Arkadiusz Gradys, Ph.D., Eng.

Laboratory of Polymers and Biomaterials (SPPiB)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 171
room: 334
e-mail: argrad

Doctoral thesis
2010-11-25Przemiany polimorficzne substancji małocząsteczkowych i polimerów 
supervisor -- Prof. Paweł Sajkiewicz, Ph.D., Dr. Habil., Eng., IPPT PAN
636
 
Recent publications
1.Gradys A., Geometrical effects during crystallization under confinement in electrospun core-shell fibers. DSC study of crystallization kinetics, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2016.12.009, Vol.108, pp.383-394, 2017
Abstract:

Calorimetric studies on poly(ethylene glycol) Mn = 400 g/mol, encapsulated in polystyrene fibers show non-trivial crystallization behavior. Analysis, assuming constant Avrami exponent n, is unsuitable. Approach allowing for changes in the exponent n, requires assumption of the crystallization rate function, derived from the nucleation theory. Changes in Avrami exponent n, follow the changes in geometry of crystal growth and in nucleation mechanisms. Crystallization in micrometer fibers starts from heterogeneous nucleation with three-dimensional crystal growth e as in bulk e but changes to two and one-dimensional, terminated by homogeneous nucleation. For bulk and in 1 and 0.6 micron thick fibers, the approach evidences similar thermodynamic parameters. In 0.6 micron thick fibers, crystallization rate is lower due to higher energy barrier for diffusion, ED = 10 kJ/mol versus 8.7 kJ/mol for bulk and 1 micron thick fibers. Additionally, fiber thickness depends not only on parameters of the electrospinning process but also on the thermal history.

Keywords:

Core-shell fibers, Confinement effects, Crystallization kinetics, DSC, Polyethylene glycol

Affiliations:
Gradys A.-IPPT PAN
2.Gradys A., Sajkiewicz P., Zhuravlev E., Schick C., Kinetics of isothermal and non-isothermal crystallization of poly(vinylidene fluoride) by fast scanning calorimetry, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2015.11.020, Vol.82, pp.40-48, 2016
Abstract:

Crystallization from melt of poly(vinylidene fluoride) was studied by thin film chip calorimetry at cooling rates from 500 to 100,000 Ks−1 and isothermally down to 76°C. At ca. 70°C, for cooling rates higher than 2000 Ks−1, there appears a change in crystallization from high temperature α phase to low temperature β phase. The amorphous state is preserved at cooling rate 100,000 Ks−1. Analysis of the crystallization kinetics with Ziabicki model reveals maximum of the steady-state crystallization rate of β phase as 2200 s−1 at 22°C, and the highest crystallization rate of α phase as 200 s−1 at 70°C. Approximation of the temperature dependent steady-state crystallization rate with the Turnbull and Fisher nucleation model results in the equilibrium melting temperatures 227 and 173°C for the α and β phase, respectively, and in the energy barrier for short-distance transport, ED, as 70–80 kJ mol−1 at high supercooling.

Keywords:

Poly(vinylidene fluoride), Ultra-fast calorimetry, Crystallization kinetics

Affiliations:
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Zhuravlev E.-University of Rostock (DE)
Schick C.-University of Rostock (DE)
3.Świątek Z., Gradys A., Maj Ł., Morgiel J., Marszałek K.W., Mania R., Szlezynger M., XRD and TEM in situ Heating of Large Period Ni/Al Multilayer Coatings, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.130.880, Vol.130, No.4, pp.880-883, 2016
Abstract:

The Ni/Al multilayer coating of λ ≈100 nm was deposited onto (001)-oriented monocrystalline silicon substrate using double target magnetron sputtering system equipped with rotating sample holder. The thicknesses of alternating layers were adjusted in the way to preserve the chemical composition ratio close to 50%Al:50%Ni (at.%). The in situ X-ray diffraction and in situ transmission electron microscopy heating experiments were carried out at relatively low heating rates (20°C/min) in order to study the phase transformation sequence. The investigations revealed that the reaction between Ni and Al multilayers starts at ≈200°C with precipitation of Al₃Ni phase, while above 300°C dominates precipitation of Ni₃Al and NiAl intermetallic phases. Both the X-ray and electron diffractions acquired at 450°C confirmed presence of the Ni₃Al and NiAl intermetallics, but the former pointed at still lasting traces of Ni(Al) solid solution.

