America’s First Polymer Scientists: Rubber Processing, Use and Transport in Mesoamerica

Abstract

AbstractAncient Mesoamericans were making rubber by at least 1600 B.C, mixing latex from Castilla elastica trees with juice from Ipomoea alba (morning glory) vines. The combination of ethnographic, archaeological and mechanical data presented in this text illustrate that ancient Mesoamericans had fully developed this process, and consciously tailored the mechanical properties of rubber to suit requirements of specific applications by altering the ratio of latex to I. alba juice. Our data focus on rubber balls, sandal soles, and rubber bands for hafting and joining. Elasticity, the mechanical property that defines the ability of a rubber ball to bounce, is maximized with a 1:1 volume ratio of latex to I. alba juice. Rubber with high wear resistance, vital to the life and functionality of a sandal sole, can be created by mixing C. elastica latex with 25 percent I. alba juice by volume. Unprocessed C. elastica latex, without I. alba juice, is the material best suited for joining applications, such as adhesives or hafting bands, where strength and ability to absorb shock is of the greatest importance. Tribute data from sixteenth-century codices substantiate that rubber was processed for specific applications within the Aztec empire—rubber and latex goods were processed and constructed in the C. elastica-bearing regions, and then shipped to the capital for use or further distribution.