Optimization of injection parameters to obtain selected properties on foamed PP with hollow glass microspheres and thermally expandable microspheres using Taguchi method

A foaming system composed by hollow glass microspheres (HGM) and thermally expandable microspheres (EM) was used to achieve a balance between selected properties of foamed polypropylene (PP) by injection molding, combining the higher flexural properties and lower density required on automotive interior parts. Taguchi’s L16 (44.23) was employed for the experimental plan and signal to noise ratio (S/N) for the optimization of the system raised. The two important injection molding parameters affecting selected properties were melt and mold temperature. The most important effect on flexural modulus was the amount of HGM, and for density the amount of EM.