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Phase Morphology (phase + morphology)
Selected AbstractsPhase Morphology in Electrospun Zirconia MicrofibersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Erin Davies Electrospinning of sol,gels has been used to produce zirconium-doped polymer microfibers from zirconyl chloride and poly(vinylpyrollidone) precursors. Calcination of these structures between temperatures of 370° and 930°C resulted in the formation of zirconia nanograined microfibers whose diameters ranged from 1200 to 800 nm at the higher temperatures and whose average grain size ranged from 9 to 33 nm. X-ray diffraction analysis revealed varying amounts of monoclinic and tetragonal zirconia present in the fibers and established how this varied with calcination temperature and time. The tetragonal phase was shown to be unstable and disappeared on heating the material beyond around 750°C. The amount of zirconia yielded from the precursor material was measured and was found to be consistently greater than the theoretical yield. Average grain size within the microfibers increased with increasing calcination temperature and is effectively doubled when a 10 kPa pressure was applied. The effect of pressure also results in the creation of new crystal structures within the nanofibers and, as with traditional zirconia processing, the addition of impurity ions was found to stabilize the tetragonal phase. [source] Preparation and linear rheological behavior of polypropylene/MMT nanocompositesPOLYMER COMPOSITES, Issue 3 2003Li Jian Maleic anhydride grafted low isotactic homopolypropylene elastomer (LiPP-g-MAH) is used as a compatibilizer in the melting mixing of polypropylene (PP) and clay. The microstructures of the composites of PP/clay (PPCN) are investigated using a wide-angle X-ray diffractometer (WAXD) and transmission electron microscope (TEM) as well as parallel rheometer, which show that PPCN with different phase morphologies have been obtained. It is found that the weight ratio of LiPP-g-MAH to clay and the weight content of LiPP-g-MAH in PPCN have a strong effect on the final dispersibility of the clay. The rheological response to small amplitude oscillatory shear (SAOS) shows that the storage modulus (G,) at the low frequencies is greatly sensitive to the microstructures in comparison with WAXD measurements. The investigation further indicates that the virgin clay particles, intercalated silicate crystallites, and exfoliated layers may coexist in the matrix at the same time, resulting in the great enhancement of G, plateau at low frequency region. [source] Effects of SBS on phase morphology of iPP/aPS blendsPOLYMER ENGINEERING & SCIENCE, Issue 10 2000The supermolecular structure of binary isotactic polypropylene/poly(styrene- b -butadiene- h -styrene) (iPP/SBS) and isotactic polypropylene/atactic polystyrene (iPP/aPS) compression molded blends and that of ternary iPP/aPS/SBS blends were studied by optical microscopy, scanning and transmission electron microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. Nucleation, crystal growth, solidification and blend phase morphology are affected by the addition of amorphous components (SBS and aPS). As a compatiblizer in immiscible iPP/aPS blends, SBS formed interfacial layer between dispersed honeycomb-like aPS/SBS particles and the iPP matrix, thus influencing the crystallization process in iPP. The amount of SBS and aPS, and compatibilizing efficiency of SBS, determine the size of dispersed aPS, SBS, and aPS/SBS particles and, consequently, the final blend phase morphologies: well-developed spherulitic morphology, cross-hatched structure with blocks of sandwich lamellae and co-continuous morphology. The analysis of the relationship between the size of spherulites and dispersed particles gave the criterion relation, which showed that, in the case of a well-developed spherulitization, the spherulites should be about fourteen times larger than the incorporated dispersed particles; i.e. to be large enough to engulf dispersed inclusions without considerable disturbing of the spherulitic structure. [source] The study of the miscibility and morphology of poly(styrene-co-4-vinylphenol)/poly(propylene carbonate) blendsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2004Furong Qiu Abstract Blends of poly(propylene carbonate) (PPC) with copolymer poly(styrene-co-4-vinyl phenol) (STVPh) have been studied by electron spin resonance (ESR) spin probe method and Raman spectroscopy. The ESR results indicated that the nitroxide radical existed in a PPC-rich and an STVPh-rich micro domain in the blends, corresponding to the fast-motion and slow-motion component in the ESR spectra, respectively. And in the temperature dependence composite spectra, the fast-motion fraction increased with increasing the hydroxyl group content in copolymer STVPh. Moreover, the ESR parameter T5mT, rotational correlation times (,c) and activation energies (Ea) showed similar dependence on the hydroxyl group content as the fast-motion fraction. It resulted from the enhancement of the hydrogen-bonding interaction between the hydroxyl groups in STVPh and the carboxyl groups and ether oxygen in PPC. However, the distinct band shift and intensity change among the Raman spectra of pure polymer components