Paper number 477

ENVIRONMENTAL DURABILITY OF POLYURETHANE BASED THERMOSET ADHESIVE BONDING OF A COMPOSITE TO GALVANIZED STEEL

Jonathan Verhoff¹, Ganesan Kumar¹, Karthik Ramani¹, Norman Blank², Steven Rosenberg²

1 School of Mechanical Engineering, Purdue University
West Lafayette, IN 47907-1288, USA
2Sika Corporation, 201 Polito Avenue
Lyndhurst, NJ 07071

Summary

Hot-dipped galvanized steel was bonded to fiber-reinforced unsaturated polyester (FRP) using a moisture cure urethane. Single lap shear joints were made with a 0.76 mm bond-line thickness and 25.4 mm2 bond area. Single lap shear joints were aged by cataplasma, cyclic moisture, QUV, Weather-Ometer and an oven at 60oC. Cataplasma aging and cyclic moisture aging resulted in a 23% and a 28% drop, respectively, in lap shear strength of acetone wiped samples. QUV and oven aged samples resulted in increases in lap shear strength with a change in failure mode for oven aged samples from adhesive at the galvanized steel interface to cohesive failure. Weather-Ometer aged samples failed adhesively at the FRP interface, although some adhesive could be seen on the surface via ESEM. Any accelerated aging of adhesive joints made with FRP that allow light to penetrate to the interface must carefully consider the light source used in the aging experiments.

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