Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Miscibility

  • good miscibility

  • Terms modified by Miscibility

  • miscibility gap

  • Selected Abstracts

    Miscibility and rheological properties of poly(vinyl chloride)/styrene,acrylonitrile blends prepared by melt extrusion

    Hyun Sik Moon
    Abstract Styrene,acrylonitrile (SAN) with acrylonitrile (AN) concentrations of 11.6,26 wt % and ,-methylstyrene acrylonitrile (,MSAN) with a wide range of AN concentrations are miscible with poly(vinyl chloride) (PVC) through solution blending. Here we examine the rheological properties and miscibility of PVC/SAN and PVC/,MSAN blends prepared by melt extrusion for commercial applications. We have investigated the rheological properties of the blends with a rheometer and a melt indexer. The PVC/SAN and PVC/,MSAN blends have a low melting torque, a long degradation time, and a high melt index, and this means that they have better processability than pure PVC. The miscibility of the blends has been characterized with differential scanning calorimetry, dynamic mechanical thermal analysis, and advanced rheometrics expansion system analysis. The miscibility of the blends has also been characterized with scanning electron microscopy. The SAN series with AN concentrations of 24,31 wt % is immiscible with PVC by melt extrusion, whereas ,MSAN with 31 wt % AN is miscible with PVC, even when they are blended by melt extrusion, because of the strong interaction between PVC and ,MSAN. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Raman spectroscopy of conducting poly (methyl methacrylate)/polyaniline dodecylbenzenesulfonate blends

    Abdul Shakoor
    Abstract Polyaniline soluble in organic solvents was prepared using dodecylbenzenesulphonic acid (DBSA) as functional dopant. The solubility parameter was calculated and the most suitable solvent chloroform was checked for the solubility and the most compatible polymer PMMA was selected for blending. Miscibility was maximized with 1% by weight of hydroquinone. Blending of doped polyaniline with dodecylbenzenesulphonic acid (PAni.DBSA) in poly (methyl methacrylate) (PMMA) was explained by a change in the conformation of the polymeric chains leading to an increase in the conductivity. The electrical conductivity increased as the weight percent of PAni.DBSA increased, showing a percolation threshold as low as 3.0% by weight and the highest conductivity was achieved at 20% by wt of PAni.DBSA. Scanning electron micrographs showed lowest level of phase separation. Raman spectroscopy is used to characterize the blending process of two polymers aiming to understand the transformations in different types of charged segments. Raman results give complementary data about the blending process showing that together with the structural change of the polymeric chains, there is also a chemical transformation of these polymers. Analysis of Raman spectra was done investigating the relative intensities of the bands at 574 cm,1 and 607 cm,1. A relationship between conductivity and Raman was also proposed. Copyright 2009 John Wiley & Sons, Ltd. [source]

    Crystallization Behavior of Poly(, -caprolactone) Grafted onto Cellulose Alkyl Esters: Effects of Copolymer Composition and Intercomponent Miscibility

    Ryosuke Kusumi
    Abstract Graft copolymers of CA and CB with PCL were prepared at compositions rich in PCL. Kinetic DSC data were analyzed in terms of a folded-chain crystallization formula expanded for a binary mixing system of amorphous/crystalline polymers. The order of crystallization rates was plain PCL,>,CA- g -PCL (DS,=,2.98),>,CB- g -PCL (DS,=,2.1,2.95),>,CA- g -PCL (DS,=,2.1,2.5), and the fold-surface free energy of the PCL crystals obeyed the reverse order. POM revealed a generally tardy growth of spherulites for all the graft copolymers. The slower crystallization process may be ascribed primarily to the compulsory effect of anchoring PCL chains onto the semi-rigid cellulose backbone. Intercomponent miscibility of the CA/PCL and CB/PCL pairs was also taken into consideration. [source]

    Miscibility and Physical Properties of Poly(3-hydroxybutyrate -co- 3-hydroxyhexanoate)/Poly(ethylene oxide) Binary Blends

    Fang Yu
    Abstract In order to improve some inferior physical properties of bacterial poly(3-hydroxybutyrate -co- 3-hydroxyhexanoate) [P(3HB -co- 3HHx)] by blending with PEO, the miscibility, spherulite morphology, crystallization behavior and mechanical properties of P(3HB -co- 3HHx)/PEO binary biodegradable polymer blends were investigated. A good miscibility between P(3HB -co- 3HHx) with a 3HHx unit content of 11 mol-% and PEO in the amorphous state was found when the PEO weight fraction was 10,wt.-%, while the miscibility decreased dramatically when the PEO weight fraction exceeded 20,wt.-%. Strongly depending on the blend composition, the mechanical properties of P(3HB -co- 3HHx) was found to be significantly improved by blending with PEO with a weight fraction of ,5,17.5,wt.-%. [source]

