Antistatic ability of 1-n-tetradecyl-3-methylimidazolium bromide and its effects on the structure and properties of polypropylene

In this study, 1-n-tetradecyl-3-methylimidazolium bromide (C₁₄mim]Br), one kind of imidazolium ionic liquid (imi-IL), was incorporated into polypropylene (PP) via melt blending. The measurement of surface resistance (R_s) and volume resistance (R_v) of neat PP and PP/C₁₄mim]Br blends indicated that C₁₄mim]Br had excellent antistatic properties. The PP/C₁₄mim]Br blend had the best antistatic ability, when the weight ratio of C₁₄mim]Br to PP reached 3/100. The surface resistance of PP/C₁₄mim]Br decreased from the 7.67 × 10¹³ to 1.40 × 10⁷ Ω whereas the volume resistance of PP decreased from 2.67 × 10¹⁴ to 2.60 × 10⁷ Ω. Semicrystalline morphology and crystal structure were investigated by polarized optical microscopy (POM) and X-ray diffraction (XRD). The spherulites of PP became smaller with the addition of C₁₄mim]Br, implying that C₁₄mim]Br had a nucleating effect in the PP matrix. The XRD study indicates the crystallization process of PP was affected by C₁₄mim]Br, and the crystallinity of PP was thus decreased. Scanning electron microscopy (SEM) studies reveal that C₁₄mim]Br had good dispersion in PP; thermogravimetric analysis (TGA) shows the addition of C₁₄mim]Br remarkably increased the thermal stability of PP even though it is a small molecule.