Keywords:

transmission electron microscopy, multilayers

Affiliations:
Świątek Z.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Gradys A.-IPPT PAN
Maj Ł.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Morgiel J.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Marszałek K.W.-AGH University of Science and Technology (PL)
Mania R.-AGH University of Science and Technology (PL)
Szlezynger M.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
4.Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Gradys A., Majewski M., Cristea M., Tobushi H., Hayashi S., Thermomechanical properties of polyurethane shape memory polymer–experiment and modelling, SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/24/4/045043, Vol.24, pp.045043-1-16, 2015
Abstract:

In this paper extensive research on the polyurethane shape memory polymer (PU-SMP) is reported, including its structure analysis, our experimental investigation of its thermomechanical properties and its modelling. The influence of the effects of thermomechanical couplings on the SMP behaviour during tension at room temperature is studied using a fast and sensitive infrared camera. It is shown that the thermomechanical behaviour of the SMP significantly depends on the strain rate: at a higher strain rate higher stress and temperature values are obtained. This indicates that an increase of the strain rate leads to activation of different deformation mechanisms at the micro-scale, along with reorientation and alignment of the molecular chains. Furthermore, influence of temperature on the SMP's mechanical behaviour is studied. It is observed during the loading in a thermal chamber that at the temperature 20°C below the glass transition temperature (Tg) the PU-SMP strengthens about six times compared to the material above Tg but does not exhibit the shape recovery. A finite-strain constitutive model is formulated, where the SMP is described as a two-phase material composed of a hyperelastic rubbery phase and elastic-viscoplastic glassy phase. The volume content of phases is governed by the current temperature. Finally, model predictions are compared with the experimental results.

Keywords:

shape memory polyurethane, thermomechanical couplings, infrared camera, temperature change, dynamic mechanical analysis, strain rate, constitutive model

Affiliations:
Pieczyska E.A.-IPPT PAN
Maj M.-IPPT PAN
Kowalczyk-Gajewska K.-IPPT PAN
Staszczak M.-IPPT PAN
Gradys A.-IPPT PAN
Majewski M.-IPPT PAN
Cristea M.-Petru Poni Institute of Macromolecular Chemistry (RO)
Tobushi H.-Aichi Institute of Technology (JP)
Hayashi S.-SMP Technologies Inc. (JP)
5.Boas M., Gradys A., Vasilyev G., Burman M., Zussman E., Electrospinning polyelectrolyte complexes: pHresponsive fibers, SOFT MATTER, ISSN: 1744-683X, DOI: 10.1039/c4sm02618g, Vol.11, pp.1739-1747, 2015
Abstract:

Fibers were electrospun from a solution comprised of oppositely charged polyelectrolytes, in efforts to achieve highly confined macromolecular packaging. A stoichiometric ratio of poly(allylamine hydrochloride) and poly(acrylic acid) solution was mixed in an ethanol–water co-solvent. Differential scanning calorimetry (DSC) analysis of electrospun fibers demonstrated no indication of glass transition, Tg. Infrared spectroscopy (FTIR) analysis of the fibers as a function of temperature, demonstrated an amidation process at lower temperature compared to cast film. Polarized FTIR indicated a preference of the functional groups to be perpendicular to the fiber axis. These results imply formation of mixed phase fibers with enhanced conditions for intermolecular interactions, due to the highly aligned and confined assembly of the macromolecules. The tunable intermolecular interactions between the functional groups of the polyelectrolytes, impact pH-driven, reversible swelling–deswelling of the fibers. The degree of ionization of PAA at pH 5.5 and pH 1.8 varied from 85% to 18%, correspondingly, causing transformation of ionic interactions to hydrogen bonding between the functional groups. The chemical change led to a massive water diffusion of 500% by weight and to a marked increase of 400% in fiber diameter, at a rate of 0.50 μm s−1. These results allow for manipulation and tailoring of key fiber properties for tissue engineering, membranes, and artificial muscle applications.

