Miscibility and crystallization behavior of poly(ethylene-co-vinylalcohol)/poly(maleic anhydride-alt-ethylene) blend

The miscibility of poly(vinylalcohol-co-ethylene) (PEVA) with poly(ethylene-alt-maleic anhydride) (PEMAH) blends was investigated over a wide range of compositions by viscosimetry and DSC analyses using Krigbaum–Wall and Kwei approaches. The results revealed that the blends were completely miscible in all proportions due to the specific interactions between the hydroxyl groups of PEVA and the carbonyl groups of PEMAH. From Nishi equation, the interaction parameter of Flory was found to be −0.89. The nonisothermal crystallization behavior and kinetics of this system were also investigated and compared with those of the pure PEVA. There were strong dependencies of the degree of crystallinity (X_T), peak crystallization temperature (T_p), half time of crystallization (t_1/2), and Ozawa exponent (m) on PEMAH content and cooling rate. The crystallization activation energy (E_c) that was calculated from Kissinger model increased with increasing PEMAH composition in the blend. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Miscibility of poly(acrylic acid)/poly(methyl vinyl ketone) blend and in vitro application as drug carrier system

A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml^?1. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50).     

Miscibility and crystallization of poly(ethylene succinate)/poly(vinyl phenol) blends

Miscibility of biodegradable poly(ethylene succinate) (PES)/poly(vinyl phenol) (PVPh) blends has been studied by differential scanning calorimetry (DSC) in this work. PES is found to be miscible with PVPh as shown by the existence of single composition dependent glass transition temperature over the entire composition range. Spherulitic morphology and the growth rates of neat and blended PES were investigated by optical microscopy (OM). Both neat and blended PES show a maximum growth rate value in the crystallization temperature range of 45-65 °C, with the growth rate of neat PES being higher than that of blended PES at the same crystallization temperature. The overall crystallization kinetics of neat and blended PES was also studied by DSC and analyzed by the Avrami equation at 60 and 65 °C. The crystallization rate decreases with increasing the temperature for both neat and blended PES. The crystallization rate of blended PES is lower than that of neat PES at the same crystallization temperature. However, the Avrami exponent n is almost the same despite the blend composition and crystallization temperature, indicating that the addition of PVPh does not change the crystallization mechanism of PES but only lowers the crystallization rate.     

Miscibility and crystallization in crystalline/crystalline blends of poly(butylene succinate)/poly(ethylene oxide)

Miscibility and crystallization behavior have been investigated in blends of poly(butylene succinate) (PBSU) and poly(ethylene oxide) (PEO), both semicrystalline polymers, by differential scanning calorimetry and optical microscopy. Experimental results indicate that PBSU is miscible with PEO as shown by the existence of single composition dependent glass transition temperature over the entire composition range. In addition, the polymer-polymer interaction parameter, obtained from the melting depression of the high-T_m component PBSU using the Flory-Huggins equation, is composition dependent, and its value is always negative. This indicates that PBSU/PEO blends are thermodynamically miscible in the melt. The morphological study of the isothermal crystallization at 95 °C (where only PBSU crystallized) showed the similar crystallization behavior as in amorphous/crystalline blends. Much more attention has been paid to the crystallization and morphology of the low-T_m component PEO, which was studied through both one-step and two-step crystallization. It was found that the crystallization of PEO was affected clearly by the presence of the crystals of PBSU formed through different crystallization processes. The two components crystallized sequentially not simultaneously when the blends were quenched from the melt directly to 50 °C (one-step crystallization), and the PEO spherulites crystallized within the matrix of the crystals of the preexisted PBSU phase. Crystallization at 95 °C followed by quenching to 50 °C (two-step crystallization) also showed the similar crystallization behavior as in one-step crystallization. However, the radial growth rate of the PEO spherulites was reduced significantly in two-step crystallization than in one-step crystallization.     

Poly(butylene succinate)/poly(vinyl phenol) blends. Part 1. Miscibility and crystallization

Miscibility has been investigated in blends of poly(butylene succinate) (PBSU) and poly(vinyl phenol) (PVPh) by differential scanning calorimetry in this work. PBSU is miscible with PVPh as shown by the existence of single composition dependent glass transition temperature over the entire composition range. In addition, the polymer–polymer interaction parameter, obtained from the melting depression of PBSU using the Nishi–Wang equation, is composition dependent, and its value is always negative. This indicates that PBSU/PVPh blends are thermodynamically miscible in the melt. Preliminary morphology study of PBSU/PVPh blends was also studied by optical microscopy (OM). OM experiments show the spherulites of PBSU become larger with the PVPh content, indicative of a decrease in the nucleation density, and the coarseness of PBSU spherulites increases too with increasing the PVPh content in the blends.     

