Segregation morphology of poly(3-hydroxybutyrate)/poly(vinyl acetate) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate)/poly(vinyl acetate) blends as studied via small angle X-ray scattering

Segregation morphology of poly(3-hydroxybutyrate) (PHB)/poly(vinyl acetate) (PVAc) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate) (P(HB-co-10% HV)/PVAc blends crystallized at 70 °C have been investigated by means of small angle X-ray scattering (SAXS). Morphological parameters including the crystal thickness (l_c) and the amorphous layer thickness (l_a) were deduced from the one-dimensional correlation function (γ(z)). Blending with PVAc thickened the PHB crystals but not the P(HB-co-10% HV) crystals. On the basis of the composition variation of l_a, and the volume fraction of lamellar stacks (?_s) revealed that PHB/PVAc blends created the interlamellar segregation morphology when the weight fraction of PVAc (w_PVAc)≤0.2 and the interlamellar and interfibrillar segregation coexisted when w_PVAc>0.2, while P(HB-co-10% HV)/PVAc blends yielded the interfibrillar segregation morphology at all blend compositions. For both PHB/PVAc and P(HB-co-10% HV)/PVAc blends, the distance of PVAc segregation was promoted by increasing PVAc composition and the distance of PVAc segregation in P(HB-co-10% HV)/PVAc blends was greater than in PHB/PVAc at a given PVAc composition. The crystal growth rate played a key role in controlling the segregation of PVAc.     

Solid-state NMR study on the structure and mobility of the noncrystalline region of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The noncrystalline structures of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers were studied by variable temperature solid-state wide-line ¹H NMR and solid-state high-resolution ¹³C NMR spectroscopy. It is found that at room temperature there exists a rich and rigid component in the noncrystalline region of PHB and PHBV. The content of this component decreases with the increase in 3-hydroxyvalerate content in PHBV and with the increase in temperature. The brittleness of PHB may be partly attributed to the rigidness of the noncrystalline region at room temperature, while the improvement of the properties of PHBV may come from the enhanced mobility of the noncrystalline region.     

Miscibility and carbon dioxide transport properties of poly(3-hydroxybutyrate) (iPHB) and its blends with different copolymers of styrene and vinyl phenol

This work summarizes the miscibility and transport properties of different polymer blends obtained by mixing a bacterial, isotactic poly(3-hydroxybutyrate) (iPHB) with copolymers of styrene and vinyl phenol (Sty-co-VPh copolymers). Given that iPHB and pure commodity poly(styrene) (PS) form immiscible blends, PS has been modified by copolymerizing it with vinyl phenol (VPh) units, in an attempt to promote blend miscibility. VPh units have appropriate functional groups that interact with iPHB ester moieties. The potential miscibility was investigated by differential scanning calorimetry (DSC) measuring the glass transition temperatures of blends of different compositions. As an additional test, the interaction parameter between the two components, using the iPHB melting point depression caused by the second component, was also measured. Copolymers containing less than 90% styrene showed miscibility with iPHB.Given the remarkable barrier properties of iPHB to gases and vapours, the study has been completed by measuring transport properties of carbon dioxide through different iPHB/Sty-co-VPh copolymer blends, using gravimetric sorptions in a Cahn electrobalance. A clear difference was observed between the behaviour of rubbery blends and those that exhibit a glassy behaviour at the selected experimental temperature (303 K).     

Intermolecular interactions and crystallization behaviors of biodegradable polymer blends between poly (3-hydroxybutyrate) and cellulose acetate butyrate studied by DSC, FT-IR, and WAXD

Relationships between composition- and temperature-dependent intermolecular interactions and cold crystallization behaviors of poly(3-hydroxybutyrate) (PHB)/ cellulose acetate butyrate (CAB) blends have been investigated mainly by infrared (IR) spectroscopy, together with differential scanning calorimetry, and wide-angle X-ray diffraction (WAXD). Weak intermolecular hydrogen bondings between OH groups in CAB and CO groups in amorphous part of PHB define as inter were detected in OH stretching bands of the blends. These interactions occur in the blends with high CAB content (w_CAB) and highly depend on temperature. For all the blends having 0.2 ≤ w_CAB ≤ 0.7, when temperature is raised (e.g., above 90 °C for the blend with w_CAB = 0.5) the cold crystallization of PHB was discerned, as evidenced by an increase of the absorbance of the band due to CO stretching in the crystal field. The crystallization was found to involve the dissociation of inter and transformation of inter into intramolecular hydrogen bondings within PHB and within CAB as summarized in Table 2 in this text, which promotes the crystallization and enhances stabilization of the crystals. Consequently, the crystallization of the PHB is influenced by exchanges of the hydrogen bondings as described above with raising temperatures. X-ray diffraction from PHB crystals in the blends show a remarkable decrease of crystallinity with w_CAB and eventually disappear when w_CAB ≥ 0.8.     

