Investigation on isothermal crystallization, melting behaviors, and spherulitic morphologies of multiblock copolymers containing poly(butylene succinate) and poly(1,2‐propylene succinate)

Abstract

In this article, isothermal crystallization, melting behaviors, and spherulitic morphologies of highimpact multiblock copolymers, comprising of PBS as hard segment and poly(1,2-propylene succinate) (PPSu) as soft segment with hexamethylene diisocyanate as a chain extender, were investigated. The results from differential scanning calorimetry (DSC) suggest that the two segments of multiblock copolymers are miscible in amorphous region. The crystallization kinetics were analyzed by the Avrami equation. The effect of PBS segment length as well as the introduction of PPSu segment on the crystallization kinetics and melting bebaviors of block copolymers was studied. Both crystallization rate (G) and spherulitic growth rate (g) are markedly increased with the increase of PBS segment length or decreased with the incorporation of PPSu segment. All the multiblock copolymers show the multiple melting behaviors, whose position and area depend on PBS segment length and the presence of PPSu segment. The melting peaks shift to higher temperature region with increasing PBS segment length. Spherulitic morphologies of the multiblock copolymers after being isothermally crystallized were examined by polarized optical microscopy. It is the first time to investigate the effect of one segment length on crystallization bebavior of block copolymers based on a fixed weight ratio systematically.

Critical Stress for Crystal Transition in Poly(butylene succinate)-Based Crystalline–Amorphous Multiblock Copolymers

“…In the previous reports, − PPS was termed as amorphous block in PBS- co -PPS without providing any diffraction information. Based on the analysis of glass transition temperature, it was proposed that PPS block is miscible with the amorphous phase of PBS. − Here we present a more systematic investigation on the microstructure of PBS- co -PPS. Figure shows the WAXS intensity profiles of PBS- co -PPS.…”

“…The T g of PBS- co -PPS is higher than that of PBS homopolymer, which increases with the PPS content. The T g * listed in Table is estimated by the Fox equation 1 T g * = 1 − w normal P P S * T g , PBS + w PPS * T g , PPS where T g, PBS and T g, PPS are 240.55 and 267.85 K, respectively. The weight fraction of PPS ( w * PPS ) is calculated taking account of the crystallinity of the system: w PPS * = w PPS 1 − X normalc It can be observed that the measured T g deviated from the estimated T g * remarkably as the PPS fraction increasing.…”

“…Recently, multiblock copolymers consisting of PBS blocks and amorphous poly(1,2-propylene succinate) blocks (PPS) were synthesized to improve the impact toughness of PBS. − Based on the single glass transition temperature ( T g ), the PPS blocks were assumed to be miscible with the amorphous phase of PBS . These copolymers provide an opportunity to explore the effect of chain composition on the stress-induced crystal transition and to further understand the micromechanical deformation mechanism of semicrystalline polymers.…”

The crystallization behaviors of copolymeric flame‐retardant poly(ethylene terephthalate) with organophosphorus

“…Many investigators thought that the Peak I corresponded to the melting subsidiary lamellae and it was due to the melting of the material crystallized previously. Meanwhile, the Peak II corresponded to the melting the recrystallization . According to Hoffman–Weeks theory , the equilibrium melting temperature T m 0 was obtained by extrapolating the line of the temperature of Peak I versus T c to the line of T m = T c .…”

Crystallization and photo‐curing kinetics of biodegradable poly(butylene succinate‐co‐butylene fumarate) short‐segmented block copolyester

“…The aim of designing copolymers is to improve the homopolymer properties and to achieve better processability, chemical resistance and higher mechanical properties. In fact, final and favorable modified properties of copolymers can be achieved, depending on the type, amount and distribution of the comonomer units along the polymer chain . More recently, the mechanical properties of PBS were improved through preparation of biodegradable PBS multiblock copolymers via copolycondensation of succinic acid and butandiol with low molecular weight poly(ethylene oxide) or via chain extension of PBS with other hydroxy‐terminated polymers, such as poly(1,2‐propylene succinate) or poly(1,2‐propylene terephthalate), or through melt mixing of PBS and poly(triethylene succinate) .…”