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Studies on Binary Blends of Poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyhexanoate) and Natural Polyphenol Catechin: Specific Interactions and Thermal Properties
Author(s) -
Zhu Bo,
Li Jianchun,
He Yong,
Inoue Yoshio
Publication year - 2003
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200390036
Subject(s) - glass transition , differential scanning calorimetry , crystallinity , dynamic mechanical analysis , materials science , catechin , hydrogen bond , fourier transform infrared spectroscopy , analytical chemistry (journal) , polymer chemistry , miscibility , chemistry , crystallography , chemical engineering , polyphenol , composite material , organic chemistry , thermodynamics , polymer , molecule , physics , antioxidant , engineering
The existence of a specific intermolecular hydrogen‐bonding interaction between poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyhexanoate) [P(3HB‐ co ‐3HH)] and (+)‐catechin in their blends was demonstrated by Fourier‐transform infrared spectroscopy (FT‐IR). It was found that the experimentally estimated fraction of hydrogen‐bonded carbonyl groups was much lower than the theoretically predicted maximum fraction. Only one glass transition temperature ( T g ) occurred in the blends with the compositions detected by differential scanning calorimetry (DSC), being further confirmed by the results of dynamic mechanical thermal analysis (DMTA). The decrease of the melting point ( T m ) and the increase of the glass transition temperature of the blends observed by the DSC measurements also suggested the existence of a strong intermolecular interaction. It was interesting to note that, as a low‐molecular‐weight compound, catechin showed a glass transition, which arises from strong self‐association. As expected, the crystalline structure of P(3HB‐ co ‐3HH) in the blends showed no change, but the crystallinity of the copolymer component in the blends, calculated by wide‐angle X‐ray diffraction, decreased with the increase of catechin weight content. Investigated by tensile experiments, the maximum strength and modulus decreased sharply with the increase of catechin content; on the contrary, the elongation changed slowly.The FT‐IR spectra in the wave‐number 1 680–1 780 cm −1 region for blends of P(3HB‐ co ‐3HH)/catechin. A: HBH; B: HBHC10; C: HBHC20; D: HBHC30; E: HBHC40; F: HBHC50; and G: catechin.