From Event: SPIE Optics + Photonics for Sustainable Energy, 2015
The channel crack and delamination phenomena that occurred during tensile tests were utilized to study surface cracking
and delamination properties of a multilayered backsheet. A model sample of commercial PPE (polyethylene
terephthalate (PET)/PET/ethylene vinyl acetate (EVA)) backsheet was studied. Fragmentation testing was performed
after accelerated aging with and without ultraviolet (UV) irradiation in two relative humidity (RH) levels (5 % RH and
60 % RH) at elevated temperature (85 °C) conditions for 11 days and 22 days. Results suggest that the embrittled surface
layer resulting from the UV photo-degradation is responsible for surface cracking when the strain applied on the sample
is far below the yielding strain (2.2 %) of the PPE sample. There was no surface cracking observed on the un-aged
sample and samples aged without UV irradiation. According to the fragmentation testing results, the calculated fracture
toughness (KIC) values of the embrittled surface layer are as low as 0.027 MPa·m1/2 to 0.104 MPa·m1/2, depending on the
humidity levels and aging times. Surface analysis using attenuated total reflectance Fourier transform infrared and
atomic force microscopy shows the degradation mechanism of the embrittled surface layer is a combination of the photodegradation
within a certain degradation depth and the moisture erosion effect depending on the moisture levels.
Specifically, UV irradiation provides a chemical degradation effect while moisture plays a synergistic effect on surface
erosion, which influences surface roughness after aging. Finally, there was no delamination observed during tensile
testing in this study, suggesting the surface cracking problem is more significant than the delamination for the PPE
backsheet material and conditions tested here.
Chiao-Chi Lin, Yadong Lyu, Donald L. Hunston, Jae Hyun Kim, Kai-Tak Wan, Deborah L. Stanley, and Xiaohong Gu, "Cracking and delamination behaviors of photovoltaic backsheet after accelerated laboratory weathering," Proc. SPIE 9563, Reliability of Photovoltaic Cells, Modules, Components, and Systems VIII, 956304 (Presented at SPIE Optics + Photonics for Sustainable Energy: August 09, 2015; Published: 23 September 2015); https://doi.org/10.1117/12.2188557.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the proceedings. They include the speaker's narration with video of the slides and animations. Most include full-text papers. Interactive, searchable transcripts and closed captioning are now available for most presentations.
Search our growing collection of more than 29,500 conference presentations, including many plenaries and keynotes.