Keywords:

polyelectrolytes, electrospinning, pH responsive fibers

Affiliations:
Boas M.-Technion-Israel Institute of Technology (IL)
Gradys A.-IPPT PAN
Vasilyev G.-Technion-Israel Institute of Technology (IL)
Burman M.-Technion-Israel Institute of Technology (IL)
Zussman E.-Technion-Israel Institute of Technology (IL)
6.Gradys A., Sajkiewicz P., Determination of the melting enthalpy of beta phase of poly(vinylidene fluoride), E-POLYMERS, ISSN: 1618-7229, DOI: 10.1515/epoly-2013-0119, Vol.13, No.1, pp.203-216, 2014
Abstract:

Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR) analyses of phase composition and of thermal properties of PVDF samples, crystallized at temperatures 27 - 155°C by casting from N,N-dimethyl formamide (DMF) solution, are reported. Samples obtained at 27°C contain only β crystal phase and with increase of casting temperature content of β phase decreases in favor of α phase. Evaluation of combined: phase content (WAXS) and melting heat (DSC), leads to two fold higher than for 100 % α phase value of 100% β melting enthalpy, ΔHβ0= 219.7 J.g-1, which may be justified by strong polar interactions in β phase TTT conformation. The relation ΔHβ0 > ΔHα0 leads either to the thermodynamic stability of β phase in whole temperature range (if Tmβ0 ≥ Tmα0) or to the limited temperature range of thermodynamic stability of α phase (if Tmβ0 < Tmα0).

Keywords:

pvdf, WAXS, FTIR, DSC, crystallinity, polymorphism

Affiliations:
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
7.Alhazov D., Gradys A., Sajkiewicz P., Arinstein A., Zussman E., Thermo-mechanical behavior of electrospun thermoplastic polyurethane nanofibers, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2013.09.028, Vol.49, pp.3851-3856, 2013
Abstract:

Analysis of the thermo-mechanical behavior of electrospun thermoplastic polyurethane (TPU) block co-polymer nanofibers (glass transition temperature ∼−50°C) is presented. Upon heating, nanofibers began to massively contract, at ∼70°C, whereas TPU cast films started to expand. Radial wide-angle X-ray scattering (WAXS) profiles of the nanofibers and the films showed no diffraction peaks related to crystals, whereas their amorphous halo had an asymmetric shape, which can be approximated by two components, associated with hard and soft segments. During heating, noticeable changes in the contribution of these components were only observed in nanofibers. These changes, which were accompanied with an endothermic DSC peak, coinciding with the start of the nanofibers contraction, can be attributed to relaxation of an oriented stretched amorphous phase created during electrospinning. Such structure relaxation becomes possible when a portion of the hard segment clusters, forming an effective physical network, is destroyed upon heating.

Keywords:

Block-copolymer, Electrospinning, Nanofibers, Thermo-mechanical properties

Affiliations:
Alhazov D.-Technion-Israel Institute of Technology (IL)
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Arinstein A.-Technion-Israel Institute of Technology (IL)
Zussman E.-Technion-Israel Institute of Technology (IL)
8.Krasowska K., Janik H., Gradys A., Rutkowska M., Degradation of polyurethanes in compost under natural conditions, JOURNAL OF APPLIED POLYMER SCIENCE, ISSN: 0021-8995, DOI: 10.1002/app.36597, Vol.125, No.6, pp.4252-4260, 2012
Abstract:

The estimation of compostability of different polyurethanes under natural weather depending conditions in compost with active sludge at waste treatment plant was the subject of this study. The incubation of polymer samples took place for a period up to 24 months. The characteristic parameters of compost: temperature, pH, moisture content and activity of dehydrogenases were monitored and their influence on degradation of polyurethanes was discussed. The proper compoststability of polyurethanes was investigated by changes of weight, tensile strength and morphology of polyurethane samples after incubation in environment. The degradation study revealed that the degree of degradation of polyurethanes in the natural environment, like compost, is dependent on their chemical and structural composition.

Keywords:

polyurethanes, degradation, compost

Affiliations:
Krasowska K.-other affiliation
Janik H.-other affiliation
Gradys A.-IPPT PAN
Rutkowska M.-other affiliation
9.Sajkiewicz P., Gradys A., Misztal-Faraj B., Quantitative analysis of crystallization kinetics by light depolarization technique. Possibilities and limitations, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2010.07.011, Vol.46, pp.2051-2062, 2010
Abstract:

The kinetics of isothermal crystallization of various polymers was investigated by light depolarization technique (LDT) using the new setup with direct registration of depolarization ratio. Experimental data were analyzed using new method proposed by Ziabicki who shown that degree of crystallinity is a non-linear function of degree of depolarization, crystal thickness, and its birefringence. Other experimental methods were involved providing supplementary information on crystal thickness (SAXS) and allowing comparison of crystallization kinetics (WAXS, DSC). The advantage of LDT relies on high sampling rate allowing on-line measurements and lack of inertia effects that exist in other methods like calorimetry. The limitations of the applicability of the method are discussed. The method needs supplementary information not only on crystal thickness but also on variable optical birefringence of real crystals. Our results show that LDT can be used in a simple way for investigation of crystallization kinetics at relatively high temperatures, providing large and perfect crystals. In such a case it is sufficient to use crystal intrinsic birefringence and final crystal thickness typical at particular temperature of crystallization. On the other hand, depolarization ratio combined with measurements by other methods (crystallinity and crystal thickness) can be used for estimation of crystal birefringence.

