Investigation on phase transition from flow-induced oriented form II to I in isotactic polybutene-1 with in-situ microbeam X-ray diffraction technique

Su, Fengmei; Yang, Xiaokang; Dong, Beibei; Zhao, Jiateng; Lv, Fei; Ji, Youxin; Liu, Chuntai; Li, Liangbin

doi:10.1016/j.polymer.2019.121719

Cited by 24 publications

(15 citation statements)

References 63 publications

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“…Further increase of TUR led to the four-spot patterns along the machine direction (MD). This suggests highly oriented crystal is formed under the strong flow field [43,44,45]. Such transition from low anisotropy to high orientation was further confirmed by the 2D SAXS patterns, as shown in Figure 7b.…”

Section: Resultsmentioning

confidence: 54%

Preparation of Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Films with Tunable Surface Properties through Manipulating Processing Parameters during Film Blowing

Ali

Zhang

et al. 2019

Polymers

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Polymer films based on polyethylene (PE) and ionomer ethylene/methacrylic acid (EMAA) copolymer blend were prepared by film blowing, whose surface properties were tuned by varying processing parameters, i.e., take up ratio (TUR). Blends of PE/EMAA copolymer were firstly prepared by the melt-mixing method, before being further blown to films. The wettability of the film was investigated by measuring the contact angle/water-film encounter time, and optical properties, i.e., the haze and transmittance. The wettability was found to be enhanced with the increase of TUR. So too was the haze, while the transmittance was found to be almost independent of TUR. The XPS and AFM results directly show the increasing polar functional groups (–COO−) on the surface and roughness with increasing TUR. Further analysis of the 2D SAXS and WAXS unveiled the origin of the invariant transmittance, which resulted from the minor change of the crystallinity and the monotonic increase of the haze, with TUR resulting from the evolution of crystal orientation. In addition to other post-modification methods, the current study provides an alternative route to prepare large-scale PE films as the template for the advanced potential applications, i.e., covering in the layer of roof, the privacy of protective windows, and multitudes of packaging.

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Section: Resultsmentioning

confidence: 54%

Preparation of Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Films with Tunable Surface Properties through Manipulating Processing Parameters during Film Blowing

Ali

Zhang

et al. 2019

Polymers

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“…Recently, it was reported that in the polymorphic butene-1 copolymers, the flow is able to change the crystallization competition between the tetragonal and trigonal phases (form I′ vs form II) and accelerate the kinetics of phase transition (from form II to form I). ,, Then, the effect of flow on the formation of the thermodynamically stable trigonal phase (including forms I′ and I) has a 2-fold meaning, i.e., the flow dependences of the melt crystallization (into form I′) and the solid phase transition (into form I). The flow-induced crystallization and phase transition were studied employing the isothermal protocol, where an elevated temperature of 60 °C was chosen to slow the evolution kinetics for easy observation.…”

Section: Results and Discussionmentioning

confidence: 99%

“…38 Su et al also reported that the highly oriented fibrillar form II shows the significantly accelerated phase transition. 37 Considering the important role of flow in determining the polymorphism of crystallization and the kinetics of II-I phase transition, flow-induced crystallization must be studied for the butene/pentene copolymers.…”

Section: Introductionmentioning

confidence: 99%

“…It was found that the total phase transition kinetics was determined by two steps of nucleation and growth. In addition, the crystallization behavior was strongly dependent on the typical processing parameter of flow. , For the polymorphic polymer, the flow can vary the relative competition between the thermodynamically stable phase and the kinetically favored phase, which is mainly determined by temperature in the quiescent crystallization. − Wang et al combined the extensional rheology and ultrafast X-ray scattering methods to establish the nonequilibrium structural and morphology diagrams of homopolymer PB and found that the flow induced the appearance of orthorhombic form III, which was metastable and had a short lifetime of several tens of milliseconds . Liu et al found that the acceleration effect of flow on the crystallization kinetics of form II is much more pronounced than that of form I′ .…”

Section: Introductionmentioning

confidence: 99%

“…Chen et al studied the phase transition of the flow-induced form II crystallites and found that the induction time of II-I phase transition decreases with increasing orientation degree of form II lamellae . Su et al also reported that the highly oriented fibrillar form II shows the significantly accelerated phase transition . Considering the important role of flow in determining the polymorphism of crystallization and the kinetics of II-I phase transition, flow-induced crystallization must be studied for the butene/pentene copolymers.…”

