Comparison of melting and crystallization behaviors of polylactide under high-pressure CO2, N2, and He

Non-isothermal crystallization behaviors of poly(lactic acid)/cellulose nanofiber composites in the presence of CO2

“…This minimizes their thermal degradation and maximizes the processing window. Moreover, the presence of CO 2 can also enhance the polymer's crystallization [8,12,[79][80][81]. All these benefits from a CO 2 -assisted polymer process would enable to produce PLA composite with superior mechanical properties [9,67,69,70].…”

“…In CO 2 environment, the PLA crystallization behaviors can be significantly affected by the dissolved CO 2 due to the plasticization effect. The dissolved CO 2 can depress the glass transition temperature (T g ) [8,12,79,86,87] and the crystallization temperature (T c ) [8,12,79] of PLA by facilitating the molecular chain mobility. Nofar et al reported a decrease of about 40°C and 15°C in the T g and T c , respectively, for a linear PLA when it was exposed to 60 bar CO 2 pressure at a cooling rate of 2°C/min [8,12].…”

“…Some researchers concluded that during isothermal crystallization, the dissolved CO 2 enhanced PLA's crystallization rate in the crystal-growth controlled region, whereas it reduced the crystallization rate in the nucleation controlled region [87,88]. In contrast, Nofar et al found that the crystallization rate was enhanced in presence of CO 2 and the rate was enhanced to various degrees depending on the gas pressure [8,12,79]. However, the final crystallinity did not always increase with the gas pressure because PLA's crystallization kinetics (that is, crystal nucleation and growth) is pressure dependent [8,12,79].…”

Expanded polylactide bead foaming - A new technology

“…However, we have extensively investigated how the PLA's crystallization kinetics can be enhanced under atmospheric condition and in the presence of dissolved gas by varying branching degree [8][9][10], by adding nano-/micro-sized additives [11], and PLA with varying D-lactide content [12].…”

Effect of processing conditions on the cell morphology distribution in foamed injection molded PLA samples

“…Poly(lactic) acid is a biodegradable thermoplastic currently used in a lot of different applications due to its properties, such as high strength, high modulus, and transparency. However, its applications are limited in many manufacturing processes because of the low melt strength, the narrow processing window and the slow crystallization rate [1][2][3][4][5][6][7]. Supercritical nitrogen utilized in the foam injection molding process reduces the melt viscosity due to its plasticization effect, allowing the processability of the PLA at decreased pressure and temperatures [8,9].…”