Improving antistatic and mechanical properties of glass fiber reinforced polypropylene composites through polar adsorption and anchoring effect of organic salt

Matrix toughness and viscosity, fiber length, interface bonding, and crystalline structure play significant roles in tuning the antistatic and mechanical properties of polypropylene (PP) composites. However, there is no report available concerning the development of antistatic PP composites by considering all these factors. In this study, we fabricate antistatic long glass fiber reinforced polypropylene random copolymer composites filled with Li-TFSI (LGF/PPR/Li-TFSI) and explore how crystallization behavior due to Li-TFSI affects the interfacial strength and conductive mechanism. It is found that the polar effect promotes the adsorption of Li-TFSI on the surface of LGF to form a conductive track, and consequently, the three-dimensional conductive network formed by intertwined LGF effectively reduces the percolation threshold (i.e., 0.15 wt/wt%). Besides, the heterogeneous nucleation induced by Li-TFSI promotes the nucleation and crystal growth of PPR molecular chains on the surface of Li-TFS. Thus, Li-TFSI wrapped by spherulites improves the anchoring effect of the LGF on the PPR matrix. However, the anchorage degree is related to the close proximity of conductive particles, specifically, 0.05 wt/wt% Li-TFSI results in the highest level of stress transfer. Meanwhile, although the addition of 0.15 wt/wt% Li-TFSI causes a slight decrease in the interface strength, it leads to competitive nucleation between Li-TFSI and LGF, thereby generating thicker lamellae, which makes LGF/PPR/Li-TFSI the largest modulus. This study provides some new insights into the tailoring of material properties using Li-TFSI for antistatic PP composites.