Interphase analysis of hierarchical composites via transmission electron microscopy

Abstract

Observation and analysis of the interphase are essential for a detailed understanding of the global composite properties when nanofillers are incorporated as interfacial agents. Techniques such as atomic force microscopy and nano-indentation provide valuable information on interfacial properties associated with the viscoelastic behavior of each phase. However, when the morphology of this region is observed in detail, instrumental errors may regularly appear, decreasing the accuracy of measurements. In this work, the use of transmission electron microscopy (TEM) was explored to image the glass fiber-reinforced polymer GFRP interphase containing interfacial nanocellulose. TEM lamellas were prepared via a focused ion beam to observe the phases disposed within the composite arrangement. Energy dispersive X-ray spectroscopy was also performed to determine the elemental composition in each sample phase. Interphase sizes between 25 and 50 nm thick were found, highlighting the ability of this characterization route to give accurate interfacial measurements. This kind of measurement will open new routes for getting rich information on hierarchically structured composites containing a nanostructure as an interfacial agent.

Keywords:

• Interphase width
• microscopic techniques
• cellulose derivative
• polymer composites

Acknowledgements

The authors would like to thank Dr. Raul Arenal (Instituto de Nanosciencia de Aragón, Universidad de Zaragoza, Spain) for developing the EDS-STEM and HRTEM analysis and his scientific contribution.