Swelling of glass-fiber reinforced polyamide 66 during conditioning in water, ethylene glycol, and antifreeze mixture

• Published in: Polymer composites 2011-04, Vol.32 (4), p.639-647
• Main Authors: Thomason, James L., Porteus, Glen
• Format: Article
• Language: English
• Subjects: Antifreezes; Applied sciences; Composites; Conditioning; Ethylene glycol; Exact sciences and technology; Forms of application and semi-finished materials; Glass fiber reinforced plastics; Polyamide resins; Polymer industry, paints, wood; Polymer matrix composites; Swelling; Technology of polymers
• ISSN: 0272-8397; 1548-0569
• DOI: 10.1002/pc.21054

The weight and dimensional changes of injection‐molded glass‐fiber reinforced polyamide 66 composites based on two glass fiber products with different sizing formulations and unreinforced polymer samples have been characterized during conditioning in water, ethylene glycol, and a water‐glycol mixture at 50°C and 70°C for a range of times up to 900 h. The results reveal that hydrothermal ageing in these fluids causes significant changes in the weight and dimensions of these materials. All conditioned materials showed a time dependent weight and dimension increase. The change observed in water could be well modeled by a simple Fickian diffusion process; however, the absorption process followed a more complex pattern in the other conditioning fluids. It was not apparent that changing the glass fiber sizing affected the dimensional stability of the composites under these relatively mild conditions. There was a strong correlation between the swelling of these samples and the level of fluid absorption. The composites exhibited highly aniosotropic levels of swelling. These effects were well in line with the influence of fibers on restriction of the matrix deformation in the fiber direction. The polymer and composite swelling coefficients correlated well with data previously obtained at higher conditioning temperatures. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers