Development and Testing of a Debond-on-Demand Polyurethane Adhesive Through Induction Heating

  • Jacob E Goodenough

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

The growing adoption of Fiber-Reinforced Polymer (FRP) materials in structural applications has brought to the forefront the pressing issue of their recycling and associated environmental impacts. Mitigating these concerns hinges on the development of ease of disassembly, repair, replacement, and recycling to enable the circular economy of FRP structures. This endeavour aligns with the broader objective of promoting sustainability and embracing the principles of a circular economy for FRP materials. This academic study is dedicated to shedding light on the intricate processes underlying the formulation and evaluation of such adhesive systems.
The research begins by developing a debond-on-demand methodology using a hot melt adhesive (HMA) as a prototype controlled by induction heating. Followed by exploring various adhesive formulations, initially considering epoxy, and polyurethane systems. The epoxy uses a disulfide-based epoxy resin, EPS 35, which initially showing promise due to its reported self-healing properties. However, challenges in achieving the desired debonding properties prompt a shift towards polyurethane formulations. The successful polyurethane adhesive formulations are modified by the introduction of various polyols with varying functionalities. An extensive rheological analysis is conducted to assess changes in viscosity upon heating and ascertain the potential for debond-on-demand behaviour. The study investigates the relationship between the choice of polyols, cross-linking density, and shear strength, ultimately identifying formulations that exhibit the desired debond-on-demand properties suitable. The chosen PU adhesive formulation, designated PU15N, serves as a baseline with a single lap shear strength of 7 MPa and a 30-minute debonded time facilitated by the developed debonding methodology of induction heating. Subsequently, the study examines the incorporation of iron oxides in various forms and weight fractions to explore their impact on debond time and adhesive properties. Alongside physical parameters including bondline thickness and finally, long term studies in water and saline solution to see if the debonding behaviour is robust and long-lasting
Date of Award19 Mar 2024
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorIan Hamerton (Supervisor) & Ian P Bond (Supervisor)

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