and those of the blends were observed. In the carboxyl-stretching region, the band shifted to lower frequency with increasing the hydroxyl groups. Furthermore, the phase morphologies of the blends were obtained by optical microscopy. All could be concluded that the hydrogen-bonding interaction between the two components was progressively favorable to the mixing process and was the driving force for the miscibility enhancement in the blends. Copyright © 2004 John Wiley & Sons, Ltd. [source] Morphology of poly(ethylene terephthalate) blends: An analysis under real processing conditions by rheology and microscopyADVANCES IN POLYMER TECHNOLOGY, Issue 3 2009lhan Özen Abstract The present work describes the formation of co-continuous phase morphologies in uncompatibilized and compatibilized poly(ethylene terephthalate) (PET),poly(m -xylene adipamide) (MXD6) and PET, poly(ethylene- co -vinyl alcohol) (EVOH) melt-extruded blends. Phase continuity has been determined by using the Jordhamo relationship. Viscosity values, which are essential for the calculation of the phase continuity, have been obtained by capillary rheometry. Thermal behavior of the blends has been analyzed by employing differential scanning calorimetry and phase continuity has been investigated for the noncompatibilized and the compatibilized blends by scanning electron microscopy. PET,MXD6 blends [92.35:7.65 (v/v) and 84.5:15.5 (v/v)] and PET,EVOH blends [73.63:26.37 (v/v)] exhibit droplet-in-matrix phase morphology, whereas uncompatibilized PET,MXD6 [75.8:24.2 (v/v)] blend has a combination of rod-like, droplet,matrix structure, and quasi-interpenetrating network structure. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:173,184, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20156 [source] Investigation of the phase morphology of dynamically vulcanized PVC/NBR blends using atomic force microscopyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010S. M. Gheno Abstract Dynamic vulcanization is a mixing process employed in the melt state of elastomers with thermoplastics. This process may result in the formation of thermoplastic vulcanized (TPV) materials with improved properties such as mechanical strength, Young's modulus, hardness, and abrasion fatigue. In this study, a vulcanized thermoplastic was obtained by the dynamic vulcanization of poly(vinyl chloride)/acrylonitrile butadiene rubber (PVC/NBR) blends using a curative system based on sulfur (S)/tetramethylthiuram disulfide (TMTD) and mercaptobenzothiazyl disulfide (MBTS). The formation of crosslinks was characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties were analyzed by tensile tests and the phase morphology was investigated using atomic force microscopy (AFM) operating in the tapping mode-AFM. The phase images of the dynamically vulcanized blends showed an elongated morphology, which can be associated to the formation of crosslinks that give the material its excellent mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Morphology, mechanical properties, and thermal stability of poly(L -lactic acid)/poly(butylene succinate- co -adipate)/silicon dioxide compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009Ruyin Wang Abstract Poly(butylene succinate- co -adipate) (PBSA) and two types of SiO2 (hydrophilic or hydrophobic) were used to modify poly(L -lactic acid) (PLLA). The mechanical properties, rheological and thermal behavior, phase morphology, and thermal stability of PLLA/PBSA/SiO2 composites were investigated. The impact strength, flexural strength, and modulus of PLLA/PBSA blends increased after the addition of hydrophobic SiO2 without decreasing the elongation at break, and the elongation at break monotonically decreased with increasing hydrophilic SiO2 content. The melt elasticity and viscosity of the PLLA/PBSA blend increased with the addition of SiO2. The hydrophilic SiO2 was encapsulated by the dispersed PBSA phase in the composites, which led to the formation of a core,shell structure, whereas the hydrophobic SiO2 was more uniformly dispersed and mainly located in the PLLA matrix, which was desirable for the optimum reinforcement of the PLLA/PBSA blend. The thermogravimetric analysis results show that the addition of the two types of SiO2 increased the initial decomposition temperature and activation energy and consequently retarded the thermal degradation of PLLA/PBSA. The retardation of degradation was prominent with the addition of hydrophobic SiO2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Improving low-density polyethylene/poly(ethylene terephthalate) blends with graft copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008D. E. El-Nashar Abstract Blends of low-density polyethylene (LDPE) and poly(ethylene terephthalate) (PET) were prepared with different weight compositions with a plasticorder at 240°C at a rotor speed of 64 rpm for 10 min. The physicomechanical properties of the prepared blends were investigated with special reference to the effects of the blend ratio. Graft copolymers, that is, LDPE-grafted acrylic acid and LDPE-grafted acrylonitrile, were prepared with ,-irradiation. The copolymers were melt-mixed in various contents (i.e., 3, 5, 7, and 9 phr) with a LDPE/PET blend with a weight ratio of 75/25 and used as compatibilizers. The effect of the compatibilizer contents on the physicomechanical properties and equilibrium swelling of the binary blend was investigated. With an increase in the compatibilizer content up to 7 phr, the blend showed an improvement in the physicomechanical properties and reduced equilibrium swelling in comparison with the uncompatibilized one. The addition of a compatibilizer beyond 7 phr did not improve the blend properties any further. The efficiency of the compatibilizers (7 phr) was also evaluated by studies of the phase morphology (scanning electron microscopy) and thermal properties (differential scanning calorimetry and thermogravimetric analysis). