Recent advances in understanding flow effects on polymer. A model for the description of the combined process of quiescent and flow. View the article pdf and any associated supplements and figures for a period of 48 hours. Induced crystallisationinpolymers monday20th,wednesday22ndjanuary2020 leedsandbradford,uk monday20jan location. We present a study on flow induced crystallization of polymers filled with rigid particles.
Crystallization in polymers is a physical property that has strong influence on other engineering properties, such as strength and degradation rate. Meijer dutch polymer institute, materials technology. Pdf on jan 1, 2005, rja steenbakkers and others published modeling flowinduced crystallization of polymers find, read and cite all the research you need on researchgate. On the orientationinduced crystallization of polymers mdpi. Flow induced crystallization of polymers salerno, italy impact to processing and manufact properties 1417 october 2001 the influence of flow induced crystallization on the impact toughness of highdensity polyethylene b. It is a wellknown fact that the crystallization kinetics of polymers crystallizing from the melt are influenced. Flow induced crystallization fic is a nonequilibrium thermodynamic phase transition occurring in daily industrial processing of semicrystalline polymers with an annual consumption of hundred.
Differential scanning calorimetry and synchrotron radiation were used to investigate the combined effect of shear flow and pressure on sc crystallization. Orientationinduced nucleation in polymer crystallization. In this perspective, we first discuss some recent modifications and improvements on early coarsegrained approaches like the coilstretch transition. Heat transfer, fluid flows, and thermal systems, parts a, b and c. However, a deeper understanding of flow effects on polymer crystallization. Pdf development and validation of a recoverable strain. Towards a rheological classification of flow induced. Flowinduced crystallization of propyleneethylene random. Flowinduced crystallization kinetics, recoverable strain. Dario cavallo, fiorenza azzurri, luigi balzano, sergio s. Kinetics and morphology of flow induced polymer crystallization in. The numerical simulations reveal the interplay between filler particles, the polymer melt, flow and flow induced crystallization. In this connection also a monograph janeschitzkriegl 2009 must be mentioned, which has been written last year by the first author of this article. Effect of branching on flowinduced crystallization of.
Reviews on flow induced crystallization can be found in eder et al. Flow induced crystallization fic of polymers is a longstanding, industrial relevant, nonequilibrium thermodynamic challenge. Proceedings of the asme 2009 international mechanical engineering congress and exposition. A phase field technique for modeling and predicting flow. The model predicts crystallization kinetics as well as rheological and rheooptical behavior of semicrystalline systems. Stress induced crystallization in elongational flow. Extensional flowinduced crystallization of polypropylene erica e. Some indispensable fundamental aspects of the kinetics of polymer crystallization are summed up. We studied the correlation between shearinduced crystallization and rheological behavior of syndiotactic polystyrene. Keller it is apparent from the last example that fibrous crystallization can be induced through an array of fine holes in a gauze, presumably because of the longitudinal velocity gradient generated along the centre line of each hole.
To explore the kinetics and morphology of flow induced crystallization of polymers, a nucleationgrowth evolution model for. The model allows to predict in detail the spatial distribution of the cryst. A macroscopic, continuum model based on the hamiltonianpoisson bracket formalism, combined with the avrami equation, is developed to simulate flowinduced crystallization of polymer melts in homogeneous flow fields under isothermal conditions. Flow induced crystallization of semicrystalline polymers is an important issue in polymer science and engineering because the changes in morphology strongly affect the properties of polymer materials. Formation of oriented precursors in flowinduced polymer. This research shows that crystallization in copolymer films with two types of crystals is manipulated by film fabrication conditions, namely casting solvent and drying temperature. Modeling of flowinduced crystallization of particlefilled. T140 polymer, 1973, vol 14, january 19 flow induced crystallization of polyethylene melts.
Current work on the molecular origins of fic is providing insight into this fascinating, kinetically driven, nonequilibrium phase transition. In this work, the combined effect of particles and flow on the crystallization of polymers has been investigated, using a rheooptical approach. The key process of flow induced nucleation occurs on a very rapid time scale and on a highly localized lengthscale and so is. The morphology and orientation distribution of the. This has been called orientationinduced or stressinduced nucleation. The crystallization rate enhanced by the flow effect is obtained by the inclusion of the elevated equilibrium melting temperature in the modified hoffmanlauritzen equation. Those aspects are of particular interest in the development of crystalline structures during polymer processing. When the molten state of a semicrystalline polymer is subjected to sufficiently intense flow before crystallization, the crystallization kinetics are accelerated and the crystalline superstructure is transformed from spherulites to smaller anisotropic structures. The morphology observed within a semicrystalline polymer product is closely related to the thermal and mechanical history of the poly mer. Keywords random co polymers flow induced crystallization polypropylene flow regimes rheology introduction properties of polymer products depend on the morphology distribution within the product, which itself depends on both the molecular properties of the polymer used and the pro. The influence of flow induced crystallization on the. Flow induced crystallization of polymers reminiscent of teeth, bone and sea shells, semicrystalline polymers combine strength with toughness by forming a nanoscale composite with plateletlike crystals stacked with noncrystalline material between them. Oct 22, 2010 flow induced crystallisation fic in polymers is simultaneously of great fundamental and practical importance.
