TY - JOUR
T1 - On the kinetics of melting and crystallization of poly(l-lactic acid) by TMDSC
AU - Sánchez, M. Salmerón
AU - Gómez Ribelles, J. L.
AU - Hernández Sánchez, F.
AU - Mano, J. F.
N1 - Funding Information:
The authors thank Kadriye Tuzlakoglu for providing the PLLA used in this work. MSS and JLGR acknowledge the support of CICYT through the MAT 2001-2678-C02-01 project and the support to their research group by the Generalitat Valenciana through the Gupos03/018 project. JFM acknowledges the financial support from FCT, through the POCTI and FEDER programmes.
PY - 2005/6
Y1 - 2005/6
N2 - The crystallization and melting process of poly(l-lactic acid), PLLA, is investigated by temperature modulated differential scanning calorimetry, TMDSC. The sample is cooled from the melt to different temperatures and the crystallization process is followed by subjecting the material to a modulated quasi-isothermal stage. From the average component of the heat flow and the application of the Lauritzen-Hoffman theory two crystallization regimes are identified with a transition temperature around 118 °C. Besides, the oscillating heat flow allows calculating the crystal growth rate via the model proposed by Toda et al., what gives, in addition, an independent determination of the transition temperature from modulated experiments. Further, the kinetics of melting is studied by modulated heating scans at different frequencies. A strong frequency dependence is found both in the real and imaginary part of the complex heat capacity in the transition region. The kinetic response of the material to the temperature modulation is analyzed with the model proposed by Toda et al. Finally, step-wise quasi-isothermal TMDSC was used to investigate the reversible surface crystallization and melting both on cooling and heating and a small excess heat capacity is observed.
AB - The crystallization and melting process of poly(l-lactic acid), PLLA, is investigated by temperature modulated differential scanning calorimetry, TMDSC. The sample is cooled from the melt to different temperatures and the crystallization process is followed by subjecting the material to a modulated quasi-isothermal stage. From the average component of the heat flow and the application of the Lauritzen-Hoffman theory two crystallization regimes are identified with a transition temperature around 118 °C. Besides, the oscillating heat flow allows calculating the crystal growth rate via the model proposed by Toda et al., what gives, in addition, an independent determination of the transition temperature from modulated experiments. Further, the kinetics of melting is studied by modulated heating scans at different frequencies. A strong frequency dependence is found both in the real and imaginary part of the complex heat capacity in the transition region. The kinetic response of the material to the temperature modulation is analyzed with the model proposed by Toda et al. Finally, step-wise quasi-isothermal TMDSC was used to investigate the reversible surface crystallization and melting both on cooling and heating and a small excess heat capacity is observed.
UR - http://www.scopus.com/inward/record.url?scp=17744400702&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=17744400702&partnerID=8YFLogxK
U2 - 10.1016/j.tca.2005.01.066
DO - 10.1016/j.tca.2005.01.066
M3 - Article
AN - SCOPUS:17744400702
SN - 0040-6031
VL - 430
SP - 201
EP - 210
JO - Thermochimica Acta
JF - Thermochimica Acta
IS - 1-2
ER -