Mechanical properties of biodegradable composites from poly lactic acid (PLA) and microcrystalline cellulose (MCC)

TLDR

PLA is a lactic acid polyester and MCC is cellulose derived from high‑quality wood pulp via acid hydrolysis. The study aims to enhance composite performance by dispersing cellulose aggregates into microfibrils and improving adhesion. Composites were fabricated with MCC up to 25 wt % in a PLA matrix, using wood flour and wood pulp as references. MCC/PLA composites exhibited lower mechanical strength than wood‑based references, though MCC addition raised storage modulus; XRD revealed lower crystallinity, SEM showed MCC aggregates and poor matrix adhesion, and WF composites degraded faster than WP and MCC composites. © 2005 Wiley Periodicals, Inc., J Appl Polym Sci 97: 2014–2025.

Abstract

Abstract Biodegradable composites were prepared using microcrystalline cellulose (MCC) as the reinforcement and polylactic acid (PLA) as a matrix. PLA is polyester of lactic acid and MCC is cellulose derived from high quality wood pulp by acid hydrolysis to remove the amorphous regions. The composites were prepared with different MCC contents, up to 25 wt %, and wood flour (WF) and wood pulp (WP) were used as reference materials. Generally, the MCC/PLA composites showed lower mechanical properties compared to the reference materials. The dynamic mechanical thermal analysis (DMTA) showed that the storage modulus was increased with the addition of MCC. The X‐ray diffraction (XRD) studies on the materials showed that the composites were less crystalline than the pure components. However, the scanning electron microscopy (SEM) study of materials showed that the MCC was remaining as aggregates of crystalline cellulose fibrils, which explains the poor mechanical properties. Furthermore, the fracture surfaces of MCC composites were indicative of poor adhesion between MCC and the PLA matrix. Biodegradation studies in compost soil at 58°C showed that WF composites have better biodegradability compared to WP and MCC composites. The composite performances are expected to improve by separation of the cellulose aggregates to microfibrils and with improved adhesion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2014–2025, 2005