    Miscibility in Blends of Isotactic/Syndiotactic Polystyrenes at Melt or Quenched Amorphous Solid State

    Shu Hsien Li
    Abstract Summary: Miscibility in amorphous phase and behavior in a crystalline phase of blends of two semicrystalline and isomeric polymers, isotactic polystyrene (iPS) and syndiotactic polystyrene (sPS), was probed. Optical and scanning electron microscopy results indicate no discernible heterogeneity in iPS/sPS blends in either melt state or rapidly quenched amorphous super-cooled state, while the Tg behavior of the quenched amorphous blends shows an intimately mixed state of two polymer chains. The crystal forms of the blends were further analyzed to provide additional evidence of miscibility in the amorphous domain. The sPS in the iPS/sPS blends upon melt crystallization was found to predominantly exist as the more stable , -form (rather than mixed , -form and , -form in neat sPS), which also suggests evidence of miscibility in the iPS/sPS blends. The melting behavior of semicrystalline sPS in the iPS/sPS mixtures was analyzed using the Flory-Huggins approach for estimation of interactions. By measuring the equilibrium melting point of the higher-melting sPS species in the sPS/iPS blends, a small negative value, for the interaction parameter (,,,,,0.11) was found. Further, by introducing a third polymer, poly(2,6-dimethyl- p -phenylene oxide) (PPO), a ternary iPS/sPS/PPO blend system was also proven miscible, which constituted a further test for stable phase miscibility in the iPS/sPS blend. General nature of miscibility in blends composed of two crystalline isomeric polymers is discussed. Issues in dealing with blends of polymers of the same chemical repeat unit but different tacticities were addressed. X-ray diffractograms for neat sPS and iPS/sPS blends, each having been isothermally crystallized at 245,C for 4 h. [source]

    Investigations of Miscibility in Interpenetrated Systems of Polyurethane and Polystyrene Obtained at Room Temperature

    Jean-Michel Widmaier
    Abstract Interpenetrating polymer systems based on crosslinked polyurethane (PU) and polystyrene (PS) were prepared at room temperature by a one-shot (in situ) method, starting from an initial homogeneous mixture of reagents via non interfering mechanisms. Both polymerizations were performed either simultaneously or one after the other. Crosslinks and/or covalent bonds between components were deliberately introduced by the addition of appropriate monomers, in order to tailor the degree of microphase separation. Depending on the formation process, transluscent or transparent films were obtained, despite the difference in refractive index of the components. The maximum of miscibility, taken as from the glass transition criterion, was obtained for sequential tightly graft interpenetrating networks. [source]

    Effect of Pressure on the Miscibility of Polyethylene/Poly(ethylene- alt -propylene) Blends

    Phillip Choi
    Abstract Summary: Effect of density, and hence pressure, on the miscibility of a 50:50 mol/mol PE/PEP blend was studied using a coarse-grained MC simulation approach on a high-coordination lattice, with the conformations of the coarse-grained chains constrained by the RIS model. Interchain pair correlation functions are used to assess the miscibility of the mixtures. Miscibility increases with increasing temperature over the range ,50,150,C. It is rather insensitive to pressure at high temperatures, but at ,50,C, the blend miscibility increases with decreasing pressure. The findings are consistent with the fact that the blend is an UCST blend and that the simulation temperatures used, except ,50,C, were considerably higher than the UCST of the blend. The pressure dependence of the blend miscibility observed near ,50,C is also in agreement with the experimental observation that the blend exhibits a negative volume change of mixing. The present work demonstrates that the coarse-grained MC approach, when it is used with periodic boundary cells of different sizes filled with the same number of chains, is capable of capturing the pressure dependence of UCST blends. In addition, such a simulation also provides us with insights about the molecular origin of the observed pressure dependence of miscibility. In the present case, the segregation of PE and PEP chains at low temperatures and high pressure simply originates from the fact that fully extended segments of PE chains tend to cluster so that their intermolecular interactions can be maximized. As the temperature increases, there is a decrease in the probability of a trans state at a CC bond in PE, and therefore the attraction between the PE chains is reduced at higher temperatures, promoting miscibility and the UCST behavior. Density (pressure) dependence of the 2nd shell pair correlation function values for a 50/50 PE/PEP blend at ,50,C. [source]

