Polymorph selection during crystallization of random copolymers

Lai, Yuqing; Men, Yongfeng

doi:10.1016/j.eurpolymj.2018.02.038

Cited by 27 publications

(20 citation statements)

References 33 publications

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“…In the case of polymorphic polymers, the content of the different crystalline phases can also vary, depending on the self-nucleation temperature. The effect of the self-nucleation thermal procedure on the content of polymorphism has been studied for several polymers, such as iPP 43 , poly(1-butene) 51,54,87 , poly(amide 11) 45 , poly(vinylidenefluoride) 85,119 , poly(butylene adipate) 73 among others [138][139][140] . The relevant literature is summarized in Table S2 of the Supporting Information.…”

Section: Effect Of Self-nucleation Temperature On Crystalline Morphology and Structurementioning

confidence: 99%

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: Effect Of Self-nucleation Temperature On Crystalline Morphology and Structurementioning

confidence: 99%

Self-Nucleation Effects on Polymer Crystallization

2020

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“…Therefore, it is plausible that the direct melt-crystallization of Form I′ was induced by the earlier presence of Form I crystals by solid state transformation. Using a butene-1/ethylene copolymer, with high content of ethylene comonomer (9.8 %), Men et al 28,29,40 found that the Form I′ crystals can be formed by melt memory effect which is independently from the original crystalline structure present before the melting stage.…”

Section: Self-nucleation Of Butene-1/ethylene Statistic Copolymer: the Formation Of Form I′ Crystalsmentioning

confidence: 99%

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

et al. 2018

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The formation of Form I nuclei of polybutene-1 (PB-1) and its copolymer with polyethylene (PB1-ran-PE) has been studied by means of modified self-nucleation protocols. Even when the self-nucleation temperature was high enough and all Form II crystals melt, re-crystallization can be accelerated if the melt-crystallized sample was annealed at low temperatures (below 60 o C for PB-1 and 75 o C for PB1-ran-PE) for just 3 min. These results suggest the formation of latent Form I nuclei within Form II crystals. This hypothesis is consistent with the observed growth of a small amount of Form I crystals during heating, after previous annealing at temperature lower than 20 °C.In addition, a peculiar phenomenon was found in PB1-ran-PE, as both Form II and Form I′ can be induced by the presence of latent Form I nuclei, due to cross-nucleation and self-nucleation effects, respectively. The final ratio of the two kinds of crystal Forms is a result of the competition between the two nucleation rates, which strongly depend on crystallization temperature. In this work, we have shown that careful design of novel self-nucleation protocols can yield evidence of the early stages of Form II to Form I transition, even when the degree of transformed crystals is below the limit of detection of conventional techniques sensitive to crystalline order (DSC, WAXD, FTIR).

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“…In addition to the physical approaches, such as the mechanical stretching and the supercritical fluid, the copolymerization of extra co‐units has shown the high capability to effectively tune the formation and evolution of crystallites. [ 17‐23 ]…”

Section: Background and Originality Contentmentioning

confidence: 99%

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

Liu

Lou

et al. 2022

Chin. J. Chem.

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Comprehensive Summary The dimethylpyridylamidohafnium catalyst was used to synthesize 1‐butene/cyclohexene and 1‐butene/vinylcyclohexane random copolymers, which have extra six‐membered cyclic co‐units in main chain and side chain, respectively. For the obtained copolymers of different incorporations, the crystallization from amorphous melt and the solid phase transition from tetragonal to trigonal phases were investigated with differential scanning calorimetry. Both of the incorporated cyclic co‐units decrease the crystallization kinetics, but the presence of cyclohexene keeps the melting temperature of copolymers constant. Interestingly, the strong memory effect of crystallization can appear at the elevated temperature even above the equilibrium melting temperature, as the content of co‐units was increased. The 1‐butene/vinylcyclohexane copolymer with 1.52 mol% co‐units exhibits a rather strong memory effect with the broad Domain IIa width of 43°C and the crystallization temperature raising of 24°C. Furthermore, the transition of tetragonal phase into trigonal phase was also explored for different co‐units and incorporations. It was found that both of the cyclohexene co‐units and vinylcyclohexane co‐units effectively slow down the kinetics of phase transition. However, the vinylcyclohexane co‐units have a much higher efficiency in suppressing phase transition than the cyclohexene co‐units, where 0.53 mol% vinylcyclohexane can completely stop phase transition within 1320 h. Considering the fact that copolymers with vinylcyclohexane co‐units actually have lower glass transition temperatures, it was indicated that the suppression of phase transition is also largely influenced by the steric co‐units in the side chain for the helical and positional adjustments, not only by the segmental mobility.

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Polymorph selection during crystallization of random copolymers

Cited by 27 publications

References 33 publications

Self-Nucleation Effects on Polymer Crystallization

Self-Nucleation Effects on Polymer Crystallization

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

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