During the past decades, there has been a significant effort towards the manufacturing of sustainable polymers and polymer biocomposites. Combining synthetic plastics with natural fibers has served as the traditional approach in developing biocomposite formulations. Such composites offer the combined benefits of (i) enabling processing by mature methods already optimized for synthetic plastics, and (ii) creating materials with improved environmental footprint by integrating the natural fiber components and reducing the amount of synthetic plastic required to reach a certain performance. The biobased filler phases commonly studied as fillers in biocomposites include: (a) natural fibers, such as hemp or flax, which are hierarchical biopolymer composite structures with cross-sectional diameters larger than 10 μm, and (b) pure biopolymer fibers extracted from plant biomass, such as cellulose fibers, with much higher aspect ratios than natural fibers and diameters in the micron or nanometer range.<br/><br/>In this work, we use a mesoscale biopolymer composite structure as a natural filler for poly-lactic acid (PLA) biocomposites and study the effects of altering the morphology of the filler on the structure, mechanical and thermal properties of the produced biocomposites. In addition, we study the effects of varying the amount of algal biomass in the structure and properties of PLA. In order to alter the morphology and surface area of algae particles, we use sonication and milling methods, and characterize the resulting particles through optical and scanning electron microscopy (SEM). We then mix various amounts (1-50 wt.%) of filler, either in intact and disintegrated forms, with PLA, through melt-mixing in a twin-screw extruder. The morphology and crystallinity of the produced biocomposite films are characterized by SEM, and X-ray diffraction (XRD), respectively. The multi-scale mechanical properties of the biocomposites are studied through tensile tests (reporting Young’s modulus, ultimate tensile strength, elongation to break), which reveal the macro-scale properties, and nanoidentation (reporting reduced modulus and hardness), which probes the local properties of the biocomposites at the microscale. The thermal stability of the biocomposites is studied through thermogravimetric analysis (TGA). The measured mechanical and thermal properties are corelated to the structural and morphological observations, and structure-property relationships are drawn.

Effects of algal biomass in the structure, mechanical and thermal properties of PLA

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.