Multiple melting behavior of poly(butylene succinate). II. Thermal analysis of isothermal crystallization and melting process

Autor: Shinsuke Tsubakihara, Tadashi Satou, Koji Iura, Munehisa Yasuniwa
Rok vydání: 2005
Předmět:
Zdroj: Journal of Polymer Science Part B: Polymer Physics. 43:2039-2047
ISSN: 1099-0488
0887-6266
DOI: 10.1002/polb.20499
Popis: The multiple melting behavior of poly(butylene succinate) (PBSu) was studied with differential scanning calorimetry (DSC). Three different PBSu resins, with molecular weights (MWs) of 1.1 x 10 5 , 1.8 x 10 5 , and 2.5 x 10 5 , were isothermally crystallized at various crystallization temperatures (T c ) ranging from 70 to 97.5 °C. The T c dependence of crystallization half-time (z) was obtained. DSC melting curves for the isothermally crystallized samples were obtained at a heating rate of 10 K min -1 . Three endothermic peaks, an annealing peak, a low-temperature peak L, and a high-temperature peak H, and an exothermic peak located between peaks L and H clearly appeared in the DSC curve. In addition, an endothermic small peak S appeared at a lower temperature of peak H. Peak L increased with increasing T c , whereas peak H decreased. The T c dependence of the peak melting temperatures [T m (L) and T m (H)], recrystallization temperature (T re ), and heat of fusion (ΔH) was obtained. Their fitting curves were obtained as functions of T c . T m (L), T re , and ΔH increased almost linearly with T c , whereas T m (H) was almost constant. The maximum rate of recrystallization occurred immediately after the melting. The mechanism of the multiple melting behavior is explained by the melt-recrystallization model. The high MW samples showed similar T c dependence of τ, and τ for the lowest MW sample was longer than that for the others. Peak L increased with MW, whereas peak H decreased. In spite of the difference of MW, T m (L), T m (H), and T re almost coincided with each other at the same T c . The ΔH values, that is crystallinity, for the highest MW sample were smaller than those for the other samples at the same T c .
Databáze: OpenAIRE
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