US EPA

7262605 

Journal Article 

In Situ Phase Change Characterization of PVDF Thin Films using Raman Spectroscopy 

Riosbaas, MT; Loh, KJ; O'Bryan, G; Loyola, BR; , 

2014 

Unk 

Proceedings of SPIE
ISSN: 0277-786X
EISSN: 1996-756X 

SPIE-INT SOC OPTICAL ENGINEERING 

BELLINGHAM 

Proceedings of SPIE 

9061 

10.1117/12.2045430 

WOS:000344110800025 

The development of a piezoelectric impact detection sensor is desired for aerospace, civil, and military applications. Implementation of a poly(vinylidene fluoride) (PVDF)-based architectural coating is ideal for such a purpose as it is designed to be easily deposited on complex geometries, be mechanically robust, and piezoelectric properties can be induced into the coating. In order to utilize PVDF as a sensor, the polymer must be converted from typical alpha phase to beta phase prior to electrostatic poling. This research focuses on the in situ characterization of mechanical activation of the beta phase in a non-sprayable PVDF thin film using in situ Raman spectroscopy for real time monitoring of PVDF phase content. The PVDF thin films were experimentally characterized as freestanding thin films drawn in a tensile stage, while in-situ Raman spectroscopic measurements were obtained at a wavelength of 532 nm. The Raman spectrum of each phase of PVDF is known to be unique and was correlated with the amount of alpha and beta phases in the characterized film during and after phase transition. The load and strain data from the tensile stage was associated with the in situ Raman spectra of the PVDF, thereby providing a relationship between load, strain, and beta phase content in these PVDF thin films. 

Beta phase; in situ characterization; piezoelectric; PVDF; Raman spectroscopy 

Lynch, JP; Wang, KW; Sohn, H; 

Conference on Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 

San Diego, CA