Macromorphology of polypropylene homopolymer tacticity mixtures

Phillips, Robert

doi:10.1002/1099-0488(20000801)38:15<1947::aid-polb10>3.0.co;2-m

Cited by 33 publications

(44 citation statements)

References 18 publications

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“…5 This latter observation is sensitive to blend molecular weight and aPP tacticity microstructure in equal molecular weight mixtures. 5 This study aims to address the relationship between the blend composition and morphology in the iPP/aPP system. Morphology development in equal molecular weight (M w ϳ200,000 g mol Ϫ1 ) iPP/aPP blends has been investigated by time-resolved simultaneous smalland wide-angle X-ray scattering (SWAXS) methods with synchrotron radiation.…”

Section: Introductionsupporting

confidence: 57%

“…8 Upper critical solution temperature (UCST) behavior below the melt temperature has been suggested for an equimolecular weight (M w ϳ 200,000 g mol Ϫ1 ) iPP/aPP blend with pooling of aPP within the growing iPP spherulite at low undercooling. 5 This latter observation is sensitive to blend molecular weight and aPP tacticity microstructure in equal molecular weight mixtures. 5 This study aims to address the relationship between the blend composition and morphology in the iPP/aPP system.…”

Section: Introductionmentioning

confidence: 65%

“…3 More recent work has shown volume-filling spherulites in equal molecular weight iPP/ aPP blends to very high aPP concentrations, depending on the molecular weight, melt history, crystallization temperature, and aPP microstructure. 5 The miscibility between iPP and aPP has also received attention. [5][6][7][8] The aPP component has been reported to be miscible with iPP in the molten state on the basis of an evaluation of an equation of state.…”

Section: Introductionmentioning

confidence: 96%

“…5 The miscibility between iPP and aPP has also received attention. [5][6][7][8] The aPP component has been reported to be miscible with iPP in the molten state on the basis of an evaluation of an equation of state. 6 The aPP sample in this study had a low molecular weight [weight-average molecular weight (M w ) ϭ 50,000 g mol Ϫ1 ].…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Phillips

Hsiao

2000

J. Polym. Sci. B Polym. Phys.

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Section: Introductionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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

Wang

Phillips

Hsiao

2000

J. Polym. Sci. B Polym. Phys.

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“…They suggest a state of mixture bordering on phase separation or in other words, the blend iPP/sPP is immiscible. It is also confirmed by Phillips [10] and by Wang et al [11] on iPP/sPP blend of composition 50/50 (wt/wt). Zou et al [12] also examined this composition and its behavior during injection-molding.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the morphology of iPP/sPP blends with various compositions

Bourbigot¹,

Garnier²,

Revel³

et al. 2013

Express Polym. Lett.

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Abstract. The paper investigates the morphology and the structural properties of blends of isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) having different compositions using different techniques. Solid-state nuclear magnetic resonance (NMR) permits via appropriate sequence to measure the composition, conformation and dynamics, and intimacy of mixing of polymeric materials. Measurement of relaxation times gives information on local structure of phases with different mobility. The morphology is directly related to the structural organization of the blends. The crystallization rate decreases as a function of the sPP content. The minor component is dispersed as a nodule in the main component of the blend and it plays the role of nucleating agent on it. Besides, morphology changes occur for the composition 50/50 (wt/wt) of the blend iPP/sPP. Different phases are identified, namely free amorphous, constrained amorphous and crystalline regions which exhibit different molecular mobilities. It is also shown at the interphase matrix-nodules, the nodules create a constrained amorphous zone.

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Tacticity in Vinyl Polymers

Woo

Chang

2011

Encyclopedia of Polymer Science and Technology

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Various issues of tacticity in vinyl polymers are discussed. First, tacticity is defined and the concepts of tactic forms in polymers as a stereoregular configuration order are introduced, and illustration schemes for common polymer tacticity are shown. Effects of tacticity in polymer structures on crystalline morphology and property are briefly discussed. Several commercially useful tactic polymers are examined, by using examples of vinyl‐type polymers such as tactic polypropylene (PP), polystyrene (PS), and poly(methyl methacrylate) (PMMA). Catalysts and synthesis routes for producing stereoregular tactic polymers are discussed mainly using PMMA as an example. Tacticity in polymers is related to differences in microstructures, morphology, crystalline polymorphism, and physical/mechanical properties. Tactic polymers possess structural order and are to crystallize. Tacticity and crystalline properties of polymers are discussed. Crystal polymorphism in some tactic polymers, such as syndiotactic polystyrene (s‐PS), is discussed in greater detail. Complex formation in mixtures of polymers of opposite tacticities, just like mixtures of polymers of opposite chiral forms, has been reported. Complex formation in mixtures of polymers of opposite (s‐ and i‐tacticity) is discussed using examples of isotactic PMMA (i‐PMMA) and syndiotactic PMMA (s‐PMMA); on the other hand, complex formation of mixtures of other tactic polymers, such as i‐PS/s‐PS or i‐PP/s‐PP, is not known. Effects of tacticity on the miscibility and phase behavior in blends of tactic polymers with other polymers are surveyed and expounded. Blends of polymers of same chemical structure but opposite tacticities are not always miscible, as exemplified in a blend of nonpolar and highly crystalline s‐PP with i‐PP, showing immiscibility with upper critical solution temperature behavior but a‐PP being miscible with s‐PP or i‐PP. In addition, phase behaviors of binary blends of two isomeric polymers are addressed. In blends with weak interactions and borderline phase homogeneity, the tacticity effect on miscibility is usually more pronounced; in contrast, the effect on the phase behavior may be minimal in systems with strong intermolecular interactions.

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Macromorphology of polypropylene homopolymer tacticity mixtures

Cited by 33 publications

References 18 publications

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

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

Characterization of the morphology of iPP/sPP blends with various compositions

Tacticity in Vinyl Polymers

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