Beeswax–chitosan emulsion coated paper with enhanced water vapor barrier efficiency

• Published in: Applied surface science Vol. 300; pp. 80 - 85
• Main Authors: Zhang, Weiwei, Xiao, Huining, Qian, Liying
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2014; Elsevier
• Subjects: Barriers; Beeswax; Beeswax–chitosan emulsion; Coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contact angle; Cross-disciplinary physics: materials science; rheology; Drying; Emulsions; Exact sciences and technology; Lipids; Physics; Water vapor; Waxes; WVTR; Beeswax–chitosan emulsion; Coating; Contact angle; WVTR; Water; Beeswax-chitosan emulsion
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.02.005

•The water vapor barrier efficiency of paper was enhanced via green-based emulsion coating.•Extremely high lipid content in the emulsion coating layer was firstly utilized to reduce WVTR in emulsion-based film.•A controlled WVTR of beeswax–chitosan emulsion coating could be obtained by dying at specific temperature. For lipid–hydrocolloid emulsion based film, the increase of lipid amount would improve its water vapor barrier property, but also reduce the mechanical strength of the film in the meantime thus leading to a compromised lipid content in the film. However, when the emulsion is coated on paper surface, more lipid could be used for emulsion preparation to enhance the moisture resistance without considering the weakened strength of the film induced by lipid, because the mechanical properties of emulsion coated paper is mainly governed by the strength of base paper instead of the coating layer. In this study, beeswax–chitosan emulsion was first prepared and then coated on paper surface to improve paper's water vapor barrier and water resistance properties. The range and variance analysis of orthogonal test design showed that the order of priorities of the factors accordingly was beeswax solid content, drying temperature and chitosan concentration. The effect of drying temperature on water vapor transmission rate (WVTR) and water contact angle of coated paper was further investigated using 1.2wt% chitosan and 96% beeswax solid content in the coating layer. The results indicated that water vapor barrier property was in accordance with the density of the coating layer. Atomic force microscope (AFM) was also used to characterize the surface morphology and explain the hydrophobicity of beeswax–chitosan coated paper. It was found that surface beeswax particles melted to wrinkle at high drying temperatures, while roughness values maintained at micro-scale over the temperature range investigated.