Effect of stabilizers on the failure behavior of glass fiber reinforced polyamides for mounting and framing of solar energy applications

In the present paper, the influence of stabilizers on the fatigue crack growth (FCG) behavior of glass fiber reinforced polyamides (PA) for mounting and framing of photovoltaic modules, photovoltaic/thermal modules and other thermal collectors was investigated. A proper polymer stabilization is essential for a sophisticated substitution of commonly used materials (aluminum, stainless steel) to ensure longer product lifetimes. The implementation of polymeric materials to such applications induce the advantages of lightweight and cost-effectiveness. In total, five different glass fiber reinforced PA grades differing in their stabilizer packages were characterized. As a benchmark material, a commercial grade with a low stabilizer content was used. To establish the other four materials, this PA grade was modified with masterbatches varying in their stabilizer packages. While one masterbatch contained no stabilizer, the three remaining masterbatches comprised phenolic- and amino-based stabilizers. Tests were performed at the temperatures 80°C and 95°C in the environmental media air and water with compact type specimens. The effect of loading conditions on FCG behavior was investigated showing significantly reduced resistance with increasing temperature and a slightly lower resistance in water environment. Moreover, an influence of the used stabilizer package on the FCG kinetics was obtained. Inferior FCG resistance was determined for the PA modified with the non-stabilized masterbatch. The PA grade containing the phenolic-based stabilizer package exhibited a significantly superior FCG resistance compared to the benchmark material.