Investigation of the Mechanical Properties of aPressure-sensitive adhesivePart 2 Investigation of the Effect of Polydispersity Index（PDI） onMechanical Properties of Acrylic Polymers

Abstract

Effect of molecular weight and the molecular weight distribution（ polydispersity index；PDI） of butylacrylate - acrylic acid copolymer as main component of pressure sensitive adhesives（ PSAs） on the gelformation and the mechanical properties were studied. The copolymer was lightly crosslinked and the extentwas varied. The PDI showed considerable effect on both the initiation of gel formation using low concentrationof the crosslinking agent（ 4-functional epoxy） and the apparent saturation of the gel fraction with increasingthe crosslinking agent. Also, the PDI contributed greatly to the change of creep compliance（ time dependencyof deformation）. In general, creep compliance relates to flow or deformation of PSAs after pasting, whichaffects to the adhesive strength and tack with changing contact time. Therefore, creep compliance and theretardation spectra would be the powerful tools to analyze mechanical and adhesive properties of PSAs.