Keywords:

Polymer, Crystallization kinetics, Light depolarization, Crystal birefringence

Affiliations:
Sajkiewicz P.-IPPT PAN
Gradys A.-IPPT PAN
Misztal-Faraj B.-IPPT PAN
10.Sajkiewicz P., Gradys A., Ziabicki A., Misztal-Faraj B., On the metastability of beta phase in isotactic polypropylene: Experiments and numerical simulation, E-POLYMERS, ISSN: 1618-7229, No.124, pp.1-20, 2010
Abstract:

Phase transitions in isotactic polypropylene were investigated during isothermal crystallization and heating after isothermal crystallization using various experimental techniques. The results obtained by wide angle x-ray scattering (WAXS), light depolarization technique (LDT), differential scanning calorimetry (DSC) and optical microscopy show that crystallization of isotactic polypropylene can result in simultaneous formation of two crystal modifications, alpha and beta. There is clear experimental evidence that beta phase tends to convert into alpha modification during crystallization as well as during subsequent heating. Experimental results are compared with numerical simulation performed according to the model of nucleation-controlled phase transitions in multiphase systems. The results of simulation show that beta phase is not thermodynamically stable in any temperature range. The reason for the appearance of beta phase is related to low interfacial tension of melt vs. beta. It has been also shown that maximum crystallinity reached in experiments does not exceed 40–50% in agreement with the concept of constrained amorphous phase.

Keywords:

polypropylene, polymorphism, metastability, crystallization

Affiliations:
Sajkiewicz P.-IPPT PAN
Gradys A.-IPPT PAN
Ziabicki A.-IPPT PAN
Misztal-Faraj B.-IPPT PAN
11.Misztal-Faraj B., Sajkiewicz P., Savytskyy H., Bonchyk O., Gradys A., Ziabicki A., Following phase transitions by depolarizing light intensity. The experimental setup, POLYMER TESTING, ISSN: 0142-9418, DOI: 10.1016/j.polymertesting.2008.09.012, Vol.28, pp.36-41, 2009
Abstract:

A new setup for light depolarization measurements was designed. Two innovative elements have been introduced. The first is an electronic system which enables depolarization ratio to be registered directly. The second is a system of temperature control allowing effective implementation of a temperature–time program according to the particular requirements. Direct registration of depolarization ratio instead of intensity of depolarized light for individual components (parallel and perpendicular), as is performed in the usual apparatus, allows elimination of light scattering effects because of the insensitivity of depolarization ratio to the scattering level. Application of the new setup was shown for crystallization and melting of isotactic polypropylene (i-PP). Comparison of phase transitions in i-PP, as registered by light depolarization and DSC, indicates some differences. Possible sources of the observed differences are discussed.

Keywords:

Light depolarization, Polymers, Crystallization, Melting, Kinetics of phase transitions

Affiliations:
Misztal-Faraj B.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Savytskyy H.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
Bonchyk O.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
Gradys A.-IPPT PAN
Ziabicki A.-IPPT PAN
12.Di Lorenzo M.R., Sajkiewicz P., Gradys A., La Pietra P., Optimization of melting conditions for the analysis of crystallization kinetics of poly(3-hydroksybutyrate), E-POLYMERS, ISSN: 1618-7229, Vol.27, pp.1-12, 2009
Abstract:

Studies of kinetics of polymer crystallization are generally performed by heating the material above the melting point, in order to erase previous thermal and mechanical history, followed by rapid cooling to the desired crystallization temperature or by cooling at a constant rate. For poly(3-hydroxybutyrate) this procedure implies some degradation of the polymer chain, which starts below the onset of melting. In this article the effects of melting conditions on the subsequent crystallization kinetics are discussed. It is shown that in order to sufficiently cancel memories of previous crystalline order of the analyzed PHB, it is necessary to bring the material at a temperature higher than 192 °C. Thermal treatments conducted at lower temperatures are not sufficient to destroy all solid aggregates, and crystallization of PHB has an anticipated onset of crystallization due to nucleation occurring via self-seeding. The chain degradation attained upon exposure at high temperatures has much lesser influence on crystallization kinetics than incomplete melting, with some effects detectable on the spherulitic morphology and on the final degree of crystallinity.

