研究目的
Investigating the effects of moisture on a polymerized monomeric reactant (PMR)-type polyimide (TriA X) and associated composites, focusing on moisture absorption behavior and long-term hydrothermal aging.
研究成果
The study demonstrated that TriA X polyimide and its composites exhibit promising stability for long-term performance in humid service conditions, with minimal permanent chemical damage and negligible changes in thermal properties after 2000-h aging. However, mechanical properties, particularly ductility and toughness, were affected by long-term moisture exposure due to hydrolysis and moisture plasticization. The findings suggest potential for long service life in hot-wet conditions, but further investigation is needed to fully understand the relationship between structural relaxations and mechanical behavior.
研究不足
The study focuses on a specific type of polyimide (TriA X) and its composites, which may limit the generalizability of the findings to other polyimide systems. The long-term hydrothermal aging was conducted at 95°C, and the effects at higher temperatures or under different environmental conditions were not investigated.
1：Experimental Design and Method Selection:
Conducted water uptake tests at various temperatures and relative humidity levels to investigate moisture absorption behavior. Long-term hydrothermal aging at 95°C was performed on neat polyimide and carbon fiber composites.
2：Sample Selection and Data Sources:
Neat polyimide panels and films were prepared by molding PMDA di-ester/p-ODA/PEPA mono-ester powder blend in a hot press. Polyimide prepreg was fabricated using an 80 wt% PMDA di-ester/p-ODA/PEPA mono-ester solution in ethanol, combined with de-sized T650-35/8HS/3K carbon fabric.
3：List of Experimental Equipment and Materials:
Digital heating controller (MC810, Electrothermal, UK), stand-alone data loggers (EL-USB-2, Lascar Electronics, UK), ATR-FTIR (Nicolet 4700, Thermo Fisher Scientific), XPS (Kratos AXIS Ultra, Kratos Analytical, UK), DMA (Q800, TA Instruments), TGA (Q5000, TA Instruments), load frame (5567, Instron), 3-D optical displacement measuring system (ARAMIS; Adjustable Base 2.3 M, GOM, Germany).
4：3 M, GOM, Germany).
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Short-term moisture uptake experiments were conducted at different temperatures and relative humidity levels. Long-term hydrothermal aging tests at 95°C were conducted to investigate the effects of moisture absorption on the properties of the neat polymer and associated composites.
5：Data Analysis Methods:
Curve fitting based on published mathematical models was used to determine the Arrhenius temperature dependence and moisture saturation as functions of temperature and humidity.
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