Wills physics laboratory, university of bristol, bristol, uk in situ optical observations have been made of the way polyethylene melt can crystallize whilst subject to certain longitudinal velocity gradients. Dutch polymer institute, eindhoven university of technology, eindhoven, the netherlands stress induced crystallization in elongational flow stress induced crystallization is studied in an extensional flow device a crossslot flow cell for an isotactic polypropylene ipp by measuring the microstructure that develops after flow. Flowinduced crystallization fic of polymers is a longstanding. On the onset of oriented structures in flowinduced crystallization of polymers. About eight different experimental devices were used to measure flow induced nucleation and crystallization see table 1. The key process of flow induced nucleation occurs on a very.
Molecular aspects of flow induced crystallization of polymers julie kornfield1 1california institute of technology, pasadena, ca, usa 1. This understanding also has the potential to be hugely beneficial to the plastics industry. Flow induced crystallization of polyethylene melts. The effect of particle size, concentration, shape, and aggregation on the kinetics of flow induced crystallization is investigated. Flow induced crystallization in isotactic polypropylene. On the kinetics of shear induced crystallization in polypropylene. Flowinduced crystallization in polymer request pdf. These chains fold together and form ordered regions called lamellae, which compose larger spheroidal structures named spherulites. Results of calculation with a com puter indicated that the thickness of a specimen with relatively large heat of crystallization should be less than 0.
The ensemble of phenomena, which collectively can be viewed as an increase in the kinetics and under certain conditions as a change in. Flow induced crystallization kinetics, recoverable strain. Molecular modelling of flowinduced crystallisation in polymers. Pdf modeling flowinduced crystallization of polymers. However, in many respects, it is not or only partly understood yet. Flowinduced crystallization of polybutene1 and effect of molecular parameters a thesis submitted for the degree of doctor of philosophy chitiur hadinata school of civil, environmental, and chemical engineering rmit university melbourne, australia march 2007. Work in situ xray scattering studies of flowinduced. A macroscopic, continuum model based on the hamiltonianpoisson bracket formalism, combined with the avrami equation, is developed to simulate flow induced crystallization of polymer melts in homogeneous flow fields under isothermal conditions. While the quiescent crystallization was found to be essentially mwindependent, a strong effect of mw on the flow induced crystallization kinetics was observed. Pdf flow induced crystallization of polymers researchgate. These data describe the temperature, width, velocity and crystallinity distributions along the drawing direction under. For comparison, in the case of shear flow induced crystallization, such an effect on the crystallization time is obtained with a shear rate of 0. Flowinduced crystallization fic of polymers is a longstanding, industrial relevant, nonequilibrium thermodynamic challenge.
In this study, flow induced crystallization fic of polyamide 66 pa 66 was investigated using rheology and polarized optical. Multiscale and multistep ordering of flowinduced nucleation. Shearinduced crystallization and rheological behavior of. Stress induced crystallization is studied in an extensional flow device a crossslot flow cell for an isotactic polypropylene ipp by measuring the microstructure that develops after flow. When polymers crystallize from melts subject to flow. On the kinetics of shear induced crystallization in.
The flow induced crystallisation from a polymer melt is much more interesting from a practical point of view, and thus it was the subject of a lot of research, di. Polymers free fulltext a phase field technique for. Here, ow induced crystallization is a phenomenon that plays an important role. Multiple crystal phases and morphologies giovanna grosso, enrico m. Flow induced crystallization of polybutene1 and effect of molecular parameters a thesis submitted for the degree of doctor of philosophy chitiur hadinata school of civil, environmental, and chemical engineering rmit university melbourne, australia march 2007. The results show that shear flow was helpful for sc formation. Easy processability and high versatility combined with low costs make polymers the materials for an increasing number. T c q, with t c q the crystallization temperature in quiescent conditions and t c. Photomicrographs of the sheared specimens indicated that peek crystallites orient along the flow direction.
It is shown that at high enough flow rates, flow will dominate the nucleation process, independent of the presence of. Flow induced crystallization of polyolefins afinitica. A computational model for processing of semicrystalline polymers. However, simulating flow induced crystallisation in polymers is notoriously difficult due to the very wide spread of length and timescales, especially as the most pronounced flow induced effects occur for long chains at low undercooling. Development and validation of a recoverable strainbased model for flowinduced crystallization of polymers. In situ xray scattering studies of flowinduced crystallization in polymer melts under uniaxial extensional flow. Thanks to the development of in situ time and spatial resolved techniques like rheology and synchrotron radiation xray scattering, substantial progress on the understanding of fic has been achieved in past 20 years. Different polyamides6 with varying molecular weight have been studied. Flow induced crystallization of semicrystalline polymers is an important issue in polymer science and engineering because the changes in morphology strongly affect the properties of polymer.
