The effect of surface morphology on the peel performance of UV-induced adhesion-reducing adhesives

In this paper, end-hydroxy fumaryl chloride-diol copolyesters (EHFDCP) with different double bond contents were prepared by the reaction of fumaryl chloride and diols. The molecular weight of the target hydroxy polyesters was controlled to be essentially the same, EHFDCP prepared from 1,8-octanediol, 1,5-pentanediol and ethylene glycol named EHFDCP-1, EHFDCP-2 and EHFDCP-3, respectively. The UV-induced adhesion-reducing adhesives (ARA) were prepared with EHFDCP, isophorone diisocyanate (IPDI), chain extender and photoinitiator. The ARA-1, ARA-2 and ARA-3 were produced by EHFDCP-1, EHFDCP-2 and EHFDCP-3, respectively. After UV curing, all the surfaces of ARA-1, ARA-2, and ARA-3 had a high number of concave and convex areas, which helped to reduce the contact area between the adhesive and the substrate surface. The surface roughness of ARA-2 is the highest and the adhesion reduction effect is the most significant. The higher surface roughness of ARA-2 came from moderate double bond content and crosslinking density. With the increasing photoinitiator content, the 180° peel strength after UV curing decreased. The 180° peel strength of ARA-2 was reduced to 0.16 N/25 mm at 4 wt% of photoinitiator content, and it also had a high initial 180° peel strength of 18.55 N/25 mm due to the absence of small molecule polyfunctional monomers.