Miscibility and crystallization of poly(ethylene oxide) and poly(ε-caprolactone) blends

Blends of poly(ethylene oxide) (PEO) with poly(ε-caprolactone) (PCL), both semicrystalline polymers, were prepared by co-dissolving the two polyesters in chloroform and casting the mixture. Phase contrast microscopy was used to probe the miscibility of PEOB/PCL blends. Experimental results indicated that PEO was immiscible with PCL because the melt was biphasic. Crystallization of PEO/PCL blends was studied by differential scanning calorimetry and analyzed by the Avrami equation. The crystallization rate of PEO decreased with the increase of PCL in the blends while the crystallization mechanism did not change. In the case of the isothermal crystallization of PCL, the crystallization mechanism did not change, and the change in the crystallization rate was not very big, or almost constant with the addition of PEO, compared with the change of the crystallization rate of PEO.     

Crystallization kinetics and morphology of poly(butylene succinate)/poly(vinyl phenol) blend

Biodegradable crystalline poly(butylene succinate) (PBSU) can form miscible polymer blends with amorphous poly(vinyl phenol) (PVPh). The isothermal crystallization kinetics and morphology of neat and blended PBSU with PVPh were studied by differential scanning calorimetry (DSC), optical microscopy (OM), wide angle X-ray diffraction (WAXD), and small angle X-ray scattering (SAXS) in this work. The overall isothermal crystallization kinetics of neat and blended PBSU was studied with DSC in the crystallization temperature range of 80-88 °C and analyzed by applying the Avrami equation. It was found that blending with PVPh did not change the crystallization mechanism of PBSU, but reduced the crystallization rate compared with that of neat PBSU at the same crystallization temperature. The crystallization rate decreased with increasing crystallization temperature, while the crystallization mechanism did not change for both neat and blended PBSU irrespective of the crystallization temperature. The spherulitic morphology and growth were observed with hot stage OM in a wide crystallization temperature range of 75-100 °C. The spherulitic morphology of PBSU was influenced apparently by the crystallization temperature and the addition of PVPh. The linear spherulitic growth rate was measured and analyzed by the secondary nucleation theory. Through the Lauritzen-Hoffman equation, some parameters of neat and blended PBSU were derived and compared with each other including the nucleation parameter (K_g), the lateral surface free energy (σ), the end-surface free energy (σ_e), and the work of chain folding (q). Blending with PVPh decreased all the aforementioned parameters compared with those of neat PBSU; however, the decrease extent was limited. WAXD result showed that the crystal structure of PBSU was not modified after blending with PVPh. SAXS result showed that the long period of blended PBSU increased, possibly indicating that the amorphous PVPh might reside mainly in the interlamellar region of PBSU.     

Liquid-liquid phase separation and crystallization behavior of poly(ethylene terephthalate)/poly(ether imide) blend

The liquid-liquid (L-L) phase separation and crystallization behavior of poly(ethylene terephthalate) (PET)/poly(ether imide) (PEI) blend were investigated with optical microscopy, light scattering, and small angle X-ray scattering (SAXS). The thermal analysis showed that the concentration fluctuation between separated phases was controllable by changing the time spent for demixing before crystallization. The L-L phase-separated specimens at 130 °C for various time periods were subjected to a temperature-jump of 180 °C for the isothermal crystallization and then effects of L-L phase separation on crystallization were investigated. The crystal growth rate decreased with increasing L-L phase-separated time (t_s). The slow crystallization for a long t_s implied that the growth path of crystals was highly distorted by the rearrangement of the spinodal domains associated with coarsening. The characteristic morphological parameters at the lamellar level were determined by the correlation function analysis on the SAXS data. The blend had a larger amorphous layer thickness than the pure PET, indicating that PEI molecules in the PET-rich phase were incorporated into the interlamellar regions during crystallization.     