Flowinduced crystallization of polyamide6 international. Modelling flowinduced crystallisation in polymers chemical. Kinetics and morphology of flow induced polymer crystallization in 3d shear flow investigated by monte carlo simulation chunlei ruan school of mathematics and statistics, henan university of science and technology, luoyang 471023, china. Unlimited viewing of the articlechapter pdf and any associated supplements and figures. The effects of shearing and elongational flows on flow induced crystallization in polymer melts were investigated for the twophase system of high molecular weight polyethylene suspended in a linear low density polyethylene carrier phase.
Eindhoven university of technology, department of mechanical engineering, materials technology, eindhoven, the netherlands. Understanding flowinduced crystallization in polymers. A fundamental understanding of fic can benefit the research of nonequilibrium ordering in matter systems and help to tailor the ultimate. This thesis presents new insights into the early events of formation of oriented precursors in flow induced crystallization of polymers, specifically isotactic polypropy. Flow induced crystallization of polyethylene melts m. In this study, a phase field technique considering polymer characteristics was established for modeling and predicting the resulting morphologies.
Pdf a computational model for processing of semicrystalline. A continuum model for flowinduced crystallization of. Data from ipp film casting experiments served as a basis to model the effect of flow on polymer crystallization kinetics. Pdf flow induced crystallization of polymers in extension. In this work, research has been conducted on the flow induced crystallization of another important class of polymers, namely polyamides. Extensionalflowinduced crystallization of polypropylene. Development and validation of a recoverable strain. Flowinduced crystallization fic is a typical nonequilibrium phase transition and a core industry subject for the largest group of commercially useful polymeric materials. Departing from molecular based rheology and rubber theory, four different flow regimes are identified associated to 1 the equilibrium configuration of the chains, 2 orientation of the contour path, 3 stretching of the contour path, and 4 rotational isomerization and a deviation from the gaussian configuration of the polymer chain under strong stretching conditions. A continuum model for flowinduced crystallization of polymer.
Finally, at the experimental temperature of 145 c and depending on the shear strength, ipp. There is a vast body of literature that describes the effects of flow on polymer crystallization, which has been summarized previously. At this moment, a welldefined extensional flow was employed. Flow induced crystallization of polymers materials technology. Rheology and morphology of the flow induced crystallization in polymers supervisors ph. Squeeze flow induced crystallization monitoring in polymers.
Flow induced crystallization in polymers is an important problem in both fundamental polymer science and industrial polymer processing. Modeling of flowinduced crystallization of particle. Pdf modelling flowinduced crystallization in polymers. Polymer melts were rapidly cooled below the nominal crystallization temperature, and subjected to a shear flow of varying shear rate but constant total deformation. Requirements of an apparatus for measuring flow induced crystallization of polymers were discussed on the basis of a nonisothermal crystallization theory. Flow induced crystallization of polymers, application to injection moulding by hans zuidema. Coupling between kinetics and rheological parameters in the flow.
The quantitative information provided by this data set is well suited for validation and extension of our models for flow induced crystallization of polymers. Some fundamental aspects of the kinetics of flowinduced. The effect of the flow on the crystallization kinetics is expressed by the dimensionless transition temperature. Flow induced crystallization has been widely studied for a variety of polymers with the main focus on polyolefins. Introduction polymer crystallization is an important factor affecting the microstructure and determining the mechanical properties of the products 1,2. Flowinduced crystallization in polymer processing springerlink. Flow induced crystallization fic is a typical nonequilibrium phase transition and a core industry subject for the largest group of commercially useful polymeric materials. On the kinetics of shear induced crystallization in polypropylene s. Flowinduced crystallization in polymers correlates with the stresses that occur during viscoelastic flow much more than with the macroscopic strain or the strain rate. The key process of flow induced nucleation occurs on a very rapid time scale and on a highly localized lengthscale and so is extremely difficult to observe directly in experiments. Jul 08, 2010 a numerical model for nonisothermal flow induced crystallization in thermoplastic polymers. Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation. Bischoff white university of massachusetts amherst follow this and additional works at. Introduction reminiscent of teeth, bone and sea shells, semicrystalline polymers combine strength with toughness by.
Shear flow promoted the phase mixing of the polymer blends and. Crystallization affects optical, mechanical, thermal and chemical. Rheology and morphology of the flowinduced crystallization in polymers supervisors ph. Molecular aspects of flowinduced crystallization of polymers. Extensional flow induced crystallization of polypropylene erica e. Introduction polyether ether ketone, peek, s train induced crystallization of polymers is a commonly observed phenomenon associ ated with polymer processing operations. Flow induced crystallization of polyolefins polymers are a widespread class of materials that provide an often advantageous combination of properties. Pdf modeling flow induced crystallization in film casting. It was found that after applying a steady shear flow around the nominal melting temperature t m 270 c, crystal growth rate was accelerated compared with the quiescent state and a morphology of oriented lamellae kebabs was observed. Becausethese three polymers are representatives of flexible and semirigidchain polymers, the occurrenceof a mesophase suggests a similar behaviour for. Crystallization of polymers is a process associated with partial alignment of their molecular chains. Isothermal flowinduced crystallization of polyamide 66. Flowinduced crystallization of isotactic polypropylene.
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