Aging semicrystalline polymers

Struik, L. C. E., The mechanical and physical aging of semicrystalline polymers 1, Polymer, 28, 1521-1533 (1987a). 

In amorphous polymers the physical aging takes place atTp -F 30°C erases the glassy structure. In semicrystalline polymers,... 

In immiscible blends, the t-T principle does not hold. For immiscible amorphous blends, it was postulated that two processes must be taken into account the t-T superposition and the aging time (Maurer et al. 1985). On the other hand, in immiscible blends, at the test temperature, the polymeric components are at different distances from their respective glass transition temperatures, T — Tgi T — Tg2. In blends of semicrystalline polymers, such as PE/PP, the superposition is limited to the molten state, within a narrow, high temperature range (Dumoulin 1988). 

The effects of structural recovery are not limited to fully amorphous materials. In semicrystalline polymers, the amorphous regions physically age in a similar manner to the process in fully amorphous materials. Obviously, however, the change in properties will be only a fraction of that found in fully amorphous materials since the amount of amorphous material makes up only a fraction of the... 

Similar to many semicrystalline polymers, PLA exhibits both Tg and 7j . The Tg of PLA can range from 35 to 60°C depending on molecular weight, the presence of plasticizers, physical aging, polymer architecture, and degree of crystallinity [14]. Above Tg PLA is rubbery, while below Tg it becomes a glass, but it is still able to creep until it is cooled to its 3 transition temperature at approximately —45°C, below which it behaves like a brittle polymer [15]. In applications where mechanical properties are important, such as packaging... 

Struik C. E. Leen. The mechanical behavior and physical ageing of semicrystalline polymers 2. Polymer. 28 no. 9 (1987) 1534-1542. 

The effects of structmal recovery are not limited to fully amorphous materials. In semicrystalline polymers, the amorphous regions physically age in a similar... 

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