Miscibility Of Poly Research Articles

Macromolecular design of novel sulfur‐containing copolyesters with promising mechanical properties

AbstractThe miscibility of poly(butylene succinate) (PBS)/poly(butylene thiodiglycolate) (PBTDG) blends was investigated by DSC technique. PBS and PBTDG were completely immiscible in as blended‐state, as evidenced by the presence of two Tgs at −34 and −48°C, respectively. The miscibility changes upon mixing at elevated temperature: the original two phases merged into a single one because of transesterification reactions. Poly(butylene succinate/thiodiglycolate) block copolymers, prepared by reactive blending of the parent homopolymers, were studied to investigate the effects of transesterification reactions on the molecular structure and solid‐state properties. 13C‐NMR analysis evidenced the formation of copolymers whose degree of randomness increased with mixing time. Thermal characterization results showed that all the samples were semicrystalline, with a soft rubbery amorphous phase and a rigid crystal phase whose amount decreased by introducing BTDG units into the PBS chain (20 ≤ χc ≤ 41). Lastly, the mechanical properties were found strictly related to crystallinity degree (χc), the random copolymer, exhibiting the lowest elastic modulus (E = 61 MPa) and the highest deformation at break (εb (%) = 713). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polystyrene-based blend nanorods with gradient composition distribution

The polystyrene-based polymer blends, partially miscible poly(bisphenol A carbonate)/polystyrene (PC/PS) and completely miscible poly(2,6-dimethylphenylene oxide)/polystyrene (PPO/PS), in nanorods with gradient composition distribution were discussed. The polymer blend nanorods were prepared by infiltrating the polymer blends into nanopores of anodic aluminum oxide (AAO) templates via capillary action. Their morphology was investigated by micro-Fourier transform infrared spectroscopy (micro-FTIR) and nano-thermal analysis (nano-TA) with spatial resolution. The composition gradient of polymer blends in the nanopores is governed by the difference of viscosity and miscibility between the two polymers in the blends and the pore diameter. The capillary wetting of porous AAO templates by polymer blends offers a unique method to fabricate functional nanostructured materials with gradient composition distribution for the potential application to nanodevices.

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

AbstractThe 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 (XT), peak crystallization temperature (Tp), half time of crystallization (t1/2), and Ozawa exponent (m) on PEMAH content and cooling rate. The crystallization activation energy (Ec) that was calculated from Kissinger model increased with increasing PEMAH composition in the blend. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Crystal Orientation Behavior and Shape-Memory Performance of Poly(vinylidene fluoride)/Acrylic Copolymer Blends

The crystal orientation behavior and shape-memory performance of miscible poly(vinylidene fluoride) (PVDF)/acrylic copolymer blends in various ratios have been investigated. With the incorporation of amorphous acrylic copolymer into the gallery of PVDF lamellae, the molecular connection (tie molecule concentration) between the neighboring PVDF crystals decreases gradually. For the blends with more than 80 wt % PVDF, most of the PVDF α-crystals are transformed into β-crystals upon deformation, and the molecular chains of the β-crystals are aligned along the stretching direction because tie molecules transfer the loading effectively. For the blends with less than 30 wt % PVDF, almost all of the PVDF crystals are isolated from each other with very few tie molecules. Mechanical deformation induces the perpendicular crystal molecular chain arrangement with no crystal form transitions. For the blends with 40 wt % to 70 wt % PVDF, the c-axis-oriented β-phase and the tilt-oriented α-phase coexist in the uniaxially stretched blends. The shape-memory properties of the blends were also evaluated over the same blend composition range. The maximum shape-memory recovery properties were observed for the blend sample containing 50 wt % PVDF, in which a small amount of tie molecules connect the PVDF crystallites to form a deformable elastic network. This network contributes to the good shape-memory properties of the blend. For the blends with very few tie molecules or high tie molecule concentrations, the deformation induces the slipping of the amorphous molecules or the large fibrillar crystal structure, respectively; thus, these samples exhibit relatively low shape-memory performance.

