ABSTRACT
Natural rubber was the first base polymer for early pressure-sensitive adhesives (PSAs) intended for medical plasters. The rubber-based PSA can be considered an innovative material because industrial and academic interest is under continuing development. Rubber-based adhesives are probably the most commonly known family of adhesives on the general market. Thermoplastic block copolymers were used for rubber-based PSA and rubber-based hot-melt adhesives from the mid 1960s. Rubber-based PSAs typically contain an elastomer and a tackifying or modifying resin as the key components, but other ingredients are also included. Rubber is composed of very large molecules containing thousands of atoms, arranged one after another in a string-like manner. Viscosity, loop tack, and peel strength of epoxidized natural rubber-based PSAs was studied in the presence of 10–50 phr zinc oxide. Plasticizers reduce hardness, enhance tack, and reduce cost in rubber-based adhesives formulations. Raw rubber is an entanglement of high-molecular-weight hydrocarbon chains.
