Reinforcement of High Impact Polystyrene by Aramid Nanoparticle Fillers Prepared via an In situ Bottom-up Approach

In this work, aramid nanoparticles (ANPs) were prepared in dimethyl formamide (DMF) solution containing high impact polystyrene (HIPS) via a bottom-up approach. Transmission electron microscopy (TEM) images showed that the obtained ANPs were evenly distributed in the HIPS matrix without any agglomeration. Chemical composition of the ANPs, i.e., poly(p-phenyl-p-phenylenediamine) (PPTA), was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). The ANP/HIPS composites, obtained after ethanol precipitation, were added to neat HIPS as fillers to fabricate ANP/HIPS composite sheets. The surface roughness and the glass transition temperature (T_g) of the sheets were characterized by atomic force microscope (AFM) and differential scanning calorimetry (DSC), respectively. Compared with neat HIPS, the mechanical properties of the composite sheet were significantly improved, and the Young’s modulus increased from 246.55 MPa to 2025.12 MPa, the tensile strength increased from 3.07 MPa to 29.76 MPa, and the toughness increased from 0.32 N/mm² to 3.92 N/mm², with an increase rate of 721%, 869% and 1125%, respectively. Moreover, the thermal stability of the composites improved with the increase in ANP content.