Effect of melt viscosity on the crystallization kinetics of pre-sheared metallocene polyethylene melts

Krakowiak, Joanna; Martins, José A.; Zhang, Weidong

doi:10.1007/s00396-011-2451-7

Cited by 2 publications

(1 citation statement)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, once crystals disappear and only self-nuclei exist in the melt, direct observation of the morphology or structure of the self-nucleated melt or individual self-nuclei is difficult. Calorimetry is the simplest yet effective way to infer the existence of self-nuclei indirectly, compared to rheology or dielectric spectroscopy. ,− …”

Section: Introductionmentioning

confidence: 99%

Thermal-Field-Tuned Heterogeneous Amorphous States of Poly(vinylidene fluoride) Films with Precise Transition from Nonpolar to Polar Phase

Dong

et al. 2022

Macromolecules

View full text Add to dashboard Cite

In this work, we explore how melt memory, induced by a previous crystalline state, can be used to tune the polymorphs of poly(vinylidene fluoride) during the recrystallization process. In situ experiments were conducted to monitor the melting and chain relaxation of highly oriented α-PVDF crystals during the heating process. Accordingly, a series of heterogeneous amorphous states (induced by self-nucleating the sample) can be made by controlling the thermal treatment temperature (i.e., the self-nucleation temperature, T s ), and the effect of the relaxation state of oriented crystals on the subsequent polymorphic crystallization behavior is studied in depth. A complete α → γ phase transition occurs during the cooling process if the sample is thermally treated in the self-nucleation temperature range of 181−186 °C within the Domain IIa region (i.e., within the melt memory Domain). Only if the oriented molecular chains relax to a certain degree and the 3D structures of the α lamellae are molten, can the retained ordered segments develop γ nuclei in the subsequent crystallization process. If the samples are heated to T s within Domain I (i.e., isotropic melt) or Domain IIb (self-seeding Domain), an α phase is preferred upon subsequent cooling. Hence, a temperature region of 181−186 °C leads to a special heterogeneous self-nucleated melt that can cultivate the rich γ nuclei developed from the relaxation along with segmental flip-flop and inversion motions of oriented molecular chains with a TGTG′ conformation. As a result, the rich γ nuclei enable the formation of pure γ crystals during the cooling process.

show abstract

Section: Introductionmentioning

confidence: 99%

Thermal-Field-Tuned Heterogeneous Amorphous States of Poly(vinylidene fluoride) Films with Precise Transition from Nonpolar to Polar Phase

Dong

et al. 2022

Macromolecules

View full text Add to dashboard Cite

show abstract

How cooling surface affect nucleation and impurity migration behavior during layer melt crystallization: A case study of 2′,4′-dichloro-5′-fluoroacetophenone

Xu,

Liu,

et al. 2024

Surfaces and Interfaces

View full text Add to dashboard Cite

Effect of melt viscosity on the crystallization kinetics of pre-sheared metallocene polyethylene melts

Cited by 2 publications

References 29 publications

Thermal-Field-Tuned Heterogeneous Amorphous States of Poly(vinylidene fluoride) Films with Precise Transition from Nonpolar to Polar Phase

Thermal-Field-Tuned Heterogeneous Amorphous States of Poly(vinylidene fluoride) Films with Precise Transition from Nonpolar to Polar Phase

How cooling surface affect nucleation and impurity migration behavior during layer melt crystallization: A case study of 2′,4′-dichloro-5′-fluoroacetophenone

Contact Info

Product

Resources

About