Effect of high pressure treatment on thermal properties of polylactides

• Published in: Journal of food engineering Vol. 93; no. 3; pp. 308 - 312
• Main Authors: Ahmed, Jasim, Varshney, Sunil K., Zhang, Jian-Xin, Ramaswamy, Hosahalli S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2009; [New York, NY]: Elsevier Science Pub. Co; Elsevier
• Subjects: Amorphous; biodegradable products; Biological and medical sciences; chemical structure; crystal structure; Crystallinity; crystallization; Enthalpy; Food engineering; Food industries; food packaging; Fourier transform infrared spectroscopy; Fundamental and applied biological sciences. Psychology; General aspects; Glass transition temperature; high pressure treatment; Melting; melting point; packaging materials; polymers; thermal properties; Amorphous; Melting; Crystallinity; Glass transition temperature; Enthalpy; Heat treatment; Physical dressing; High pressure
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2009.01.026

Effect of high pressure treatment on thermal properties of amorphous and semi-crystalline polylactides (PLA) was studied. Three different PLA isomers (D, L and DL) with molar mass in the range of 3800–6200 were pressurized (350, 450 and 650
MPa) for a holding time of 15
min and the process temperature was maintained in the range of 22–26
°C. Thermal properties (glass transition temperature, melting behavior and crystallinity) of post-process samples were analyzed by a differential scanning calorimetery (DSC) and compared with untreated sample. The glass transition temperature (
T
g) was found to decrease as pressure was applied to lactides. During pressure treatment, it was observed that both melting and crystallization peak of L-isomer were significantly reduced at 650
MPa and the observation was quantified by decrease in fusion (Δ
H
m) and crystallization enthalpy (Δ
H
c). Fourier transform infrared (FTIR) spectroscopy could not detect the change in the crystalline band (1300–1150
cm
−1) of pressure treated L-isomer. This study suggests that PLA could be further experimented for development of food packaging material under high pressure treatment either individually or in combination with other materials.