A modified polymer includes a diene-based polymeric chain and at least one end terminated with a blocked isocyanate group. The blocked isocyanate group may be the reaction product of an isocyanate and a blocking agent, and the blocking agent is selected, such that the modified polymer deblocks at temperatures of at least 100 C. An aqueous emulsion of the modified polymer may be provided that may be surfactant-free. The emulsion may be combined with one or more latexes to provide a treatment solution for a fabric or fiber that does not require the use of resorcinol and formaldehyde. Once treated and dried, the fabric or fiber may be used to impart tensile strength to rubber products, such as tires, air springs, flexible couplings, power transmission belts, conveyor belts, and fluid routing hoses.