Improved adhesion properties of natural rubber-based pressure-sensitive adhesives by incorporating particulate fillers

Abstract

A new concept of producing natural rubber (NR) based pressure-sensitive adhesive (PSA) using solid particles relatively at a low-cost as tack enhancer has been proposed. The effect of tack enhancer (i.e., xyloglucan (XG), rice flour (RF), calcium carbonate (CaCO3), and silica (SiO2)) on the adhesion properties of the PSA was investigated. Moreover, stress relaxation, tan δ, initial plasticity (Po), and molecular weight of NR which relates to the adhesion properties were also determined. The study found that XG, RF, and SiO2 can be used as tack enhancers for NR-based PSA. The obtained PSA from those tack enhancers can adhere and peel off on a polypropylene (PP) substrate without any adhesive residue. An increase in the adhesion properties of NR-based PSA can be explained by the effect of fillers on the viscoelastic properties and molecular weight of the PSA. Stress relaxation and molecular weight of the NR-based PSA were significantly found to be decreased, while the tan δ was increased by the addition of particulate tack enhancers compared to the masticated neat NR. NR-based PSA with the highest peel strength (2.11 × 102 N/m) was successfully developed by using XG (40 phr). The NR-based PSA with XG was also showed the ability to resist the unfavorable aged hardening of the NR-based PSA in 180 days.