Potential of all‐cellulose composites in corrugated board applications: Comparison of chemical pulp raw materials

• Published in: Packaging technology & science 2018-04, Vol.31 (4), p.173-183
• Main Authors: Tervahartiala, Tero, Hildebrandt, Nils C., Piltonen, Petteri, Schabel, Samuel, Valkama, Jukka‐Pekka
• Format: Article
• Language: English
• Subjects: All‐cellulose composite; Bend strength; Bleaching; Cellulose; corrugated board; Crush tests; Dissolution; dissolution of cellulose; Electron microscopy; Eucalyptus; Mechanical properties; Pulp & paper industry; Raw materials; Self‐reinforcing composite; Stiffness; Tensile properties
• ISSN: 0894-3214; 1099-1522
• DOI: 10.1002/pts.2365

All‐cellulose composites (ACCs) were produced using various commercially available chemical pulps by partial dissolution method using an aqueous zinc chloride (ZnCl2) solvent. Characterization methods used for defining material performance, keeping especially corrugated board products in mind, were as follows: scanning electron microscopy, tensile strength, 2‐point bending stiffness, concora medium test, and short‐span crush test. Hardwood (bleached eucalyptus), softwood (bleached spruce, bleached and unbleached pine), speciality softwood pulps (sulphite dissolving with 530 and 398 mL/g intrinsic viscosities), and annual plant pulp (bleached abaca) were investigated to give a broad overview of the potential for making ACCs. Softwood pulps, especially bleached, showed highest increase in mechanical properties across the board. Hardwood pulp showed relatively good results, and the selected annual plant pulp (abaca) responded partially negatively to treatment. Comparing unbleached and bleached softwood ACCs, it seems that bleaching is beneficial for tensile properties. However, when material comes under compressive or bending loads, unbleached pulp performs very well. Comparing sulphite dissolved pulps, it could be proven that pulps with higher intrinsic viscosities, thus higher polymerization grade, respond better to partial dissolution. It was proven that a wide set of pulps, also of lesser cellulose purity, used in the paper industry are viable for ACC production. Furthermore, results from short‐span crush test and concora medium tests show high potential of ACCs for corrugated board applications. All‐cellulose composites (ACCs) were produced using various commercially available chemical pulps by 1‐step partial dissolution method using an aqueous zinc chloride (ZnCl2) solvent. Testing methods used to characterise paper boards for corrugated board were applied with excellent results. Conventional pulps used in paper making are applicable for making ACCs and depending on pulp type can result in excellent mechanical properties.