Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity

Koji Yamada; Masamichi Hikosaka; Akihiko Toda; Shinichi Yamazaki; Katsuharu Tagashira

doi:10.1081/mb-120021603

Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity

Koji Yamada, Masamichi Hikosaka, Akihiko Toda, Shinichi Yamazaki, Katsuharu Tagashira

Research output: Contribution to journal › Article › peer-review

21 Citations (Scopus)

Abstract

Molecular weight (M) dependence of the equilibrium melting temperature (T_m⁰) of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%) was studied. Four fractionated iPPs with M_n = 23 × 10³, 64 × 10³ 94 × 10³, and 263 × 10³ were used. T_m⁰ was obtained by using an improved method based on the Gibbs-Thomson plot proposed in previous papers. The effect of "melting kinetics" on melting temperature (T_m) was eliminated by observing isothermal melting of spherulites. The effect of lamellar thickening on T_m during T_m measurement at high temperature was also eliminated by observing thick lamellae formed at high crystallization temperatures (T_c = 148-166°C). With increase of M, T_m⁰ increased significantly. The empirical equation, T_m⁰ = 199.5 + 23.6 × log M - 2.0 × (log M)² (°C), was obtained. The molecular weight dependence of the α2-α2′ transition was observed. The transition temperature (T_α2-α2′) also increased with increase of M. The ΔT dependence of lamellar thickness was concluded to be controlled by that of lamellar thickening.

Original language	English
Pages (from-to)	733-752
Number of pages	20
Journal	Journal of Macromolecular Science - Physics
Volume	42 B
Issue number	3-4 SPEC.
DOIs	https://doi.org/10.1081/mb-120021603
Publication status	Published - 2003
Externally published	Yes

Keywords

Equilibrium melting temperature
Gibbs - Thomson plot
Isotactic polypropylene
Lamellar thickening
Melting kinetics
Molecular weight dependence

ASJC Scopus subject areas

Chemistry(all)
Condensed Matter Physics
Polymers and Plastics
Materials Chemistry

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10.1081/mb-120021603

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Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity. / Yamada, Koji; Hikosaka, Masamichi; Toda, Akihiko; Yamazaki, Shinichi; Tagashira, Katsuharu.

In: Journal of Macromolecular Science - Physics, Vol. 42 B, No. 3-4 SPEC., 2003, p. 733-752.

Research output: Contribution to journal › Article › peer-review

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title = "Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity",

abstract = "Molecular weight (M) dependence of the equilibrium melting temperature (Tm0) of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%) was studied. Four fractionated iPPs with Mn = 23 × 103, 64 × 103 94 × 103, and 263 × 103 were used. Tm0 was obtained by using an improved method based on the Gibbs-Thomson plot proposed in previous papers. The effect of {"}melting kinetics{"} on melting temperature (Tm) was eliminated by observing isothermal melting of spherulites. The effect of lamellar thickening on Tm during Tm measurement at high temperature was also eliminated by observing thick lamellae formed at high crystallization temperatures (Tc = 148-166°C). With increase of M, Tm0 increased significantly. The empirical equation, Tm0 = 199.5 + 23.6 × log M - 2.0 × (log M)2 (°C), was obtained. The molecular weight dependence of the α2-α2′ transition was observed. The transition temperature (Tα2-α2′) also increased with increase of M. The ΔT dependence of lamellar thickness was concluded to be controlled by that of lamellar thickening.",

keywords = "Equilibrium melting temperature, Gibbs - Thomson plot, Isotactic polypropylene, Lamellar thickening, Melting kinetics, Molecular weight dependence",

author = "Koji Yamada and Masamichi Hikosaka and Akihiko Toda and Shinichi Yamazaki and Katsuharu Tagashira",

year = "2003",

doi = "10.1081/mb-120021603",

language = "English",

volume = "42 B",

pages = "733--752",

journal = "Journal of Macromolecular Science - Physics",

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TY - JOUR

T1 - Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity

AU - Yamada, Koji

AU - Hikosaka, Masamichi

AU - Toda, Akihiko

AU - Yamazaki, Shinichi

AU - Tagashira, Katsuharu

PY - 2003

Y1 - 2003

N2 - Molecular weight (M) dependence of the equilibrium melting temperature (Tm0) of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%) was studied. Four fractionated iPPs with Mn = 23 × 103, 64 × 103 94 × 103, and 263 × 103 were used. Tm0 was obtained by using an improved method based on the Gibbs-Thomson plot proposed in previous papers. The effect of "melting kinetics" on melting temperature (Tm) was eliminated by observing isothermal melting of spherulites. The effect of lamellar thickening on Tm during Tm measurement at high temperature was also eliminated by observing thick lamellae formed at high crystallization temperatures (Tc = 148-166°C). With increase of M, Tm0 increased significantly. The empirical equation, Tm0 = 199.5 + 23.6 × log M - 2.0 × (log M)2 (°C), was obtained. The molecular weight dependence of the α2-α2′ transition was observed. The transition temperature (Tα2-α2′) also increased with increase of M. The ΔT dependence of lamellar thickness was concluded to be controlled by that of lamellar thickening.

AB - Molecular weight (M) dependence of the equilibrium melting temperature (Tm0) of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%) was studied. Four fractionated iPPs with Mn = 23 × 103, 64 × 103 94 × 103, and 263 × 103 were used. Tm0 was obtained by using an improved method based on the Gibbs-Thomson plot proposed in previous papers. The effect of "melting kinetics" on melting temperature (Tm) was eliminated by observing isothermal melting of spherulites. The effect of lamellar thickening on Tm during Tm measurement at high temperature was also eliminated by observing thick lamellae formed at high crystallization temperatures (Tc = 148-166°C). With increase of M, Tm0 increased significantly. The empirical equation, Tm0 = 199.5 + 23.6 × log M - 2.0 × (log M)2 (°C), was obtained. The molecular weight dependence of the α2-α2′ transition was observed. The transition temperature (Tα2-α2′) also increased with increase of M. The ΔT dependence of lamellar thickness was concluded to be controlled by that of lamellar thickening.

KW - Equilibrium melting temperature

KW - Gibbs - Thomson plot

KW - Isotactic polypropylene

KW - Lamellar thickening

KW - Melting kinetics

KW - Molecular weight dependence

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Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity

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