Top PDF Isothermal Melt Crystallization Kinetic Behavior of Poly (vinylidene fluoride)

Isothermal Melt Crystallization Kinetic Behavior of Poly (vinylidene fluoride)

Isothermal Melt Crystallization Kinetic Behavior of Poly (vinylidene fluoride)

were depressed with either the adding of PVAc or the increasing of crystallization temperature. The kinetics retardation was ascribed to the decrease in PVDF molecular mobility and dilution of PVDF concentration due to the addition of PVAc, which has a higher glass transition temperature. By decreasing molecular mobility and dilution of PVDF concentration, which is due to the adding of PVAc, the kinetics retardation was ascribed, having a higher glass transition temperature. Fan and Zheng [20] studied the miscibility behavior in blends of poly(methyl methacrylate) and poly(vinylidene fluoride). The Avrami exponent decreases with increasing crystallization temperature. Sencadas et al. [8] studied the isothermal melt crystallization of PVDF at different crystallization temperatures. The Avrami parameters and the Hoffman-Weeks were discussed to obtain the equilibrium melting temperature. The crystallization of poly (vinylidenefluoride) / poly (3-
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An investigation on non-isothermal crystallization behavior and morphology of polyamide 6/ poly(ethylene-co-1-butene)-graft-maleic anhydride/organoclay nanocomposites

An investigation on non-isothermal crystallization behavior and morphology of polyamide 6/ poly(ethylene-co-1-butene)-graft-maleic anhydride/organoclay nanocomposites

Specific interactions between polymer matrix and organoclay, e.g., hydrogen bonding, dipole-dipole interaction, ionic interaction, etc, provide more compatibility of these pairs. As described by Lee and Han [16] the degree of compatibility between polymer chains and organoclay determines the degree of dispersion of organoclay platelets, which in turn dominates the crystallization and melting behavior of polymer matrix. The structure of organo-modifier which is applied in the nanoclay platelets governs the degree of interaction and compatibility of polymer matrix and nanoclay. To our knowledge, the influence of organoclay modifier on the melting behavior and the crystal forms of toughened PA6 has not been studied sufficiently. The main objective of this study is to investigate the effect of organoclay type on the crystallization behavior and thermal properties of PA6/ poly(ethylene- co- 1-butene)- graft- maleic anhydride/ organoclay nanocomposites using DSC and WAXD. The effect of blend ratio and organoclay concentration has been also discussed. Since the distribution and morphology of nanoclay has an important role in crystallization behavior of the compound, the location and morphology of nanoclay was tracked using TEM and SAXS.
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Non-isothermal crystallization kinetic behavior of Specific Cu(1-X)ZnX Ferrite Formation in the 
Flow Injection Synthesis Co-precipitation Reactor

Non-isothermal crystallization kinetic behavior of Specific Cu(1-X)ZnX Ferrite Formation in the Flow Injection Synthesis Co-precipitation Reactor

. Flow Injection Synthesis is one way to do co-precipitation synthesis which can be done automatically by using a data acquisition system supported datalogger instrument completed both high resolution of the digital pH meter and digital thermometer. In this study the data acquisition could be used to expected the necessary of performing material parameter such as the activation energy of crystallization, particle size, reaction rate, isothermal or non-isothermal reaction and especially to get activation energy of Cu-Zn Ferrite. Thermodynamics of Cu-Zn ferrite behavior have been observed by many scientists since intensively in University of Michigan [8] use sophisticated calorimeter. At room temperature is 5.367 [cal/mol] [8]. According to Cu-Zn ferrite as co-precipitation yield of chlorine Cu 2+ , Zn 2+ , Fe 3+ and Fe 3+ to alkaline hydroxide as precursor, the metal salts are in the negligible side, causing by suggest that all of input compound completely be amount of yields, but not in precipitant solution, the solution concentrate decrease proportional with increasing of yield concentrate [8], such as equation
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Unusual Formation of Precursors for Crystallization of Ultra-High Performance Polypropylene and Poly(ethylene terephthalate) Fibers by Utilization of Ecologically Friendly Horizontal Isothermal Bath.