Keywords:

PHB, thermal history, crystallization, degradation

Affiliations:
Di Lorenzo M.R.-other affiliation
Sajkiewicz P.-IPPT PAN
Gradys A.-IPPT PAN
La Pietra P.-other affiliation
13.Sajkiewicz P., Di Lorenzo M.L., Gradys A., Transient nucleation in isothermal crystallization of poly(3-hydroksybuty-rate), E-POLYMERS, ISSN: 1618-7229, Vol.85, pp.1-16, 2009
Abstract:

The time dependence of nucleation rate in isothermal crystallization of poly(3-hydroxybutyrate) was experimentally shown, both in heterogeneous and homogeneous nucleation. The time dependence of nucleation rate is one of the important limitations for the applicability of the simplified form of Kolmogoroff- Avrami-Evans model with time independent kinetic characteristics. The presented results are interpreted in terms of non-steady-state cluster size distribution underlying transient nature of nucleation. The relaxation time needed for reaching a steady-state cluster size distribution and thus steady-state nucleation rate is relatively long, exceeding the time of exhaustion of heterogeneities. The relaxation time estimated from homogeneous process was tens of seconds in the temperature range between 83 and 120 oC. Application of Arrhenius law allows estimation of relaxation time in broader temperature range, showing an increase of relaxation time with decreasing temperature.

Keywords:

PHB, isothermal crystallization, nucleation rate

Affiliations:
Sajkiewicz P.-IPPT PAN
Di Lorenzo M.L.-other affiliation
Gradys A.-IPPT PAN
14.Gradys A., Sajkiewicz P., Adamovsky S., Minakov A.A., Schick C., Crystallization of poly(vinylidene fluoride) during ultra-fast cooling, THERMOCHIMICA ACTA, ISSN: 0040-6031, DOI: 10.1016/j.tca.2007.05.023, Vol.461, pp.153-157, 2007
Abstract:

Melt-crystallization of polyvinylidene fluoride (PVDF) was investigated in non-isothermal mode at ultra-high cooling rates ranging between 30–3000 K/s as well as at constant temperatures after quenching at 6000 K/s. An increase of the cooling rate above 150 K/s leads to the formation of betaphase manifested by a low temperature shoulder of crystallization exotherm in addition to the alphamodification. At the cooling rates above 2000 K/s there is only low temperature exothermic peak that is attributed to the crystallization of pure betamodification. Isothermal crystallization was possible to realize at 110 oC as the lowest, resulting in form. Much higher crystallization rate in submicrogram samples, as compared to standard DSC experiments, is also reported.

Keywords:

Polyvinylidene fluoride, Crystallization, Ultra-fast calorimetry, Polymorphism

Affiliations:
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Adamovsky S.-Universitaet Rostock (DE)
Minakov A.A.-other affiliation
Schick C.-University of Rostock (DE)
15.Di Lorenzo M.L., Sajkiewicz P., La Pietra P., Gradys A., Irregularly shaped DSC exotherms in the analysis of polimer crystallization, POLYMER BULLETIN, ISSN: 0170-0839, DOI: 10.1007/s00289-006-0621-4, Vol.57, pp.713-721, 2006
Abstract:

This article details a study of irregularly shaped DSC exotherms of poly(3-hydroxybutyrate) (PHB) developed during isothermal and non-isothermal crystallization. Due to the extreme purity of the polymer, PHB crystallization is mainly initiated by homogeneous nucleation, with the formation of very large spherulites, especially under slow nucleation conditions. When the number of growing spherulites is low, the evolution of latent heat is very sensitive to every act of nucleation as well as to the space limitations in the process of growth, resulting in non-monotonous development of latent heat, with sudden increases and decreases in crystallization rates. This results in non conventional DSC exotherms, under given crystallization conditions, characterized by spikes or shoulders associated to nucleation of new spherulites.

