“…Materials. Atactic poly( R , S -3-hydroxybutyrate) (a-PHB; diad isotacticity determined by 13 C NMR is 0.5) was synthesized through anionic polymerization in bulk with potassium oleate/18-crown-6 ether complex as an initiator. , The weight-averaged molecular weight ( M w ) and the molecular weight distribution ( M w / M n ) of a-PHB, estimated by GPC measurement, are 4.55 × 10 4 and 1.17, respectively. 1 First-run DSC traces of pure a-PHB, PVPh, and their blends with PVPh content of 20 (80/20), 30 (70/30), 40 (60/40), 50 (50/50), and 60 wt % (40/60).…”
An interesting phenomenon, the thickening and thinning of polymer films in the water
media, was investigated in this paper. The studied polymer films were cast from atactic poly(R,S-3-hydroxybutyrate)/poly(4-vinylphenol) (PVPh) and syndiotactic poly(R,S-3-hydroxybutyrate)/PVPh blends
solution. The physical properties of the blend films were characterized by differential scanning calorimetry
(DSC), and the hydrogen-bonding network in the blends was characterized with the employment of Fourier
transform infrared spectroscopy (FT-IR). The thickening and thinning process of the polymer films in
water media was monitored by the measurement of the thickness. The effects of temperature and
surfactants on the process were evaluated, furthermore, and the essence of the thickening and thinning
of the polymer films was discussed.
“…Materials. Atactic poly( R , S -3-hydroxybutyrate) (a-PHB; diad isotacticity determined by 13 C NMR is 0.5) was synthesized through anionic polymerization in bulk with potassium oleate/18-crown-6 ether complex as an initiator. , The weight-averaged molecular weight ( M w ) and the molecular weight distribution ( M w / M n ) of a-PHB, estimated by GPC measurement, are 4.55 × 10 4 and 1.17, respectively. 1 First-run DSC traces of pure a-PHB, PVPh, and their blends with PVPh content of 20 (80/20), 30 (70/30), 40 (60/40), 50 (50/50), and 60 wt % (40/60).…”
An interesting phenomenon, the thickening and thinning of polymer films in the water
media, was investigated in this paper. The studied polymer films were cast from atactic poly(R,S-3-hydroxybutyrate)/poly(4-vinylphenol) (PVPh) and syndiotactic poly(R,S-3-hydroxybutyrate)/PVPh blends
solution. The physical properties of the blend films were characterized by differential scanning calorimetry
(DSC), and the hydrogen-bonding network in the blends was characterized with the employment of Fourier
transform infrared spectroscopy (FT-IR). The thickening and thinning process of the polymer films in
water media was monitored by the measurement of the thickness. The effects of temperature and
surfactants on the process were evaluated, furthermore, and the essence of the thickening and thinning
of the polymer films was discussed.
“…It is being used in clinics as a surgical material,7 and in controlled‐drug delivery systems 8. To fulfill the growing need of the biomaterials for medical applications, a significant amount of research has been devoted to the biodegradable polyester blend to modify their mechanical, thermal, and degradation properties 9–18. There have been ample reports that many factors might influence bio‐degradability of polymers, such as functional groups, side chains, crystalline forms, crystalline structures, crystallinities, etc.…”
Specific interactions and miscibility are demonstrated in a series of binary miscible blend comprising of bio-compatible/biodegradable polyesters, such as poly(epsilon-caprolactone) (PCL), poly(ethylene adipate) (PEA), or poly (butylene adipate) (PBA), and a macromolecular ester with polyphenol groups, tannic acid (TA). Thermal analysis and infrared spectroscopy were used for proving existence of favorable interactions, and polarized-light optical microscopy was used for characterizing the changes in crystal growth. The appearance of a single composition-dependent glass transition temperature (T(g)) observed by differential scanning calorimetry (DSC) indicated that TA is miscible with PCL, PBA, and PEA, respectively, over the entire range of compositions. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of specific intermolecular hydrogen bonding interactions between the carbonyl groups of polyesters and the phenolic hydroxyl groups of TA. The blend T(g)'s generally exhibited various extents of positive-then-negative deviation from linearity with the compositions. The T(g)-composition relationships for three blend systems could all be fitted by the Kwei equation with large negative q values of -80 to -110 for different polyesters. Significant effects by TA on the spherulitic crystallization growth in the polyester/TA blends were also discussed to support the miscibility and strong interactions. Overall, the behavior of blends of polyesters with TA is similar to that of blends of polyesters with poly(vinyl p-phenol) (PVPh) that have been more widely studied and reported. However, TA is naturally bio-resourceful, bio-compatible, and bio-degradable but PVPh is not. Synergism of miscibility, natural bio-compatibility, and biodegradability in these blends by introducing naturally biodegradable macromolecules such as TA may offer greater potential in intended applications.
“…In the past few years, our research has been focused on poly(hydroxyalkanoic acid)s (PHAs) 12–16. Recently we noted, when we investigated the properties of the of PHA inclusion complex and cyclodextrin, that the nucleation of the PHA segment in its partial inclusion complex with cyclodextrin was enhanced and the crystallization was accelerated 17.…”
The effect of ␣-cyclodextrin (␣-CD) on the crystallization behavior of poly(3hydroxybutyrate) (PHB) was investigated with polarized optical microscopy, differential scanning calorimetry, and wide-angle X-ray diffraction. We found that the addition of ␣-CD can greatly accelerate the crystallization of PHB and that ␣-CD has a potential not only to enhance the nucleation but also to accelerate the crystallization of PHB. Compared to a conventional nucleation agent, such as talc, ␣-CD is a natural product and has many advantages because it is environmentally friendly and safe to humans.
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