Surface-modified calcium carbonate particles by admicellar polymerization to be used as filler for isotactic polypropylene

Admicellar polymerization was used to produce a thin layer of polypropylene (PP) on the surface of calcium carbonate (CaCO3) particles using sodium dodecyl sulfate (SDS) as the surfactant template and sodium persulfate (Na2S2O8) as the thermal initiator. The admicellar-treated CaCO3 particles were characterized by Fourier-transformed infrared spectroscopy (FT-IR), gravimetric analysis, and particle size analysis. FT-IR analysis suggested successful coating of atactic polypropylene (aPP) on the surface of the particles. The behavior of these coated particles in an isotactic polypropylene (iPP) matrix was compared to that of uncoated and stearic acid-coated ones. Non-isothermal crystallization studies indicated that surface treatment of CaCO3 particles reduced the ability for CaCO3 particles to nucleate the iPP matrix. Compared to composites made from the uncoated material, composites made with stearic acid-coated and admicellar-treated CaCO3 particles had lower tensile strength, Young's modulus, and flexural strength, but higher impact strength. Observation of the fractured surfaces of the composites by scanning electron microscopy (SEM) revealed an improvement in the dispersion and distribution of the CaCO3 particles within the iPP matrix as a result of the surface treatment.