Flexibly Controlling the Polycrystallinity and Improving the Foaming Behavior of Polylactic Acid via Three Strategies

Abstract

Controlling foamability plays the central role in preparing PLA foams with high performances. To achieve this, chain extension was often used to improve the rheological property of PLA resins; however, despite the availability of this approach, it often deteriorates the biodegradability of PLA and greatly increases the processing cost and complexity. Hence, we reported a special crystallization induction method to design PLA foams with a tunable cellular structure and a high expansion ratio. A novel crystallization-promoting agent combination (D-sorbitol, CO2, and phenylphosphonic acid zinc salt) was used to induce PLA to enhance the chain interaction force and chain mobility and to provide crystallization templets. A series of PLAs with tunable stereocomplex (Sc)/α crystallinity and rapid non-isothermal crystallization ability were obtained. The effect of various crystallization properties on the foaming behavior of PLA was studied. The results demonstrated that proper crystallization conditions (a small spherulite size, a crystallinity of 6%, and rapid crystallization ability) could virtually contribute to the optimized cellular structure with the highest cell density of 4.36 × 106 cell/cm3. When the Sc crystallinity was above 10%, PLA had a superior foamability, which thereby resulted in a high foaming expansion ratio of 16.2. A variety of cellular morphologies of PLA foams could be obtained by changing the foaming temperature and the crystallization property. The proposed crystallization-induced approach provided a useful method for controlling the cellular structure and the performances of the PLA foams.

Preparation of modified polylactic acid fiber containing anti‐hydrolysis agents

“…While the change in crystallinity calculated by 1D‐WAXD for the fibers with anti‐hydrolysis agents added is consistent with the DSC result, there is a slight difference in the crystallinity calculated by DSC and XRD methods. This difference may explain why the intermediate phase between the crystalline and the amorphous phases is not accurately identified in the DSC measurement 68 …”

Antimicrobial Poly (Lactic Acid)/Copper Nanocomposites for Food Packaging Materials

“…Copper clusters act as catalysts in the reaction of PLA decomposition, affecting the thermal properties of PLA-Cu composites. On the other hand, the dispersed Cu clusters can act as nucleating agents, leading to a heterogeneous PLA crystallization [ 50 ].…”

CNT@LDH functionalized poly(lactic acid) membranes with super oil–water separation and real‐time press sensing properties

“…ΔH 0 c is the standard crystallization enthalpy PLA, which is equal to 93.6 J/g. [29] Polarized optical microscope (POM) (BX51, Olympus, Japan) was used to characterize the spherulite morphology of PLA. In order to induce the grow of PLA spherulite, PLA composites were directly heated to 190 C and kept for 6 min.…”