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pps proceeding
Symposium: Rheology & Advanced Characterization
Oral Presentation
 
 

Shrinkage in Relation to the TTT-Features of an Epoxy Adhesive

Geiss Paul Ludwig (1)*, Hohn Anita (1), Schumann Melanie (1), Götz Lukas (1)

(1) University of Kaiserslautern - Rhineland-Palatinate - Germany

In the progress of curing of a thermoset adhesive the viscosity of the resin and hardener formulation rises as the chemical reaction increases the average length and the degree of cross-linking between the constituent oligomers. Gelation occurs once a continuous 3-dimensional network of polymer chains has been created. After gelation the micro-structure of the resin is fixed and further cure is affected by diffusion limitations. Under confined conditions in an adhesive joint, shrinkage stress occurring at an early state of the curing process is likely to cause defects due to local debonding and thus negatively impair strength and durability1. Therefore mastering of the curing kinetics and the physico-chemical changes in the transition from the liquid to the solid state are essential to successfully process adhesives in demanding applications. This paper therefore will discuss different criteria and experimental methods for the kinetik and rheological analysis of the curing of a two component epoxy adhesive. DSC-measurements and results of rheological experiments are related to the features of the time-temperature-transition-diagram to pursuit the generation of shrink-induced stress under confined curing conditions.