundamental understanding of crystallization behavior is essential for the processing of both virgin and recycled polymers. This research delves into the crystallization characteristics and non‐isothermal crystallization kinetics of recycled polyethylene terephthalate (rPET) and its blends with poly butylene terephthalate (PBT), which have been modified using epoxy‐based multifunctional chain extenders (CE). The preparation of rPET/PBT blends involved a twin‐screw extruder, with varying weight ratios and different CE concentrations. Differential scanning calorimetry was employed to perform crystallization analysis on the samples. The results underscore the profound impact of blend composition on the thermal characteristics of the system, with CE exerting only a marginal influence. The glass transition temperatures (Tg) of the two polymers were measured at 49 and 79°C. During blending, the Tg values demonstrated variations relative to the proportions but did not adhere to the Fox equation. Furthermore, PBT was found to enhance the crystallization tendencies of rPET, resulting in an increase in relative crystallinity from 11% to 36%. Notably, the crystallization rate of PBT at 0.40 min−1 exceeded that of rPET at 0.36 min−1. PBT minimally affected the crystallization rate constant of rPET‐dominant blends, while rPET significantly reduced the crystallization rate in PBT‐dominant blends.

Melt Rheological and Bead Foaming Behavior of Recycled Polyethylene Terephthalate/Polybutylene Terephthalate Blends Modified with a Joncryl Chain Extender

“…In a previous study, it was demonstrated that when the processed PET/PBT blends are fast-cooled, crystalline phases are immiscible, whereas slow cooling could cause the cocrystallization of PET and PBT, leading to the full miscibility of PET and PBT polymers . The crystallization kinetics of the 25/75 blend sample, which confirms our discussion, is comprehensively studied elsewhere …”

“…54 The crystallization kinetics of the 25/75 blend sample, which confirms our discussion, is comprehensively studied elsewhere. 94 3.3. Bead Foaming Behavior.…”