Mechanical properties of carbon nanotube–PMMA based hybrid coatings: the importance of surface chemistry

The poor miscibility of carbon nanotubes (CNTs) in common organic solvents and organic monomers requires their modification by suitable functional (reactive or not) groups prior to their incorporation in thermoplastic polymers. We studied the influence of the functionalization of the surface of CNTs on their miscibility in poly(methyl methacrylate), following two main strategies: (i) the covalent grafting of hydrolyzable Si(OEt)3 groups on oxidized CNTs and (ii) the non-covalent adsorption of a polycation on pristine CNTs, allowing for further reactions by the sol–gel process. The mechanical properties of CNT/polymer-based nanocomposite thin films were studied using the nanoindentation technique. The hardness and the elastic indentation modulus were found to improve using modified CNTs, with more sensitivity observed on the elastic response.

Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) with high molecular weight poly(lactic acid) blends determined by thermal analysis

AbstractAn important strategy used in the polymer industry in recent years is blending two bio‐based polymers to attain desirable properties similar to traditional thermoplastics, thus increasing the application potential for bio‐based and bio‐degradable polymers. Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with poly(L‐lactic acid) (PLA) were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Three different grades of commercially available PLAs and one type of PHBV were blended in different ratios of 50/50, 60/40, 70/30, and 80/20 (PHBV/PLA) using a micro‐compounder at 175°C. The DSC and TGA analysis showed the blends were immiscible due to different stereo configuration of PLA polymer and two distinct melting temperatures. However, some compatibility between PHBV and PLA polymers was observed due to decreases in PLA's glass transition temperatures. Additionally, the blends do not show clear separation by SEM analysis, as observed in the thermal analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Miscibility enhancement on the poly(vinylchloride)/poly(methylmethacrylate) blend and characterization by inverse gas chromatography: The corrected polymer–polymer interaction parameters from the probes dependency

AbstractThe miscibility of poly(vinyl chloride)/poly(methylmethacrylate) (PVC/PMMA) system was improved by introducing some pyrrolidone units into the main chains of PMMA. For that purpose, we have synthesized two copolymers of poly(methylmethacrylate‐co‐vinylpyrrolidone) (MMVP) through a radical polymerization and carried out a comparative study of PVC/MMVP blends by inverse gas chromatography (IGC) and differential scanning calorimetry (DSC) methods. The adequacy of seven n‐alkane probes has been tested to determine the thermodynamic parameters. The miscibility of the two systems has been proved by a single Tg for each blend. This observation was also confirmed by DSC analysis. To highlight the presence of interaction and its intensity between PVC and MMVP in the blends, the polymer–polymer interaction parameters have been evaluated by IGC trough which the influence of the solute has been resolved. The Schneider approach confirmed the miscibility of these systems as the K deviates positively from unity. The miscibility has been appeared highlighted from the positive difference in surface energy between the pure polymers and their blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Novel miscible poly(ethylene sebacate)/poly(4-vinyl phenol) blends: Miscibility, melting behavior and crystallization study

High molecular weight samples of the novel biodegradable polyester poly(ethylene sebacate) (PESeb) were synthesized. Miscible poly(ethylene sebacate)/poly(4-vinyl phenol) semicrystalline/amorphous blends were prepared by applying the solvent casting method. Miscibility was proved by the single composition dependent glass transition temperature over the entire composition range observed in DSC traces of the quenched blend samples and also by the melting point depression. The Flory–Huggins interaction parameter was found to be x12 = −1.3. Also, FTIR spectra supported the hypothesis of intermolecular interactions due to hydrogen bonding. The crystallization of PESeb in blends was studied. As expected, isothermal crystallization rates decreased in the blends with increasing the PVPh content. The Lauritzen–Hoffman analysis was tested. The values of nucleation constant Kg did not show any substantial variation. The non-isothermal crystallization of the blends was also tested. It was found that the crystallization is retarded in the case of blends, compared to the neat PESeb.

