Emulsion polymerized styrene acrylic/nanocellulose composite coating to improve the strength and hydrophobicity of kraft paper

• Published in: Progress in organic coatings Vol. 182; p. 107634
• Main Authors: Shankar, Abhay, A.K., Abdul Malik, Narayan, Ramanuj, Chakrabarty, Arindam
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2023
• Subjects: Cellulose nanofiber; Mini-emulsion polymerization; Nanocomposite latex; Paper coating; Nanocomposite latex; Mini-emulsion polymerization; Cellulose nanofiber; Paper coating
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2023.107634

Improving the mechanical and water repelling property of kraft paper will extend its use for packaging application. In this work, we developed a cellulose nanofiber (CNF)-based colloidal polymer nanocomposite that was used as coating for improving those properties of kraft paper. In this case, the polymer latex was obtained by the mini-emulsion copolymerization of styrene (St), 2-ethyl hexyl acrylate (EHA) initiated by ammonium persulfate. The CNFs were incorporated into the styrene-acrylic copolymer matrix by the in-situ polymerization and ex-situ mixing process keeping the CNF concentration up to 1.0 wt%. All the latexes showed particle size below 100 nm and excellent colloidal stability (Zeta potential > −32 mV) for several months. The nanocomposite films showed improved mechanical properties (tensile strength upto 7.8 MPa, elongation upto 1096 %) than the pristine copolymer. The in-situ prepared nanocomposite at 1.0 wt% CNF showed the highest storage modulus. The latex-coated kraft paper showed improved tensile index (31.0–45.1 Nm/g) compared to the uncoated paper (20.3 Nm/g) and also high hydrophobicity (water contact angle ∼120°) for the ex-situ prepared nanocomposites. The results are quite promising to develop paper-based packaging materials using nanocellulose in combination with synthetic polymers. •Colloidal nanocomposite of styrene acrylic copolymer/nanocellulose was synthesized.•Nanocellulose was incorporated by in-situ polymerization and ex-situ mixing process.•Nanocomposite films had improved mechanical strength.•The dip-coated kraft papers showed improved tensile index and hydrophobicity.