Studies on Spherulitic Morphology and Crystallization Kinetics of Poly(3-hydroxybutyrate) Blended with a Medium-Molecular-Weight Poly(ethylene oxide)

Trong-Ming Don; Pi-Che Chen; Wei-Wei Shang; Hsiu-Jung Chiu

doi:10.6180/jase.2006.9.3.10

Studies on Spherulitic Morphology and Crystallization Kinetics of Poly(3-hydroxybutyrate) Blended with a Medium-Molecular-Weight Poly(ethylene oxide)

Trong-Ming Don This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Pi-Che Chen¹ , Wei-Wei Shang¹ and Hsiu-Jung Chiu²

¹Department of Chemical and Materials Engineering, Tamkang University, Tamsui, Taiwan 251, R.O.C.
²Department of Chemical and Materials Engineering, Ta Hwa Institute of Technology, Chiunglin, Hsinchu 30703, Taiwan, R.O.C.

Received: December 4, 2005
Accepted: December 20, 2005
Publication Date: September 1, 2006

Download Citation: ||https://doi.org/10.6180/jase.2006.9.3.10

ABSTRACT

Spherulitic morphology and crystallization kinetics of poly(ethylene oxide)/poly(3- hydroxybutyrate) blends, PEO/P(3HB), were investigated using differential scanning calorimeter (DSC), polarized optical microscope (POM) and scanning electronic microscope (SEM). A single glass transition temperature was observed for all the blends and the Gordon-Taylor equation follows the T_g-composition dependence very well. Furthermore, the melting point of P(3HB) was depressed by the addition of PEO component and from which the interaction parameter χ₁₂ was calculated to be -0.059 using the Nishi-Wang equation. Thus, it can be concluded that P(3HB) and PEO are miscible in the level of molecular mixing. From POM and SEM observations, P(3HB) spherulites exhibit a banded texture due to the twisting of lamellar crystals. The band spacing is almost a constant, ca. 20 μm, when the crystallization temperature is below 90 ºC, at which the maximum growth rate of P(3HB) spherulites occurs. When P(3HB) is blended with PEO, the growth rate of P(3HB) spherulites decreases because of the dilution effect and a decrease in the degree of undercooling. According to the polymer-diluent theory, the nucleation factor Kg and the folded surface free energy σ_e of P(3HB) crystals are calculated to be 5.648 x 10⁵ K² and 47.2 erg/cm² , respectively. Both values decrease when PEO is added.

Keywords: Poly(3-hydroxybutyrate), Poly(ethylene oxide), Blends, Spherulite

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