Paper number 478

PROCESSING AND DURABILITY COMPARISON OF A POLYURETHANE THERMOSET AND A HOT-MELT THERMOPLASTIC ADHESIVE SYSTEM BONDED TO GALVANIZED STEEL

Chongchen Xu1, Jonathan Verhoff1 and Karthik Ramani1

1 School of Mechanical Engineering
Purdue University
West Lafayette, IN 47907-1288, USA

Summary A new thermoplastic bonding process, whose total cycle is less than 120 seconds, has been developed for galvanized steel (GS) to glass fiber reinforced polypropylene (GFRPP). The durability and failure modes of this thermoplastic adhesive bonded system, GS/HDPE (high density polyethylene based adhesive)/GFRPP, were compared to a thermoset adhesive bonded system, which is a GS/MCU (moisture cure urethane adhesive)/FRP (fiber reinforced polyester composite), after cataplasma and cyclic moisture aging. The solvent wipe bonded joints for both systems show the same durability in cataplasma environment, but in cyclic moisture aging the thermoplastic system retained a higher percentage of its strength than the thermoset system. The thermoset system adhesively failed at galvanized steel/adhesive both before and after aging, however the thermoplastic system failed adhesively at the PP composite/adhesive interface before aging and was partially cohesive failure after aging. Both the thermoplastic system coated with a primer on galvanized steel surface and the thermoset system treated with cleaner show reduced moisture durability compared to untreated samples.
Keywords adhesive bonding, durability, fiber reinforced, moisture cure urethane, modified high density polyethylene (HDPE), galvanized steel, single lap shear.

Theme : Joints ; Bonded joints

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