    Miscibility, crystallization behavior and specific intermolecular interactions in thermosetting polymer blends of novolac epoxy resin and polyethylene glycol

    Chen Qin
    Thermosetting polymer blends of novolac epoxy resin (EPN) and polyethylene glycol (PEG) were studied. The miscibility and crystallization behavior of the blends before curing reaction were investigated by polarized optical microscopy and differential scanning calorimetry (DSC). Overall uncured blend compositions were homogeneous in amorphous state. Single composition-dependent glass-transition temperature (Tg) for each blend could be observed, and the experimental Tg's of blends with EPN content ,40 wt% could be explained well by the Gordon,Taylor equation. Thermal properties of blends cured with 4,4,-diaminodiphenylmethane were also determined by DSC. The capability of PEG to crystallize in cured blends was different from that in uncured ones because of the topological effect of highly crosslinking structure. On the basis of Fourier transform infrared spectroscopy results, it was judged that there were intermolecular hydrogen-bonding interactions between EPN and PEG in both cured and uncured blends. POLYM. ENG. SCI., 2008. 2008 Society of Plastics Engineers [source]

    Poly(butylene terephthalate)/poly(,-caprolactone) blends: Miscibility and thermal and mechanical properties

    Maria Laura Di Lorenzo
    Miscibility and thermal and mechanical properties of poly(butylene terephthalate) (PBT) blends with poly(,-caprolactone) (PCL) were analyzed as a function of the molecular mass of PCL. It was found that the components are miscible when oligomeric PCL is blended with PBT, probably due to favorable interactions between OH end groups of poly(,-caprolactone) and ester groups of PBT. In the blends containing high molar mass PCL, the concentration of hydroxyl end groups is lower, allowing only partial miscibility of the components. The resulting materials display good mechanical properties, with enhanced performance at rupture compared to plain PBT. POLYM. ENG. SCI., 47:323,329, 2007. 2007 Society of Plastics Engineers. [source]

    Ternary miscibility in blends of three polymers with balanced binary interactions

    E. M. Woo
    This study demonstrates and discusses ternary miscibility in a three-polymer blend system based on balanced binary interactions. A truly miscible ternary blend comprising poly(,-caprolactone) (PCL), poly(benzyl methacrylate) (PBzMA), and poly(vinyl methyl ether) (PVME), was discovered and reported. Miscibility with phase homogeneity (excluding the PCL crystalline domain) in a wide composition range has been demonstrated using criteria of thermal transition behavior, cloud point, and microscopy characterization. At ambient temperature, the three-polymer ternary system is completely miscible within the entire composition range (i.e., no immiscibility loop). However, at slightly elevated temperatures above the ambient. phase separation readily occurred in this originally miscible ternary blend. A quite low "lower critical solution temperature" (LCST) near 75C was found for the ternary blend, which is much lower than any of those for the binary pairs. Balanced interactions with no offsetting ,, among the three binary pairs were a key factor leading to a ternary miscible system. [source]

    Synthesis of poly[(2-oxo-1,3-dioxolane- 4-yl)methyl methacrylate-co-styrene] by addition reaction of carbon dioxide and its compatibility with poly(methyl methacrylate) or poly(vinyl chloride)

    Sung-Young Park
    Abstract We investigated the chemical fixation of carbon dioxide (CO2) to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer to polymer blends. In the synthesis of poly[(2-oxo-1,3-dioxolane-4-yl)methyl methacrylate-co-styrene] [poly(DOMA-co-St)] from the addition of CO2 to poly(glycidyl methacrylate-co-styrene) [poly(GMA-co-St)], quaternary ammonium salts showed good catalytic activity at mild reaction conditions. The CO2 addition reaction followed pseudo first-order kinetics with the concentration of poly(GMA-co-St). In order to expand the applications of the CO2 fixed copolymer, polymer blends of this copolymer with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) were cast from N,N,-dimethylformamide (DMF) solution. Miscibility of blends of poly(DOMA-co-St) with PMMA or PVC have been investigated both by differential scanning calorimetry (DSC) and visual inspection of the blends, and the blends were miscible over the whole composition ranges. The miscibility behaviors were also discussed in terms of FT-IR spectra. Copyright 2002 John Wiley & Sons, Ltd. [source]

