Kinetics of hardness evolution during annealing of gamma-irradiated polycarbonate

2012 ◽  
Vol 112 (11) ◽  
pp. 113509 ◽  
Author(s):  
S. H. Yeh ◽  
P. Y. Chen ◽  
Julie Harmon ◽  
Sanboh Lee
Keyword(s):  
Gamma Irradiated ◽  
Kinetics Of

Kinetics of non-isothermal melting and crystallization of gamma-irradiated isotactic polypropylene

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Emanuel Nedkov ◽  
Tatyana Dobreva
Keyword(s):  
Constant Temperature ◽  
Isotactic Polypropylene ◽  
Crystallization Rate ◽  
Melting Rate ◽  
Isothermal Kinetics ◽  
Lamellar Thickness ◽  
Scanning Calorimetry ◽  
Gamma Irradiated ◽  
Kinetics Of ◽  
Melting And Crystallization

Abstract The non-isothermal kinetics of melting and crystallization of gamma-irradiated isotactic polypropylene were investigated by differential scanning calorimetry. At constant temperature the melting rate increased with the dose. During the melting, the average lamellar thickness, the free surface energy and the transport energy through the phase boundary reduced with increasing the dose. The crystallization rate decreased with increasing dose at constant temperature. Mixed α-γ spherulites were grown during crystallization. The non-isothermal crystallization rate expressed, in fact, the rate of secondary nucleation of the lamellae in the spherulites and their growth. Raising the irradiation doses led to a decrease of the crystallization temperature. A critical dose of irradiation of about 200 kGy was found, where the dependences of the calculated kinetic parameters underwent an important change. This change could be successfully connected with the effect of radiation annealing and melting.

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