Multimodal Non-Destructive In Situ Observation of Crystallinity Changes in High-Density Polyethylene Samples with...

Area of Science:

• Materials Science
• Optics
• Spectroscopy

Background:

• Non-destructive optical testing methods are crucial for material research, providing diverse material parameter information.
• RECENDT developed a multimodal experimental setup integrating terahertz (THz) spectroscopy, optical coherence tomography (OCT), infrared (IR), and Raman spectroscopy.
• This setup is coupled with a tensile test stage for in-situ material analysis.

Purpose of the Study:

• To gather material information, specifically crystallinity and optical parameters, of high-density polyethylene (HDPE) during tensile testing.
• To compare the effectiveness of common IR and Raman spectroscopy with less common THz and OCT methods.
• To establish correlations between optical parameters and changes in material crystallinity.

Main Methods:

• Utilized a multimodal experimental setup combining THz spectroscopy, OCT, IR spectroscopy, and Raman spectroscopy.
• Performed tensile testing on HDPE samples with varying crystallinity.
• Analyzed optical parameters including refractive index, birefringence, scattering coefficient of decay, and penetration depth.

Main Results:

• Demonstrated complementarity between different optical methods (THz, OCT, IR, Raman) due to their distinct frequency ranges and measurement approaches.
• Successfully correlated determined optical parameters with observed changes in HDPE crystallinity during tensile testing.
• Showcased the interconnectedness of various optical methods and their derived material parameters.

Conclusions:

• The multimodal optical setup effectively characterizes material properties like crystallinity and optical parameters during mechanical stress.
• Future optimization could enable observation of fiber alignment in composites and stress distribution in polymers.
• This research opens avenues for advanced polymer characterization, including quality control and material testing.