    Focal electroporation in ovo

    J. E. Simkin
    Abstract Gene expression fields in embryogenesis are spatially precise and often small, so experimental gene expression often requires similar spatial definition. For in ovo electroporation, typically a gene construct is injected into a natural body cavity in the embryo prior to electroporation. Limited control of the size and location of the electroporated field can be obtained by varying electrode placement and geometry, and by altering the miscibility and viscosity of the construct vehicle but it is difficult to tightly constrain electroporation to small regions. Electroporation of different constructs in close proximity has not been possible. We show that loading the construct into an agarose bead, which is then microsurgically implanted, allows for focal electroporation. Different constructs can be electroporated in close proximity by emplacing several agarose beads. This technique is simple, cheap, rapid, and requires no more specialised equipment than that required for conventional in ovo electroporation. Developmental Dynamics 238:3152,3155, 2009. 2009 Wiley-Liss, Inc. [source]

    An Alternative Approach to Constructing Solution Processable Multifunctional Materials: Their Structure, Properties, and Application in High-Performance Organic Light-Emitting Diodes

    Shanghui Ye
    Abstract A new series of full hydrocarbons, namely 4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(N,N -diphenylaniline) (DTPAFB), N,N,-(4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(4,1-phenylene))bis(N -phenylnaphthalen-1-amine) (DNPAFB), 1,3-bis(9-(4-(9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, and 1,3-bis(9-(4-(3,6-di- tert -butyl-9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, featuring a highly twisted tetrahedral conformation, are designed and synthesized. Organic light-emitting diodes (OLEDs) comprising DNPAFB and DTPAFB as hole transporting layers and tris(quinolin-8-yloxy)aluminum as an emitter are made either by vacuum deposition or by solution processing, and show much higher maximum efficiencies than the commonly used N,N,-di(naphthalen-1-yl)- N,N,-diphenylbiphenyl-4,4,-diamine device (3.6 cd A,1) of 7.0 cd A,1 and 6.9 cd A,1, respectively. In addition, the solution processed blue phosphorescent OLEDs employing the synthesized materials as hosts and iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] picolinate (FIrpic) phosphor as an emitter present exciting results. For example, the DTPAFB device exhibits a brightness of 47 902 cd m,2, a maximum luminescent efficiency of 24.3 cd A,1, and a power efficiency of 13.0 lm W,1. These results show that the devices are among the best solution processable blue phosphorescent OLEDs based on small molecules. Moreover, a new approach to constructing solution processable small molecules is proposed based on rigid and bulky fluorene and carbazole moieties combined in a highly twisted configuration, resulting in excellent solubility as well as chemical miscibility, without the need to introduce any solubilizing group such as an alkyl or alkoxy chain. [source]

    Functional Chromium Wheel-Based Hybrid Organic,Inorganic Materials for Dielectric Applications

    Vito Di Noto
    Abstract The first example of organic,inorganic hybrid materials based on the embedding of a chromium,nickel wheel cluster {[(n-C3H7)2NH2]- [Cr7NiF8(O2C4H5)16]} (Cr7Ni) into poly(methyl methacrylate) (PMMA) and the characterization of the dielectric properties of the obtained material is described. By an optimized copolymerization of the methacrylate-functionalized chromium,nickel wheel with methyl methacrylate in a cluster/monomer 1:200 molar mixture, a homogeneous hybrid material CrNi_MMA200 is obtained. The electrical responses of the non-doped PMMA and of the hybrid material were studied by broadband dielectric spectroscopy (BDS) from 0.01,Hz to 10,MHz and over the temperature range of 5,115,C. The permittivity profiles reveal two relaxation peaks in the materials, which correspond to the , and , relaxation modes of the PMMA matrix. The position of these modes shifts toward higher frequencies as temperature increases. BDS is a powerful tool revealing the intimate miscibility of the various components of the hybrid material, thus indicating that, on a molecular scale, the material proposed is a homogeneous system. Finally, a value of the dielectric constant of 2.9 at 25,C and 1,kHz is determined. This value is noticeably lower than the value of 3.2 obtained for pristine PMMA prepared following the same synthesis protocol. Thus, these results classify the hybrid CrNi_MMA200 as an appealing starting material for the development of dielectric polymeric layers for the development of innovative capacitors, transistors, and other microelectronic devices. The vibrational properties of the hybrid materials are investigated by Fourier-transform infrared (FT-IR) and Raman spectroscopy, whereas the thermal behavior is analyzed by thermogravimetric analysis (TGA). Swelling experiments are used to qualitatively evaluate the crosslinking density of the hybrid materials. The integrity of the wheels once embedded in the macromolecular backbone is confirmed by extended X-ray absorption fine structure (EXAFS) and electron spin resonance (EPR) spectroscopic measurements. [source]