The domain structure and mobility of semi-crystalline poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate): A solid-state NMR study

Solid-state NMR techniques have been employed to investigate the domain structure and mobility of the bacterial biopolymeric metabolites such as poly(3-hydroxybutyrate) (PHB) and its copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 2.7 mol% (PHBV2.7) and 6.5 mol% (PHBV6.5) 3-hydroxyvalerate. Both single-pulse excitation with magic-angle spinning (SPEMAS) and cross-polarization magic-angle spinning (CPMAS) ¹³C NMR results showed that these biopolymers were composed of amorphous and crystalline regions having distinct molecular dynamics. Under magic-angle spinning, ¹H T_1ρ and ¹³C T₁ showed two processes for each carbon. Proton relaxation-induced spectral editing (PRISE) techniques allowed the neat separation of the ¹³C resonances in the crystalline regions from those in the amorphous ones. The proton spin-lattice relaxation time in the tilted rotating frame, , measured using the Lee-Goldburg sequence with frequency modulation (LGFM) as the spin-locking scheme, was also double exponential and significantly longer than ¹H T_1ρ. The difference between for the amorphous and crystalline domains was greater than that of ¹H T_1ρ. Our results showed that the differences could be exploited in LGFM-CPMAS experiments to separate the signals from two distinct regions. ¹H spin-diffusion results showed that the domain size of the mobile components in PHB, PHBV2.7 and PHBV6.5 were about 13, 24 and 36 nm whereas the ordered domain sizes were smaller than 76, 65 and 55 nm, respectively. The results indicated that the introduction of 3-hydroxyvalerate into PHB led to marked molecular mobility enhancement in the biopolymers.     

Microbial synthesis and properties of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

Microbial synthesis of copolymers of [R]-3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB), P(3HB-co-4HB), by Alcaligenes eutrophus, Alcaligenes latus, and Comamonas acidovorans from various carbon sources has been studied. The copolyester compositions varied from 0 to 100 mol% 4HB, depending on the microorganism and the combination of carbon substrates supplied. The thermal and physical properties of compositions with 0–100 mol% 4HB were investigated. The copolyesters represented a wide variety of polymeric materials, from hard crystalline plastic to very elastic rubbers, depending on composition. The copolyester films with high 4HB fractions (64–100 mol% 4HB) exhibited the characteristics of a thermoplastic elastomer, and the tensile strength increased from 17 to 104 MPa as the 4HB fraction increased. The enzymatic degradation of P(3HB-co-4HB) films was studied in an aqueous solution of extracellular polyhydroxybutyrate (PHB) depolymerase from Alcaligenes faecalis or lipase from Rhizopus delemer. The erosion rate of P(3HB-co-4HB) films was strongly dependent on the copolymer composition. In addition, environmental degradation of P(3HB-co-4HB) films in sea water was investigated.     

Blends of bacterial poly(3-hydroxybutyrate) and a poly(epichlorohydrin-co-ethylene oxide) copolymer: thermal and CO2 transport properties

