Non-Isothermal Crystallization Kinetics of Green Microalgae Filled Poly(Lactic Acid)

Abstract

In this study, the effect of green microalgae as a nucleating agent on the non-isothermal crystallization of poly(lactic acid) (PLA) was investigated by differential scanning calorimeter and polarized optical microscope. The parameters of non-isothermal crystallization kinetics of PLA and PLA/green microalgae composites were obtained through common kinetic models such as Avrami, Ozawa, and combined Avrami and Ozawa. Moreover, nucleating activity of green microalgae and activation energies of composites were determined by the Dobreva-Gutzow and the Friedman methods, respectively. Dispersion of green microalgae in PLA was characterized using scanning electron microscopy. PLA/green microalgae composites having different green microalgae content from 5 to 20 wt% were prepared via solvent casting method. Although some agglomerated green microalgae was observed in the PLA matrix, it was found that the green microalgae were homogeneously distributed within the matrix at its lower loading levels. The Avrami and combined Avrami-Ozawa results showed that PLA/green microalgae composites have faster melt crystallization rates than that of pure PLA. Nucleating activity of green microalgae was proved by the Dobreva and Gutzow kinetic approach. Moreover, polarized optical microscope analysis revealed that crystallization onset temperature of PLA shifted to higher temperature upon cooling in the presence of green microalgae.

Synthesis, characterization and crystallization kinetics of a bio-based, heat-resistance nylon 5T/10T

“…22,29 It is because when the cooling rate is high, the molecular chain does not have enough time to overcome the barrier to form perfect crystalline region, so the lower crystallization temperature and wider crystallization peak. 30 More excitingly, according to Table 2, at the same cooling rate, the change rule of crystallization temperature is consistent with that of melting temperature, which decreases first and then increases with increasing 10T units. This is also due to the comprehensive effect of the introduction of 10T units on the crystalline region and molecular chain structure of the copolymer.…”

Isothermal crystallization kinetics of pure and surface‐modified silica/high‐density polyethylene nanocomposites

“…The values obtained for X t in different nanocomposite samples are plotted as a function of annealing time (Figure 5), and as expected, all the obtained curves show a sigmoidal behavior. 42 The crystallization process is slow at the beginning and becomes faster with time, and again at the end of the process, it progresses slowly. It should be noted that the rest of the related graphs are represented in Figures S8-S14.…”