The Influence of Processing Parameters on the Process and Product Properties of Polylactic Acid/Natural Rubber Blown Films

This research investigates key parameters in the pilot-scale production of polylactic acid (PLA)/natural rubber (NR) blends for film-blowing applications. The study is aimed at analyzing the influence of process parameters including screw speed, output rate, compounding steps, and screw configuration on die stock pressure, temperature, %Torque, and retention time. The compounds were characterized for morphology, melt flow index, and film processability, whereby the resulting films were evaluated for surface appearance, transparency, and mechanical properties. It was found that the MFI value could be a good indicator of effective natural rubber dispersion, where higher screw speed and output rate contributed to slightly improved rubber dispersion due to higher shearing effects. Furthermore, an increase in the number of compounding steps and screw configurations with moderate mixing intensity led to further improved rubber dispersion. This was reflected by the reduced average rubber size from 4.1 to 1.0 μm, lower viscosity (higher MFI), smoother films, and improved mechanical properties.