Fibrillar crystals of isotactic polystyrene. II. Aggregation in stirred suspensions
作者:
A.G. Wikjord,
D.H. Page,
R.St. John Manley,
期刊:
Journal of Macromolecular Science, Part B
(Taylor Available online 1970)
卷期:
Volume 4,
issue 2
页码: 413-436
ISSN:0022-2348
年代: 1970
DOI:10.1080/00222347008212511
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Macroscopic particles of various morphological forms are created by the crystallization of isotactic polystyrene from rapidly stirred solutions. Crystallization from trimethylbenzene over a 150° C temperature range produced spherical particles, globules, fibers, and rings depending upon the growth temperature. Crystallization from cyclohexanol (θ = 83.5°C) produced fibers in the temperature range of 85° to 140° C. Globular structures, similar to those formed by stirrer crystallization in trimethylbenzene developed during the Ziegler-Natta polymerization of styrene in trimethylbenzene between 25° and 75°C. Highly birefringent conical appendages appeared on many of the globules and fibers. The fibers often exhibited a skin-core effect with an average longitudinal and transverse orientation of the chain molecules in the skin and core, respectively. The skin frequently displayed periodic banded extinctions. All of these macrostructures consisted of a highly porous assembly of constituent microfibrillar units. It is believed that the morphogenesis of these structures involves the gradual aggregation of microfibrils under the influence of the flow patterns of the system.
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