Polymorphic transformation morphology of isotactic poly(1-butene)/poly(propylene-co-1-butene-co-ethylene) blends

Valter, Silvana da Silva; Costa, Carlos Alberto Rodrigues; Battirola, Liliane Cristina; Farias, Marcelo Alexandre de; Galembeck, Fernando; Gonçalves, Maria do Carmo

doi:10.1007/s10965-016-1178-z

Cited by 1 publication

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“…We found that the nucleation of Form I is preferred at some conditions, such as lower annealing temperatures, stress, and short chains. Thermal stress effects and tightening of tie molecules are considered to be the key factors in the local extension of the 11/3 into the 3/1 helical conformation. − In the case of the quiescent condition, Form I nuclei may localize at sites with irregular stacks, bending of lamellae, stressed layers, and varied lamellar thicknesses. ,, In addition, research − on polymorphic transformation of copolymer of PB-1 have found that the nucleation rate of Form I can be accelerated by increasing the ethylene comonomer. This is probably attributed to the varied composition of the rigid amorphous portions at the lamellar basal planes of the copolymer crystals, which may enhance segmental mobility and increase internal stress within the amorphous phase.…”

Section: Introductionmentioning

confidence: 99%

Nucleation Mechanism for Form II to I Polymorphic Transformation in Polybutene-1

Wang

et al. 2020

Macromolecules

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By means of in situ small-/wide-angle X-ray scattering (SAXS/WAXS) techniques, nucleation mechanism for Form I crystals of polybutene-1 (PB-1) has been investigated by heating the early-stage polymorphic transformation specimens (from Form II to Form I) above the nominal melting temperature of Form II crystals. Upon selective melting of Form II crystals at 124 °C, the SAXS curves of the few surviving Form I nanocrystals (volume content about 4.6%) in the melt can be fitted using a form factor for polydisperse cylinders. The geometrical size of Form I cylindrical nanocrystals was around height ≈40 ± 2 nm and radius ≈ 23 ± 1 nm when the aging time reached 12 h. Surprisingly, the height of Form I nanocrystals not only increased with lamellar thickness (d c) of initial Form II crystals but also was always larger than the d c of both initial Form II and pure Form I (i.e., complete transformation). We estimated that the Form I folded-chain nanocrystals consist of two parts, namely, the nuclei of Form I and the epitaxial growth of Form I crystals. Furthermore, our findings suggested that nucleation of Form I has a higher chance to occur at the thicker part of initial Form II crystals. This is probably because the longer parallel-chain stems give rise to a reduction of conformational entropy of the chains, allowing a smaller energy barrier for nucleation of Form I.

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Section: Introductionmentioning

confidence: 99%

Nucleation Mechanism for Form II to I Polymorphic Transformation in Polybutene-1

Wang

et al. 2020

Macromolecules

View full text Add to dashboard Cite

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Polymorphic transformation morphology of isotactic poly(1-butene)/poly(propylene-co-1-butene-co-ethylene) blends

Cited by 1 publication

References 41 publications

Nucleation Mechanism for Form II to I Polymorphic Transformation in Polybutene-1

Nucleation Mechanism for Form II to I Polymorphic Transformation in Polybutene-1

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