    Phase Segregation in Thin Films of Conjugated Polyrotaxane, Poly(ethylene oxide) Blends: A Scanning Force Microscopy Study,

    L. Sardone
    Abstract Scanning force microscopy (SFM) is used to study the surface morphology of spin-coated thin films of the ion-transport polymer poly(ethylene oxide) (PEO) blended with either cyclodextrin (CD)-threaded conjugated polyrotaxanes based on poly(4,4,-diphenylene-vinylene) (PDV), ,-CD,PDV, or their uninsulated PDV analogues. Both the polyrotaxanes and their blends with PEO are of interest as active materials in light-emitting devices. The SFM analysis of the blended films supported on mica and on indium tin oxide (ITO) reveals in both cases a morphology that reflects the substrate topography on the (sub-)micrometer scale and is characterized by an absence of the surface structure that is usually associated with phase segregation. This observation confirms a good miscibility of the two hydrophilic components, when deposited by using spin-coating, as suggested by the luminescence data on devices and thin films. Clear evidence of phase segregation is instead found when blending PEO with a new organic-soluble conjugated polymer such as a silylated poly(fluorene)- alt -poly(para -phenylene) based polyrotaxane (THS,,-CD,PF,PPP). The results obtained are relevant to the understanding of the factors influencing the interfacial and the intermolecular interactions with a view to optimizing the performance of light-emitting diodes, and light-emitting electrochemical cells based on supramolecularly engineered organic polymers. [source]

    Generation of Compositional-Gradient Structures in Biodegradable, Immiscible, Polymer Blends by Intermolecular Hydrogen-Bonding Interactions,

    B. Hexig
    Abstract A biodegradable, immiscible poly(butylenes adipate- co -butylenes terephthalate) [P(BA- co -BT)]/poly(ethylene oxide) (PEO) polymer blend film with compositional gradient in the film-thickness direction has been successfully prepared in the presence of a low-molecular-weight compound 4,4,-thiodiphenal (TDP), which is used as a miscibility-enhancing agent. The miscibilities of the P(BA- co -BT)/PEO/TDP ternary blend films and the P(BA- co -BT)/PEO/TDP gradient film were investigated by differential scanning calorimetry (DSC). The compositional gradient structure of the P(BA- co -BT)/PEO/TDP (46/46/8 w/w/w) film has been confirmed by microscopic mapping measurement of Fourier-transform infrared spectra and dynamic mechanical thermal analysis. We have developed a new strategy for generating gradient-phase structures in immiscible polymer-blend systems by homogenization, i.e., adding a third agent that can enhance the miscibility of the two immiscible polymers through simultaneous formation of hydrogen bonds with two component polymers. [source]

    Solution-Processed Solid Solution of a Novel Carbazole Derivative for High-Performance Blue Phosphorescent Organic Light-Emitting Diodes

    ADVANCED MATERIALS, Issue 37 2010
    Shanghui Ye
    Blue light: Incorporation of two fluorenyl rings into a phenyl group at the C9 position of fluorene builds a bulky and rigidly tetrahedral framework, which is functionalized by two carbazole groups. This molecule possesses excellent thermal and morphological stability, miscibility to the phosphorescent dopant, and high triplet energy, leading to narrow blue phosphorescent emission. [source]

    Small-angle neutron scattering study of the miscibility of metallocene-catalyzed octene linear low-density polyethylene and low-density polyethylene blends

    Tae Joo Shin
    Small-angle neutron scattering (SANS) analysis was performed to investigate the miscibility of blends of metallocene-catalyzed octene linear low-density polyethylene (octene-mLLDPE) and low-density polyethylene (LDPE). The quantitative SANS analysis found that the blends are miscible in both the melt and the quenched states. Moreover, this analysis confirmed that the radii of gyration of octene-mLLDPE(D) and LDPE(H) remain unchanged in the quenched state and that the two polymer components cocrystallize via fast crystallization from the melt state. [source]

