Sustainable route toward processing of polylactic acid/sawdust-based cellulose composites via grafting: energy consumption during extrusion

Lignocellulosic materials derived from by-products such as cellulose typically provide enhanced interfacial properties when functionalized with coupling agents, such as maleic anhydride (MA), and incorporated into polylactic acid (PLA) polymers. This research aims to identify the optimal conditions for either improving or maintaining PLA properties evaluating interactions by incorporating varying amounts of cellulose (5–28 wt%) extracted from sawdust biomass and PLA-g-MA (3–20 wt%) composites into pure PLA. This is accomplished through an extreme vertices mixture design (EVMD). Structural studies reveal that the carbonyl (C=O) is the primary chemical modification in PLA, which enhances its semi-crystalline structure. The mechanical properties indicate an increase in hardness and Young's modulus upon the addition of cellulose to MA grafted PLA, while the tensile strength remains unchanged in the optimal PLA/PLA-g-MA/Cellulose (with a ratio of 76/9/15). Importantly, the addition of the cellulose to the PLA does not compromise its properties, unlike other similar systems that exhibit poor mechanical performance when cellulose fibers are added. This research opens up avenues for valorizing common waste materials found worldwide. The specific energy consumption of the optimal composite is 1.68 kWh/kg, which shows a slight increase compared to pure PLA (1.11 kWh/kg). However, it is still 5.6 % lower than that of low-density polyethylene (1.78 kWh/kg), a common polymer used in the packaging industry. The optimal sample provides good processability and is suitable for producing biodegradable products for the packaging industry, such as plastic plates that can be safely used in food-to-go applications.<p></p>