a pressure sensitive adhesive composition particularly suitable for use as a protective skin barrier material for sealing the faceplate of an ostomy appliance , such as the faceplate of a one - piece or two - piece urostomy or an ileostomy appliance , to skin surfaces surrounding a patient &# 39 ; s stoma . the composition includes a blend of two viscoelastic adhesive elastomers , specifically , high molecular weight polyisobutylene and a styrene block copolymer , which , along with a plasticizer and a suitable tackifier and antioxidant , form a continuous phase in which hydrocolloids such as sodium carboxymethylcellulose and pectin are dispersed . the composition is exceptional for its durability , flexibility and strength , even when saturated , and for its controlled swelling upon hydration .