Tailoring the properties of polypropylene in the polymerization reactor using polymeric nucleating agents as prepolymers on the Ziegler–Natta catalyst granule

Rosa, Claudio De; Auriemma, Finizia; Tarallo, Oreste; Girolamo, Rocco Di; Troisi, EM Enrico; Esposito, Serena; Liguori, Dario; Piemontesi, Fabrizio; Vitale, Gianni; Morini, Giampiero

doi:10.1039/c6py01950a

Cited by 18 publications

(46 citation statements)

References 24 publications

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“…The samples iPP‐0 and iPP‐PVCH crystallize from the melt by slow cooling in the α form (profiles a and c of Figure ), whereas the sample iPP‐PTMAS crystallizes in a mixture of α and β forms (profile b of Figure ). This indicates that, as expected, PVCH induces crystallization of the α form being a nucleant selective for the α form, and even traces of PTMAS induce crystallization of the β form of iPP . PTMAS is a nucleating agent for iPP but it is selective for the β form …”

Section: Polymorphism and Propertiessupporting

confidence: 73%

“…The β form of iPP can be obtained only in particular conditions of crystallization, often in mixture with α form. For example, it crystallizes in the presence of selective nucleating agents as for instance γ‐quinacridone, disodium orthophthalate, pimelic acid/calcium stearate, or even polymeric species, such as poly(trimethyl allyl sylane), or by crystallization in a temperature gradient, from sheared or strained melt . In general, the β form crystallizes in mixture with α form, and the most convenient and reliable method to obtain iPP with high content of β form is the addition of specific nucleating agents …”

Section: Polymorphism and Propertiesmentioning

confidence: 99%

“…Another method for driving crystallization of iPP toward a specific polymorphic form is the addition of selective nucleating agents. As discussed in Section 4.1.2, the β form of iPP can be obtained only in particular conditions of crystallization, in particular in the presence of selective nucleating agents, as for instance, γ‐quinacridone, disodium orthophthalate, pimelic acid/calcium stearate, or even polymeric species, such as poly(trimethyl allyl sylane) . The crystallization of the β form produces samples of iPP with mechanical properties different from those of the α form according to the well‐known better deformability at reduced yield stress of the trigonal crystals of β form compared to the α form .…”

Section: Polymorphism and Propertiesmentioning

confidence: 99%

“…For examples, the different behavior of selective polymeric nucleating agents for α and β forms is shown in Figures and . The X‐ray powder diffraction profiles of compression‐molded specimens slowly crystallized from the melt of the neat iPP sample (iPP‐0) and of the samples containing isotactic poly(trimethyl allyl sylane) (iPP‐PTMAS) and isotactic poly(vinylcyclohexane) (iPP‐PVCH) are shown in Figure . The samples iPP‐0 and iPP‐PVCH crystallize from the melt by slow cooling in the α form (profiles a and c of Figure ), whereas the sample iPP‐PTMAS crystallizes in a mixture of α and β forms (profile b of Figure ).…”

Section: Polymorphism and Propertiesmentioning

confidence: 99%

“…This indicates that, as expected, PVCH induces crystallization of the α form being a nucleant selective for the α form, and even traces of PTMAS induce crystallization of the β form of iPP . PTMAS is a nucleating agent for iPP but it is selective for the β form …”

Section: Polymorphism and Propertiesmentioning

confidence: 99%

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Polymorphism in polymers: A tool to tailor material's properties

Rosa

Scoti

Girolamo

et al. 2020

Polymer Crystallization

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In this review, the phenomenon of polymorphism in polymers is discussed on the basis of the thermodynamic stability of different polymorphs that defines the conformations of chains in the crystalline lattice and the packing mode. In particular, we show that the symmetry and energy stability of the chain conformation, the crystal density and entropy of packing, and the presence of defects and disorder in the crystals are the main factors that define the mode of crystallization of polymers and induce polymorphism. How specific polymorphs are selected and the effects of the molecular structure and processing conditions on polymorphism are analyzed. How crystallization of particular polymorphs affects the material's properties and ultimate applications is also discussed. The polymorphic behaviors of isotactic polypropylene and poly(1-butene) are described as examples of how processing and the controlled modification of the molecular structure of polyolefins using methods of controlled synthesis that allow controlled incorporation of configurational and constitutional defects may drive crystallization of a desired polymorph. The possibility to select a particular polymorph using these strategies results in a tool to tailor the physical and mechanical properties of polymers.polymorphism in polymers, principles that define polymorphic behavior, effect of processing and molecular structure on polymorphism, influence of defects, tailoring properties by controlling polymorphism, isotactic polypropylene and poly(1-butene) through stabilization or destabilization of a particular conformation or crystal lattice or increasing crystallization rate. [1,4,5] Even though crystallizability of polymers requires, generally, a regularity in the constitution of the macromolecules, in the configuration of the possibly present stereoisomeric centers and in the conformation of the chains, [1,2,4] defects in the regular constitution and configuration may be in general tolerated in the crystal lattice of polymers and may not prevent crystallization. [1,2,4,5] When the amount of defects and of structural disorder is significant, highly disordered metastable polymorphic forms may crystallize. These metastable forms have been described as solid mesophases and are characterized by different types of structural disorder that do not prevent crystallization. [1,2,[4][5][6] The studies of the crystal structures of the disordered polymorphic forms of many different polymers [1] allowed asserting a new view of the concepts of crystallinity and crystals in polymers, introducing the modern polymer crystallography. [1] The first concept is that crystallinity in polymeric materials is compatible with the absence of true three-dimensional long-range order. Second, in these disordered crystalline polymorphic forms of polymers (solid mesophases), the disorder may be described as a structural feature, using the methods of interpretation of the X-ray scattering and electron diffraction. [1] Since advanced methods of polymer synthesis allow controlling the mol...

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Section: Polymorphism and Propertiessupporting

confidence: 73%

Section: Polymorphism and Propertiesmentioning

confidence: 99%

Section: Polymorphism and Propertiesmentioning

confidence: 99%

Section: Polymorphism and Propertiesmentioning

confidence: 99%

Section: Polymorphism and Propertiesmentioning

confidence: 99%

See 3 more Smart Citations

Polymorphism in polymers: A tool to tailor material's properties

Rosa

Scoti

Girolamo

et al. 2020

Polymer Crystallization

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Model of Crystallization Behavior of Isotactic Polypropylene: The Role of Defects

Scoti

Stefano

Girolamo

et al. 2022

Macro Chemistry & Physics

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The crystallization behavior of propene–ethylene (iPPC2), propene–butene (iPPC4), propene–pentene (iPPC5), and propene–hexene (iPPC6) isotactic copolymers, prepared with single center metallocene catalysis, is described. Thanks to the perfectly random distribution of comonomers along the macromolecules, these copolymers can be considered as model for the crystallization behavior of isotactic polypropylene (iPP) that is mainly defined by the average length of the regular propene sequences. A model of the crystallization behavior of iPP is described based on the definition of a double effect of defects (stereodefects and comonomers), the interruption effect of defects excluded from the crystals that shortens the length of the crystallizable propene sequences inducing crystallization of the γ form, and the effect of inclusion of defects in the crystals of α form, γ form or δ form that induces the crystallization of the form whose lattice is less disturbed by the defect.

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