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A series of thermally reversible gels made from a solution of bio-based, biodegradable poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBHx) in dimethylformamide (DMF) were analyzed using wide angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). WAXD results demonstrate the existence of crystalline PHBHx in the polymer gel...
Understanding the crystal structure and thermal behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx) and its blends thin film under spatial confinement is crucial for its application in molecular scale devices and advanced nanotechnology. In this study, we investigate the influence of polyethylene glycol (PEG) on the morphology and molecular orientation of PHBHx thin films using scanning...
The rheological properties of a series of microbially synthesized poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)s (PHB-HHxs), with varying comonomer (HHx) content, were systematically investigated. Shear viscosities show dependence on the rate of deformation, temperature, molecular weight, and copolymer compositions. The zero-shear viscosity η 0 follows the classical Mw3.4 power-law relationship...
With the ultimate goal to design renewable polymer nanocomposites with optimal mechanical properties, this study reports an investigation of structure–property relationships for a model system – silica/poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx) nanocomposites. Two molecular weights of PHBHx (M w =903,000g/mol and M w =633,000g/mol) and two types of silica nanoparticles (nominally...
The miscibility, crystallization and subsequent melting behavior in binary biodegradable polymer blends of poly(l-lactic acid) (PLLA) and low molecular weight poly(3-hydroxybutyrate) (PHB) have been investigated by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and wide-angle X-ray diffraction (WAXD). DSC analysis results indicted that PLLA showed no miscibility...
Thermally induced structural and conformational changes in polyethylene (PE) samples were explored by using near-infrared (NIR) spectroscopy. The differences in the temperature-dependent structural disordering process among six PE samples were depicted by monitoring the intensities of NIR bands characteristic of orthorhombic crystalline phase. The temperature dependency of bands in the NIR region...
Thermally induced conformational changes that occur in high-density polyethylene (HDPE) crystal were studied by mid-infrared (MIR) spectroscopy. Spectral changes of four conformational “defect mode” bands in 1390–1280cm −1 region were observed during the heating up to the melt. The spectra were analyzed by generalized two-dimensional (2D) correlation technique to elucidate correlations in...
The multiple melting behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) (HHx=12mol%) isothermally crystallized from the melt state has been characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The influence of different experimental variables (such as crystallization temperature, time, and heating rate) on the multiple melting...
Biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-HHx)/hydrophobically modified silica hybrid composites were prepared using simple melt compounding and the effect of hydrogen bonding on their crystallization behavior was observed. The intermolecular hydrogen bonding between PHB-HHx and silica increased gradually with the increase of silica content of the hybrid composites. However,...
Comparison of miscibility and structure of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) (P(HB-co-HHx)) (M w =638,000gmol −1 ) and poly(l-lactic acid) (PLLA) (M w =150,000gmol −1 ) with those of poly((R)-3-hydroxybutyrate) (PHB) (M w =600,000gmol −1 ), and PLLA having the blending ratios was investigated by wide angle X-ray diffraction (WAXD),...
The structure, dispersibility, and crystallinity of poly(3-hydroxybutyrate) (PHB) and poly(l-lactic acid) (PLLA) blends are investigated by using Raman microspectroscopy. Four kinds of PHB/PLLA blends with a PLLA content of 20, 40, 60, and 80wt% were prepared from chloroform solutions. Differences in the Raman microspectroscopic spectra between the spherulitic and nonspherulitic parts in the blends...
Crystallization behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) (HHx=12mol%) was studied by means of two-dimensional infrared (2D IR) correlation spectroscopy. Three types of crystallization; the gradual cooling from the melt, the isothermal crystallization of the supercooled melt, and the isothermal crystallization of the solution-cast film were investigated. The order of...
The surface melting and crystallization behavior of two biodegradable polyesters, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) (HHx=12mol%) and poly(3-hydroxybutyrate) (PHB), were investigated by using attenuated total reflection (ATR) and transmission infrared (IR) spectroscopy coupled with the generalized two-dimensional (2D) correlation analysis. IR bands in the CO stretching vibration...
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