Pressure-sensitive adhesives (PSAs) are materials that display a high level permanent tack at room temperature and can be applied with very light pressure.
The PSAs are used as tapes and labels for electronic circuits and automotive parts, as well as medical products and more.
One distinct application of PSAs is temporary protection of surfaces for products based on plastics sheets, metals, carpets and glasses. For this purpose, special type of PSAs are needed like Removable Pressure-Sensitive Adhesives (R-PSAs).
Two types of R-PSAs, based on two-phase semi-crystalline system, were studied using cast co-extrusion technology:
1) Olefin-Block Copolymer (OBC) and a midblock-associating resin
2) Amorphous a-olefin copolymer (APO) and a midblock-associating resin.
In comparison with Styrenic-based systems these systems are environmentally friendly thermally stable.
The R-PSAs were characterized by Parallel Plate Rheometer (PPR) in different modes: Stress sweep, frequency sweep and temperature sweep. The experimental PPR results and the effects of thermal history on the viscoelastic properties of the R-PSAs were analyzed in view of theoretical criteria and models for PSAs. It was found that the models did not always agree with the experimental results of the studied R-PSAs.
Only a few investigations dealt with order-disorder transitions of two- phase amorphous systems (SIS, SBS. etc.) demonstrating the effect of annealing on the structure, viscoelasticity and mechanical properties.
In this study, the order-disorder transitions of two- phase semi-crystalline systems was characterized and investigated.