Study of thermomechanical,structural and antibacterial properties of poly(lactic acid) reinforced with graphene oxide nanoparticles via melt mixing

Addition of graphene oxide (GO) to poly(l ‐lactic acid) (PLLA) offers an alternative approach for tuning its crystallinity, improving its mechanical properties and transfusing an antibacterial behavior. GO/PLLA nanocomposites were prepared by melt extrusion, thus avoiding the potentially toxic, for biomedical applications, residue of organic solvents. Fourier transform infrared spectroscopy verified the formation of intermolecular hydrogen bonds. Using differential scanning calorimetry experiments concerning the isothermal crystallization of PLLA and PLLA containing 0.4 wt% GO, a two‐dimensional disc‐like geometry of crystal growth was determined, whereas at 125 and 130 °C the nanocomposite developed three‐dimensional spherulitic growth. Higher crystallization rate constant values suggest that the incorporation of 0.4 wt% GO accelerated the crystallization of PLLA. The lowest crystallization half‐time for PLLA was observed at 115 °C, while at 110 °C GO caused its highest decrease, accompanied by the highest increase in melting enthalpy (ΔH_m), as compared to that of PLLA, after completion of isothermal crystallization. Their ΔH_m values increased with T_ic, whereas multiple melting peaks transited to a single one with increasing T_ic. GO improved the PLLA thermal stability, tensile strength and Young's modulus. Incorporation of 0.8 wt% GO endowed PLLA with another potential application as a biomaterial since the derived composite presented good thermomechanical properties and effective prohibition of Escherichia coli bacteria attachment and proliferation. This effect was more prominent under simulated sunlight exposure than in the dark. The preparation method did not compromise the intrinsic properties of GO. © 2020 Society of Chemical Industry     

Poly(hydroxybutyrate)/poly(butylene succinate) blends: miscibility and nonisothermal crystallization

Four blends of poly(hydroxybutyrate) (PHB) and poly(butylene succinate) (PBSU), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHB/PBSU ranging from 80/20 to 20/80 by co-dissolving the two polyesters in N,N-dimethylformamide and casting the mixture. Differential scanning calorimetry (DSC) and optical microscopy (OM) were used to probe the miscibility of PHB/PBSU blends. Experimental results indicated that PHB showed some limited miscibility with PBSU for PHB/PBSU 20/80 blend as evidenced by the small change in the glass transition temperature and the depression of the equilibrium melting point temperature of the high melting point component PHB. However, PHB showed immiscibility with PBSU for the other three blends as shown by the existence of unchanged composition independent glass transition temperature and the biphasic melt. Nonisothermal crystallization of PHB/PBSU blends was investigated by DSC using various cooling rates from 2.5 to 10 °C/min. During the nonisothermal crystallization, despite the cooling rates used two crystallization peak temperatures were found for PHB/PBSU 40/60 and 60/40 blends, corresponding to the crystallization of PHB and PBSU, respectively, whereas only one crystallization peak temperature was observed for PHB/PBSU 80/20 and 20/80 blends. However, it was found that after the nonisothermal crystallization the crystals of PHB and PBSU actually co-existed in PHB/PBSU 80/20 and 20/80 blends from the two melting endotherms observed in the subsequent DSC melting traces, corresponding to the melting of PHB and PBSU crystals, respectively. The subsequent melting behavior was also studied after the nonisothermal crystallization. In some cases, double melting behavior was found for both PHB and PBSU, which was influenced by the cooling rates used and the blend composition.     

Miscibility and crystallisation behaviour of poly(ethylene terephthalate)/polycarbonate blends

Poly(ethylene terephthalate)/polycarbonate blends were produced in a twin-screw extruder with and without added transesterification catalyst, lanthanum acetyl acetonate. The miscibility of the blends was studied from their crystallisation behaviour and variation in glass transition temperature with composition using differential scanning calorimetry, scanning electron microscopy and change in mechanical properties. The blends prepared without the catalyst showed completely immiscible over all compositions, while those prepared in the presence of the catalyst showed some limited miscible. The presence of PC inhibited the crystallisation of PET but this was much greater in the blends prepared in the presence of catalyst suggesting that some reaction had taken place between the two polyesters. The tensile properties showed little differences between the two types of blends.     

Miscibility and mechanical properties of poly(styrene-co-4-vinylpyridine) and poly(butyl acrylate-co-acrylic acid) ionomer blends

The miscibility of polystyrene with poly(butyl acrylate) is very poor. Ionic interactions have been utilized recently as miscibility enhancers. In this paper, dynamic mechanical studies indicate that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of polystyrene and poly(butyl acrylate). The styrenes contain 0–15mol% quaternary ammonium salt of 4-vinylpyridine, while the butyl acrylates contain 0–15mol% potassium acrylate groups. The miscibility increases with increase of ion content. When the ion content exceeds 11mol%, the polymers can be completely miscible. The mechanical properties of the ionomers and their blends were also studied. The results indicate that the tensile strength of ionomer blends is higher than that of corresponding poly(butyl acrylate-co-potassium acrylate)s (PBA-AA-K). The elongation at break of ionomer blends is higher than that of the corresponding poly(styrene-co-N-methyl-4-vinylpyridinium iodide) (PS-4VP-Q). © 1998 SCI.     

