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  • 1
    Electronic Resource
    Electronic Resource
    Influence of specimen thickness on isothermal crystallization kinetics. A theoretical analysis (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 366-373 
    Details
    ISSN: 1435-1536
    Keywords: kinetics ; isothermal crystallization ; polymer ; spherulite ; differential scanning calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the DSC technique, isothermal crystallization experiments are usually performed on thin flat specimens, but their interpretation generally uses theories developed for an unbounded volume. In this paper, isothermal crystallization of spherical entities in the volume limited by two parallel infinite planes is considered. Our model, derived from Avrami's theory, gives an analytical expression for the transformed volume fraction as a function of time. It is shown that the influence of thickness becomes important when thickness becomes of the order of or smaller than the average spherulite radius. The main effects of a decreasing thickness are a slower crystallization kinetics and a decrease in the Avrami exponent. These results can be used to interpret experimental data obtained in isothermal polymer crystallization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410254
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  • 2
    Electronic Resource
    Electronic Resource
    Experimental study of shear-induced crystallization of an impact polypropylene copolymer (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 197-208 
    Details
    ISSN: 1435-1536
    Keywords: Shear-induced crystallization ; nucleation ; growth ; overall kinetics ; polymer ; polypropylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The crystallization kinetics of polypropylene was observed during shear and after shear experiments under isothermal condition. The crystallizations were performed in a plate-plate and a fiber pull-out device. The nucleation density, the crystalline growth and the overall kinetics were measured and compared with data obtained in a similar way but during static experiments. The morphologies are spherulitic and formed from nuclei which seem to be randomly distributed. α-phase spherulites are always observed but with a nucleation density and a growth rate which depend on shearrate. The nucleation density is strongly enhanced by shear and acts as the main factor on the overall kinetics. The overall kinetics can be analyzed with a two-step Avrami model, where an Avrami exponentn 1 with a very high value is always observed first after shear and a more usual parametern 2 for the subsequent crystallization period. This high value ofn 1 seems to be related to the strong enhancement of nucleation density. The growth rate increases with the shear-rate, but the basic growth mechanisms do not seem to be modified. For crystallizations after shear the growth rate decreases with a long-time delay after shear but not down to the static value. The effect is characteristic of a partial relaxation of chain orientation after shear but with a very unusual time constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00665636
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of random copolymerization on growth transition and morphology change in polypropylene (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 679-687 
    Details
    ISSN: 1435-1536
    Keywords: Ethylene-propylene randomcopolymer ; isothermalcrystallization ; spherulite ; growth rate ; equilibriummelting temperature ; surfaceenergy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The growth rate of an ethylene-propylene random copolymer with a 2.8% w/w ethylene content was studied in a similar manner to polypropylene. A growth regime transition associated with a birefringence change was observed at 130
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410276
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  • 4
    Electronic Resource
    Electronic Resource
    Isothermal crystallization kinetics in a limited volume. A geometrical approach based on Evans' theory (1989)
    Springer
    Colloid & polymer science 267 (1989), S. 668-680 
    Details
    ISSN: 1435-1536
    Keywords: Kinetics ; isothermalcrystallization ; limited volume ; polymer ; spherulite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new theoretical approach of the isothermal crystallization of a thin polymer film is proposed. This model, derived from Evans' theory, is in very good agreement with a previous one, but is much more interesting because it makes it possible to calculate the transformed volume fraction anywhere in the film. The main effects of decreasing thickness are a slower average crystallization of the film and a decrease in the Avrami exponent caused by a slower crystallization of the polymer close to the surfaces. A slight modification of the model allows us to calculate the isothermal crystallization kinetics at any point of the film when it contains two identical transcrystalline regions on its surfaces. All the models are well verified by computer simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01524369
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of nucleation rate in polymers using isothermal crystallization experiments and computer simulation (1993)
    Springer
    Colloid & polymer science 271 (1993), S. 343-356 
    Details
    ISSN: 1435-1536
    Keywords: Crystallization ; nucleation ; polymer-spherulite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Within the frame of overall kinetics of crystallization, polymer crystallization is characterized by only three parameters: the initial density of potential nucleiN 0, their activation frequencyq and the growth rateG. The growth rateG is rather easy to measure, whereas the nucleation parameters are generally unknown. Our purpose is to determine bothN 0 andq using experimental isothermal two-dimensional crystallizations and computer simulation. Both these parameters are deduced from the rate of appearance of spherulites expressed as a function of the transformed surface fraction. The activation times of the spherulites are deduced from the shape of the boundaries between spherulites at the end of the transformation. When the growth rateG is known, the evolution of the transformed surface fraction is rebuilt using a computer simulation, so that only one observation of the final stage of the crystallization is needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657416
