Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene.

Vasiliki-Maria Archodoulaki,Sascha Stanic,Thomas Koch,Simone Knaus,Klaus Schmid

doi:10.3390/polym13071137

Abstract

Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.

Highlights

This study showed that the blending of long-chain branched polypropylenes (LCB-PP) can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process
The LCB-PPs, which were used for the blends, were based on HC 600TF (PP2) appropriated for thermoforming applications, which was supplied by Borealis (Vienna, Austria), and the peroxides PODIC C126 or PEROXAN LP from Pergan
PP2 = 2.8 g/10 min, LCB-PP modified by PODIC C126 = 7.7 g/10 min, LCB-PP modified by PEROXAN LP = 6.0 g/10 min

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The worldwide production of plastics has experienced great growth in the last decades and the consumption of plastics has increased more and more. Plastics and their products are already being promoted as the material of the 21st century. The three largest areas in which plastic products play an important role are the packaging industry with 40%, building and construction with 20%, and the automotive industry with

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