The concept of weak algebraic hyperstructures or Hv-structures constitutes a generalization of the well-known algebraic hyperstructures (semihypergroup, hypergroup and so on). The overall aim of this paper is to present an introduction to some of the results, methods and ideas about chemical examples of weak algebraic hyperstructures. In this paper after an introduction of basic definitions and...

polyurethanes (purs) are polymers that can be generated by a step-growth polyadditionreaction of diisocyanates with polyols. the number of well-developed chemical procedures applicable to theirmanufacture, and the diversity of chemical structures in which polyurethanes can be built, account for thewidespread use of these materials in the last few decades for both domestic and technical applicat...