Miscibility,morphology and thermal properties of poly(para‐dioxanone)/poly(D,L‐lactide) blends

BACKGROUND: Poly(para‐dioxanone) (PPDO) is a biodegradable polyester with excellent biodegradability, bioabsorbability, biocompatibility and mechanical flexibility. However, its high cost and relatively fast degradation rate have hindered the development of commercial applications. Blending with other polymers is a simple and convenient way of modifying the properties of aliphatic polyesters. Poly(D ,L ‐lactide) (PDLLA) is another polyester that has been extensively studied for biomedical applications due to its biocompatibility and suitable degradation rate. However, to our knowledge, blends of PPDO/PDLLA have not been reported in the literature. RESULTS: A series of biodegradable polymers were blended by solution co‐precipitation of PPDO and PDLLA in various blend ratios. The miscibility, morphology and thermal properties of the materials were investigated. DSC curves for all blends revealed two discrete glass transition temperatures which matched the values for pure PPDO and PDLLA. SEM images of fracture surfaces displayed evidence of phase separation consistent with the DSC results. The contact angles increased with the addition of PDLLA. CONCLUSION: PPDO/PDLLA blends exhibit two distinct glass transition temperatures that remain nearly constant and correspond to the glass transition temperatures of the homopolymers for all blend compositions, indicating that blends of PPDO and PDLLA are immiscible. Images of the surface obtained using SEM were also suggestive of a two‐phase material. The crystallinity of the PPDO phase in the blends was affected by the PDLLA content. The mechanical properties of the blends changed dramatically with composition. Adding PDLLA makes the blends less hydrophilic than PPDO. Copyright © 2008 Society of Chemical Industry     

Mechanical and thermal properties of biocomposites from poly(lactic acid) and DDGS

Distillers dried grains with solubles (DDGS), an ethanol industry coproduct, is used mainly as a low‐value feedstuff. Poly(lactic acid) (PLA) is a leading biodegradable polymer, but its applications are limited by its relatively high cost. In this study, low‐cost, high‐performance biodegradable composites were prepared through thermal compounding of DDGS and PLA with methylene diphenyl diisocyanate (MDI) as a coupling agent. Mechanical, morphological, and thermal properties of the composites were studied. The coupling mechanism of MDI in the PLA/DDGS system was confirmed via Fourier‐transform infrared spectra. The PLA/20% DDGS composite with 1% MDI showed tensile strength (77 MPa) similar to that of pure PLA, but its Young's modulus was 25% higher than that of pure PLA. With MDI, strong interfacial adhesion was established between the PLA matrix and DDGS particles, and the porosity of the composites decreased dramatically. Crystallinity of PLA in the composites was higher than that in pure PLA. Composites with MDI had higher storage moduli at room temperature than pure PLA. This novel application of DDGS for biocomposites has significantly higher economic value than its traditional use as a feedstuff. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,Characterization, and Release Dynamic of Acetylsalicylic Acid From Acetylsalicylic Acid/Poly(vinylalcohol-co-ethylene) Membrane

A series of poly(vinylalcohol-co-ethylene)/acetylsalicylic acid blends (PEVA/AcSa) of different AcSa contents were prepared and characterized by the solubility test, differential scanning calorimetry, and scanning electron microscopic analyses. The results revealed that AcSa was perfectly soluble in PEVA at certain composition and uniformly distributed throughout the polymer matrix. The release dynamic of AcSa from PEVA/AcSa material was studied at body temperature during 92 h in which the influence of AcSa initially incorporated in PEVA, the pH of media, the membrane thickness, and the stability of AcSa release rate on the release dynamic were detailed.     

Reactable versus soluble DOPO derivatives in poly(lactic acid)/poly(butylene adipate-co-terephthalate) composites: Flame retardance,mechanical properties and morphology

