Structure, Morphology, and Crystallization Behavior of Syndiotactic Polystyrene

Sorrentino, Andrea; Vittoria, Vittoria

doi:10.1002/9780470557006.ch9

Cited by 8 publications

(4 citation statements)

References 104 publications

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“…The lower the value of Ts, the higher is the Tc upon cooling from the melt, indicating a stronger nucleation effect. This peculiar nucleation effect has been termed in different ways in the literature: crystalline memory 38,39,41,[56][57][58]61,63,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80] , melt memory 49,52,60,64,[81][82][83][84][85][86][87][88][89][90][91][92][93][94] , in some works both terms are used indistinctly 18,47,48,62,65,[95][96][97][98] and in other cases a mo...…”

Section: Melt Memory As a Special Case Of Homogeneous Nucleationmentioning

confidence: 99%

“…The lower the value of T s , the higher is the T c upon cooling from the melt, indicating a stronger nucleation effect. This peculiar nucleation effect has been termed in different ways in the literature: crystalline memory, ,,,− ,,,− melt memory, ,,,,− in some works both terms are used indistinctly, ,,,,,− and in other cases a more general term, memory effect, has been employed. ,,,− ,,− In this Perspective, we will use the term melt memory to emphasize that this effect occurs when, according to calorimetric evidence, there are no crystal fragments present in the melt (i.e., in the so-called Domain IIa ; see section ).…”

Section: Introduction and Phenomenology Of Self-nucleation And Melt M...mentioning

confidence: 99%

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Self-Nucleation Effects on Polymer Crystallization

2020

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The existence of a "memory" of the previous crystalline state, which survives melting and enhances re-crystallization kinetics by a self-nucleation process, is wellknown in polymer crystallization studies. Despite being extensively investigated, since the early days of polymer crystallization studies, a complete understanding of melt memory effects is still lacking. In particular, the exact constitution of self-nuclei is still under debate. In this perspective, we provide a comprehensive and critical overview of melt memory effects in polymer crystallization. After the phenomenology of the process and some key concepts are introduced, the main experimental results of the last decades are summarized. Analogies and discrepancies of the melt memory characteristics of different polymeric systems are highlighted. Based on this background, the most significant interpretations and theories of melt memory effects are described; underlining that different interpretations may apply to various specific cases. Recent insights on self-nucleation, gained thanks to a multi-technique approach (combining calorimetry, rheology, infrared and dielectric spectroscopy), are presented. The role of intra/inter-chain segmental contacts in the strength of melt memory effects, and the differences between homopolymers and copolymers behavior, are discussed. Finally, we identify areas where further research in the field is needed to shed light on the longstanding questions regarding the origin of melt memory effects in semi-crystalline polymers.

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Section: Melt Memory As a Special Case Of Homogeneous Nucleationmentioning

confidence: 99%

“…The lower the value of T s , the higher is the T c upon cooling from the melt, indicating a stronger nucleation effect. This peculiar nucleation effect has been termed in different ways in the literature: crystalline memory, ,,,− ,,,− melt memory, ,,,,− in some works both terms are used indistinctly, ,,,,,− and in other cases a more general term, memory effect, has been employed. ,,,− ,,− In this Perspective, we will use the term melt memory to emphasize that this effect occurs when, according to calorimetric evidence, there are no crystal fragments present in the melt (i.e., in the so-called Domain IIa ; see section ).…”

Section: Introduction and Phenomenology Of Self-nucleation And Melt M...mentioning

confidence: 99%

Self-Nucleation Effects on Polymer Crystallization

2020

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“…Moreover, this polymer can be easily melt-processed (also in industrial plants) leading not only to films but also to solid samples of any shape (e.g., by injection molding), which can be made fully amorphous by simple quenching procedures , As a consequence, materials and devices exhibiting chiral optical responses in selected wavelengths, based on the procedures described in the present paper, can be easily designed and produced.…”

Section: Discussionmentioning

confidence: 99%

Chiral Optical Films Based on Achiral Chromophore Guests

2011

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Films constituted by an achiral host polymer and an achiral guest chromophore, which exhibit intense chiral optical responses for both host and guest peaks in the infrared as well as in the UV-visible regions, have been obtained. Such films can have any thickness from the nanoscale up to the macroscopic scale. This unexpected chiral optical behavior is easily achieved by crystallization of a robust commercial stereoregular host polymer (syndiotactic polystyrene, s-PS) from the amorphous phase as induced by a nonracemic guest, followed by exchange of the nonracemic guest with the achiral guest, leading to the formation of polymer-host/chromophore-guest cocrystalline phases. This finding opens the possibility to achieve s-PS-based films with chiral optical response at selected wavelengths. It has been also found that the chiral optical cocrystalline phase of s-PS with azulene exhibits a monoclinic δ-clathrate form with equal proportions of left- and right-handed helices. This confirms that the observed chiral optical behavior arises by the nonracemic native morphology of the crystalline regions, which has been induced by the temporary nonracemic guest.

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“…Syndiotactic polystyrene, in particular, was the object of many studies because of its impressive material properties and unusual polymorphism . Despite the numerous papers dealing with crystallization of sPS, the combined effect of flow, pressure, and high cooling rate on the solidification process of sPS is still not fully clarified. , …”

Section: Introductionmentioning

confidence: 99%

Process-Induced Morphology Distribution in Injection Molded Syndiotactic Polystyrene Samples

Pantani

Sorrentino

Speranza

et al. 2012

Ind. Eng. Chem. Res.

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In this work, syndiotactic polystyrene was injection molded with different molding conditions. The morphology distribution inside the molded parts was analyzed by several techniques, including optical microscopy, IR spectroscopy, and X-ray diffraction. The final morphology distribution was found to be strongly affected by mold temperature and holding pressures. A peculiar morphology distribution, an alternation of several amorphous and crystalline layers, was found along the samples thickness. The experimental results were analyzed and discussed by means of a software code developed at the University of Salerno. The software implements a model for crystallinity evolution that is able to consider the effects of high cooling rates and high pressures. Furthermore, the software is able to predict the orientation evolution during the injection molding. On commenting on the differences between the experimental data and the model predictions for crystallinity and orientation, it was possible to gain some insights on the causes of the peculiar morphology distributions inside the molded samples.

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Structure, Morphology, and Crystallization Behavior of Syndiotactic Polystyrene

Cited by 8 publications

References 104 publications

Self-Nucleation Effects on Polymer Crystallization

Self-Nucleation Effects on Polymer Crystallization

Chiral Optical Films Based on Achiral Chromophore Guests

Process-Induced Morphology Distribution in Injection Molded Syndiotactic Polystyrene Samples

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