Poly(l-lactic acid) (PLLA) was investigated by differential scanning calorimetry and dynamic mechanical and dielectric spectroscopies. In the dynamic mechanical and dielectric spectra no secondary relaxations were observed below the glass-to-rubber transition (70°C at 3 Hz). The thermal history strongly affects the physical properties of PLLA, inducing changes of crystalline: amorphous ratio as well as large physical ageing effects on the glassy amorphous phase. This latter phenomenon is clearly observed as a consequence of room-temperature storage and develops at a faster rate as the ageing temperature Ta approaches Tg. Ageing experiments carried out at the same undercooling (ΔT = Tg - Ta) on PLLA samples of different molecular weight ( M ̄v = 5300, 20 000, 691 000) show that a decrease in molecular weight increases the magnitude of the enthalpy relaxation at the glass transition. © 1992.

Celli A., Scandola M. (1992). Thermal properties and physical ageing of poly (l-lactic acid). POLYMER, 33(13), 2699-2703 [10.1016/0032-3861(92)90440-8].

Thermal properties and physical ageing of poly (l-lactic acid)

Celli A.;Scandola M.
1992

Abstract

Poly(l-lactic acid) (PLLA) was investigated by differential scanning calorimetry and dynamic mechanical and dielectric spectroscopies. In the dynamic mechanical and dielectric spectra no secondary relaxations were observed below the glass-to-rubber transition (70°C at 3 Hz). The thermal history strongly affects the physical properties of PLLA, inducing changes of crystalline: amorphous ratio as well as large physical ageing effects on the glassy amorphous phase. This latter phenomenon is clearly observed as a consequence of room-temperature storage and develops at a faster rate as the ageing temperature Ta approaches Tg. Ageing experiments carried out at the same undercooling (ΔT = Tg - Ta) on PLLA samples of different molecular weight ( M ̄v = 5300, 20 000, 691 000) show that a decrease in molecular weight increases the magnitude of the enthalpy relaxation at the glass transition. © 1992.
1992
Celli A., Scandola M. (1992). Thermal properties and physical ageing of poly (l-lactic acid). POLYMER, 33(13), 2699-2703 [10.1016/0032-3861(92)90440-8].
Celli A.; Scandola M.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/908244
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