In this work the miscibility and the carbon dioxide transport properties of a bacterial, isotactic poly(3-hydroxybutyrate) (iPHB) and its blends with a copolymer of epichlorohydrin and ethylene oxide (ECH-co-EO) have been studied. Blends were prepared by solution/precipitation. The aim to obtain miscible blends of iPHB with a rubbery second component (such as the ECH-co-EO copolymer) is to have mixtures with glass transition temperatures below room temperature. In these conditions, the iPHB chains not involved in the crystalline regions retain its mobility. This mobility seems to be necessary for the attack of microorganisms and the corresponding biodegradability.Miscibility is the general rule of these mixtures, as shown by the existence of a single glass transition temperature for each blend and by the depression of the iPHB melting point. The interaction energy density stabilising the mixtures, calculated using the Nishi-Wang treatment, was similar to those of other polymer mixtures involving different polyesters and poly(epichlorohydrin) (PECH) and ECH-co-EO copolymers. The so-called binary interaction model has been used in order to simulate the evolution of the interaction energy density with the ECH-co-EO copolymer composition. Previously reported experimental data on blends of iPHB with PECH and poly(ethylene oxide) (PEO) have been used to quantify the required segmental interaction energy densities.In the determination of the CO₂ transport properties of the mixtures, only iPHB rich blends containing up to 40% of copolymer were considered. The effect of the ECH-co-EO copolymer is to increase the sorption and the diffusion of the penetrant (and, consequently, the permeability) with respect to the values of the pure iPHB. This is primarily due to the reduction of the global crystallinity of the blends and to the low barrier character of the ECH-co-EO copolymer. Sorption data can be reasonably reproduced using an extension of the Henry's law to ternary systems.     

Survey on transport properties of liquids,vapors, and gases in biodegradable poly(3-hydroxybutyrate) (PHB)

The transport properties of carbon dioxide, water, and different organic solvents in bacterial poly(3-hydroxybutyrate) (PHB) at 30°C were investigated. CO₂ sorption was measured by the gravimetric method using a recording microbalance at subatmospheric pressures. Results were adequately interpreted in terms of Henry's law. Organic solvent and water permeabilities for both vapors and liquid were measured using a gravimetric cell. The data were interpreted in different terms depending on the units in which permeability was measured. Most of the solvent-polymer systems showed the typical time-lag plot, but in liquid permeation experiments, some anomalous behaviors were observed, with a transient period of rapid permeation at the beginning of the experiment before reaching the steady state. The transport properties of PHB were compared with those of other polymers, either from synthetic or biodegradable origin. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1849–1859, 1997     

Biodegradable polymer blends of poly(3-hydroxybutyrate) and starch acetate

The thermal behaviour and phase morphology of poly(3-hydroxybutyrate) (PHB) and starch acetate (SA) blends have been studied by differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy and polarizing optical microscopy. PHB/SA blends were immiscible. The melting temperatures of PHB in the blends showed some shift with increase of SA content. The melting enthalpy of the PHB phase in the blend was close to the value for pure PHB. The glass transition temperatures of PHB in the blends remained constant at 9°C. The FTIR absorptions of hydroxyl groups of SA and carbonyl groups of PHB in the blends were found to be independent of the second component at 3470cm^-1 and 1724cm^-1, respectively. The crystallization of PHB was affected by the addition of the SA component both from the melt on cooling and from the glassy state on heating. The temperature and enthalpy of non-isothermal crystallization of PHB in the blends were much lower than those of pure PHB. The crystalline morphology of PHB crystallized from the melt under isothermal conditions varied with SA content. The cold crystallization peaks of PHB in the blends shifted to higher temperatures compared with that of pure PHB. ©1997 SCI     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)研究进展

介绍了生物可降解材料聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P(3HB-co-4HB))的性能及特点;综述了针对P(3HB-co-4HB)加工温度窄、脆性大、成本高等缺点而进行的增塑改性、扩链改性、共混改性的技术进展以及P(3HB-co-4HB)纺丝成纤技术;阐述了利用P(3HB-co-4HB)可塑性、生物降解性和生物相容性等在医疗领域的应用情况及发展前景;指出P(3HB-co-4HB)的研究将集中在其材料加工流动性、结晶性能的改善及其纤维加工技术与纤维表面整理技术等方面。     

Characterization of polypropylene–poly(1-butene)–hydrogenated olygo(cyclopentadiene) ternary blends

Ternary blends containing polypropylene (PP), poly(1-butene) (PB), and hydrogenated oligo(cyclopentadiene) (HOCP) have been studied using microscopic calorimetric and dynamic mechanical techniques, with no phase separation having been observed in the melt for all the considered compositions. The morphology of the crystallized blends and spherulite growth rate of the PP component appeared to be influenced by the blend composition. The presence of one or two T_gs revealed by dynamic mechanical thermal analysis (DMTA) on quenched or crystallized blends has suggested that demixing phenomena can occur during the crystallization of the components. The blend composition has been found to affect the overall crystallization rate and the equilibrium melting temperature of the PP component. A parameter describing the enthalpic interactions between the PP component and the diluent fraction evidenced that the addition of HOCP to PP and PB increases the stability of the ternary blend. The above results suggest that the three components can form a miscible blend in the melt. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1659–1665, 1997     

