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<p>Polymeric materials with various reinforcements are frequently used in radomes and enclosures to protect sensitive electronics from weather and mechanical damage. This work focuses on attenuation of radio frequency (RF) signals beyond 1&#xa0;GHz when composites have experienced long-term aging effects due to ultraviolet (UV) exposure. Glass fibre (GF) reinforced epoxy, GF-reinforced polyester and natural flax fibre-reinforced epoxy are studied. The methods are attenuation measurements using the free space method for RF attenuation, split-post dielectric resonator, and mechanical testing via flexural tests. The results indicate decreases in strength for polyester-based GF-reinforced composite and pure matrix specimens, 8.9–23%, respectively, after UV aging of 72 and 180 days, respectively. The aging increased brittleness of the composite with a decrease in the strain at peak stress by 12%. Also the epoxy-matrix composites with flax reinforcement experienced degradation, shown by 43% decrease in flexural stiffness. 18 days of UV aging led to an increase of loss tangent in pure UPE (0.0078±0.00007 versus 0.00872±0.00012).</p>

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Aging in Mechanics and Electromagnetic Properties of Polymer Composites for Signal Frequencies Beyond the Gigahertz Limit

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月21日

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  • Lahti A,
  • Asp A,
  • George L,
  • Jutila L,
  • Hentilä T,
  • Järveläinen J,
  • Hakala P,
  • Karunarathna A,
  • Di Vito D,
  • Kanerva M

摘要

Polymeric materials with various reinforcements are frequently used in radomes and enclosures to protect sensitive electronics from weather and mechanical damage. This work focuses on attenuation of radio frequency (RF) signals beyond 1 GHz when composites have experienced long-term aging effects due to ultraviolet (UV) exposure. Glass fibre (GF) reinforced epoxy, GF-reinforced polyester and natural flax fibre-reinforced epoxy are studied. The methods are attenuation measurements using the free space method for RF attenuation, split-post dielectric resonator, and mechanical testing via flexural tests. The results indicate decreases in strength for polyester-based GF-reinforced composite and pure matrix specimens, 8.9–23%, respectively, after UV aging of 72 and 180 days, respectively. The aging increased brittleness of the composite with a decrease in the strain at peak stress by 12%. Also the epoxy-matrix composites with flax reinforcement experienced degradation, shown by 43% decrease in flexural stiffness. 18 days of UV aging led to an increase of loss tangent in pure UPE (0.0078±0.00007 versus 0.00872±0.00012).