title: Crystalline/amorphous phase structure and molecular mobility of biodegradable poly(butylene adipate-co-butylene terephthalate) and related polyesters.
abstract: Differential scanning calorimetry (DSC), atomic force microscopy (AFM), wide-angle X-ray scattering (WAXD), and solid-state (13)C NMR have been used to investigate the crystalline/amorphous structure and molecular mobility of biodegradable poly(butylene adipate-co-44 mol % butylene terephthalate) [P(BA-co-44 mol % BT)] copolyester sample crystallized from the melt. The DSC endothermic peak, which is ascribed to the melting of the crystalline region, was broad relative to those reported for conventional partially crystalline polyesters. In AFM observation, spherulitic morphology was not observed while small particles with a size of about 100 nm were detected. The WAXD pattern of the sample was very broad. These results have indicated that a melt-crystallized P(BA-co-44 mol % BT) sample contains small crystals with a wide distribution in size. A solid-state (13)C NMR technique was also used to perform molecular-level and selective analyses for both butylene terephthalate and butylene adipate units. For the butylene terephthalate units, the existence of two components with different microstructure and molecular mobility was detected: one component was assigned to the alpha-form crystal of poly(butylene terephthalate) homopolymer (PBT) and the other was in amorphous regions. In contrast, all of butylene adipate units were located in amorphous regions. Solid-state NMR data have suggested that sizes of crystalline regions are less than 3 nm.
authors.affiliation: Polymer Chemistry Laboratory and Characterization Center, RIKEN Institute, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kuwabara
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Gan
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Doi
mesh_terms: D001673:Biodegradation, Environmental; D002072:Butylene Glycols / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D002072:Butylene Glycols; D011091:Polyesters; D011108:Polymers; C009204:butylene glycol adipic acid polyester