Keywords:

PHB, crystallization, nucleation, DSC

Affiliations:
Di Lorenzo M.L.-other affiliation
Sajkiewicz P.-IPPT PAN
La Pietra P.-other affiliation
Gradys A.-IPPT PAN
16.Sajkiewicz P., Hashimoto T., Saijo K., Gradys A., Intermediate phase in poly(ethylene) as elucidated by the WAXS. Analysis of crystallization kinetics, POLYMER, ISSN: 0032-3861, DOI: 10.1016/j.polymer.2004.11.018, Vol.46, pp.513-521, 2005
Abstract:

The analysis of WAXS profiles for various polyethylenes indicates that the proper description of a structure needs the introduction of a kind of ‘third phase’ in addition to the classical crystalline and amorphous phases. The structure of the additional phase is intermediate between that of the amorphous and crystalline phase. With increasing branch content and molecular weight the intermediate phase becomes more similar to the structure of amorphous phase. The experimental evidence for the intermediate phase is derived not only from the crude approximation of WAXS profiles based on the two phase model but also from the unexpected behavior of the parameters of amorphous halo during crystallization. When crystallization is started, an analysis based upon two-phase model results in an apparent increase of the diffraction angle and width of amorphous halo with time above the values anticipated from the range before the start of crystallization. This is caused by the fact that the amorphous fitting function tries to cover a peak of the intermediate component that appears between morphous halo and (110) reflection of crystalline phase. The conventionally applied two-phase model leads to several serious errors in determination of structural parameters of both phases. The analysis of crystallization kinetics using three-phase model provides additional information on the nature of crystallization itself.

Keywords:

Polyethylene, Crystallization, Intermediate phase

Affiliations:
Sajkiewicz P.-IPPT PAN
Hashimoto T.-other affiliation
Saijo K.-other affiliation
Gradys A.-IPPT PAN
17.Gradys A., Sajkiewicz P., Minakov A.A., Adamovsky S., Schick C., Hashimoto T., Saijo K., Crystallization of polypropylene at various cooling rates, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2005.08.167, Vol.413-414, pp.442-446, 2005
Abstract:

Crystallization of polypropylene (PP) can result in formation of different crystal modifications depending on external conditions. The mechanisms of formation of various crystal modifications in polypropylene are still under discussion.We have investigated non-isothermal melt crystallization of isotactic polypropylene at cooling rates ranging from 1 up to 180,000 K/min using two types of differential scanning calorimeters-standard device Perkin–Elmer DSC Pyris-1 and ultra-fast calorimeter. Additional results were obtained by means of wide angle X-ray scattering and optical microscopy. At cooling rates below 6000 K/min there is only one exothermic peak corresponding to simultaneous crystallization ofalpha andbeta modifications. At cooling rates higher than 6000 K/min there is additional low temperature DSC peak corresponding to formation of mesomorphic phase. At the rates higher than 36,000 K/min there is no trace of formation of any ordered phase. In our opinion this complex behavior observed during crystallization of polypropylene can be explained using the concept of metastable phases. An increase ofbeta content in samples with quinacridone pigment has been observed only at very low cooling rates, corresponding to high temperatures of crystallization and low homogeneous nucleation rate.

Keywords:

Polypropylene, Crystallization, Utra-fast calorimetry, Crystallographic modifications, Metastable phases

Affiliations:
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Minakov A.A.-other affiliation
Adamovsky S.-Universitaet Rostock (DE)
Schick C.-University of Rostock (DE)
Hashimoto T.-other affiliation
Saijo K.-other affiliation

Conference abstracts
1.Świątek Z., Gradys A., Morgiel J., Marszałek K.W., Mania R., Szlezynger M., Maj Ł., XRD in-situ heating of large period Ni/Al reactive multilayer, XXIII Conference on Applied Crystallography, 2015-09-20/09-24, Krynica Zdrój (PL), pp.23-26, 2015
2.Alhazov D., Gradys A., Denis P., Sajkiewicz P., Arinstein A., Zussman E., Thermo-mechanical behavior of electrospun thermoplastic polyurethane nanofibers, EPF2013, European Polymer Congress, 2013-06-16/06-21, Pisa (IT), pp.O2-23, 2013

Patents
Numer/data zgłoszenia patentowego
Ogłoszenie o zgłoszeniu patentowym
Twórca / twórcy
Tytuł
Kraj i Nazwa uprawnionego z patentu
Numer patentu
Ogłoszenie o udzieleniu patentu
pdf
390382
2010-02-08
BUP 17/2011
2011-08-16
Sajkiewicz P., Misztal-Faraj B., Savytskyy H., Bonchyk O., Ziabicki A., Gradys A.
Sposób i urządzenie do badania kinetyki przemian fazowych metodą pomiaru depolaryzacji światła
PL, Instytut Podstawowych Problemów Techniki PAN
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