Even with the hype and promise of nano-materials relatively little attention has been placed on new process control techniques of key physiochemical changes that occur during processing nanocomposites.
Complexity, practicality, and tradition have limited many conventional approaches to simple environmental control protocols such as staged environmental conditions (temperature, pressure, mass flow) based on laborious and time-consuming tests and offline validation.
This works for common material systems, but for advanced materials where critical properties depend on the finite structure and the synergistic effects of matrix and nanofiller interfaces, this approach is complicated, inefficient and unproductive.
The Air Force has been working on this issue and previously developed and disclosed (provisional application 61/353,704) “Online impedance spectroscopy of thermoset nanocomposites for material in situ process control” – a computer automated processing system with both integrated impedance spectroscopy sensing and electric field directed morphology.
This system is the first to successfully incorporate multi-sensor impedance spectroscopy as an online characterization component in a comprehensive computer automated system for processing nano-clay/epoxy thermosets in a controlled and repeatable process. The related invention described in this summary provides two very critical components of any such processing system – the sample mold and sensor cells for holding and instrumenting materials being processed.
These additional components address the common problem of sample deformation during curing of thermal expansion by adding a vented cavity behind the electrodes. They also address the problem of air entrapment and bubble formation in a sample by providing a channel for injecting the sample from top to bottom.
- The injection mold and sensor cell is designed for low-viscosity materials where the pre-cure suspension can be injected using a syringe
- The compression mold and sensor cell was developed for higher viscosity materials where direct injection is not possible
- Provides a robust means for acquiring repeatable impedance measurements
- US patent 8,763,479 available for license