Miscibility in blends of poly(3-hydroxybutyrate) and poly(vinylidene chloride-co-acrylonitrile) (original) (raw)
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Miscibility and Crystallization of Poly(β-hydroxybutyrate) and Poly(p-vinylphenol) Blends
Macromolecules
The miscibility and crystallization behavior of poly(-hydroxybutyrate) (PHB) and poly(pvinylphenol) (PVPh) blends were studied by differential scanning calorimetry and optical microscopy (OM). The blends exhibit a single composition-dependent glass transition temperature, characteristic of miscible systems. A depression of the equilibrium melting temperature of PHB is observed. The interaction parameter values obtained from analysis of the melting point depression are of large negative values, which suggests that PHB and PVPh blends are thermodynamically miscible in the melt. Isothermal crystallization kinetics in the miscible blend system PHB/PVPh was examined by OM. The presence of the amorphous PVPh component results in a reduction in the rate of spherulite growth of PHB. The spherulite growth rate is analyzed using the Lauritzen-Hoffman model. The isothermally crystallized blends of PHB/PVPh were examined by wide-angle X-ray diffraction and small-angle X-ray scattering (SAXS). The long period obtained from SAXS increases with the increase in PVPh component, which implies that the amorphous PVPh is squeezed into the interlamallar region of PHB.
Thermochimica Acta, 2006
With the objective of developing new biodegradable materials, the miscibility and the crystallinity of blends of poly(3-hydroxybutyrate), P(3HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), have been studied. P(3HB) (300 kg mol −1 )/P(3HB-co-3HV)-10% 3HV (340 kg mol −1 ) blends were prepared by casting in a wide range of proportions, and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The experimental values for the glass transition temperatures (T g ) are in good agreement with the values provided by the Fox equation, showing that the blends are miscible. It was observed that the T g and the melting temperature (T m ) decreases with the increase in the P(3HB-co-3HV)-10% 3HV content, while the crystallization temperature (T c ) increases. FT-IR analyses confirmed the decrease on the crystallinity of P(3HB)/P(3HB-co-3HV)-10% 3HV blends with higher copolymer contents. Bands related to the crystallinity were changed, due to the copolymer content that produced miscible and less crystalline blends.
Miscibility, Crystallinity and Morphology of Polymer Blends of Polyamide-6/ poly (β-hydroxybutyrate)
Polyamide-6 (PA6) with bacterial poly (β-hydroxybutyrate) (PHB) are typical polyamide and polyester, respectively. PA6 is known to be high-strength engineering thermoplastic. Although it is ductile at room temperature, it becomes brittle under severe conditions such as high strain rates and/or low temperatures. This is due to the low crack propagation resistance of polyamides. PHB is a biodegradable and biocompatible thermoplastic polymer of high melting temperature (180 o C) and crystallinity. PHB has attracted much attention as an environmentally degradable resin to be used for agricultural, marine and medical applications. One of the limitations of PHB for these applications is its brittleness and narrow processing window. Blending of friendly environmental biopolymers with synthetic polymers has proven to be a suitable tool to produce novel materials with combined characteristics in having both improved application properties and low cost advantages in material performance. In this study, the segmental interaction parameters, crystallinity, miscibility and morphology of polymer blends (PB) of PA6 and PHB have been studied at different weight fractions and different crystallization temperatures. The experimental approaches utilized are Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) and Polarized Optical Microscopy (POM). The interaction parameters were calculated using the Nishi-Wang equation, which is based on the Flory-Huggins theory. The values of interaction parameters 12 χ were negative for all blend compositions suggesting that depends on the volume fraction (12 χ Φ) of the polymer.
Macromolecular Symposia, 2019
The aim of this study is to investigate the influence of vinyl acetate (VA) content on the thermal and rheological properties of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/poly(ethylene-co-vinyl acetate) (EVA) blends. Binary blends of PHBV and EVA containing 65 wt% (EVA65) and 90 wt% (EVA90) VA were prepared by torque rheometry and their thermal properties were studied by differential scanning calorimetry (DSC). Rheograms of PHBV/EVA65 containing up to 40 wt% EVA showed that the torque values decrease as a function of mixing time due to the thermo-mechanical degradation, which preferentially for PHBV is chain scission. The increase in the EVA65 concentration results in torque stability probably due to the balance between chain scission of the PHBV and chain branching of the EVA65. For PHBV/EVA90 blends, the torque values are stable indicating that the presence of EVA90 decreases the degradation process of the PHBV and hence increases the thermal stability of blends. DSC curves showed that the PHBV cold crystallization temperature (T cc) increased and cold crystallization (ΔH cc) and melting enthalpies (ΔH m) decreased with the increase in the EVA content, independently of VA content and blend morphology. DSC curves of PHBV/EVA65 showed two glass transition temperatures and clear phase separations, in all studied formulations, typical of immiscible systems. In contrast to it, PHBV/EVA90 blends showed a single glass transition, suggesting total miscibility. Both findings were corroborated by scanning electron microscopy (SEM) analysis.
