ISSN:
0887-6266
Keywords:
isotactic polypropylene
;
β phase
;
α nucleation
;
melting
;
crystallization
;
growth transitions
;
thermal analysis
;
morphology
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The mechanisms which, in isotactic polypropylene, create α phase nuclei on partial melting of β phase spherulites are investigated by thermal analysis and optical and electron microscopy. Nuclei concentrations are determined from recrystallization characteristics. α phase nuclei are formed within β spherulites via two different mechanisms: (1) a low temperature formation of latent α phase nuclei (αβ* nuclei) linked with a hitherto unsuspected β to α growth transition at T = T* ∼ 105°C, and (2) a high temperature α phase nucleation process (αβ nuclei), also linked with a similar β to α growth transition at 140°C first reported by Varga et al. The low temperature nucleation mechanism is the more efficient one: it significantly affects the melting of β phase, and results in samples with over 1013 α nuclei · cm-3. © 1993 John Wiley & Sons, Inc.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1993.090311015
Permalink