Confined Growth of Poly(butylene succinate) in Its Miscible Blends with Poly(vinylidene fluoride): Morphology and Growth Kinetics

The morphology and confined crystallization behavior of poly(butylene succinate) (PBS) in miscible poly(vinylidene fluoride) (PVDF)/PBS blends has been studied using differential scanning calorimetry (DSC) and optical and atomic force microscopy (OM and AFM). It was found that PBS crystal lamellae nucleated and grew confined inside the matrix of PVDF spherulites. Crystallized PBS domains grow with an ellipsoidal outline within PVDF spherulites formed at a relatively high PVDF crystallization temperature (T(c,PVDF)), while circular domains, engulfing several PVDF spherulites, are seen when growing in the PVDF spherulites created at lower T(c,PVDF). The growth kinetics of PBS confined in the PVDF matrix was investigated under various conditions. The growth rate of PBS (G(PBS)) increases with decreasing crystallization temperature and increasing PBS content under a given PVDF crystallization temperature (T(c,VDF)). For T(c,PVDF) above 145 °C, G(PBS) decreases with T(c,PVDF) for both 50:50 and 30:70 PVDF/PBS blends. However, for T(c,PVDF) below 145 °C, 50:50 and 30:70 PVDF/PBS blends exhibit the opposite G(PBS) trend; that is, G(PBS) for the 50:50 blend decreases with decreasing T(c,PVDF), while for the 30:70 PVDF/PBS blend G(PBS) increases with decreasing T(c,PVDF). It is shown that this behavior cannot be associated with the effect of crossing the boundary of smaller PVDF spherulites formed at a lower temperature. Rather, the behavior appears to be related to the interleaving growth of PBS lamellae among PVDF lamellae or between bundles of PVDF lamellae (fibrils), as in situ AFM observation shows. It is found that the interconnectedness of the molten pockets within the PVDF spherulites, which depends on the PVDF crystallization temperature, is an important factor determining the growth kinetics of PBS confined within the PVDF scaffold.

Effect of blend composition and organoclay loading on the nanocomposite structure and properties of miscible poly(methyl methacrylate)/poly(styrene-co -acrylonitrile) blends

Organically-modified montmorillonite clay nanocomposites of poly(styrene-co-acrylonitrile) (SAN), poly(methyl methacrylate) (PMMA) and SAN/PMMA miscible blend are investigated. Structure characteristics at the nanoscale and microscale and thermal and tensile properties are studied as a function of polymer blend composition and filler loading fraction. Blend miscibility and Tg are unaffected by up to 10% by wt. organoclay. Thermal degradation stability increases with SAN content and exhibits an optimum value of clay loading. Stiffness shows significant improvement. Tensile strength and elongation-at-break suffer as a result of nanocomposite formation. Modulus shows a maximum enhancement of 57% (5 ± 0.06 GPa at 10 wt% filler, 20/80 SAN/PMMA) and varies linearly with clay fraction for all compositions of matrix phase. Predictions of Halpin–Tsai composite model are in excellent agreement with the experimental behavior over full range of polymer blend composition. Fundamental aspects of a polymer blend–clay nanocomposite are clarified, such as lack of additional synergy between clay platelets and matrix, and tensile ductility reduction, compared with polymer–clay system. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Effect of starch type on miscibility in poly(ethylene oxide) (PEO)/starch blends and cytotoxicity assays

This study reports results on the miscibility of polymer blends based on PEO and different starches (unmodified, cationic, and hydrophobic) and their respective cytotoxicity. Films of PEO/starch blends at different weight ratios (95/05, 90/10, 80/20, 70/30, 65/35, and 60/40), as well as films of pure PEO as control, were prepared by casting methodology. Several techniques, such as SEM, WAXS, FTIR, and FT-Raman spectroscopy were used in this study for evaluating blend miscibility. The results revealed that the miscibility of such blends is dependent on the type of starch used. Regarding the PEO/unmodified starch blends, it was concluded that the system is miscible in the ratio range from 90/10 to 65/35. Although the PEO/hydrophobic starch blends are miscible in all the studied range, blends of PEO and cationic starch are immiscible, regardless the blend ratio. The different samples presented distinct cytotoxic behaviors. PEO and hydrophobic starch presented no relevant toxicity (CC50/72>2.5mg/mL). Otherwise, the cationic starch was the most harmful for the cells. The blends presented cytotoxicity values between those of PEO and cationic starch.

