Sustainable basalt fiber reinforced polyamide 6,6 composites: Effects of fiber length and fiber content on mechanical performance

The aim of this study is to explore the use of sustainable basalt fiber (BF) as compared to glass fiber and talc in injection molded engineering polyamide 6,6 (PA 6,6) plastic composite. Basalt fibers having lengths of 3 mm and 12 mm were added to PA 6,6 at 23 and 30 wt.% to fabricate the composites. The addition of basalt fiber restricts the mobility of the polymer chain in the composites, leading to its increased viscosity. Rheological results showed that the out-of-phase response to the applied stress indicated that the 3 mm basalt fiber composite could dissipate more energy, and the elastic behaviour of the composite under deformation increased with increasing basalt fiber wt.%. The fiber length had a larger effect on the mechanical properties of the composites as compared to the fiber load. The 12 mm basalt fiber composites at 23 wt.% and 30 wt.% produced higher tensile strength and modulus than the 3 mm basalt fiber composites while the 3 mm basalt fiber composite at 30 wt.% resulted in a 25 % increase in flexural strength. The experimental and the theoretical modulus predicted by the rule of mixtures showed an interaction between the matrix and the basalt fiber. Morphological analysis shows more agglomeration in composites with 3 mm fiber than the 12 mm. Glass fiber-reinforced PA 6,6 showed slightly higher performance than basalt fiber-reinforced PA 6,6. However, the basalt fiber-reinforced composites demonstrated better performance in tensile strength, flexural modulus, flexural strength, and heat deflection temperature than talc-reinforced composites.