Effect of Testing Rate on Adhesion Properties of Acrylonitrile-Butadiene Rubber/Standard Malaysian Rubber Blend-Based Pressure-Sensitive Adhesive

The dependence of loop tack, peel strength, and shear strength of NBR/SMR L blend-based pressure-sensitive adhesives on the rate of testing was investigated using coumarone-indene resin and toluene as the tackifier and solvent, respectively. A 40% NBR content in the NBR/SMR L blend was used throughout the experiment. The adhesion properties were measured by a Lloyd Adhesion Tester operating at different rates of testing. The result indicates that loop tack, peels strength, and shear strength increase with the rate of testing due to the viscoelastic response of the adhesive. At low testing rate, the failure mode is cohesive in nature whereas adhesion failure mode occurs at higher testing rates. Adhesion properties also increase with the increase in adhesive coating thickness, an observation which is attributed to the wettability of the adhesive and viscoelastic behavior of the rubber blend. 1. Introduction Natural rubber has been commonly used to prepare pressure-sensitive adhesives. In order to increase the adhesion property of the adhesive, it is necessary to add tackifying resins such as wood resin, terpene resin, and petroleum-based resins to the rubber adhesive [1]. Besides tackifying resins, other parameters that affect the adhesion properties of rubber-based adhesives are temperature, coating thickness, molecular weight of rubber, rate of testing, and coating substrates. Recently, Rezaeian et al. [2] have reviewed the rubber adhesion to different substrates and its importance in industrial applications. Riyajan and Pheweaw [3] have studied the modification of skim rubber blended with poly(vinyl alcohol) to be applied as a biodegradable pressure-sensitive adhesive. Meanwhile, Stephen et al. [4] reported the adhesive formulations with ternary blends using simplex lattice design. Thitithammawong et al. [5] found that chlorinated epoxidized natural rubber adhesives exhibited higher shear strength compared to some commercial adhesives. Several studies on the adhesion properties of natural rubber-based adhesives have also been carried out. These include the investigation of the adhesion properties of styrene-natural rubber (SNR) adhesives [6] and adhesion properties of filled rubber adhesives [7–9]. However, with respect to adhesion properties of polymer blends, very few works were reported in the literature. Phillips et al. [10, 11] have studied the adhesive properties of polymer blends using block copolymers as the elastomers whereas Smitthipong et al. [12] reported on the self-adhesion of immiscible polyisoprene rubber-hydrogenated