Flame retardant poly(lactic acid)/poly(butylene adipate-co- terephthalate) (PLA/PBAT) composites containing 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) derivatives (phosphorus-containing diol compound of DOPO-HQ, and bis DOPO phosphonates of DIDOPO) were systematically and comparatively investigated. Results showed that the different structures of the two derivatives with reactable or soluble characteristics display different effects. DIDOPO endows a higher limiting oxygen index and a better UL-94 rating for PLA/PBAT composites compared with DOPO-HQ. Compared with that of PLA/PBAT, the peak heat release rate of PLA/PBAT/DIDOPO-12.5 is 8.4% lower and that of PLA/PBAT/DOPO-HQ-12.5 is 30.6% lower. The flame retardant mechanism of the main gaseous and minor condensed phases is evident for the flame retardant PLA/PBAT composites. In comparison, DIDOPO displays a greater flame inhibition effect, and DOPO-HQ shows better barrier and protective functions in PLA/PBAT composites. Besides, the elongation at break of the composites with DOPO-HQ is slightly superior to that of PLA/PBAT/DIDOPO. After the introduction of flame retardant, the blends show dispersed particles with size reduction relative to those of PLA/PBAT. This work provides a guidance to design PLA composites with simultaneously improved flame retardancy and toughness.     

Miscibility of poly(vinyl alcohol)/polyacrylamide blends before and after gamma irradiation

Films of polymer blends having various contents of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) were prepared by the solution casting technique using water as a common solvent. The thermal, mechanical and morphological properties of these blends before and after exposure to various doses of gamma radiation, up to 100 kGy, have been investigated. The visual observation and reflectance measurements show that PVA/PAM blends are miscible over a wide range of composition. Moreover, the differential scanning calorimetry (DSC) thermograms show only a single glass transition temperature (T_g), but not those of PVA or PAM homopolymers, giving further support to the complete compatibility of such blends. The T_g of PVA/PAM blends decreases with increasing content of PAM but increases after exposure to gamma irradiation, indicating the occurrence of crosslinking. These findings were demonstrated by the scanning electron micrographs of the fracture surfaces and the tensile mechanical properties. The TGA thermograms and percentage mass loss at different decomposition temperatures show that unirradiated PVA homopolymer possesses higher thermal stability than PAM homopolymer and their blends within the heating temperature range investigated, up to 250 °C. An opposite trend is observed within the temperature range 300–500 °C. In general, the thermal stability of homopolymers or their blends improves slighly after exposure to an irradiation dose of 100 kGy. These findings are clearly confirmed by the calculated activation energies of the thermal decomposition reaction of the homopolymers and the blends. © 2003 Society of Chemical Industry     

Fabrication and characterization of a persimmon leaves (PL)/poly(acrylonitrile) (PAN) blend bio‐fiber

Adopting persimmon leaves, PL, as a biomaterial to blend with poly(acrylonitrile) (PAN) via the wet spinning method, a PL/PAN blend biofiber was fabricated. On the basis of mechanical measurements, X‐ray diffraction, and DSC characterization, it was found that this biofiber has acceptable mechanical properties for further applying to different cases. Results also showed that though the crystal structure, especially the crystal size, is changed indeed for blend fiber, it seems to be of less influence on the thermal properties, especially the crystallization temperature, T_c. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2810–2813, 2006     

Miscibility and interactions in poly(methylthiomethyl methacrylate)/poly(vinyl alcohol) blends

Poly(methylthiomethyl methacrylate) (PMTMA) is miscible with poly(vinyl alcohol) (PVA) over the whole composition range as shown by the existence of a single glass transition temperature in each blend. The interaction between PMTMA and PVA was examined by Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. The interactions mainly involve the hydroxyl groups of PVA and the thioether sulfur atoms of PMTMA, and the involvement of the carbonyl groups of PMTMA in interactions is not significant. The measurements of proton spin-lattice relaxation time reveal that PMTMA and PVA do not mix intimately on a scale of 1-3 nm, but are miscible on a scale of 20-30 nm. In comparison, we have previously found that PMTMA is miscible with poly(p-vinylphenol) and the two polymers mix intimately on a scale of 1-3 nm.     

Properties of mineral filled poly(lactic acid)/poly(methyl methacrylate) blend

This study examines the influence of three different minerals, that is, clay, calcium carbonate, and quartz on the physical, thermal, and mechanical properties of poly(lactic acid) (PLA)/poly(methyl methacrylate) blend. Rheological behavior and phase structure were initially studied by small-amplitude oscillatory shear rheology. Clay- and quartz-filled materials presented an increase in viscosity at low frequency associated with the presence of a yield stress. However, this behavior was not observed for calcium carbonate filled materials due to a matrix degradation effect. To elucidate this aspect, thermal stability and thermal properties were examined by thermogravimetric analysis and differential scanning calorimetry, showing that calcium carbonate promotes degradation of the PLA phase. No nucleating effect was observed in the presence of the minerals. Dynamical mechanical analysis and mechanical characterization revealed an increase of the overall softening temperature and, a reinforcing effect for clay- and quartz-based composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46927.