Showing papers on "Miscibility published in 2005"
TL;DR: 50:50 blends when processed at 55 degrees C in an oven showed significant improvement in mechanical properties as well as support for cellular activity relative to chitosan.
394 citations
TL;DR: In this paper, the structure, dispersibility, and crystallinity of poly(3-hydroxybutyrate) and poly(l-lactic acid) (PLLA) blends by using FT-IR microspectroscopy and differential scanning calorimetry (DSC) were investigated.
Abstract: The present study is aimed at investigating structure, dispersibility, and crystallinity of poly(3-hydroxybutyrate) (PHB) and poly(l-lactic acid) (PLLA) blends by using FT-IR microspectroscopy and differential scanning calorimetry (DSC) Four kinds of PHB/PLLA blends with a PLLA content of 20, 40, 60, and 80 wt % were prepared from chloroform solutions Micro-IR spectra obtained at different positions of a PHB film are all very similar to each other, suggesting that there is no discernible segregated amorphous and crystalline parts on the PHB film at the resolution scale of micro-IR spectroscopy On the other hand, the micro-IR spectra of two different positions of a PLLA film, where spherulite structures are observed and they are not observed, are significantly different from each other PHB and PLLA have characteristic IR marker bands for their crystalline and amorphous components Therefore, it is possible to explore the structure of each component in the PHB/PLLA blends by using micro-IR spectroscopy
228 citations
TL;DR: The understanding of thermal and rheological properties of the various drug/polymer mixtures help established the processing conditions for hotmelt extrusion (such as extrusion temperatures and motor load) as well as provided insight into the properties ofThe final extrudates.
192 citations
TL;DR: In this paper, the effect of clay exfoliation extent on the crystallization behavior of poly(l-lactic acid), PLLA, and its nanocomposites from the melt was investigated.
Abstract: Time-lapsed Fourier transform infrared (FTIR) spectroscopy was employed to probe chain conformational changes during the isothermal crystallization of poly(l-lactic acid), PLLA, and its nanocomposites from the melt. To study the effect of clay exfoliation extent on the crystallization behavior of PLLA, intercalated and exfoliated nanocomposites were fabricated by solution casting two commercially available organoclays with different degrees of matrix miscibility. By solely varying the degree of miscibility between the organic modifier and the polymer matrix, fully intercalated and exfoliated nanocomposites were obtained. This system allowed us to systematically investigate the effect of degree of clay exfoliation on the chain conformational changes during the crystallization process. In the case of neat PLLA, interchain interactions preceded intrachain interactions during the crystallization. Conversely, the exfoliated nanocomposites exhibited an opposite behavior in that 103 helix formation and backbone ...
187 citations
TL;DR: In this paper, the effect of polyhedral oligomeric silsesquioxanes (POSS) on the thermomechanical properties of polymethyl methacrylate (PMMA) was investigated.
155 citations
TL;DR: In this article, a waterborne polyurethane (PU) aqueous dispersion was synthesized from castor oil, and blended with thermoplastic starch (TPS) to obtain a novel biodegradable plastic with improved physical properties.
155 citations
TL;DR: In this article, the effect of the initial interlayer spacing of the organoclay on the overall morphology and properties of an immiscible polycarbonate/poly(methyl methacrylate) blend was examined.
Abstract: This communication describes the effect of organic modifier miscibility with the matrices, and the effect of the initial interlayer spacing of the organoclay, on the overall morphology and properties of an immiscible polycarbonate/poly(methyl methacrylate) blend. By varying the organic-modifier-specific interactions with the blend matrices at the same time as changing the initial interlayer spacing of the organoclay, different levels of compatibilization were revealed. The evidence for the interfacial compatibilization of the organoclay was assessed by scanning electron microscopy observations and was supported by differential scanning calorimetry analyses. The effect on the level of clay exfoliation was also examined.
153 citations
TL;DR: In this paper, the formation of strong intermolecular hydrogen bonding was detected by FTIR analysis for softwood kraft lignin/polyethylene oxide (PEO/PEO) blends.
Abstract: Blends of poly(ethylene oxide) (PEO) with softwood kraft lignin (SKL) were prepared by thermal blending. The miscibility behavior and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The experimental results indicate that PEO was miscible with SKL, as shown by the existence of a single glass-transition temperature over the entire composition range by DSC. In addition, a negative polymer–polymer interaction energy density was calculated on the basis of the melting point depression of PEO. The formation of strong intermolecular hydrogen bonding was detected by FTIR analysis. A comparison of the results obtained for the SKL/PEO blend system with those previously observed for a hardwood kraft lignin/PEO system revealed the existence of stronger hydrogen bonding within the SKL/PEO blends but weaker overall intermolecular interactions between components; this suggested that more than just hydrogen bonding was involved in the determination of the blend behavior in the kraft lignin/PEO blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1437–1444, 2005
146 citations
TL;DR: In this article, a DSC and FTIR study of blends of poly(l-lactide) with poly(vinylphenol) (PVPh) was conducted.