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Poly(lactic acid) properties as a consequence of poly(butylene adipate- co -terephthalate) blending and acetyl tributyl citrate plasticizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Maria-Beatrice Coltelli Abstract This study was aimed at the modulation of poly(lactic acid) (PLA) properties by the addition of both a low-molecular-weight plasticizer, acetyl tributyl citrate (ATBC), and a biodegradable aliphatic,aromatic copolyester, poly(butylene adipate- co -terephthalate) (PBAT). PLA/PBAT, PLA/ATBC, and PLA/PBAT/ATBC mixtures with 10,35 wt % ATBC and/or PBAT were prepared in a discontinuous laboratory mixer, compression-molded, and characterized by thermal, morphological, and mechanical tests to evaluate the effect of the concentration of either the plasticizer or copolyester on the final material flexibility. Materials with modulable properties, Young's modulus in the range 100,3000 MPa and elongation at break in the range 10,300%, were obtained. Moreover, thermal analysis showed a preferential solubilization of ATBC in the PBAT phase. Gas permeability tests were also performed to assess possible use in food packaging applications. The results are discussed with particular emphasis toward the effects of plasticization on physical blending in the determination of the phase morphology and final properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Thermal properties and phase morphology of melt-mixed poly(trimethylene terephthalate)/poly(hexamethylene isophthalamide) blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Fang-Chyou Chiu Abstract This work examines the thermal properties and phase morphology of melt-mixed poly(trimethylene terephthalate) (PTT)/poly(hexamethylene isophthalamide) (PA 6I) blends. Two temperatures, i.e., 250 and 260°C, are used to prepare the blends, respectively. Differential scanning calorimetry results indicate the immiscible feature of the blends. It is thus concluded that the ester-amide interchange reaction hardly occurred in the PTT/PA 6I blends. Depending on the composition and mixing temperature, the crystallization ability of PTT in the blends is either enhanced or hindered. Basically, a lower PA 6I content shifts the PTT melt crystallization to a higher temperature, whereas a higher PA 6I content causes an opposing outcome. The original complex melting behavior of neat PTT becomes more regular after the incorporation of 60 wt % or 80 wt % of PA 6I. Thermogravimetry analyses (TGA) show that the thermal stability of the blends improves as the PA 6I content increases. The two-phased morphology of the blends is examined by scanning electron microscopy (SEM). Polarized light microscopy (PLM) results reveal that the PTT spherulites become coarser with the inclusion of PA 6I; only smaller/dispersed crystallites are observed in the blend with 20 wt % of PTT. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Yttria,polystyrene,polypropylene composite for fine dyeable fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Chengbing Yu Abstract Fine polypropylene fiber has many excellent properties, but it is difficult to dye because of the absence of dye sites in the molecular chain and high crystallinity. Fine polypropylene/hybrid polystyrene (yttria) fiber melt-spun from blends of polypropylene and a small amount of nanohybrid polystyrene with modified yttria incorporated was prepared to improve the dyeing properties. The dyeability, orientation, degree of crystallinity, phase morphology, and mechanical properties of pure polypropylene and the blend fibers were investigated. It was found that the crystallinity and morphology of these phases in the blend systems were different. With the existence of nanohybrid polystyrene, the fine modified polypropylene filaments had practical mechanical properties, the amorphous region of the polypropylene/hybrid polystyrene (yttria) fiber increased, and the modified polypropylene fiber dyed easily and had good fastness to soaping because of the complexation of the disperse dye and yttrium in the blend system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis, characterization, and molecular modeling studies of novel polyurethanes based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)] diphenol hard segments,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2006A. V. Raghu Abstract Novel polyurethanes (PUs) based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)]diphenol as hard segments containing four aromatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) have been prepared. Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H NMR and 13C NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis have been used to determine the structural characterization and thermal properties of the segmented PUs. All the PUs contain domains of both semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties have been calculated with the group contribution method. Molecular dynamics simulations have been performed on all the PUs to estimate the cohesive energy density and solubility parameter values, which compare well with the values calculated with the group contribution method. Furthermore, the simulation protocols have been applied to the PUs to produce X-ray diffraction plots to determine the phase morphology of the PUs. The surface properties of the PUs have been estimated from the simulation protocols. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6032,6046, 2006 [source] Design of Blends with an Extremely Low Viscosity Ratio between the Dispersed and Continuous Phases.MACROMOLECULAR SYMPOSIA, Issue 1 2007Dependence of the Dispersed Phase Size on the Processing Parameters Abstract Summary: This work deals with the development of the dispersed phase morphology in immiscible blends of poly(ethylene glycol)/polyamide 66 (PEG/PA) with an extremely low viscosity ratio. The blends were obtained, under different operating conditions, by melt blending in an internal mixer. The objective was to examine the influence of the main processing parameters on the particles size of the minor phase (PEG). A model was elaborated to describe the dependence of the particle size on interfacial tension, PEG concentration, shear rate and viscosity ratio between the two blend components. [source] The Morphology and Dynamics of Substrate Effects on Spinodal Decomposition in Binary Mixtures with Short-Range PotentialMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006Li-Tang Yan Abstract Summary: The SDSD of binary mixture with short-range potential is numerically simulated in 3D by cell dynamic system (CDSs), focusing on the phase morphology and dynamics in the parallel cross-sections. The formation mechanism and growth law of the wetting layer are analyzed taking thermal noise effects into account. The simulated results show that the phase inversion in the parallel cross-sections can be observed near the substrate interface. Without thermal noise, the growth law of the wetting layer is simply logarithmic. However, when the strength of thermal noise is large enough, the LS growth law can be found for a short-range surface field. The results demonstrate that thermal noise can increase the extent of phase separation and lead to a transformation between partial and complete wetting for the substrate interface. The evolution of the phase in the parallel cross-sections obeys the LS growth law and is self-similar regardless of the effects of thermal noise. Simulated pattern evolution at different values of z at ,,=,1,000 with G,=,0. [source] Influence of composition and phase morphology on rheological properties of polypropylene/poly(ethylene- co -octene) blendsPOLYMER COMPOSITES, Issue 1 2010Lin Zhu In this article, the phase morphology and rheological properties of polypropylene (PP)/poly(ethylene- co -octene) (POE) blends with a droplet-matrix microstructure were studied by scanning electron microscopy and rheological experiments. The data were analyzed to yield the variations of rheological behavior with blend composition and insight into the microstructure of PP/POE blends. The Palierne's emulsion type model was used to extract information on rheological properties, and the interfacial tensions between the PP and POE were determined by fitting the experimental data with this model. The results indicated that the interfacial tensions were shown to depend on blend composition and temperature. Rheological properties of PP/POE blends were investigated in a systemic way with varying shear histories. The results showed that shear history had an important effect on the rheological properties of the blends due to the dispersed phase (POE) domains refined with increasing preshear rate and preshear time. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] A comparative study of dispersing a polyamide 6 into a polypropylene melt in a Buss Kneader, continuous mixer, and modular intermeshing corotating and counter-rotating twin screw extrudersPOLYMER ENGINEERING & SCIENCE, Issue 4 2008Keungjin Shon We have made a study of the development of phase morphology of an immiscible blend(75/25)(polypropylene,polyamide-6) for different types of continuous mixers including (i) Buss Kneader, (ii and iii) modular intermeshing corotating and counter-rotating twin screw extruders, and (iv) NEX-T Kobelco Continuous Mixer. Comparisons are made using different screw configurations for each machine. Generally, in comparison of the different machines, the intermeshing counter-rotating twin screw extruder produced the finest dispersed morphology. Using a droplet breakup kinetic model, we interpreted the blend dispersed phase droplet breakdown rate and coalescence rate. In comparison with our earlier study of the continuous mixing of agglomerates of CaCO3 particles the polymer droplet breakup rate was smaller than that of the particle agglomerates and the coalescence rates of droplets were many times greater than the particle reagglomerates rates. