Characterization of the Polycaprolactam‐ or Polycaprolactone‐Grafted Polyurethane and the Grafting Effect on Water Vapor Permeation and Tensile Strength

Abstract Polycaprolactam or polycaprolactone was graft‐polymerized onto polyurethane ( PU ) to control the water vapor permeation and improve the tensile strength of PU . The tensile strength of the PU sharply increased with the grafting of polycaprolactam or polycaprolactone, without a decrease in the tensile strain. The soft segment melting properties did not significantly change with the increase in the lactam or lactone content. The shape recovery and shape retention of the PU series remained high after the grafting. The water vapor permeability ( WVP ) was reduced by the grafting of the polycaprolactam, whereas the WVP was increased by the grafting of polycaprolactone.