Section: Introductionmentioning

confidence: 99%

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Regulating Two Distinct Formation Pathways of the Thermodynamically Stable Phase to Tune Crystal Polymorphism: The Case of Butene/Pentene Copolymers

Lou

Liu

et al. 2021

Macromolecules

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Macromolecules with unique long-chain architecture can not only crystallize into a thermodynamically stable crystal but also form a kinetically favored crystal, where the latter may subsequently transform into the former to further lower the free energy. Therefore, to obtain the thermodynamically stable crystal, there are in principle two distinct formation pathways including the direct crystallization from the amorphous melt and the indirect phase transition from the initially generated modification, of which both are crucial to the crystal polymorphism. In the present work, a series of butene/pentene copolymers with the broad co-unit range of 4.0−36.1 mol % were synthesized to explore the correlation of crystal polymorphism with the molecular factor and external stimuli employing in situ wide-angle X-ray diffraction. The results show that different from the highly isotactic homopolymer, the incorporation of pentene co-units is able to not only induce the formations of both the thermodynamically stable trigonal phase and the kinetically favored tetragonal phase from the amorphous melt but also accelerate their solid II-I phase transition. As the concentration of pentene co-units reaches 17.6 mol % and higher, the thermodynamically stable phase has two distinct formation pathways, where those trigonal crystallites obtained from the direct melt crystallization and the indirect phase transition were referred to as forms I′ and I, respectively. It is also unexpected to find that different from the quiescent case where cooling is required to generate the thermal stress for triggering form I nucleation, both pathways can occur at the same temperature with the crystallization of the kinetically favored tetragonal phase, which can be facilitated by the increase in pentene incorporation. The elevation of temperature is beneficial to the formation of form I′, while the decrease in temperature facilitates the solid II-I phase transition into form I. Furthermore, flow-induced formation of the trigonal phase was also investigated by examining the correlation between the formation pathways and flow strength. It is interesting to find that the relatively weak flow accelerates the crystallization of both forms II and I′, while the severe flow induces the amorphous melt to completely crystallize into tetragonal crystallites and simultaneously trigger them to quickly transform into the ultimately stable form I.

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Dramatically Accelerating II−I Crystal Phase Transition of Polybutene‑1 by In Situ Incorporation of H‐Shape Long‐Chain‐Branching Structures

Yu,

Dong

2024

Macromol. Rapid Commun.

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This communication reports an effective strategy helping address the long‐troubling melt processing issue of isotactic polybutene‐1 (i‐PB) caused by its extremely slow II‐I crystal phase transition. The solution lies in a facile synthesis of i‐PB containing H‐shape long‐chain‐branching structures (LCB‐i‐PB) by applying a so‐called ω‐alkenylmethyldichlorosilane copolymerization‐hydrolysis (ACH) chemistry to butene‐1 polymerization with Ziegler‐Natta or metallocene catalysts. It is evident that the H‐shape LCB structures effectively enhance chain entanglements of i‐PB and induce an over‐the‐board acceleration of the overall melt crystallization process including nucleation, form II crystallization, and form II‐form I phase transition. As i‐PB usually requires up to a week to reach equilibrium of the II‐I phase transition, it is found that with LCB‐i‐PB such a transition is almost finished within as short as 24 hours to even higher degrees.This article is protected by copyright. All rights reserved

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Investigation on phase transition from flow-induced oriented form II to I in isotactic polybutene-1 with in-situ microbeam X-ray diffraction technique

Cited by 24 publications

References 63 publications

Preparation of Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Films with Tunable Surface Properties through Manipulating Processing Parameters during Film Blowing

Preparation of Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Films with Tunable Surface Properties through Manipulating Processing Parameters during Film Blowing

Regulating Two Distinct Formation Pathways of the Thermodynamically Stable Phase to Tune Crystal Polymorphism: The Case of Butene/Pentene Copolymers

Dramatically Accelerating II−I Crystal Phase Transition of Polybutene‑1 by In Situ Incorporation of H‐Shape Long‐Chain‐Branching Structures

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