Molecular Miscibility of Polymer−Fullerene Blends

The device function of polymer bulk heterojunction (BHJ) solar cells has been commonly interpreted to arise from charge separation at discrete interfaces between phase-separated materials and subsequent charge transport through these phases without consideration of phase purity. To probe composition, the miscibility of poly(3-hexylthiophene) (P3HT) and poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV) with phenyl-C61-butyric acid methyl ester (PCBM) has been determined, while the effects of polymer crystallinity on miscibility are probed using P3HT grades of varying regioregularity. It is found that, while no intercalation occurs in P3HT crystals, amorphous portions of P3HT and MDMO-PPV contain significant concentrations of PCBM, calling into question models based on pure phases and discrete interfaces. Furthermore, depth profiles of P3HT/PCBM bilayers reveal that even short annealing causes significant interdiffusion of both materials, showing that under no conditions do pure amorphous phases exist in BHJ or annealed bilayer devices. These results suggest that current models of charge separation and transport must be refined.

Thermal stability and miscibility of poly(hydroxybutyrate) and soda lignin blends

The thermal properties and miscibility of poly(hydroxybutyrate) (PHB) and soda lignin blends were investigated by thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR) over the entire range of composition. Although the addition of soda lignin shifts the onset of PHB decomposition to lower temperatures, the PHB/lignin blends are thermally more stable than PHB over a wider temperature range. The thermal behaviour of these blends as measured by TGA suggests compatibility for the blends containing up to 40 wt% soda lignin. These results correlate well with the glass transition temperature ( T g ) data where a single T g was obtained for these blends. At higher lignin to PHB ratios, two T g s depicting immiscibility were obtained. The infra-red data show that the miscibility of the blends containing up to 40 wt% soda lignin is associated with specific hydrogen bonding interactions between the reactive functional groups in lignin with the carbonyl groups of PHB.

Evaluation of the interaction parameter for poly(ε-caprolactone)/poly(styrene-co -acrylonitrile) blends

In this article, the miscibility of poly(e-caprolactone) (PCL) with poly(styrene-co-acrylonitrile) (SAN) containing 25 wt % of acrylonitrile is studied from both a qualitative and a quantitative point of view. The evidences coming from thermal analysis (differential scanning calorimetry) demonstrate that PCL and SAN are miscible in the whole range of composition. The Flory interaction parameter χ1,2 was calculated by the Patterson approximation and the melting point depression of the crystalline phase in the blends; in both cases, negative values of χ1,2 were found, confirming that the system is miscible. The interaction parameter evaluated within the framework of the mean field theory demonstrates that the miscibility of PCL/SAN blends is due to the repulsive interaction between the styrene and acrylonitrile segments in SAN. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010

Submicrometer Thermoplastic Vulcanizates Obtained by Reaction-Induced Phase Separation of Miscible Poly(Ε-Caprolactone)/Dimethacrylate Systems

Abstract Reaction-induced phase separation of initially miscible mixtures of poly(Ε-caprolactone) (PCL) and elastomer precursors based on difunctional methacrylate resins was applied to prepare thermoplastic vulcanizates (TPVs) with rubber particle sizes ranging from 80 to 900 nm. The radicals formed by the peroxide decomposition initiate the formation of a cross-linked rubber network with gel contents exceeding 90%, but also abstract hydrogen atoms from the aliphatic moieties in PCL. This leads to the formation of PCL-grafted rubber particles, which show a high nucleating efficiency for crystallization of the PCL matrix. It is demonstrated that the tensile and elastic properties of these TPVs are determined by a complex interplay of the morphology, the type of elastomer precursor, the extent of PCL grafting, the crystallinity, and the lamellar thickness. The materials showed a rheological behavior that is typical for TPVs, for which the melt changes from an elastic to a viscous behavior above a critical stress.

Effect of vanillin on the miscibility of poly(vinyl alcohol)/gelatin composite hydrogel: Physical and chemical properties

AbstractA composite based on poly(vinyl alcohol) (PVA) and gelatin (Gel) was prepared in the form of a miscible interphase by freezing‐thawing method using vanillin as a new compatilizer. The chemical and physical properties of PVA/Gel/vanillin composite hydrogels with different reagent concentration, and reaction time were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), tensile testing, and scanning electron microscopy (SEM). The results elicit that the formation of CN Schiff base between Gel and vanillin may break the intrahydrogen bonding of Gel. Proper reaction time and more interactive groups result in optimal interhydrogen bonding between modified Gel and PVA so that the miscibility between two polymers has been improved. In addition, the PVA/Gel/V composite with the vanillin concentration of 0.20 g/mL and 2 h stirring exhibits a better compatibility and a higher tensile strength, which can be tailored for potential use in cartilage tissue engineering. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of sequence distribution on the isothermal crystallization kinetics and successive self-nucleation and annealing (SSA) behavior of poly(ε-caprolactone- co-ε-caprolactam) copolymers

