Using gelatin protein to facilitate paper thermoformability

Publication year: 2014
Authors: A. Khakalo a, I. Filpponen a, L.S. Johansson a, A. Vishtal b, A.R. Lokanathan a,O. J. Rojas a,c, J. Laine a

a - Aalto University School of Chemical Technology, Department of Forest Products Technology, Aalto, Finland
b - VTT Technical Research Centre of Finland, Jyväskylä, Finland
c - North Carolina State University, Departments of Forest Biomaterials and Chemical and Biomolecular Engineering, Raleigh, USA

Published in: Reactive & Functional Polymers, 2014
doi: 10.1016/j.reactfunctpolym.2014.09.024

One of the main challenges of fiber-based packaging materials is the relatively poor elongation of cellulose under stress, which limits formability and molding in related products. Therefore, in this investigation we first used cellulose thin films and surface sensitive tools such as quartz crystal microbalance(QCM-D), surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS) to evaluate the cellulose–gelatin interactions. It was found that the highest adsorption of gelatin onto cellulose occurred at the isoelectric pH of the protein. Based on this and other results, a gelatin loading is proposed to facilitate molecular and surface interactions and, thus to improve the formability of cellulose-based materials in paper molding. Aqueous gelatin solutions were sprayed on the surface of wet webs composed of softwood fibers and the chemical and mechanical changes that occurred were quantified. Upongelatin treatment the elongation and tensile strength of paper under unrestrained drying was increasedby 50% (from 10% to 14%) and by 30% (from 59 to 78 N m/g), respectively. The mechanical performance of gelatin-treated fibers was further improved by glutaraldehyde-assisted cross-linking. The proposed approach represents an inexpensive and facile method to improve the plasticity of fiber networks, which otherwise cannot be processed in the production of packaging materials by direct thermoforming.

MP-SPR keywords: adsorped dry mass, gelatin interaction at different pH, Langmuir-Schaefer (LS) cellulose film, layer thickness, Packaging