Self-standing tridimensional structures from crumpling techniques made with composite films of polylactic acid and exfoliated graphite

Obtaining three-dimensional porous materials for different applications, has required complex methods to achieve the desired structure. Crumpling is an alternative to develop three-dimensional structures by randomly folding a sheet of material and offering a simple yet effective method to generate a unique, stiff and lightweight three-dimensional structure with minimal processing. Here, composite films made from polylactic acid (PLA), and exfoliated graphite (EG) were elaborated using solvent casting method. Additional pore formation is achieved adding calcium carbonate (CaCO3) particles as porogen. Films were characterized to corroborate the integration of exfoliated graphite to the PLA matrix as well as crystallinity changes due to EG and CaCO3 particles. Microscopy help to identify pore formation after CaCO3 remotion. Tensile tests, after increasing EG concentration in PLA, corroborate the formation of stiffer films with lower tensile strength, while pore formation decreased tensile strength and Young's modulus. After adding 0.5% wt. of EG, tensile strength partially recovered while Young's modulus was maintained. Composite films allowed to obtain 3D crumpled structures. Tests under compression help finding that 0.5% wt. of EG in PLA matrix resulted in a yield strength (26.6 MPa) and Young ' s modulus (32.5 MPa) increase, making necessary the application of considerable force to deform them.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).