Eco-friendly surface hydrophobization of all-cellulose composites using layer-by-layer deposition

O. Korhonen, N. Forsman, M. Österberg, T. Budtova*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

All-cellulose composites were prepared by dispersing kraft fibers in a matrix made from pulp dissolved in NaOH-water. To hydrophobize the composite surface while maintaining the material fully bio-based and biodegradable, layer-by-layer deposition of cationic starch and carnauba wax was performed. Various options of surface coating, drying, and curing were tested, including partial and complete melting of the wax. The composite surface was characterized by water contact angle, roughness and scanning electron microscopy, and material properties by adsorption and absorption of water (in vapor and liquid form) and tensile testing. The highest water contact angle was obtained when the layer-by-layer deposition was performed by dipping the dry composite into cationic starch solution, then in wax dispersion, and partially melting the wax after coating. However, it was demonstrated that the dipping approach was detrimental to material tensile properties, due to heterogeneous swelling of cellulose during the treatment and multiple drying sequences. Process optimization via spraying resulted in composites with Young's modulus of 6 GPa and hydrophobic surface with water contact angle 122 degrees C.

Original languageEnglish
Pages (from-to)896-907
Number of pages12
JournalExpress Polymer Letters
Volume14
Issue number10
DOIs
Publication statusPublished - Oct 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • Biocomposites
  • Biopolymers
  • Carnauba wax
  • Cellulose
  • Hydrophobization
  • Tensile properties

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