CNCs extraction from single-use cups: effects of grafting it onto MMA monomer

BACKGROUND: The difficulty of separating fiber from polyolefin coatings of single-use plastic (SUP) cups for cold (carbonated) or hot (coffee) drinks, has led us to investigate a recycling method to obtain new high-performance materials. The present work relates to valorization of ICEE S.A. de C.V. cups into crystalline nanocellulose (CNC), while studying the effects on the structural, thermal, morphological and particle size properties in dependence of the acid hydrolysis concentration (40 and 64% v/v) employing sulfuric acid to remove amorphous cellulose. RESULTS: On the basis of results, optimal CNC was found at 64% v/v concentration obtaining ribbon-like morphologies rich in cellulose types Iα (27%) and II (45.1%) of triclinic and monoclinic structures, respectively, high crystallinity percentage (91%) and nanosize scale (26.70 nm). CNC was successfully grafted through the C₂ in cellulose onto the methyl methacrylate (MMA) monomer to obtain PMMA-g-CNC, considering different concentrations (5, 10, 20 and 30 wt%) of CNC. A reduction of crystallinity % was found when CNC is grafted onto MMA owing to the amorphous nature of the poly(methyl methacrylate) (PMMA). However, this is not a limitation. CONCLUSIONS: PMMA-g-CNC samples displayed high thermal stability (345 °C) and nanometric scale (165–260 nm), which have potential to be studied as reinforcement agents for incompatible polymers such as PMMA and poly(urethane) (PU) through Interpenetrating Polymer Networks. Preliminary mechanical studies indicated that PMMA-g-CNC systems are able to reinforce the tensile properties becoming the PMMA/PU into ductile materials. Specially, the MMA₉₀CNC₁₀ system improved the strain four-fold compared to the pure PMMA/PU IPN.