Crystallization kinetics of polypropylene fractions

Hoshino, Sadao; Meinecke, Eberhard A.; Powers, Joseph R.; Stein, Richard S.; Newman, Seymour

doi:10.1002/pol.1965.100030901

Cited by 32 publications

(11 citation statements)

References 6 publications

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“…The same value has been obtained for PP crytallization under isothermal conditions [13,14]. The reduction in the Avrami parameter in filled and hybrid matrices may be attributed to the change in geometry of the growth of crystalline structures in consequence of the heterogeneity of the materials.…”

Section: Y Thermal Anal 361990supporting

confidence: 72%

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Non-isothermal crystallization kinetics of filled blends of polypropylene and low density polyethylene

Kerch¹,

Irgen²

1990

Journal of Thermal Analysis

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Non-isothermal crystallization kinetics of filled polymer blends was investigated by DTA. Crystallization in hybrid matrices containing small amounts of low density polyethylene was shown to proceed more rapidly than that in pure polypropylene. This effect was more pronounced in the presence of a mineral filler. The Kolmogorov-Avrami kinetic model can be used to describe the crystallization process under non-isothermal conditions.Processing of thermoplastics involves cooling through the crystallization region. Under non-isothermal conditions, the length of the processing cycle depends to a certain extent on the kinetic behaviour of the systems undergoing phase transformations. It is possible to accelerate the crystallization process with suitable additives.The joint effects of polymer and mineral additives on crystallization and melting temperatures have been studied on polypropylene (PP) [1]. The rate of nucleation in PP, as judged by the value of the initial slope of the crystallization exotherm for the blends is greater than that for the pure PP sample and shows a maximum at a low density polyethylene (LDPE) content of 15%. This is in good agreement with the result obtained for blends of PP and high density polyethylene [2]. Thermoanalytical techniques can be used to measure the time evolution of phase transformations under non-isothermal conditions [3,4]. The case of non-isothermal crystallization more closely simulates the fabrication process. DTA has not been employed to investigate non-isothermal kinetics of crystallization in ternary systems PP/LDPE/mineral filler. Only a few papers are concerned with the applica- John Wiley & Sons, Limitea~ ChichesterAkaddmiai Kiad6, Budapest

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Section: Y Thermal Anal 361990supporting

confidence: 72%

“…Evidence in favour of such an explanation has been given by morhological studies [15]. The second stage probably involves lamellar crystal growth within spherulites [14,16,17]. In consequence of the two-dimensional growth of the crystals, the value of n should be equal to 2.…”

Section: Y Thermal Anal 361990mentioning

confidence: 95%

Non-isothermal crystallization kinetics of filled blends of polypropylene and low density polyethylene

Kerch¹,

Irgen²

1990

Journal of Thermal Analysis

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“…The flatness of the experimental cr (t) curves is often observed in crystallization experiments. It was sometimes interpreted in terms of secondary crystallization [9][10][11]. It is important to note that our model provides another consistent explanation for such a phenomenon.…”

Section: Influence Of Specimen Thickness On Crystallization Kineticsmentioning

confidence: 86%

Influence of specimen thickness on isothermal crystallization kinetics. A theoretical analysis

Escleine

Monasse

Wey

et al. 1984

Colloid & Polymer Sci

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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.

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“…This clearly corresponds to the radial decrease of crystallinity observed in the spherulite as a result of two consecutive crystallization processes: primary spherulitic and secondary spherulitic or nonspherulitic crystallization [12,14]. This clearly corresponds to the radial decrease of crystallinity observed in the spherulite as a result of two consecutive crystallization processes: primary spherulitic and secondary spherulitic or nonspherulitic crystallization [12,14].…”

Section: Discussionmentioning

confidence: 71%

Morphology influence on the permeation properties of styrene and polystyrene modified polyethylene membranes

Milczarek

Pluta

Κryszewski

1989

Colloid & Polymer Sci

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Influence of the structure of styrene and polystyrene modified PE membranes on their permeation properties is presented. It is demonstrated that the temperature of styrene treatment (N membranes) and the presence of polystyrene (P membranes) results in high differentiation of the permeation properties. SALS studies have shown the structural reorganization depending on modification extent and diffusion of the penetrant. It is also shown that the morphology of the dried films remains unchanged. This work proves that the appropriate modification of PE films results in membranes with controlled permeation behavior.

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Crystallization kinetics of polypropylene fractions

Cited by 32 publications

References 6 publications

Non-isothermal crystallization kinetics of filled blends of polypropylene and low density polyethylene

Non-isothermal crystallization kinetics of filled blends of polypropylene and low density polyethylene

Influence of specimen thickness on isothermal crystallization kinetics. A theoretical analysis

Morphology influence on the permeation properties of styrene and polystyrene modified polyethylene membranes

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