Crystallization and melting behavior of blends comprising poly(3‐hydroxy butyrate‐co‐3‐hydroxy valerate) and poly(ethylene oxide)

Blends of poly(3‐hydroxy butyrate‐co‐3‐hydroxy valerate) (PHBV) and poly(ethylene oxide) (PEO) were prepared by casting from chloroform solutions. Crystallization kinetics and melting behavior of blends have been studied by differential scanning calorimetry and optical polarizing microscopy. Experimental results reveal that the constituents are miscible in the amorphous state. They form separated crystal structures in the solid state. Crystallization behavior of the blends was studied under isothermal and nonisothermal conditions. Owing to the large difference in melting temperatures, the constituents crystallize consecutively in blends; however, the process is affected by the respective second component. PHBV crystallizes from the amorphous mixture of the constituents, at temperatures where the PEO remains in the molten state. PEO, on the other hand, is surrounded during its crystallization process by crystalline PHBV regions. The degree of crystallinity in the blends stays constant for PHBV and decreases slightly for PEO, with ascending PHBV content. The rate of crystallization of PHBV decreases in blends as compared to the neat polymer. The opposite behavior is observed for PEO. Nonisothermal crystallization is discussed in terms of a quasi‐isothermal approach. Qualitatively, the results show the same tendencies as under isothermal conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2776–2783, 2006     

Surface segregation of components in poly(vinyl chloride)–polydimethylsiloxane and polystyrene–poly(propylene oxide) solvent-cast blends

X-ray photoelectron spectroscopy and scanning electron microscopy are used to study the surface composition and morphology of poly(vinyl chloride)–polydimethylsiloxane (PVC–PDMS) and polystyrene–poly(propylene oxide) (PS–PPO) solvent-cast blends as a function of the blend composition and constituent molecular weights. The PVC–PDMS blends show a pronounced surface enrichment of PDMS, which is higher the lower the molecular weight of PDMS. The surface behavior ofthe PPO–PS blends is strongly dependent on the solvent used. Despite the much lower surface tension of PPO compared to that of PS, no surface segregation of PPO isobserved in the PPO–PS blends cast from tetrahydrofuran, while the blends cast from chloroform exhibit a high surface enrichment of PPO. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 517–522, 1998     

Development and material properties of poly(lactic acid)/poly(3‐hydroxybutyrate‐co−3‐hydroxyvalerate)‐based nanocrystalline cellulose nanocomposites

This study is focused on the development and analysis of the thermal and structural behavior of nanocrystalline cellulose (NCC)‐based bionanocomposites (BCs). Nanocrystalline cellulose was prepared by controlled acid hydrolysis of oil palm empty fruit bunch fibers. The resulting NCC was surface modified using TEMPO‐mediated oxidation and solvent exchange methods for surface functionalization and also to improve dispersion of fillers. Solvent exchange NCC reinforced polymer blend containing poly(lactic acid)/poly‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) was prepared by using solution casting technique at various NCC loading percentages. The addition of NCC resulted in the improvement of structural, thermal, and mechanical properties of BCs as compared to that of the polymer blend. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44328.     

Miscibility,morphology and tensile properties of vinyl chloride polymer and poly(ε‐caprolactone) blends

The miscibility, morphology and tensile properties of three blend systems of poly(ε‐caprolactone) (PCL) with poly(vinyl chloride) (PVC) and with two chlorinated PVCs (CPVCs) with different chlorine contents (63 wt% and 67 wt% of Cl) have been studied. Based on the shifts of single glass transition temperature, the Gordon–Taylor K parameter is calculated as a measurement of interaction strength between PCL and (C)PVCs. Higher K values are found for blends of (C)PVCs with higher chlorine content, together with the interaction χ parameters estimated from the melting point depression results. The morphology observed with polarized light microscopy shows that spherulites exist in blends rich in PCL (≥50 wt%) only. Wide angle X‐ray diffraction studies indicate that the crystal structure of PCL is independent of the Cl content of (C)PVCs. The tensile properties of various blends exhibit a minimum as the PCL content increases. The elongation at break increases with increasing PCL content. © 2000 Society of Chemical Industry     

