Method for Locally Measuring Strength of a Polymer-Inorganic Interface During Cure and Aging

A nondestructive test system is under development for thorough, rapid and economical evaluation of the structure and properties of polymer-inorganic interfaces during curing and in service. The system is capable of in-situ, real-time and spatially resolved monitoring of the molecular structure and properties. It employs (single-sided) NMR relaxometry principles to detect and quantify defects and damage/degradation conditions of interfaces and also bulk polymers. Our team has so far identified viable system design and operation variables, devised data analysis and interpretation procedures, and verified some key system capabilities in application to adhesively bonded joints. These capabilities include: (i) real-time monitoring of the interface (and bulk polymer) structure and properties during curing at room and elevated temperatures; (ii) evaluation of the surface treatment effects on the polymer structure at and near the interface; (iii) monitoring of polymer-inorganic interfaces subjected to different accelerated aging effects; (iv) versatility for monitoring the interfaces formed  by different polymers on non-conductive and conductive surfaces; and (v) generating nondestructive test data that are supported by the outcomes of (generally destructive) bond strength, FTIR, DSC and surface energy test methods. The proposed Sequential Phase II effort will improve and expand upon these capabilities towards development of a robust nondestructive test system that meets key market requirements. For this purpose, the proposed effort will: (i) ascertain the primary Army, broader military and industrial applications of the technology, and identify relevant materials, components, performance requirements and constraints; (ii) develop models and procedures for nondestructive condition assessment and damage detection at polymer-inorganic interfaces; (iii) optimize the single-sided NMR system for field applications that address the Army, broader military and industrial needs; (iv) deploy and evaluate the system at sites involved in manufacturing and maintenance of assets with adhesively bonded structural joints and protective coatings; and (v) assess the value of the nondestructive test system towards improving the safety, reliability, and initial and life-cycle economy of military and civilian assets.