    A study of the recycling and stability of flexographic photopolymer plates

    Cristina C. Cordeiro
    Abstract Flexographic photopolymer plates have a wide range of commercial applications despite the fact that recycling of such materials is difficult. In consequence, there is a large bulk of leftover material around the world. In this research, the photopolymer plate waste products, identified as styrene-butadiene rubber (SBR)/polyester are blended into common polypropylene (PP) and ethylenevinylacetate (EVA) resins at different loading percentages. PP and EVA are used as the polymer matrix and the recovered styrene-butadiene rubber (SBR) material as the filler. Evaluation of the mechanical, spectroscopic, thermal and chemical properties, as well as morphology, is done by means of scanning electron microscopy (SEM). Mechanical results show that elongation strongly depends on the matrix polymer: the greater the amount of solid-sheet photopolymer (SSP), the smaller the elongation. No specific interactions were detected; however, thermal degradation and transitions were displaced, suggesting some miscibility. More homogeneity is seen for EVA blends, with no significant chemical attack detected. It is possible to reuse these recycled materials in blends with PP and EVA resins. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Preparation and flame retardancy of 2-EHA/n -BA acrylic PSA containing single and combined flame retardants

    Eun-Young Park
    Abstract UV curable acrylic PSAs (pressure-sensitive adhesives) were modified with organic and inorganic flame retardants to improve flame retardancy of PSAs minimize the sacrifice of adhesion properties. The flame retardancy (UL-94 test) of acrylic PSAs were enhanced by the addition of 5,30 wt % of an organic flame retardant such as TCEP (Tris(2-chloroethyl)phosphate), PBPE (pentabromophenyl ether), and TBBPA(3,3,5,5,-tetrabromobisphenol A). Especially, TBBPA is the best flame retardant for acrylic PSAs when it works alone. However, PSAs compounded with aluminum trihydroxide (Al(OH)3) showed a little reduction in burning time up to 30 wt %. An apparent synergic effect was observed only for an acrylic PSAs with a combination of TCEP and PBPE flame retardants. The addition of flame retardants brought a no significant effect on curing even in high amount. It was surmised that the miscibility between PSAs and flame retardant was closely related with flame retardancy and adhesion properties of acrylic PSAs. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    The totally miscible in ternary hydrogen-bonded polymer blend of poly(vinyl phenol)/phenoxy/phenolic

    Shiao-Wei KuoArticle first published online: 28 MAY 200
    Abstract The individual binary polymer blends of phenolic/phenoxy, phenolic/poly(vinyl phenol) (PVPh), and phenoxy/PVPh have specific interaction through intermolecular hydrogen bonding of hydroxyl,hydroxyl group to form homogeneous miscible phase. In addition, the miscibility and hydrogen bonding behaviors of ternary hydrogen bond blends of phenolic/phenoxy/PVPh were investigated by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, and optical microscopy. According to the DSC analysis, every composition of the ternary blend shows single glass transition temperature (Tg), indicating that this ternary hydrogen-bonded blend is totally miscible. The interassociation equilibrium constant between each binary blend was calculated from the appropriate model compounds. The interassociation equilibrium constant (KA) of each individually binary blend is higher than any self-association equilibrium constant (KB), resulting in the hydroxyl group tending to form interassociation hydrogen bond. Photographs of optical microscopy show this ternary blend possess lower critical solution temperature (LCST) phase diagram. 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

    The effect of ionic interaction on the miscibility and crystallization behaviors of poly(ethylene glycol)/poly(L -lactic acid) blends

    Wei-Chi Lai
    Abstract The effect of end groups (2NH2) of poly(ethylene glycol) (PEG) on the miscibility and crystallization behaviors of binary crystalline blends of PEG/poly(L -lactic acid) (PLLA) were investigated. The results of conductivity meter and dielectric analyzer (DEA) implied the existence of ions, which could be explained by the amine groups of PEG gaining the protons from the carboxylic acid groups of PLLA. The miscibility of PEG(2NH2)/PLLA blends was the best because of the ionic interaction as compared with PEG(2OH, 1OH-1CH3, and 2CH3)/PLLA blends. Since the ionic interaction formed only at the chain ends of PEG(2NH2) and PLLA, unlike hydrogen bonds forming at various sites along the chains in the other PEG/PLLA blend systems, the folding of PLLA blended with PEG(2NH2) was affected in a different manner. Thus the fold surface free energy played an important role on the crystallization rate of PLLA for the PEG(2NH2)/PLLA blend system. PLLA had the least fold surface free energy and the fast crystallization rate in the PEG(2NH2)/PLLA blend system, among all the PEG/PLLA systems studied. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Behavior of flexible poly(vinyl chloride)/poly(hydroxybutyrate valerate) blends