Unusual Formation of Precursors for Crystallization of Ultra-High Performance Polypropylene and Poly(ethylene terephthalate) Fibers by Utilization of Ecologically Friendly Horizontal Isothermal Bath.

deformation of tie chains occurred with the chains slip through crystals during the drawing of i-PP and also the lamellar disintegration is leading activation of constrained amorphous places 39 . Samuels et al. 40 conducted studies to observe a quantitative morphological description the uniaxial deformation of both melt cast sheet and melt spun filament. He concluded the location of the radii where a spherulite deformation occurs depended on the applied load and this deformation is divided in two stages. During the first stage, lamellar slip leading to c-axis orientation until obtaining fully oriented structure. Once this point is reached, the additional extension causes a new type of deformation mechanism which called crystal cleavage. At this point any further extension leads separation of lamellae in blocks and the helical chain axis of the noncrystalline molecules become more oriented to evolve into a fibrillar structure 40 . Any more deformation after this point causes to develop flaws and the sample breaks.
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Inhibition effect of polyvinyl butyral on crystallization of polypropylene

Inhibition effect of polyvinyl butyral on crystallization of polypropylene

I n this work, a series of polypropylene/polyvinyl butyral (PP/PVB) blends were prepared by melt-blending process, at PVB loadings 3 wt%, 10 wt%, and 30 wt%. The effects of PVB on crystallization behavior of PP were investigated by differential scanning calorimetry (DSC), and polarized optical microscopy (POM). The isothermal crystallization kinetics were analyzed by Avrami equations. It was found that the addition of PVB strikingly reduced the overall crystallization rate of PP. The POM results further indicated that the crystallization rate of PP/ PVB was significantly reduced by reducing the nucleation density of PP with the addition of PVB. The fractured surface morphology of PP/PVB blends was characterized by scanning electron microscopy (SEM), and the results showed that the PVB was uniformly dispersed in the PP matrix as small spherical particles, with a good dispersion and dimensional stability. Polyolefins J (2018) 5: 141-151
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Threadline Modification of Poly(ethylene terephthalate) (PET) High-Speed Melt Spinning by Integration of Horizontal Liquid Isothermal Bath (HIB) and Drawing Process.

Threadline Modification of Poly(ethylene terephthalate) (PET) High-Speed Melt Spinning by Integration of Horizontal Liquid Isothermal Bath (HIB) and Drawing Process.

As a matter of fact, the observed value of tensile properties of commercial polymer fibers are relatively lower than that of theoretical value which were calculated by utilizing classical kinetic and thermodynamic methods. Some researchers believed this limitation is inevitable and has to be accepted during manufacturing due to a consequence of high random and entangled structures of precursor polymer melt. The imperfections in the current fiber extrusion processes also lead to this gap as Dr. Cuculo’s group reported (121). Meanwhile, it was argued that if the optimal conditions can be found, then it is possible to directly form fully oriented filaments from isotropic polymer melt (39, 123). This transformation could lead to actual tensile properties of filaments close to the theoretical limit value.
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Non-Isothermal Crystallization Kinetics of Phb/Tio2 Nanocomposites

Non-Isothermal Crystallization Kinetics of Phb/Tio2 Nanocomposites

melt mixing in a laboratory internal mixer; five compositions were produced with TiO 2 content ranging from 1% to 10% by weight. The non-isothermal melt and cold crystallization processes were investigated by DSC applying heating/cooling/reheating cycles (six different heating/cooling rates). Kinetic results were described using the Pseudo-Avrami model. Friedman’s isoconversional methodology [16] was employed to estimate the activation energies as functions of the relative crystallinity.

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Kinetic Analysis of Crystallization Process in Amorphous Se90 xTe10Pbx Glasses

Kinetic Analysis of Crystallization Process in Amorphous Se90 xTe10Pbx Glasses

the melt, the tube was frequently rocked to intermix the constituents and to increase the homogenization of the melt. This treatment was followed by fast quenching in ice–water mixture. The glassy nature of the as-prepared as well as the crystalline phase structures for annealed samples was identified using a Philips diffractometer type 1710. DTA experiments were carried out on the as-prepared powder samples by using a Perkin-Elmer DTG-60 under non- isothermal conditions. The values of the glass transition temperature (T g ), the onset crystallization temperature (T c ),
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Dispersion and Performance Properties of Carbon Nanotubes (CNTs) Based Polymer Composites: A Review

Dispersion and Performance Properties of Carbon Nanotubes (CNTs) Based Polymer Composites: A Review

