Polymeric coupling agents for enhancing the adhesion of epoxy to steel

Date of Completion

January 1997


Chemistry, Polymer|Engineering, Materials Science|Plastics Technology




The work described in this dissertation involves the conceptualization, design, development and testing of new polymers for their efficiency as coupling agents to enhance the bonding of steel to epoxy. Two novel series of polymeric coupling agents have been tested viz., a quinone-amine polyurethane (QAP) series and a $\beta$-diketone functionalized polymer (BFP) series.^ Several QAP and BFP polymers were synthesized and studied. These polymers were characterized using Infrared spectroscopy, thermal analyses (Thermogravimetric Analysis, Differential Scanning Calorimetry) and Gel Permeation Chromatography.^ The surfaces of QAP and BFP polymeric coupling agent treated steel coupons were analyzed using Infrared Reflection Spectroscopy, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy. These tests gave indications that the QAPs and BFPs interact with the steel surface chemically.^ The QAPs and BFPs were found to be very effective coupling agents for the steel-epoxy system. The coupling agent treated epoxy-steel torsional joints were tested (in dry and wet environments) in shear. The QAPs were compared with commercial silanes and demonstrated a 10-15% better strength retention and hot water durability.^ The QAP treated and epoxy resin topcoated steel coupons demonstrated excellent corrosion resistance when tested in a lab-scale salt-spray chamber.^ The process conditions (in the coupling agent based polymer coating process for steel described in this dissertation) are mild and process control is relatively simple. This organic coating process is more environmentally friendly than other conventionally used toxic processes for steel like Chrome Etching. ^