    A. Marcilla
    Abstract Blends of flexible poly(vinyl chloride) (PVC) and a poly(hydroxybutyrate valerate) (PHBV) copolymer were prepared and characterized with different techniques. The tensile strength of PVC did not show a marked reduction at PHBV concentrations up to 50 phr, despite a lack of miscibility between the two polymers. The crystallization of the PHBV copolymer was markedly hindered by the presence of PVC, as calorimetric results revealed. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Observations of physical aging in a polycarbonate and acrylonitrile,butadiene,styrene blend

    Jacky K. Y. Tang
    Abstract The effects of physical aging of a 75 : 25 PC/ABS blend have been studied using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). From DSC, two distinct peak endotherms at about 90C and 110C, which are associated with the glass transition of ABS (Tg,ABS) and PC (Tg,PC) components, respectively, were observed. When progressive aging was monitored at 80C for over 1000 h, the changes in enthalpic relaxation, glass and fictive temperatures for the blend followed similar trends to those already seen in the literature for PC aged between 125 and 130C. The rate of enthalpy relaxation was also comparable. The plot of peak endotherm against logarithmic aging time for the PC blend constituent, however, behaved quite differently from the linear relationship known for highly aged PC. The ABS peak component also appeared to be insensitive to aging. Both observations were confirmed to be statistically significant using analysis of variance methods. Using temperature modulated-DSC, there is evidence that aging increases the blend miscibility as the Tg,PC shifts toward the stationary Tg,ABS during aging. Parallel FTIR investigations found oxidation of butadiene during aging to be even at this relatively low temperature, forming hydroxyl and carbonyl degradation products. The presence of ABS in the blend also appeared to have prevented the shifting from the trans-cis to trans-trans arrangement of the carbonate linkage, which is a well-known phenomenon during elevated temperature aging of PC alone. Moreover, the carbonate linkage appears to have been at the lower energy, trans-trans, arrangement prior to the aging process. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Properties of styrene-methyl methacrylate grafted DPNR latex at different monomer concentrations

    Siti Hajjar Che Man
    Abstract The graft copolymerization of styrene and methyl methacrylate (MMA) on to deproteinized natural rubber (DPNR) latex was carried out. The effect of monomer concentrations on grafting efficiency, thermal and mechanical properties was studied. The synthesized graft copolymers were characterized by proton nuclear magnetic resonance (1H NMR) and the highest grafting efficiency was found at 20 wt % monomer concentration. At low monomer concentration (10 wt %) the grafting was not significant and at 30 wt %, the grafting efficiency was slightly decreased. The thermal properties of graft copolymers were analyzed using differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The degradation temperature (Tdeg) of the graft copolymer was increased with the increase in monomer concentration which indicates the improvement in thermal stability. The DSC result showed improvement in miscibility between the components as the monomer concentration increased. The mechanical properties of gum and filled modified NR were also investigated in terms of tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break decreased with an increase in monomer concentration while tensile modulus increased as the monomer concentration increased. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Preparation and characterization of interpenetration polymer network films based on poly(vinyl alcohol) and poly(acrylic acid) for drug delivery

    Yu-Mei Yue
    Abstract A series of full interpenetrating polymer network (full-IPN) films of poly(acrylic acid) (PAA)/poly (vinyl alcohol) (PVA) were prepared by radical solution polymerization and sequential IPN technology. Attenuated total reflectance-Fourier transform infrared spectroscopy, swelling properties, mechanical properties, morphology, and glass transition temperature of the films were investigated. FTIR spectra analysis showed that new interaction hydrogen bonds between PVA and PAA were formed. Swelling property of the films in distilled water and different pH buffer solution was studied. Swelling ratio increased with increasing PAA content of IPN films in all media, and swelling ratio decreased with increasing PVA crosslink degree. Tensile strength and elongation at break related not only to the constitution of IPNs but also to the swelling ratio of IPNs. Mechanical property of glutaraldehyde (0.5%) for poly(vinyl alcohol) crosslinking was better than that of glutaraldehyde (1.0%). DSC of the IPN films showed only a single glass transition temperature (Tg) for each sample, and Tg data showed a linear relationship with network composition. Morphology was observed a homogeneous structure, indicating the good compatibility and miscibility between PAA and PVA. Potential application of the IPN films in controlled drug delivery was also examined using crystal violet as a model drug. The release rate of the drug was higher at 37C than 25C for all IPNs and also increased slightly with decreasing of poly(acrylic acid) content. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    pH-sensitive alginate/soy protein microspheres as drug transporter

