Preparation and Properties of Heat Resistant Polylactic Acid (PLA)/Nano-SiO2 Composite Filament

In order to improve the thermal properties of polylactic acid (PLA) filament, nano-SiO2 was applied to mix with PLA, then they were spun as composite filament by melt-spinning. The dispersion of nano-SiO2 and the fracture surfaces of filaments were studied by scanning electron microscopy (SEM). The properties of composite filament, such as orientation degree, mechanical properties, and surface friction properties, were analyzed. The thermal performances of composite filament were analyzed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The results showed that the nano-SiO2 modified by 5% KH-550 could disperse evenly and loosely in nano-scale, and 1 wt% and 3 wt% nano-SiO2 dispersed throughout PLA evenly. As the quantity of nano-SiO2 increased, the properties of composite filament, such as orientation degree, friction coefficient, thermal decomposition temperature, and glass transition temperature, increased more or less. The breaking tenacity increased when 1 wt% SiO2 was added in PLA, but declined when 3 wt% SiO2 was added.