Synthesis of ß-strontium hydrogen phosphate nanosheets and its effect on thermal and tribo-mechanical properties of polypropylene composites

ß-strontium hydrogen phosphate (SHP) nanosheets with a thickness range of 35-50 nm were synthesized by the hydrothermal method using strontium nitrate (Sr(NO₃)₂) and diammonium hydrogen phosphate ((NH₄)₂HPO₄) as reagents. Polypropylene (PP)/SHP nanocomposites were prepared using a melt blending technique with different filler concentrations ranging from 1 wt.% to 7 wt.%. Composites were characterized primarily by tensile test, flexural test, thermogravimetric analyses, and ball-on-disc sliding wear test. Experimental results revealed that the inclusion of nanosheets into PP improved the thermal stability of the composites. In addition, the tensile and flexural properties of the composites improved with SHP loading. A maximum increment of 6.0% in tensile strength compared to pure PP was observed at 7 wt.% SHP concentration, and the flexural strength of the composites was found to be higher than that of the pure polymer at each filler concentration. However, an increase was observed in the friction coefficient and wear rates of the composites due to increased hardness and rigidity of the matrix with the addition of SHP, which produced micro-cutting and micro-plowing actions that caused increased abrasive wear of the composites.