Carbon nanotubes (CNTs) based polymer composites have variety of engineering applications (electromagnetic shield- ing, antistatic coatings, high-strength low-density corrosion-resistant components, lightweight energy storage and many more); due to their excellent mechanical, electrical, chemical, magnetic, etc. properties. In the polymer nanocomposites CNTs are dispersed in the polymeric matrix. However the dispersion may be uniform or may not be uniform. The big- gest challenge is the effective dispersion of individual CNTs in the polymer matrices, as CNTs tends to form clusters and bundles due to strong van der Waals’ forces of attraction. The aggregated structure continue until physical (Me- chanical) or chemical modification (Encapsulation/surface modification) of CNTs. Few modification methods such as vigorous mixing of the polymers damages CNTs structure, and may hinder their properties. But these problems can be overcome by mechanical or chemical modification of CNTs surfaces. In the chemical modification, the modifier or the long tail surfactant may encapsulate and/or partially wrap the CNTs surfaces. In this review, recent work on CNTs based polymer nanocomposite is carried out with few modifiers/encapsulating agents. Incorporation of CNTs in poly- mer matrix changes the performance properties such as tensile strength, tensile modulus, elongation at break, toughness, Dynamic mechanical thermal analysis (DMTA), etc. The phase morphology of the composite materials throws light on the properties of CNTs based polymer nanocomposite. Moreover phase morphology may be directly correlated with the behavior of the material, hence reviewed here through transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Furthermore review is also carried out on the non-isothermal crystallization (DSC) and rheology of CNTs polymer nanocomposite.
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Study of Non-Isothermal Crystallization Kinetics of Biodegradable Poly(ethylene adipate)/SiO2 Nanocomposites

Study of Non-Isothermal Crystallization Kinetics of Biodegradable Poly(ethylene adipate)/SiO2 Nanocomposites

Liu et al. [16] proposed a different kinetic equation by combining the Ozawa and Avrami equations. As the degree of crystallinity was related to the cooling rate and the crystallization time t (or temperature T), the relation between α and t could be defined for a given degree of crystallinity. Consequently, a new kinetic equation for nonisothermal crystallization was derived by combining Eqs. (4) and (6):

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Isothermal and non isothermal crystallization kinetics of composites of poly(propylene) and MWCNTs

Isothermal and non isothermal crystallization kinetics of composites of poly(propylene) and MWCNTs

low cost and density and, it is readily melt processable [1,4,5]. PP is a semi-crystalline polymer and the addition of (nano) fi llers has shown to result in changes in crystalline content, crystal type, size and distribution [6]. PP is typically mixed with CNTs via melt blending in a twin screw extruder as it free of contamination from solvent residues and the number of CNT agglomerates can be minimised by way of application of appropriate shear stress [1]. During crystallisation, PP develops a partially ordered structure from the disordered melt phase. The trend towards shorter cycles times and faster cooling rates along with the addition of nucleating agents (CNTs) requires a better understanding of the crystallization kinetics of the composite and thus its fi nal properties [7].
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Effect of Melt Mixing Time in Internal  Mixer on Mechanical Properties and  Crystallization Behavior of Glycidyl  Methacrylate Grafted Poly (Lactic Acid)

Effect of Melt Mixing Time in Internal Mixer on Mechanical Properties and Crystallization Behavior of Glycidyl Methacrylate Grafted Poly (Lactic Acid)

The double melting peaks located at lower and higher temperatures were observed in Figure 5 for both pure PLA and PLA-g-GMA, which related to the less organized crystals and well-organized crystals, respectively [10]. However, the melting temperature of PLA-g-GMA was found to be lower than that of pure PLA. This im- plied that the formation of lamella was hindered by GMA grafted on PLA chains, which led to less perfect crys- tals of PLA-g-GMA [10]. Furthermore, it also indicated that GMA, on the one hand, acted as nucleation agent for the crystallization of PLA but reduced the chain mobility on the other hand.
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Non-isothermal Crystallization Kinetics of Polypropylene (PP) and Polypropylene (PP)/Talc Nanocomposite - Volume 1 Number 4 (Dec. 2010) - IJCEA

Non-isothermal Crystallization Kinetics of Polypropylene (PP) and Polypropylene (PP)/Talc Nanocomposite - Volume 1 Number 4 (Dec. 2010) - IJCEA

