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Changes In Optical Texture Of α-spherulites Of Isotactic Polypropylene Upon Partial Melting And Recrystallization

C. Yeh, A. Su, M. Chen, R. Sugimoto
Published 1995 · Materials Science

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Textural changes in α-phase spherulites of isotactic polypropylene (iPP) in a sequence of thermal events were examined by means of polarized light microscopy (PLM). This sequence of thermal events involves isothermal crystallization (atTc = 117 to 140 °C), followed by heating (at 5 °C/min) to nearly complete melting, and then recrystallization upon cooling (at -40°C/min) to Tc During isothermal crystallization, the a-spherulites were of mixed birefringenceat Tc = 117 to 127 °C or of negative birefringence at Tc = 140 °C; upon heating towards melting, the spherulitec birefringence consistently truned negative. More interestingly, after recrystallization during cooling back to Tc from nearcomplate melting, all spherulites exhibited positive birefringence. The recrystallization could also result in speckles of positive birefringence when Tc was high or upon slower cooling. The changes in optical texture are explained in terms of contributions from tangential (or, cross-hatched) subsidiary lamellae which (as compared to the radial dominant lamellae) are relatively low-melting but thicken and recrystallize more readily in the present temperature range.
This paper references
10.1016/0032-3861(91)90185-L
Single crystals of γ phase isotactic polypropylene: combined diffraction and morphological support for a structure with non-parallel chains
B. Lotz (1991)
10.1016/0032-3861(84)90076-4
On the lamellar morphology of isotactic polypropylene spherulites
D. Bassett (1984)
10.1002/POLB.1993.090311015
Self‐nucleation and recrystallization of polymers. Isotactic polypropylene, β phase: β‐α conversion and β‐α growth transitions
B. Fillon (1993)
10.1002/POL.1983.180210107
Microstructure and unit‐cell orientation in α‐polypropylene
A. J. Lovinger (1983)
10.1007/BF00657402
Effect of fusion conditions ofβ-polypropylene on the new crystallization
J. Varga (1991)
10.1007/BF02731859
Structure and properties of isotactic polypropylene
G. Natta (1960)
10.1002/MACP.1964.020750113
Crystalline forms of isotactic polypropylene
A. T. Jones (1964)
10.1016/0032-3861(85)90108-9
The spherulitic and lamellar morphology of melt-crystallized isotactic polypropylene
D. Norton (1985)
10.6028/JRES.070A.006
The Spherulitic Crystallization of Isotactic Polypropylene From Solution: On the Evolution of Monoclinic Spherulites From Dendritic Chain-Folded Crystal Precursors.
F. Khoury (1966)
10.1002/MACP.1960.020380103
Intrinsic viscosity and molecular weight of isotactic polypropylene
P. Parrini (1960)
10.1063/1.1655891
Crystallization of Low‐Molecular‐Weight Polypropylene Fractions
D. Morrow (1968)
10.1098/rspa.1981.0113
On the morphology of melt-crystallized polyethylene - I. Lamellar profiles
D. Bassett (1981)
10.1002/POL.1972.160100301
Characterization of the structure and organization of β‐form crystals in type III and type IV isotactic polypropylene spherulites
R. Samuels (1972)
10.1016/0032-3861(86)90053-4
Reply to a discussion of spherulitic crystallization and morphology
D. Bassett (1986)
10.1021/MA00220A014
γ-Isotactic polypropylene. A structure with nonparallel chain axes
S. V. Meille (1990)
10.1038/340455A0
Non-parallel chains in crystalline γ-isotactic polypropylene
S. V. Meille (1989)
10.1002/POL.1968.110060802
The β crystalline form of isotactic polypropylene
A. Turner‐Jones (1968)
10.1016/0032-3861(95)90677-T
Spherulites of cis-1,4-polybutadiene: molecular weight effects
T. Cheng (1995)



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