Modeling the effect of rate and geometry on peeling and tack of pressure-sensitive adhesives

• Published in: Journal of non-Newtonian fluid mechanics Vol. 233; pp. 85 - 94
• Main Authors: Mohammed, I.K., Charalambides, M.N., Kinloch, A.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2016
• Subjects: Adhesives; Cohesion; Cohesive zones; Computer simulation; Finite element; Mathematical models; Peel tests; Peeling; Polyethylenes; Pressure-sensitive adhesive; Separation; Tack; Time dependence; Viscoelastic; Cohesive zones; Tack; Pressure-sensitive adhesive; Peeling; Viscoelastic; Finite element
• ISSN: 0377-0257; 1873-2631
• DOI: 10.1016/j.jnnfm.2016.01.016

•Peel and probe-tack tests were conducted over a range of speeds and PSA thicknesses.•The PSA and the interface were modeled with a visco-hyperelastic material and a CZM.•The rate-dependent CZM parameters of σmax and Ga were measured from probe-tack tests.•There was good agreement between the experimental and numerical peel forces.•The rate-dependence in peeling was due to the CZM over the viscoelasticity of the PSA. A model is developed for predicting separation along interfaces of pressure sensitive adhesives. Many authors have used the cohesive zone approach to solve such problems but the parameter calibration of such models remains uncertain. This study reports a novel method for determining such parameters. In addition, it provides crucial evidence for the suitability of the cohesive zone model approach in modelling interface fractures. Peel tests were performed at various rates using specimens which consisted of a polyester backing membrane supporting an acrylic pressure-sensitive adhesive (PSA) adhered to a polyethylene substrate. Interfacial separation of the PSA from the polyethylene substrate was observed. Finite element (FE) peeling simulations were conducted which modeled the backing-membrane as an elasto-plastic power-law material, the adhesive as a viscoelastic material and the interfacial properties with a cohesive zone model (CZM). The material properties of the backing membrane and the pressure-sensitive adhesive were measured from tensile and stress relaxation experiments. The rate-dependent CZM parameters were measured directly from poker-chip probe-tack tests which were performed at pull-off speeds which corresponded to the rates employed for the peel tests. The effect of the PSA thickness and test rate on both tack and peel was investigated experimentally, as well as modeled numerically. Good agreement was found between the experimentally measured and numerically predicted peel forces for different peel angles, speeds and PSA thicknesses. In addition, it was proven that the rate dependence observed in the peel and probe-tack data was dominated by the rate dependence of the interface properties, i.e. the time dependence of the two CZM parameters of maximum stress and fracture energy, rather than the time-dependent bulk viscoelasticity of the PSA peel arm.