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High-pressure crystallization of isotactic polypropylene droplets.

Zapala K, Piorkowska E, Hiltner A, Baer E - Colloid Polym Sci (2012)

Bottom Line: Only the largest PP droplets, with average sizes of 170 μm, crystallized predominantly in the γ form.The results showed that the γ phase formed only in the droplets sufficiently large to contain the most active heterogeneities nucleating PP crystallization under atmospheric pressure.It is concluded that the presence of nucleating heterogeneities is necessary for crystallization of PP in the γ form under high pressure.

View Article: PubMed Central - PubMed

Affiliation: Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90 363 Lodz, Poland.

ABSTRACT
Dispersions of isotactic polypropylene (PP) particles in polystyrene (PS) were produced by interfacially driven breakup of nanolayers in multilayered systems that were fabricated by means of layer-multiplying coextrusion. The droplet size was controlled by the individual PP layer thickness ranging from 12 to 200 nm. In addition, PP was melt blended with PS to produce PP droplets larger than those formed by breakup of nanolayers. The dispersions of PP particles in the PS matrix were melted and annealed under high pressure of 200 MPa. Only the largest PP droplets, with average sizes of 170 μm, crystallized predominantly in the γ form. In the 42-μm droplets obtained by breakup of 200 nm layers, a minor content of the γ form was found whereas the smaller droplets obtained by breakup of the thinner nanolayers contained the α form and/or the mesophase. The results showed that the γ phase formed only in the droplets sufficiently large to contain the most active heterogeneities nucleating PP crystallization under atmospheric pressure. It is concluded that the presence of nucleating heterogeneities is necessary for crystallization of PP in the γ form under high pressure.

No MeSH data available.


Related in: MedlinePlus

WAXD diffractograms of PP/PS systems recorded with increased acquisition time; the PS contribution subtracted, PP/PS-b diffractogram normalized to PP content in other systems
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Fig8: WAXD diffractograms of PP/PS systems recorded with increased acquisition time; the PS contribution subtracted, PP/PS-b diffractogram normalized to PP content in other systems

Mentions: Figure 7a compares WAXD diffractograms of PP/PS systems and PS control sample after annealing under high pressure, whereas Fig. 7b displays these curves after subtracting the PS contribution. WAXD diffractograms of the PP/PS samples annealed under high pressure recorded in the 2θ range from 17 to 21° with increased acquisition time are collected in Fig. 8. The diffractograms of the melt blend PP/PS-b shown in these figures were normalized to the PP content in the other systems.Fig. 7


High-pressure crystallization of isotactic polypropylene droplets.

Zapala K, Piorkowska E, Hiltner A, Baer E - Colloid Polym Sci (2012)

WAXD diffractograms of PP/PS systems recorded with increased acquisition time; the PS contribution subtracted, PP/PS-b diffractogram normalized to PP content in other systems
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472077&req=5

Fig8: WAXD diffractograms of PP/PS systems recorded with increased acquisition time; the PS contribution subtracted, PP/PS-b diffractogram normalized to PP content in other systems
Mentions: Figure 7a compares WAXD diffractograms of PP/PS systems and PS control sample after annealing under high pressure, whereas Fig. 7b displays these curves after subtracting the PS contribution. WAXD diffractograms of the PP/PS samples annealed under high pressure recorded in the 2θ range from 17 to 21° with increased acquisition time are collected in Fig. 8. The diffractograms of the melt blend PP/PS-b shown in these figures were normalized to the PP content in the other systems.Fig. 7

Bottom Line: Only the largest PP droplets, with average sizes of 170 μm, crystallized predominantly in the γ form.The results showed that the γ phase formed only in the droplets sufficiently large to contain the most active heterogeneities nucleating PP crystallization under atmospheric pressure.It is concluded that the presence of nucleating heterogeneities is necessary for crystallization of PP in the γ form under high pressure.

View Article: PubMed Central - PubMed

Affiliation: Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90 363 Lodz, Poland.

ABSTRACT
Dispersions of isotactic polypropylene (PP) particles in polystyrene (PS) were produced by interfacially driven breakup of nanolayers in multilayered systems that were fabricated by means of layer-multiplying coextrusion. The droplet size was controlled by the individual PP layer thickness ranging from 12 to 200 nm. In addition, PP was melt blended with PS to produce PP droplets larger than those formed by breakup of nanolayers. The dispersions of PP particles in the PS matrix were melted and annealed under high pressure of 200 MPa. Only the largest PP droplets, with average sizes of 170 μm, crystallized predominantly in the γ form. In the 42-μm droplets obtained by breakup of 200 nm layers, a minor content of the γ form was found whereas the smaller droplets obtained by breakup of the thinner nanolayers contained the α form and/or the mesophase. The results showed that the γ phase formed only in the droplets sufficiently large to contain the most active heterogeneities nucleating PP crystallization under atmospheric pressure. It is concluded that the presence of nucleating heterogeneities is necessary for crystallization of PP in the γ form under high pressure.

No MeSH data available.


Related in: MedlinePlus