Polymorphism in Sheared Isotactic Polypropylene Containing Nucleant Particles

Phillips, Andrew W.; Bhatia, Amita; Zhu, Peng; Edward, Graham H

doi:10.1002/mame.201200199

Cited by 18 publications

(18 citation statements)

References 50 publications

(90 reference statements)

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“…[19] FIC studies for PB-1, however, on the one hand confirm the molecular weight effect, but on the other hand show an inverse effect on nucleation and growth. [165] In the end, the industrially most relevant aspect of polymer crys- have been extended to morphology development and modification variation like β-phase formation in molding, [19,154,166] but also to investigations concerning shrinkage and dimensional stability, [167] with holding pressure found as a dominant factor for the latter. A final target is the prediction of mechanic, for which mechanical concepts regarding the crystal structure and factors like lamellar thickness and the distribution between crystalline phase, rigid and mobile amorphous phase are required.…”

Section: Processing-based Modificationsmentioning

confidence: 99%

Designing polymer crystallinity: An industrial perspective

Mileva

Tranchida

Gahleitner

2018

Polymer Crystallization

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More than 50% of the thermoplastic polymers applied globally are semi‐crystalline, making crystallization part of the material and component design process for these materials. The mechanical and optical performance, but also the long‐term stability of the final articles and applications will depend upon three major groups of influence factors: Polymer structure and monomer composition, additive addition (especially nucleation) and blending with secondary components, and processing parameters. In the present review, we try to establish a connection between these three areas, the resulting combination of crystallinity and morphology, and the final application properties. Examples are drawn from the two major polyolefins, polyethylene and polypropylene, technical polymers like polyamide and polyester, but also polymers from renewable sources like poly(lactic acid).

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Section: Processing-based Modificationsmentioning

confidence: 99%

Designing polymer crystallinity: An industrial perspective

Mileva

Tranchida

Gahleitner

2018

Polymer Crystallization

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“…Although the formation of β ‐iPP is related to the chain conformation in the melt, there seems to be a conformation window of the iPP molecular chains beyond which any effects on the chain conformation would restrict the formation of β ‐iPP crystals . A recent work clarified that mesomorphic bundles serve as point‐like β ‐nucleation sites . Some researchers argued that the shear‐induced ordered smectic bundles with random ordering of helices prefer to induce the isochiral β ‐iPP nuclei rather than the α ‐iPP nuclei having strictly left‐ and right‐handed helical packing …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into the Shear-Inducedβ-Form Crystal Formation of iPP

Luo

Zhou

et al. 2016

Macromol. Chem. Phys.

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The conformation of a helical type polymer chain in the crystalline phase prefers the state with lower energy. The molecular simulation of the melting behaviors of α and β isotactic poly(propylene) (iPP) crystals with ultrafast heating shows that the ratio of right‐handed and left‐handed helix stays at 50% in α‐iPP and changes from 100% to 50% in β‐iPP before and after melting. Till date, the formation of β form crystal in iPP has not been understood well together with the mechanism of the crystallization process. One of the approaches to produce β‐iPP is to shear the melt. The influence of shear flow on the crystallization behavior of iPP was investigated via ex situ and in situ X‐ray measurements. It was found that preceding or simultaneously initiated formation of β‐iPP together with α‐iPP occurs under proper shear conditions. The β‐rich iPP sample could no longer form β crystal at 135 °C after heating to the β‐melting temperature with the melting of β‐iPP and the retaining of oriented α‐iPP, which is contrary to the accepted formation process of β‐iPP. A mechanism was proposed to understand the shear‐induced β crystal in iPP, considering the mesophase and stereocomplex type helical conformation of the polymer chains.

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“…Recently, some nucleating agents with hydrogen bonds were identified to self‐assemble into diverse topological structures . It was also reported that the self‐assembled structure as a template could direct the following lateral growth of the chain‐folded lamella into different morphologies . For instance, Varga prepared PP samples with spherulite, fibrous, dendric morphology by adjusting the melting temperature and concentration of the nucleating agent .…”

Section: Introductionmentioning

confidence: 99%

Controllable reinforcement of stiffness and toughness of polypropylene via thermally induced self‐assembly of β‐nucleating agent

Wen

Nie

et al. 2014

J of Applied Polymer Sci

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An easy approach was reported to achieve the simultaneous reinforcement and toughening of polypropylene (PP) via thermally induced self‐assembly of β‐nucleating agent (TMB‐5). The results showed that the processing temperatures dictated the solubility and self‐assembly of TMB‐5 in the polymer melts to determine the subsequent morphology development of PP. At low processing temperature, TMB‐5 did not dissolve into the polymer melt but remained original shape to induce PP to crystallize into spherulites so that it only promoted the formation of β‐form crystals to enhance the toughness of the samples. At high processing temperature, TMB‐5 gradually dissolved into the polymer melts. On cooling, the dissolved nucleating agent self‐assembled into high aspect ratio fibrils through intermolecular hydrogen‐bonding interactions. Due to a favorable matching between PP and TMB‐5, PP preferred to nucleate and grow orthogonally to the fibril axis and into oriented hybrid shish‐kebab morphology with rich β‐form crystals. Compared with isotropic spherulites, the anisotropic structure exhibited excellent properties of the β‐form crystal and shish‐kebab morphology to simultaneously improve the strength and toughness of TMB‐5‐modified PP samples. With the increasing processing temperature, more dissolved TMB‐5 was involved in the self‐assembly procedure to generate longer fibrils and induce more lamellae to grow on the surface. As a consequence, the anisotropy of the PP samples increased further, bringing out more improvements of the tensile strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40605.

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Polymorphism in Sheared Isotactic Polypropylene Containing Nucleant Particles

Cited by 18 publications

References 50 publications

Designing polymer crystallinity: An industrial perspective

Designing polymer crystallinity: An industrial perspective

Mechanistic Insights into the Shear-Inducedβ-Form Crystal Formation of iPP

Controllable reinforcement of stiffness and toughness of polypropylene via thermally induced self‐assembly of β‐nucleating agent

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