Foams with Enhanced Ductility and Impact Behavior Based on Polypropylene Composites.

Santiago Muñoz-Pascual,Cristina Saiz-Arroyo,Mihai Cosmin Corobea,Miguel Angel Rodriguez-Perez,Zina Vuluga

doi:10.3390/polym12040943

Abstract

In this work, formulations based on composites of a linear polypropylene (L-PP), a long-chain branched polypropylene (LCB-PP), a polypropylene–graft–maleic anhydride (PP-MA), a styrene-ethylene-butylene-styrene copolymer (SEBS), glass fibers (GF), and halloysite nanotubes (HNT-QM) have been foamed by using the improved compression molding route (ICM), obtaining relative densities of about 0.62. The combination of the inclusion of elastomer and rigid phases with the use of the LCB-PP led to foams with a better cellular structure, an improved ductility, and considerable values of the elastic modulus. Consequently, the produced foams presented simultaneously an excellent impact performance and a high stiffness with respect to their corresponding solid counterparts.

Highlights

Polypropylene (PP) is a polymer with relatively low cost and excellent properties such as low density, easy processability, good recyclability, moisture resistance, high thermal stability, or excellent chemical and corrosion resistance
The results showed that brittle PC can acquire ductility if it is foamed
The linear polypropylene used for the study was BJ380MO, a low viscosity polypropylene manufactured by Borealis AG (Vienna, Austria) and presents a melt flow index (MFI) of 80 g/10 min (230 ◦ C/2.16 kg) and a density of 0.906 g/cm3

Summary

Introduction

Polypropylene (PP) is a polymer with relatively low cost and excellent properties such as low density, easy processability, good recyclability, moisture resistance, high thermal stability, or excellent chemical and corrosion resistance These versatile properties make it one of the most used commodity plastics, and this is the reason why the mechanical performance of PP arouses scientific interest. PP exhibits good stiffness and strength, but its use in certain applications is somehow limited by its impact strength because of its high degree of crystallinity and its high glass transition temperature [1,2,3] It could be said there is a gap between its mechanical properties and that of the engineering plastics, limiting its use for certain applications. A large amount of studies have been carried out using different types of elastomeric phases such as poly(styrene–ethylene–butylene–styrene) (SEBS) [2,7], ethylene–propylene rubber

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