Dielectric Relaxation Phenomena of Polylactic Acid with -Crystalline Chitin

Abstract

-crystalline chitin was added to polylactic acid (PLA), and this PLA was then heat-treated at for one minute. The crystallinity of the heat-treated PLA increased to more than 40%, and its crystallization speed also increased significantly. The temperature dependency of these materials’ relative permittivity () and relative dielectric loss factor () was also examined. The dielectric absorption peak value in curve of the PLA to which chitin was added and was smaller than that of PLA without chitin. Additionally, the Havriliak-Negami relaxation function was used to produce approximation curves for the frequency dependency of and of chitin with PLA added at . As a result, the relaxation strength of the chitin with PLA added was smaller than that of the PLA without chitin, and the relaxation time of the chitin with PLA added was approximately 2.5 times larger than that of the PLA without chitin.

Water Uptake, Distribution, and Mobility in Amorphous Poly( d , l ‐Lactide) by Molecular Dynamics Simulation

“…The fitted $ value for the "-process varied in a narrow range of 0.48-0.51 over 298-500 K, which is close to the $ value of 0.51 for the "-process at 353 K in mostly amorphous PLA. 79 A much smaller $ (0.23) was obtained for the fast decay at 298 K, suggesting a much broader distribution of relaxation modes for the $-process. Above T g , the calculated relaxation times (J) were 0.6 ns at 500 K and 67 ns at 400 K. A broad-band dielectric relaxation experiment by Mijovic and Sy 77 gave J = ∼0.3 ns at 452 K in amorphous L-PLA.…”

“…Thus, the correlation functions in Figure were fitted with one (at T > T g ) or two (at T < T g ) KWW functions. The fitted β value for the α‐process varied in a narrow range of 0.48–0.51 over 298–500 K, which is close to the β value of 0.51 for the α‐process at 353 K in mostly amorphous PLA . A much smaller β (0.23) was obtained for the fast decay at 298 K, suggesting a much broader distribution of relaxation modes for the β‐process.…”

Mechanical and Electrical Properties of Polylactic Acid with Aliphatic-Aromatic Polyester

“…The author is pursuing the possibility of using PLA as an electrically insulating material and has already found that it has excellent electrically insulating properties at temperatures that range from normal room temperature to 60 ∘ C [6,7]. However, it is known that PLA becomes a poor electrical insulator over 60 ∘ C. The authors added a nucleating agent made of -crystalline chitin particles, extracted from squid gladii, to PLA and found that this moderates the decrease in electrical insulation of PLA at temperatures over 60 ∘ C [8]. As PLA is a hard resin, it has to be softened before it can be used as electrical wire sheathing.…”

Correlation of Processing, Inner Structure, and Part Properties of Injection Moulded Thin-Wall Parts on Example of Polyamide 66

“…Furthermore, the internal structure of a polymer part affects the dielectric behaviour and was described for varied polymers [30][31][32][33][34]. In the case of polyamide 66 there are three relaxation peaks known [21].…”