Two types of miscible poly(ε-caprolactone- co-ε-caprolactam) copolymers were studied. In both cases catalyzed hydrolytic ring-opening polymerization was employed. For the first type, the comonomers were added simultaneously to obtain random copolymers. For the second type, the comonomers were added sequentially to obtain block copolymers. Successive self-nucleation and annealing (SSA) and isothermal crystallization studies were performed to both types of copolymers. The SSA results reflect the differences in molecular microstructure: block versus random copolymers. In a wide composition range only the polycaprolactam sequences were capable of crystallization in the random copolymers. Avrami indexes of approximately 3–4 were obtained corresponding to the spherulitic crystallization of these units within the copolymers. The block copolymer samples experienced a relatively small reduction of crystallization kinetics with composition, and this was attributed to the dilution effect caused by the miscible non-crystalline polycaprolactone units. On the other hand, for the random copolymers, the rate of crystallization strongly increased with polycaprolactam content while the energy barrier for secondary nucleation decreased exponentially. The comparison between miscible block and random copolymers provides a unique opportunity to distinguish the dilution effect of the polycaprolactone units (a moderate effect) on the isothermal crystallization and melting of the polyamide phase from the molecular microstructural effect in the random copolymers case (a dramatically strong effect), where the polycaprolactam sequences are interrupted statistically by polycaprolactone sequences.

Phase Behavior and Proton Conduction in Poly(vinylphosphonic acid)/Poly(ethylene oxide) Blends

The miscibility of poly(vinylphosphonic acid) (PVPA) and poly(ethylene oxide) (PEO) is studied for the first time in this work, and a miscibility diagram is obtained based on thermoanalytical (DSC)...

Crystallization and Physical Ageing of Poly (2‐vinyl pyridine)‐b‐poly(ethylene oxide) Diblock Copolymers

AbstractSummary: A set of melt miscible Poly(2‐vinyl pyridine)‐b‐Poly(ethylene oxide) (P2VP‐b‐PEO) block copolymers of different compositions were studied. Transmission electron microscopy shows phase separation in the materials during the crystallization process of the PEO block as crystalline lamellae are observed for all compositions evaluated. The isothermal crystallization kinetics of PEO is progressively retarded as the P2VP content in the copolymer increases, since P2VP hinders molecular mobility in the miscible amorphous phase. Polarized light optical microscopy demonstrated that the glassy P2VP block has a negative effect on the secondary nucleation of the PEO. Finally, physical ageing experiments performed in the glassy state of the amorphous mixed phase, at different ageing times, demonstrated that a nucleating effect can be induced in the glassy state as a consequence of the reorganization of the amorphous regions. This nucleating effect significantly alters the cold crystallization rate upon subsequent heating above the glass transition temperature.

Concentration Fluctuations, Local Order, and the Collective Structure of Polymer Nanocomposites

A combined theory−experiment analysis of adsorbing polymer mediated structural reorganization of silica nanoparticles in equilibrated and miscible poly(ethylene oxide) (PEO) and polytetrahydrofuran (PTHF) nanocomposites is presented. Quantitative comparison of microscopic liquid state theory calculations with small-angle X-ray scattering experiments demonstrate the theoretical approach properly accounts for the effects of adsorbed polymer layers on nanoparticle concentration fluctuations over all length scales for a wide range of volume fractions and interfacial cohesion strengths. The mixture total packing fraction is increased as particles are added to the polymer melt in order to account for equation-of-state effects which are important at very high filler loadings. A distinctive microphase separation like peak in the collective polymer structure factor is predicted. Nanoparticle potential of mean force calculations suggest a criterion for the onset of depletion or bridging induced kinetic gelation which is consistent with the observation of complete miscibility for the PEO system but nonequilibrium behavior in the PTHF nanocomposite.