Polimeros-ciencia E Tecnologia, 2010
The thermal degradation of miscible and immiscible poly (3-hidroxy butyrate) PHB/ poly (ethylene terephthalate) sulphonated (PETs) blends was investigated using thermogravimetric analyses. Model-free kinetic analysis, Vyazovkin and Flynn-Wall-Ozawa's methods, were used to determine the apparent activation energy in the whole interval of degradation of the pure polymers, immiscible blends, and miscible blends. The thermal stability of both polymers in their blends is higher when compared to the pure polymers. The synergistic effect in the thermal stability in the blends is higher for the miscible blend where the formation of the specific interaction between PHB and PETs occurs. The apparent activation energy of the individual polymers is higher in PETs/PHB blends, and this effect is potentiated by the miscibility of the blend.
Polymer, 2007
Blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-caprolactone) (PCL) have been produced by melt blending in the presence of supercritical CO 2. Infrared spectroscopy has shown that supercritical CO 2 can induce melting in PHBV at temperatures below the melting point. The miscibility of the PCLePHBV blend system produced by both mechanical and supercritical means has been characterised by a combination of differential scanning calorimetry and dynamic mechanical thermal analysis. It has been shown that PHBVePCL blends produced using mechanical means were immiscible, whereas the same blends produced using supercritical methods were found to be miscible as evidenced by a decrease in the glass transition temperature of the PHBV component. The development of miscibility is discussed in terms of enhanced interdiffusion resulting from the action of supercritical CO 2. In addition, the infrared spectrum of the blends produced using supercritical CO 2 showed negligible levels of the degradation product crotonic acid. Whereas in the samples produced using mechanical blending without supercritical CO 2 , there was a significant increase in the level of crotonic acid, which was interpreted as evidence of degradation.
Polymer, 2004
By means of full atomistic molecular dynamics simulation, the solubility parameters for pure poly(3-hydroxybutyrate) and poly(ethylene oxide) are calculated and the results are in agreement with the literature values. Furthermore, in order to reveal the blend property, the volume -temperature curve of the PHB/PEO blend system (1:2 blends in terms of repeated units) is simulated by employing the united atom approximation to obtain the glass transition temperature. From the volume -temperature curve, the glass transition temperature is about 258 K, which is compared well with the experimental results. It should be pointed out that the two simulated solubility parameters are similar and there is only one glass transition of the blend system, these indicate that the studied blend system is miscible. q
e-Polymers, 2011
A series of ethylene vinyl acetate random copolymer EVA, with vinyl acetate (VA) varied from 9 to 91m%, was investigated by differential scanning calorimetry DSC and polarized optical microscopy. Biodegradable polymer blends of polyhydroxybutyrate PHB and EVA, having VA in EVA in range from 40m% till 91m%, were prepared by film casting from a chloroform solution. The miscibility and crystallization behavior of these blends were investigated. The isothermal crystallization behaviors of PHB and PHB/EVA blends are discussed in terms of the half time of crystallization t 1/2 . Experimental results indicated that blends of PHB/ EVA91 are completely miscible blend in the entire (0 to 100 m%) compositional ranges. Blends PHB/ EVA, for VA varied from 40 till 70 m% are immiscible as evidenced by the existence of unchanged composition independent glass transition temperatures (T g ), crystallization and melting behavior. The isothermal crystallization of PHB blends was investigated from room temperature till 130 °C. 80 °C was found to be the best temperature for comparison of different blends. At 80 °C t 1/2 strongly depends on the content of VA in PHB/EVA blend, mainly due to differences in miscibility as well as due to differences in segmental mobility as identified by differences in glass transition temperature. Since both components in PHB/EVA80, pure PHB and pure EVA80, have glass transition temperatures close to 0 °C, it is difficult to decide its miscibility from T g . However from the strong dependence of the value of crystallization half time t 1/2 of PHB/EVA80 on blend composition, it was possible to reasonably infer that PHB/EVA80 is partially miscible.
Polymer, 1988
Differential scanning calorimetry and optical microscopy were used to determine the miscibility behaviour of poly-D(-)(3-hydroxybutyrate) (PHB) and poly(ethylene oxide) (PEO) mixtures. It was found that PHB and PEO are miscible in the melt. Consequently the blend exhibits a single glass transition temperature and a depression of the equilibrium melting temperature of PHB. The study of the isothermal crystallization process shows that at a given crystallization temperature the presence of PEO causes a depression in the growth rate of PHB spherulites. The blend exhibits a phase diagram characterized by the presence, below the apparent melting temperature of PHB and PEO, of interlamellar and/or interfibrillar homogeneous amorphous PHB/PEO mixtures. The Flory-Huggins interaction parameter (Xl 2), obtained from melting point depression data, is composition dependent, and its value is always negative.
Polymer, 2004
In this work a Fourier transform infrared (FTIR) study of blends of styrene–vinyl phenol copolymers (containing different proportions of styrene) with atactic PHB is presented. The equilibrium constant describing phenolic OH/ester carbonyl hydrogen bonds (KA) has been experimentally determined from the quantification of the hydrogen-bonded carbonyl group fraction as a function of temperature, and the effect of functional group accessibility on KA values has been discussed. An average value of KA=41 has been employed to perform a prediction of miscibility maps employing the association model of Painter and Coleman. A fairly good agreement between theoretical predictions and experimental results has been obtained.