Bacterial nanocellulose enhanced cardboard adhesion joint tested with Y-peel and T-peel testing methods

The demands on the adhesive joints for packaging are important during conversion, transport, storage, shelf exposure, and end-of-life operations of paper-based packaging. During this lifecycle, the adhesive joint is under constant loading from environmental conditions (e.g. forces from the surroundings such as other packaging units, dynamical forces from the machines, and/or climate changes such as temperature and relative humidity). The contribution from mechanical bonding can be particularly important for solid boards where the adhesive bonding is achieved through the mechanical interlocking of the adhesive into irregularities and pores of the carton-board surface. The formation of an adhesive joint with dispersion adhesives is affected by the rheological properties of the adhesive layer, the structure and absorption properties of the board surface. There are many test methods intended to determine the strength of an adhesive including peel, shear, cleavage and tension tests. Peel tests are common for tapes, labels, coatings and other bonded materials. The most common methods include T peel, Y peel and angle peel tests using tensile test machines. The cardboard adhesives that are currently in use have a large share of dispersion adhesives (PVAC, EVA, acrylic and PU) which are water-based adhesive systems that form bonds through physical hardening when the water evaporates. Sustainability issues require replacement of these chemicals with bio-based ones. Based on our previous research, bacterial nanocellulose (BNC) can increase the bonding strength of adhesive joints for different kinds of materials. In this study, 3 different cardboards with dispersion adhesive which had the addition of 7% of BNC were used. Zwick multitester with two methods (Y peel and T peel) was used to determine the strength of the cardboard joints. The results indicate differences in force elongation results due to different testing methods, where some of the cardboard properties and BNC had a positive effect on the overall adhesion joint strength.