Abstract: This paper reports a DSC and FTIR study of blends of poly(l-lactide) (PLLA) with poly(vinylphenol) (PVPh). According to the single Tg criterion, miscibility has been found in all the compositions range for the blends obtained by solution/precipitation in a dioxane/hexane pair. However, phase separation has been observed for PVPh-rich blends obtained by solvent casting from dioxane solutions. The Tg of the blends shows negative deviation from linearity. Hydrogen bonding has been found, and the band attributed to hydrogen-bonded carbonyl groups is shifted about 18 cm-1, suggesting relatively weak hydroxyl−ester hydrogen bonds. The equilibrium melting points of pure PLLA and different blends have been recorded, and the values of the interaction parameter χ12 = −0.42 and the interaction energy density B = −8.8 cal/cm3 have been calculated. The negative value of the interaction parameter confirms a thermodynamically miscible blend. The value of B is similar to the value found in poly(e-caprolactone) (PCL)/PVPh...
128 citations
TL;DR: It is shown that exposure of unsaturated lipids to air causes monolayer surface pressures to decrease rapidly and miscibility transition pressures to increase rapidly, and this results in limited overlap in miscibility phase behavior of monolayers and bilayers for the lipids studied.
121 citations
TL;DR: In this paper, the effect of partial miscibility and previous degradation levels of ABS and polybutadiene rubber components on the performance of ABS/polycarbonate systems was investigated.
TL;DR: In this paper, the effect of organic modification on nanocomposites was investigated by focusing of three major aspects: morphological study, property measurements, and melt rheological behavior under both small and large deformation flows.
TL;DR: In this paper, the effect of polymer-polymer interactions on the miscibility and macroscopic properties of PVC/PMMA, PVC/PS and PMMA/PS blends were studied in the entire composition range.
TL;DR: In this article, the structure and properties of the blend fibers were studied with the aid of infrared spectra, scanning electron micrography, X-ray diffraction, and thermogravimetric analysis.
Abstract: Alginate and gelatin blend fibers were prepared by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. The structure and properties of the blend fibers were studied with the aid of infrared spectra, scanning electron micrography, X-ray diffraction, and thermogravimetric analysis. Mechanical properties and water-retention properties were measured. The best values of the tensile strength and breaking elongation of blend fibers were obtained when gelatin content was 30 wt %. The water-retention values of blend fibers increase as the amount of gelatin is raised. The structural analysis indicated that there was strong interaction and good miscibility between alginate and gelatin molecules resulted from intermolecular hydrogen bonds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1625–1629, 2005
TL;DR: Solid dispersion systems of felodipine (FEL) with polyvinylpyrrolidone (PVP) were developed, in order to enhance solid state stability and release kinetics and an impressive optimization of the dissolution profile is observed.
Abstract: In the present study, solid dispersion systems of felodipine (FEL) with polyvinylpyrrolidone (PVP) were developed, in order to enhance solid state stability and release kinetics. The prepared systems were characterized by using Differential Scanning Calorimetry, X-Ray Diffraction, and Scanning Electron Microscopy techniques, while the interactions which take place were identified by using Fourier Transformation-Infrared Spectroscopy. Due to the formation of hydrogen bonds between the carbonyl group of PVP and the amino groups of FEL, transition of FEL from crystalline to amorphous state was achieved. The dispersion of FEL was found to be in nano-scale particle sizes and dependent on the FEL/PVP ratio. This modification leads to partial miscibility of the two components, as it was verified by DSC and optimal glass dispersion of FEL into the polymer matrix since no crystalline structure was detected with XRD. The above deformation has a significant effect on the dissolution enhancement and the release kinet...
TL;DR: In this article, a thermodynamic model describing a thermoset/block copolymer considered as only one entity system is proposed, and two distinct phases are present for every blends studied except for DGEBA/DDM modified with 10 wt% PEO and cured at low temperature.
TL;DR: In this article, the miscibility of polyethersulfone (PES) with hydrophilic copolymers containing 1-vinylpyrrolidone and styrene as repeated units was explored.
TL;DR: In this paper, three types of polymeric surfactants/compatibilizers were used to influence the miscibility of polyethylene with the nanoparticle surface, and the structure of the resulting micro- or nanocomposites was investigated by X-ray diffraction and transmission electron microscopy.
TL;DR: In this paper, the authors compared the conclusion on miscibility of PVA/PVP solid blends, confirmed qualitatively (DMTA, FTIR) and quantitatively (DSC, χ AB ǫ − 0.69 at 503 K) by the technique of dilute solution viscometry.
TL;DR: In this paper, the miscibility of poly(l-lactide) with poly(tetramethylene adipate-co-terephthalate) copolymer was studied by dynamic mechanical analysis and thermal mechanical analysis in a tensile mode.
TL;DR: In this article, the mixture of poly(3-hydroxybutyrate- co -hydroxyvalerate) (PHBV) and poly(e-caprolactone) (PCL) blends were prepared with the ratio of PHBV/PCL ranging from 80/20-20/80 by co-dissolving the two polyesters in chloroform and casting the mixture.
TL;DR: In this article, a mixture of polybenzoxazine (PBZ) and poly(e-caprolactone) (PCL) was prepared by solution blending of PCL and benzoxazine monomer (B-m), followed by thermal curing of B-m.