346 Abstract—This study was carried out to achieve the nonisothermal crystallization kinetics of Poly(Propylene) (PP) and poly(propylene)/nano Talc (PP/nt) nanocomposite were investigated by differential scanning calorimetry (DSC) with various cooling rates. The polymer PP and nano Talc with different % compounded by HAAKE Rheocord extruder. In order to improve the polyolefin nanocomposite formation by melt processing the use of an additional compatibilizer has been proposed. preferably for a nanocomposite material, comprising (a) a synthetic polymer, (b) a filler such as for example a natural or synthetic phyllosilicate or a mixture of such phyllosilicates, preferably in nanoparticles, and (c) a dispersing agent prepared by controlled free radical polymerization (CFRP). The degree of crystalinity of the talc- filled PP nano composite were calculated with the help of the ratio of the area under the cooling curve (heat of fusion ∆H) with respect to the area under 100 % crystalline PP material. The Avrami analysis modified by previous research was used to describe the nonisothermal crystallization process of PP and PP/Talc very well. The values of half-time and Z c showed that
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Isothermal and Non Isothermal  Crystallization Kinetics of Conductive  Polyvinylidene Fluoride/Poly(Ethylene  Terephthalate) Based Composites

Isothermal and Non Isothermal Crystallization Kinetics of Conductive Polyvinylidene Fluoride/Poly(Ethylene Terephthalate) Based Composites

It is well known that polymers properties are largely controlled by their crystallization conditions. The inves- tigation of their crystallization behavior is then an important step to optimize many of their properties, such as mechanical properties and electrical conductivity. Polymer crystallization is centered mostly on isothermal and non-isothermal crystallizations (including nucleation, crystal growth, crystal size, and crystallization rate) since they are of great importance to reach the desired end-use properties. Among polymer materials for BP applica- tions, PVDF-based blends with PMMA or PET are regarded as the most promising candidates because these two polymers exhibit good mechanical and electrical properties once appropriate conductive fillers are added. PVDF/PMMA blends were extensively studied as PMMA is miscible with PVDF. Reported works aimed at un- derstanding the effect of PMMA content on PVDF/PMMA blend morphology, its rheological and thermo-me- chanical properties, as well as miscibility, crystallinity, crystalline structure and crystallization kinetics of the PVDF phase [5] [6]. Unlike PMMA, PET is a semi-crystalline polymer and, once carbon conductive fillers are added to the PVDF/PET blend, morphology analysis revealed that that the conductive fillers are mainly confined in the PET phase. This peculiar morphology clearly yields to an improvement of PVDF/PET mechanical and electrical properties [7]. However and unlike PVDF/PMMA blends, there are few reported works on PVDF/PET crystallization [8] and, to the best of our knowledge, no detailed studies on the isothermal and non-isothermal crystallization kinetics of PVDF/PET based blends used for PEMFC bipolar plates, which represents the main objective of the present work. We based our study on a previous work [1] where we have developed PVDF/PET/ CB/GR conductive composites, in which were added small amounts of TPO-RP to facilitate BPPs demolding and cyclic butylene terephthalate (c-BT) oligomer to decrease composites viscosity and consequently to improve their process ability. In that work, we showed the effect of PVDF and PET crystallinity and crystallization tem- perature on BP through-plane resistivity. In the present work, we show how this crystallinity is developed inside the conductive PVDF/PET based composite, especially under isothermal and non-isothermal conditions, which respectively represent the real conditions of BP molding and cooling.
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Effect of Cu and P on the Crystallization Behavior of Fe Rich Hetero Amorphous FeSiB Alloy

Effect of Cu and P on the Crystallization Behavior of Fe Rich Hetero Amorphous FeSiB Alloy

electron microscopy (TEM). Thermal properties of melt- spun ribbons were measured with a differential scanning calorimeter (DSC) under flowing high purity argon. A set of DSC scans were obtained at heating rates ranging from 5 to 80 K/min. For the isothermal analysis, the melt-spun samples were first heated (at a rate of 10 K/min) to a fixed temperature, then, maintained for a certain period of time until the completion of the first exothermic process. All specimens were annealed at appropriate temperatures for 10 min in a vacuum furnace.

