Morphology development during isothermal crystallization. I. Isotactic and atactic polypropylene blends

Wang, Zhigang; Phillips, Robert; Hsiao, Benjamin S.

doi:10.1002/1099-0488(20001001)38:19<2580::aid-polb100>3.0.co;2-b

Cited by 31 publications

(15 citation statements)

References 32 publications

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“…In this case, crystallization of the i PP/ s PP blend during the early stages of crystallization (before the crystallization of s PP) may bear similarities to the crystallization of crystalline/amorphous blends and, more specifically, crystalline/amorphous i PP/atactic polypropylene ( a PP) blends 18, 19, 34–38. In a previous study,38 the morphology development in i PP/ a PP blends was investigated with differential scanning calorimetry (DSC) and synchrotron X‐ray techniques. These techniques showed relatively modest incorporation of a PP in the interlamellar regions, depending on the crystallization temperature and blend composition 38.…”

Section: Introductionmentioning

confidence: 91%

“…In a previous study,38 the morphology development in i PP/ a PP blends was investigated with differential scanning calorimetry (DSC) and synchrotron X‐ray techniques. These techniques showed relatively modest incorporation of a PP in the interlamellar regions, depending on the crystallization temperature and blend composition 38. Details of the small‐angle X‐ray scattering (SAXS) patterns suggested lamellar disorder and exclusion of a PP to size scales larger than the lamellar distance 38.…”

Section: Introductionmentioning

confidence: 99%

“…These techniques showed relatively modest incorporation of a PP in the interlamellar regions, depending on the crystallization temperature and blend composition 38. Details of the small‐angle X‐ray scattering (SAXS) patterns suggested lamellar disorder and exclusion of a PP to size scales larger than the lamellar distance 38. The possible role of the thermodynamic driving force governing the dependence of lamellar spacing on the crystallization temperature was hypothesized.…”

Section: Introductionmentioning

confidence: 99%

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Morphology development during isothermal crystallization. II. Isotactic and syndiotactic polypropylene blends

Wang

Phillips²,

Hsiao

2001

J Polym Sci B Polym Phys

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Morphology development during isothermal crystallization in equal molecular weight isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and iPP/sPP blends was studied with time‐resolved simultaneous small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray diffraction (WAXD) with synchrotron radiation. The sPP melting point is 15–20 °C below that of the iPP component, and sPP multiple melting is not affected by blending for 50–100 wt % sPP compositions. SAXS and WAXD (at 115 and 137.5 °C) show that sPP crystallizes more slowly than iPP. The sPP long spacing is larger than that of iPP at both crystallization temperatures, exhibits a broader distribution, and changes to a greater extent during crystallization. Differential scanning calorimetry (DSC) cooling and SAXS/WAXD measurements show iPP crystallizing first and nearly to completion before sPP in a 50:50 iPP/sPP blend. At 115 °C, iPP crystals nucleate sPP in a 50:50 blend and modify the sPP lamellar spacing. The nucleation does not overcome the large difference in the iPP and sPP rates at 137.5 °C. Before sPP crystallization in a 50:50 blend (115 °C), the iPP long spacing is not affected by molten sPP. The iPP long spacing is slightly expanded by molten sPP, and the WAXD induction time is delayed at 137.5 °C. The observed iPP long spacing in the presence of molten sPP is consistent with previously reported results for iPP/atactic polypropylene (aPP) blends of similar molecular weight. Quantitative differences between the two types of blends are consistent with previously reported thermodynamic rankings. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1876–1888, 2001

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphology development during isothermal crystallization. II. Isotactic and syndiotactic polypropylene blends

Wang

Phillips²,

Hsiao

2001

J Polym Sci B Polym Phys

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“…In experiments, short-chain blends of atactic polypropylene ͑aPP͒ and isotactic PP ͑iPP͒ are compatible in the melt, 14,15 while longer chains may demix from the metastable mixture cooled below the equilibrium melting temperature of iPP. 16 Blends made of very long chains are incompatible even above the melting point of iPP. 17 Blends of aPP and syndiotactic PP ͑sPP͒ are also incompatible in the melt, 15,18 as are blends of iPP and sPP.…”

Section: Discussion About the Related Experimental Observationsmentioning

confidence: 99%

Liquid–liquid demixing in a binary polymer blend driven solely by the component-selective crystallizability

Mathot

2003

The Journal of Chemical Physics

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On the basis of an extended Flory-Huggins expression for the mixing free energy of the long-chain binary polymer blend, we showed that liquid-liquid demixing can be driven solely by the propensities of crystallization differing with respect to components. Demixing prior to crystallization on cooling was demonstrated by dynamic Monte Carlo simulations of the lattice model for a symmetric polymer blend where only one component is crystallizable. We discussed the implications of this principle to several experimental observations including the ͑in͒compatibility of polymer chains with different stereochemical compositions, the memory effect of polymer crystallization, and the spinodal decomposition at an early stage of polymer crystallization.