Compatibility studies of sulfonated poly(ether ether ketone)–poly(ether imide)–polycarbonate ternary blends

Binary blends of the sulfonated poly(ether ether ketone) (SPEEK)–poly(ether imide) (PEI) and SPEEK–polycarbonate (PC), and ternary blends of the SPEEK–PEI–PC, were investigated by differential scanning calorimetry. SPEEK was obtained by sulfonation of poly(ether ether ketone) using 95% sulfuric acid. From the thermal analysis of the SPEEK–PEI blends, single glass transition temperature (T_g) was observed at all the blend composition. For the SPEEK–PC blends, double T_gs were observed. From the results of thermal analysis, it is suggested that the SPEEK–PEI blends are miscible and the SPEEK–PC blends are immiscible. Polymer–polymer interaction parameter (χ₁₂) of the SPEEK–PEI blends was calculated from the modified Lu and Weiss equation, and found to range from −0.011 to −0.825 with the blend composition. For the SPEEK–PC blends, the χ₁₂ values were calculated from the modified Flory–Huggins equation, and found to range from 0.191 to 0.272 with the blend composition. For the SPEEK–PEI–PC ternary blends, phase separation regions that showed two T_gs were found to be consistent with the spinodal curves calculated from the χ₁₂ values of the three binary blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2488–2494, 2000     

聚(3-羟基丁酸酯)的化学改性研究进展

评述了降解塑料聚(3 羟基丁酸酯)(PHB)近年来在化学改性方面的研究进展情况,特别就PHB化学改性的方法和产物的性能进行了总结和评述。PHB化学改性的方法包括辐射聚合、大单体反应改性、反应性共混等。PHB化学改性可通过分子设计合成特定结构的PHB共聚物,具有物理共混无法比拟的优势,特别是在组织工程领域有着广泛的应用前景。     

Electrically conducting polyaniline–poly(acrylic acid) blends

We report an electrically conducting polyaniline–poly(acrylic acid) blend coatings prepared by mixing the emeraldine base (EB) form of polyaniline (PANI) and poly(acrylic acid) (PAA) aqueous solution. The samples show a moderate electrical conductivity σ. If they are immersed in an HCl aqueous solution, the conductivity of the samples is increased by two or three orders of magnitude and their thermal stability is also improved. Optical transmittance spectra show a complete protonation of PANI–PAA blends after immersion in HCl aqueous solution. Fourier transform infrared spectroscopy studies indicate that the better thermal stability of σ could come from the more stable protonated imine nitrogen ions. A low percolation threshold phenomenon is observed in PANI–PAA blends, from a strong interaction between the carboxylic acid groups of PAA and the nitrogen atoms of PANI. © 1998 SCI.     

Novel Poly(3-hydroxyoctanoate)/Poly(3-hydroxybutyrate) blends for medical applications

Novel Poly(3-hydroxybutyrate)/Poly(3-hydroxyoctanoate) blends were developed with varying amounts of Poly(3-hydroxyoctanoate), P(3HO) and Poly(3-hydroxybutyrate), P(3HB) for their potential use in various medical applications. These blend films exhibited higher tensile strength and Young’s modulus values compared to neat P(3HO). The overall protein adsorption and % cell viability was also found to be significantly higher in the blend films than the neat P(3HO) film. Hydrolytic degradation was faster in the blend films and the degradation rate could potentially be tailored to achieve the optimum rate required for a particular medical application. Hence, these novel blends were found to be highly biocompatible with surface, mechanical and thermal properties suitable for a range of potential medical applications, a great step forward in the area of medical materials.     

Crystallization of poly(ethylene oxide) in i-polypropylene–poly(ethylene oxide) blends

A two-stage stable system of isotactic polypropylene–poly(ethylene oxide) blend, in which poly(ethylene oxide) can be permanent either in molten or in crystallized states in the temperature range from 280 to 327 K, was described. The behavior of that blend was explained in terms of fractionated crystallization. A fine dispersion of poly(ethylene oxide) inclusions is required for efficient suppression of crystallization initiated by heterogeneous nuclei. The application of a thin film of polypropylene-poly(ethylene oxide) 9 : 1 blend obtained by quenching for multiuse erasable and rewritable carriers for visible information has been demonstrated. The same sample exhibits different dynamic mechanical properties when poly(ethylene oxide) inclusions are molten or crystallized. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2047–2057, 1997