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Effects of SBS on phase morphology of iPP/aPS blendsPOLYMER ENGINEERING & SCIENCE, Issue 10 2000The supermolecular structure of binary isotactic polypropylene/poly(styrene- b -butadiene- h -styrene) (iPP/SBS) and isotactic polypropylene/atactic polystyrene (iPP/aPS) compression molded blends and that of ternary iPP/aPS/SBS blends were studied by optical microscopy, scanning and transmission electron microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. Nucleation, crystal growth, solidification and blend phase morphology are affected by the addition of amorphous components (SBS and aPS). As a compatiblizer in immiscible iPP/aPS blends, SBS formed interfacial layer between dispersed honeycomb-like aPS/SBS particles and the iPP matrix, thus influencing the crystallization process in iPP. The amount of SBS and aPS, and compatibilizing efficiency of SBS, determine the size of dispersed aPS, SBS, and aPS/SBS particles and, consequently, the final blend phase morphologies: well-developed spherulitic morphology, cross-hatched structure with blocks of sandwich lamellae and co-continuous morphology. The analysis of the relationship between the size of spherulites and dispersed particles gave the criterion relation, which showed that, in the case of a well-developed spherulitization, the spherulites should be about fourteen times larger than the incorporated dispersed particles; i.e. to be large enough to engulf dispersed inclusions without considerable disturbing of the spherulitic structure. [source] Morphological and fractal studies of polypropylene/poly(ethene-1-octene) blends during melt mixing using scanning electron microscopyPOLYMER INTERNATIONAL, Issue 3 2008Xinhua Xu Abstract BACKGROUND: Polymer blending creates new materials with enhanced mechanical, chemical or optical properties, with the exact properties being determined by the type of morphology and the phase dimension of the blend. In order to control blend properties, morphology development during processing needs to be understood. The formation and evolution of polypropylene/poly(ethylene-1-octene) (PP/POE) blend morphology during blending are qualitatively represented by a series of time-dependent scanning electron microscopy (SEM) patterns. The area diameter and its distribution of dispersed phase domains are discussed in detail. In order to characterize the formation and evolution of phase morphology quantitatively, two fractal dimensions, Ds and Dd, and their corresponding scaling functions are introduced to analyze the SEM patterns. RESULTS: The evolution of the area diameter indicates that the major reduction in phase domain size occurs during the initial stage of melt mixing, and the domain sizes show an increasing trend due to coalescence with increasing mixing times. The distribution in dispersed phase dimension obeys a log-normal distribution, and the two fractal dimensions are effective to describe the phase morphology: Ds for dispersed phase dimension and Dd for the distribution in it. CONCLUSIONS: The fractal dimensions Ds and Dd can be used quantitatively to characterize the evolutional self-similarity of phase morphology and the competition of breakup and coalescence of dispersed phase domains. It is shown that the fractal dimensions and scaling laws are useful to describe the phase morphology development at various mixing times to a certain extent. Copyright © 2007 Society of Chemical Industry [source] Domain structure and miscibility studies of blends of styrene,butadiene,styrene block copolymers (SBS) and styrene,glycidyl methacrylate statistical copolymers (PS-GMA) using SAXS and DMTAPOLYMER INTERNATIONAL, Issue 3 2007LB Canto Abstract The domain structure and miscibility in the solid state of a series of blends of styrene-butadiene-styrene (SBS) block copolymers and styrene-glycidyl methacrylate (PS-GMA) statistical copolymers with varying molecular weights and compositions were studied using small angle X-ray scattering and dynamic mechanical thermal analysis. Depending on the molecular characteristics of each component, different types and degrees of solubilization of PS-GMA in SBS were found which, in addition to the initially SBS phase morphology, lead to materials with multiphase domain morphologies with differences in size and structure. The degree of solubilization of PS-GMA into the PS domains of SBS was found to be higher for blends containing PS-GMA with lower molecular weight (Mw = 18 100 g mol,1) and lower GMA content (1 wt%) and/or for SBS with higher PS content (39 wt%) and longer PS blocks (Mw = 19 600 g mol,1). Localized solubilization of PS-GMA in the middle of PS domains of SBS was found to be the most probable to occur for the systems under study, causing swelling of PS domains. However, uniform solubilization was also observed for SBS/PS-GMA blends containing SBS with composition in the range of a morphological transition (PS block Mw = 19 600 g mol,1 and 39 wt% of PS) causing a morphological transition in the SBS copolymer (cylinder to lamella). Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd [source] Thermal properties and non-isothermal crystallization behavior of biodegradable poly(p -dioxanone)/poly(vinyl alcohol) blendsPOLYMER INTERNATIONAL, Issue 4 2006Zhi-Xuan Zhou Abstract Blends of two biodegradable semicrystalline polymers, poly(p -dioxanone) (PPDO) and poly(vinyl alcohol) (PVA) were prepared with different compositions. The thermal stability, phase morphology and thermal behavior of the blends were studied by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). From the TGA data, it can be seen that the addition of PVA improves the thermal stability of PPDO. DSC analysis showed that the glass transition temperature (Tg) and the melting temperature (Tm) of PPDO in the blends were nearly constant and equal to the values for neat PPDO, thus suggesting that PPDO and PVA are immiscible. It was found from the SEM images that the blends were phase-separated, which was consistent with the DSC results. Additionally, non-isothermal crystallization under controlled cooling rates was explored, and the Ozawa theory was employed to describe the non-isothermal crystallization kinetics. Copyright © 2006 Society of Chemical Industry [source] Reactive compatibilization of nylon copolymer/EPDM blends: experimental aspects and their comparison with theoryPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2008Cibi Komalan Abstract In situ reactive compatibilization was first time applied to a low melting nylon (nylon 6 and 66 copolymer) and EPDM blend system. The effects of in situ compatibilization and concentration of compatibilizer on the morphology and mechanical properties of nylon/EPDM blends have been investigated. The influence of EPM-g-MA on the phase morphology was examined by the scanning electron microscopy (SEM) after preferential extraction of the minor phase. The SEM micrographs were quantitatively analyzed for domain size measurements. The compatibilizer concentrations used were 0, 1, 2.5, 5, and 10,wt%. The graft copolymer (nylon-g-EPM) formed at the interface showed relatively high emulsifying activity. A maximum phase size reduction was observed when 2.5,wt% of compatibilizer was added to the blend system. This was followed by a leveling-off at higher loadings indicating interfacial saturation. The conformation of the compatibilizer at the interface was deduced based on the area occupied by the compatibilizer at the blend interface. The experimental compatibilization results were compared with theoretical predictions of Noolandi and Hong. It was concluded that the molecular state of compatibilizer at interface changes with concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties. Measurement of tensile properties shows increased elongation as well as enhanced modulus and strength up on compatibilization. At higher concentrations of compatibilizer, a leveling-off of the tensile properties was observed. A good correlation has been observed between the mechanical properties and morphological parameters. Copyright © 2007 John Wiley & Sons, Ltd. [source] Morphology and thermal properties of a PC/PE blend with reactive compatibilizationPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2007Bo Yin Abstract Reactive compatibilization of immiscible polymers is becoming increasingly important and hence a representative study of a polycarbonate/high density polyethylene (PC/HDPE) system is the focus of this paper. A grafted copolymer PC- graft -ethylene- co -acrylic acid (PC- graft -EAA) was generated as a compatibilizer in situ during processing operation by ester and acid reaction between PC and ethylene-acrylic acid (EAA) in the presence of the catalyst dibutyl tin oxide (DBTO). As the polyethylene (PE) matrix does not play any part during the synthesis of the copolymer and since PC and EAA are also immiscible, to simplify the system, the influence of this copolymer formation at the interface between PC and EAA on rheological properties, phase morphology, and crystallization behavior for EAA/PC binary blends was first studied. The equilibrium torque increased with the DBTO content increasing in EAA/PC blends on Haake torque rheometer, indicating the in situ formation of the graft copolymer. Scanning electron microscopy (SEM) studies of cryogenically fractured surfaces showed a significant change at the distribution and dispersion of the dispersed phase in the presence of DBTO, compared with the EAA/PC blend without the catalyst. Differential scanning calorimetry (DSC) studies suggested that the heat of fusion of the EAA phase in PC/EAA blends with or without DBTO reduced with the formation of the copolymer compared with pure EAA. Then morphological studies and crystallization behavior of the uncompatibilized and compatibilized blends of PC/PE were studied as functions of EAA phase concentration and DBTO content. Morphological observations in PC/PE blends also revealed that on increasing the EAA content or adding the catalyst DBTO, the number of microvoids was reduced and the interface was intensive as compared to the uncompatibilized PC/PE blends. Crystallization studies indicated that PE crystallized at its bulk crystallization temperature. The degree of crystallinity of PE phase in PC/PE/EAA blends was also reduced with the addition of EAA and DBTO compared to the uncompatibilized blends of PC/PE, indicating the decrease in the degree of crystallinity was more in the presence of PC- graft -EAA. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||