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“…the amount of crystalline phase, crystal type, the thickness of lamellae, etc. Isotactic polypropylene (iPP) crystallizes into several crystalline modifications, such as monoclinic (), hexagonal () and triclinic () form, depending on the conditions of crystallization and molecular characteristics [1][2][3][4][5][6][7][8][9][10]. Thermodynamically the most stable  crystalline phase originates under common crystallization conditions that occur in industrial practice during manufacturing of different iPP-based products.…”

Section: Introductionmentioning

confidence: 99%

The correlation between structure and β-nucleation efficiency of Ba, Sr, Ca and Mg pimelates in isotactic polypropylene

Janevski

Bogoeva‐Gaceva

Stefov

et al. 2015

Maced. J. Chem. Chem. Eng.

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The pimelates of the earth-alkaline elements and pimelic acid have been synthesized and studied. All prepared pimelates are crystallohydrates and Ba and Sr pimelates are isotypic. The obtained compounds have been characterized using infrared spectroscopy and X-ray diffraction, and it was found that, near and above the melting temperature of polypropylene, the pimelates of Ba and Sr are crystalline, whereas the ones of Ca and Mg are amorphous. The nucleation activity of these pimelates has been studied in the process of crystallization of polypropylene in non-isothermal conditions and followed by differential scanning calorimetry (at cooling rate V c = 1-20 K min -1 ). It was found that their nucleation activity, even at concentration of 0.1 %, differs considerably with regards to the cooling rate, and they induce different polymorphic composition of the polymer. The nucleation activity was mostly exhibited by Ca pimelate, and when it was used the content of the β crystalline phase (U β ) in polypropylene ranged from 0.90 to 0.94, depending on the cooling rate, compared to 0.18-0.35 when Mg pimelate was used. In the polymer crystallized by using Ba and Sr pimelate as nucleators, U β ranged from 0.47 to 0.77. Based on the theoretical concepts for nucleation activity of solid substrates, an attempt was made to correlate the structurаl features of the synthesized pimelates with their β-nucleation activity in the process of nonisothermal crystallization of iPP. ). Беше најдено дека нивната нуклеациона активност и при концентрации од 0,1 % значително се разликува во зависност од брзината на ладење и се добива различен однос на полиморфните модификации на полимерот. Најизразена беше нуклеационата активност на пимелатот на Ca, а во случајот кога тој беше употребен, содржината на β-кристалната фаза (U β ) во полипропиленот беше од 0,90 до 0,94, во  Dedicated to Academician Gligor Jovanovski on the occasion of his 70 th birthday.A. Janevski, G. Bogoeva-Gaceva, V. Stefov, M. Najdoski Maced. J. Chem. Chem. Eng. 34 (1), 189-199 (2015) 190 зависност од брзината на ладење, споредено со 0,18-0,35 кога беше употребен пимелат на Mg. Во полимерот кристализиран со употреба на пимелати на Ba и Sr како нуклеатори, U β е од 0,47 до 0,77. Имајќи ги предвид теоретските концепти за нуклеационата активност на супстратите, беше направен обид да се корелираат структурите на синтетизираните пимелати со нивната β-нуклеациона активност во процес на неизотермална кристализација на iPP.

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Morphology development during isothermal crystallization. I. Isotactic and atactic polypropylene blends

Cited by 31 publications

References 32 publications

Morphology development during isothermal crystallization. II. Isotactic and syndiotactic polypropylene blends

Morphology development during isothermal crystallization. II. Isotactic and syndiotactic polypropylene blends

Liquid–liquid demixing in a binary polymer blend driven solely by the component-selective crystallizability

The correlation between structure and β-nucleation efficiency of Ba, Sr, Ca and Mg pimelates in isotactic polypropylene

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