An Edge-Filtered Optical Fiber Interrogator for Thermoplastic Polymer Analysis.

Area of Science:

• Materials Science
• Polymer Science
• Optical Engineering

Background:

• Traditional thermal analysis of polymers relies on expensive and impractical laboratory equipment like differential scanning calorimetry (DSC) and thermomechanical analysis (TMA).
• There is a need for cost-effective and field-deployable methods for characterizing thermoplastic polymers.

Purpose of the Study:

• To present an alternative method for determining thermodynamic quantities of thermoplastic polymers using an optical fiber interrogator.
• To demonstrate the capability of this method for analyzing both amorphous and semi-crystalline polymers.

Main Methods:

• Utilizing an edge-filter-based optical fiber interrogator to detect boundary reflection intensities from a standard optical fiber.
• Applying Fresnel equations to measure the temperature-dependent refractive index of thermoplastic polymers.
• Deriving thermal properties such as glass transition temperature, coefficient of thermal expansion, melting temperature, and crystallization temperature.

Main Results:

• Successfully measured the temperature-dependent refractive index of thermoplastic polymers.
• Derived key thermal properties for amorphous polymers like polyetherimide (PEI) and polyethersulfone (PES), serving as alternatives to DSC and TMA.
• Detected melting and crystallization temperatures for the semi-crystalline polymer polyether ether ketone (PEEK) without requiring a crystal structure analysis.

Conclusions:

• An optical fiber interrogator provides a flexible, low-cost, and multipurpose device for thermal analysis of thermoplastic polymers.
• This method offers a viable alternative to conventional laboratory techniques, enabling field applications.
• The technique is applicable to a range of thermoplastic polymers, including amorphous and semi-crystalline types.