Upcycling of Waste Paper into Thermoplastics via Mechanochemical Esterification

Paper products serve indispensable functions in our daily life, but most of them are discarded after a single use, which raises potential environmental concerns and causes irreversible loss of cellulose resources. Herein, a feasible strategy was developed to efficiently recycle waste paper into high-value thermoplastic materials. Initially, waste paper was converted into waste paper-based thermoplastics (WPBT) with melting flow temperatures of 128–174 °C via mechanochemical esterification. Notably, the WPBT obtained from waste tissue paper showed high flexibility (elongation at break = 72.1%) and transparency (transmittance at 600 nm = 91.3%). Furthermore, unmodified waste paper (powder or sheet) was used to enhance the mechanical properties of WPBT by fabricating paper-based plastics (PBP) and paper-based laminates (PBL). In brief, blending WPBT with 30 wt % tissue paper powder via melt blending yielded a PBP with a tensile strength of 15.3 MPa. Similarly, by impregnating waste office paper sheets with WPBT/ethanol suspension, a PBL with a tensile strength of 48.3 MPa was prepared after stacking and hot pressing. This work provides a green route for recycling waste paper into sustainable thermoplastics with favorable performance, offering opportunities for agricultural plastics and industrial packaging materials.