    Hua Zheng
    Abstract The complex microspheres based on alginate (AL) and soy protein isolate (SPI) were prepared by solution blending and then Ca2+ crosslinking, and their function as drug carrier was explored as well. The effects of composition on the structures of microspheres were studied, and the XRD results proved the miscibility between components. Meanwhile, FTIR results suggested that such miscibility was driven by strong hydrogen bonding. Especially, the complex microsphere with equal content of AL and SPI had the best miscibility by morphological analysis, shown as a smooth and uniform surface of SEM images. The controlled release function of the complex microspheres was verified using theophylline as a drug model, that is, the swelling and drug release were affected by pH conditions and showed obvious differences under given pH of stomach, intestine, and colon. Moreover, the intestine and colon may be optimal site for prompt release of drugs. Except for the attribution of AL component to pH sensitivity, the complex microspheres also inherited the bioactivity of SPI component, which may lower irritants of drug to the tissues in body. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]

    Miscibility and rheological properties of poly(vinyl chloride)/styrene,acrylonitrile blends prepared by melt extrusion

    Hyun Sik Moon
    Abstract Styrene,acrylonitrile (SAN) with acrylonitrile (AN) concentrations of 11.6,26 wt % and ,-methylstyrene acrylonitrile (,MSAN) with a wide range of AN concentrations are miscible with poly(vinyl chloride) (PVC) through solution blending. Here we examine the rheological properties and miscibility of PVC/SAN and PVC/,MSAN blends prepared by melt extrusion for commercial applications. We have investigated the rheological properties of the blends with a rheometer and a melt indexer. The PVC/SAN and PVC/,MSAN blends have a low melting torque, a long degradation time, and a high melt index, and this means that they have better processability than pure PVC. The miscibility of the blends has been characterized with differential scanning calorimetry, dynamic mechanical thermal analysis, and advanced rheometrics expansion system analysis. The miscibility of the blends has also been characterized with scanning electron microscopy. The SAN series with AN concentrations of 24,31 wt % is immiscible with PVC by melt extrusion, whereas ,MSAN with 31 wt % AN is miscible with PVC, even when they are blended by melt extrusion, because of the strong interaction between PVC and ,MSAN. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Evaluation of the crystallization kinetics and melting of polypropylene and metallocene-prepared polyethylene blends

    Mohammad Razavi-Nouri
    Abstract The kinetics of the isothermal crystallization of a polypropylene (PP) random copolymer containing 5 mol % ethylene, a metallocene linear low-density polyethylene (m -LLDPE) with 3.3 mol % hexene-1 as a comonomer, and three blends were studied with differential scanning calorimetry at temperatures sufficiently high to prevent any crystallization of m-LLDPE. The analysis was carried out with the Avrami equation. The overall crystallization rate and the equilibrium melting temperature of the PP copolymer decreased with increasing amounts of m-LLDPE in the blends. The former was attributed to the effect of m-LLDPE in reducing the number of primary nuclei, and the latter was attributed to a lowering of the fold surface energy due to the limited partial miscibility of the blend components. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 634,640, 2007 [source]

    Dispersion of graphite nanosheets in polymer resins via masterbatch technique

    Guohua Chen
    Abstract The dispersion of graphite nanosheets (GNs) in polymer matrices via the masterbatch technique was investigated. Modifying resin was added to GNs to prepare blend which is designated as the masterbatch. Such masterbatches, containing 70,80 wt % of GN filler, were blended with target polymers via melt extrusion process to prepare polymer/GN nanocomposites. The extruded nanocomposites showed characteristic conducting percolation behaviors with the percolation thresholds mainly dependent on the miscibility of the modifying resin with polymer matrix. The percolation thresholds of AS (Acrylonitrile-Styrene compolymer)/GN and high-density polyethylene (HDPE)/GN nanocomposites prepared by this technique were about 9 and 14 wt % of GN, respectively. Scanning electron microscopy and other characterizations showed that the GNs were well dispersed in AS and HDPE resins. The extrusion process and compatibility of the modifying resin with target polymer proved to be important factors for the homogeneity of the nanodispersion. 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3470,3475, 2007 [source]