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  • 6
    Electronic Resource
    Electronic Resource
    Transcrystallinity effects in thin polymer films. Experimental and theoretical approach (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 633-654 
    Details
    ISSN: 1435-1536
    Keywords: Crystallization ; overall kinetics ; transcrystallinity ; polymer ; spherulite ; DSC ; PA 6-6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental and theoretical investigation of the overall crystallization kinetics of thin polymer films containing transcrystalline regions on their surfaces is presented. DSC experiments on polyamide 6-6 show that typical features of crystallization curves can be associated with the occurrence of transcrystallinity. In order to interpret these experimental results, a theoretical model is built within the frame of overall crystallization kinetics theories. It makes it possible to correlate the thickness of transcrystalline zone both to the crystallization temperature, the shape of the peak and the density of nuclei within the polymer. Computer simulation is also used to describe the different steps of structure development within a thin film containing transcrystalline regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659278
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal dependence of nucleation and growth rate in polypropylene by non isothermal calorimetry (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 117-122 
    Details
    ISSN: 1435-1536
    Keywords: Polypropylene ; non-isothermal crystallization ; nucleation ; growth rate ; differential scanning calorimetry ; surface energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Crystallization of polypropylene at a constant cooling rate is studied by differential scanning calorimetry. The results are interpreted using Ozawas theory, which allows the determination of the type of nucleation. In the studied polypropylene, a transition between a sporadic in time and an instantaneous nucleation is found at about 122 °C. Furthermore, an extension of Ozawa's theory is proposed to predict the thermal dependence of the spherulite growth rate. The results are consistent with those obtained by direct microscopic observation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414836
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  • 8
    Electronic Resource
    Electronic Resource
    Growth transition and morphology change in polypropylene (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 822-831 
    Details
    ISSN: 1435-1536
    Keywords: Polypropylene ; isothermal crystallization ; spherulite ; growth rate ; equilibrium melting temperature ; surface energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The growth rate of isotactic polypropylene is deduced from microscopic observations during isothermal crystallizations. A change in the growth regime is observed at 138
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412960
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  • 9
    Electronic Resource
    Electronic Resource
    Overall crystallization kinetics of thin polymer films. General theoretical approach. I. Volume nucleation (1989)
    Springer
    Colloid & polymer science 267 (1989), S. 1064-1076 
    Details
    ISSN: 1435-1536
    Keywords: Crystallization ; overallkinetics ; polymer ; spherulite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A general theoretical approach of the overall crystallization kinetics of thin polymer films is developed. This new model makes it possible to calculate the evolution of the transformed volume fraction anywhere in the film, whatever the cooling conditions are. In its isothermal limit this model is equivalent to previous approaches which have been well verified by a computer simulation. In conclusion, it is pointed out that both isothermal and anisothermal determinations of crystallization kinetic parameters are greatly dependent on the sample thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01496926
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  • 10
    Electronic Resource
    Electronic Resource
    Etude thermique de la N-methylmorpholine N-oxyde et de sa complexation avec l'eau (1981)
    Springer
    Journal of thermal analysis and calorimetry 22 (1981), S. 107-118 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé La N-méthylmorpholine N-oxyde (MMNO) a une température de fusion de 184.2°, une enthalpie de fusion de 160.5 J/g et une chaleur de décomposition de 1340 J/g. Son hydratation a été étudiée par analyse calorimétrique différentielle et par gravimétrie. A l'air et à la température ambiante, la quantité totale d'eau qui a diffusé dans la MMNO correspond à quatre molécules d'eau par molécule de MMNO. Plusieurs complexes MMNO-H2O cristallins ont été mis en évidence par analyse calorimétrique differentielle: un complexe MMNO-2.5 H2O (T f =40.5°,ΔH f =143.4 J/g), un complexe MMNO-1 H2O (T f = 75.6°,ΔH f =160.5 J/g) et un complexe dont la quantité d'eau n'a pas été déterminée (T f =102°,ΔH f =95 J/g).
    Abstract: Zusammenfassung Das N-Methylmorpholin N-Oxid (MMNO) hat eine Schmelztemperatur von 184.2°, eine Schmelzenthalpie von 160.5 J/g und eine Zersetzungswärme von 1340 J/g. Seine Hydratisierung wurde durch differentialkalorimetrische Analyse und durch Thermogravimetrie untersucht. In Luft und bei Raumtemperatur entspricht die gesamte, in das MMNO diffundierte Wassermenge 4 Wassermoleküle pro Molekül MMNO. Durch die differentialkalorimetrische Analyse wurden verschiedene kristalline MMNO-H2O-Komplexe nachgewiesen: ein Komplex MMNO-2.5 H2O (T f =40.5°,ΔH f =143.4 J/g), ein Komplex MMNO-1 H2O (T f =75.6°,ΔH f =160.5 J/g) und ein Komplex, dessen Wassergehalt nicht bestimmt wurde (T f =102°,ΔH f =95 J/g).
    Notes: Abstract N-methylmorpholine N-oxide (MMNO) has a melting temperature of 184.2°, an enthalpy of fusion of 160.5 J/g and a heat of decomposition of 1340 J/g. Its hydration has been investigated by differential scanning calorimetry (DSC) and by gravimetry. In air and at room temperature, the total amount of water diffusing into MMNO corresponds to four molecules of H2O per molecule of MMNO. Several MMNO-H2O crystalline complexes have been studied by DSC: an MMNO-2.5 H2O complex (T f =40.5°,ΔH f =143.4 J/g), an MMNO-1 H2O complex (T f =75.6°,ΔH f =160.5 J/g) and a complex with an unknown amount of water (T f =102°,ΔH f =95 J/g).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01915701
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