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Melt inclusion record of magmatic immiscibility in crustal and mantle magmas

Melt inclusion record of magmatic immiscibility in crustal and mantle magmas

Morphologically similar hydrosaline globules hosted in quartz (Fig. 4-6) and co-trapped with the silicate melt (Fig. 4-7) are confirmed to be compositionally alike by microthermometric experiments and microbeam analyses (Harris et al. 2003, 2004, Kamenetsky et al. 2004b). The globules are all metal- (1000’s–10000’s ppm) and chloride-rich (Fig. 4-8), although the element abundances and ratios vary significantly, even for co-trapped globules (Kamenetsky et al. 2004b). Compositional variability among hydrosaline globules suggests strong fractionation of most elements between immiscible liquids and the disequilibrium character of exsolution. The latter means that if immiscibility is a continuous process in highly evolved magmatic systems, the components of a dispersed hydrosaline phase must have varying composition, because of the variability of diffusion rates for different elements. In the residual granitic system, where crystallization and immiscibility drive chemical fractionation to the extreme, chemical disequilibrium may occur on very small spatial and temporal scales, and is maintained by slow element diffusion and delayed mixing in a relatively cold, viscous and strongly crystalline environment.
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The Vacancy Cluster Tubes Formation and Metal Properties Changes After Dynamic Centrifugal Casting

The Vacancy Cluster Tubes Formation and Metal Properties Changes After Dynamic Centrifugal Casting

Figures 1-5 show the results of electronic microscope studies of the Al and Pb metal structure obtained under conditions of high-intensity plastic deformation at the their crystallization point. The studies were performed using atomic force microscopy (AFM) on Femto Skan and Solver probe microscopes. As it follows from the data presented, vacancy cluster tubes (VCT) with average diameters ranging from 39 nm for Al and 25 nm for Pb are found in the volume of crystallized Al and Pb metals. The tubes are extended to the center of the rotor (Figures 1, 3, and 4). Vacancy cluster tubes have hexagonal symmetry in their cross section (Figures 1 and 4), which corresponds to the FCC lattices of Al and Pb and serves as additional evidence of the fact that formation of the FCC Lattice occurs in the crystallized area of the crystallization front. When crystallizing Al and Pb under high-intensive plastic deformation (HIPD) of ε′ = (10 2
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Control of a Nanocomposite Structure in Fe86Nd9B5 Alloy by Electron Irradiation

Control of a Nanocomposite Structure in Fe86Nd9B5 Alloy by Electron Irradiation

irradiation raises the energy of a crystalline phase due to lattice defects created by the electron knock-on effect. The crystalline phase cannot maintain its original structure under electron irradiation if atomic displacement by the electron knock-on effect occurs more frequently than recovery of the original positions of atomic sublattice by thermal diffusion. When a critical energy is provided to the crystalline phase by electron irradiation, transformation to the amorphous phase with a higher energy state is believed to occur. However, such a phase, namely, transformation mechanism to the higher energy state under a supply of external energy, is not applicable for the thermal crystallization or electron irradi- ation induced crystallization from an amorphous phase.
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The evolution of magma during continental rifting : new constraints from the isotopic and trace element signatures of silicic magmas from Ethiopian volcanoes

The evolution of magma during continental rifting : new constraints from the isotopic and trace element signatures of silicic magmas from Ethiopian volcanoes

there are variations in fractional crystallization between the different volcanic systems, and melt evolution is amplified in less mature rifts with lower magma flux.. despite significan[r]

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Application of Single Scan Differential Scanning Calorimetry Technique for Determination of Kinetic Parameters of Crystallisation in Se Sb Ag

Application of Single Scan Differential Scanning Calorimetry Technique for Determination of Kinetic Parameters of Crystallisation in Se Sb Ag

Different kinds of erasable phase-change optical recording materials have been investigated by several researchers. Some of the important properties of erasable phase-change optical recording materials are the laser power and pulse duration needed for writing and erasing, the maximum number of write/erase cycle and lifetime of recording spots at room temperature. In practice, the laser pulse duration used to write and erase is usually several hundred nanoseconds. It is difficult to erase a written spot in several hundred nano-seconds if the amorph- ous to crystalline (a-c) transformation rate of the recording medium is not suffi- ciently high. For this reason the study of crystallization rate and the factor that influence it are very important for the development of new kinds of erasable phase-change optical recording materials
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