TL;DR: It was concluded that the hydrophilic nature of the endblocks and polarity effects on the drug/polymer miscibility lead to enhanced release of PTx from these polymers.
TL;DR: In this paper, solid-state NMR methods were used to characterize the heterogeneous dynamics, miscibility, and microdomain structure in nanostructured thermoset blends of epoxy resin (ER) and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-blocks of polyethylene oxides (PEO−PPO−PEO) triblock copolymers.
Abstract: Solid-state NMR methods were used to characterize the heterogeneous dynamics, miscibility, and microdomain structure in nanostructured thermoset blends of epoxy resin (ER) and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymers (PEO−PPO−PEO) NMR experiments show that there is a distinct dynamic difference between the block copolymer (both PEO and PPO) and cured-ER matrix indicating the presence of phase separation, which also confirms the existence of the interphase region including a considerable amount of immobilized PEO and mobilized partially cured ER An improved method based on spin-diffusion experiments enabled a quantitative determination of the interphase thickness It is shown that a large percentage of PEO were intimately mixed with ER in the interphase region of the blends, while the rest mobile PEO and all PPO segregated from the ER network It is observed that the domain size and long period depend strongly on the PEO fraction in the c
TL;DR: In this article, the phase behavior of epoxy with poly(e-caprolactone) was analyzed using Fourier transform infrared spectroscopy (FTIR) and it was shown that the intramolecular specific interactions between sulfonyl and hydroxyl groups were the origin of phase-separated morphology for DDS-cured blends with PCL.
TL;DR: In this article, the authors examined poly(ethylene terephthalate) (PET) and a series of statistical and blocky copolymers in which up to 30% of the TG was replaced with isophthalate by copolymerization and melt blending, respectively.
Abstract: The present study examined poly(ethylene terephthalate) (PET) and a series of statistical and blocky copolymers in which up to 30% of the terephthalate was replaced with isophthalate by copolymerization and melt blending, respectively. Some level of transesterification dur- ing processing of melt blends resulted in blocky copolymers, as confirmed by NMR. Random and blocky copolymers exhibited similar properties in the glassy state, including a single glass transition, due to miscibility of the blocks. How- ever, random copolymerization effectively retarded cold- crystallization from the glass whereas blocky copolymers readily cold-crystallized to a crystallinity level close to that of PET. The polymers were oriented at four temperatures in the vicinity of the Tg and characterized by oxygen transport, wide-angle X-ray diffraction, positron annihilation lifetime spectroscopy, and infrared spectroscopy. Orientation of all the copolymers resulted in property changes consistent with strain-induced crystallization. However, blocky copolymers oriented more easily than random copolymers of the same composition and after orientation exhibited slightly lower oxygen permeability, higher density, and higher fraction trans conformers. Analysis of oxygen solubility based on free volume concepts led to a two-phase model from which the amount of crystallinity and the amorphous phase density were extracted. Dedensification of the amorphous phase correlated with the draw temperature.© 2005 Wiley Periodi-
TL;DR: In this paper, the polycarbonate/poly(e-caprolactone) (PC/PCL) blends are found to be miscible when extruded samples are studied without any further thermal treatment.
Abstract: Polycarbonate/poly(e-caprolactone) (PC/PCL) blends are found to be miscible when extruded samples are studied without any further thermal treatment. PCL crystallizes in blends containing 60% or les...
TL;DR: In this paper, a biodegradable composite foams were prepared by extruding starch acetate, with degree of substitution (DS) 1.78, with poly(tetramethylene adipate-co-terephthalate) (EBC), and they were investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM).
TL;DR: In this paper, the thermal and rheological properties of two types of metallocene-catalyzed linear low-density PEs (mLLDPEs) and two LDPEs, as well as their blends, were studied using differential scanning calorimeter (DSC) measurements and Rheometry.
Abstract: The thermal and rheological properties of two types of metallocene-catalyzed linear low-density PEs (mLLDPEs) and two LDPEs, as well as their blends, were studied using differential scanning calorimeter (DSC) measurements and rheometry. The DSC results showed that the mLLDPE-1 based on the hexene comonomer is immiscible with both LDPEs in crystalline states, whereas the mLLDPE-2 based on the octene comonomer is miscible with the LDPEs. This suggests that increasing the length of short chains in mLLDPEs can promote the miscibility of mLLDPE/LDPE blends. The linear viscoelastic properties confirmed the immiscibility of the mLLDPE-1 with the LDPEs in the molten state, and the miscibility of mLLDPE-2 with LDPEs. In addition, the Palierne [1] emulsion model provided good predictions of the linear viscoelastic data for both miscible and immiscible PE blends. However, as expected, the low-frequency data showed a clear influence of the interfacial tension on the elastic modulus of the blends for the immiscible blends. POLYM. ENG. SCI., 45:1254–1264, 2005. © 2005 Society of Plastics Engineers
TL;DR: In this article, the authors analyzed the thermal degradation of poly(1-vinylpyrrolidone-co -vinyl acetate) (HPMC/P(VP- co -VAc)) blends.