Effect of Styrene-Diene Block Copolymers and Glass Bubbles on the Post-Consumer Recycled Polypropylene Properties

Maria Râpă,Andrei Constantin Berbecaru,Cristian Andi Nicolae,Bogdan Norocel Spurcaciu,George Coman,Cristian Predescu,Raluca Augusta Gabor,Paul Niculae Ghioca,Ecaterina Matei

doi:10.3390/ma13030543

Abstract

The recycled polypropylene (rPP) materials that meet technical requirements such as reducing the dimensions and improving the tensile, elongation, impact strength, thermal stability, as well as melt processing, are required for the manufacturing industry. In this paper, we studied the mechanical and thermal properties of post-consumer rPP by adding both synthesized thermoplastic elastomers, and glass bubbles (GB) by a melt allowing process. Styrene-butadiene (SBS) and styrene-isoprene (SIS) block-copolymers that had a styrene content of 30 wt% were synthesized by anionic sequential polymerization. The obtained post-consumer rPP composites were characterized by optical microscopy, scanning electron microscopy (SEM), mechanical analyses (tensile, density, hardness, VICAT softening temperature (VST), heat deflection temperature (HDT), dynamic mechanical analysis (DMA), IZOD strength) and thermal analyses (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)). Weight reduction and improvement of the tensile, elongation, impact strength, thermal stability, as well as melt processing of post-consumer recycled polypropylene (rPP) properties compounded with thermoplastic elastomers and glass bubbles, sustain the use of these formulations for engineering applications.

Highlights

Polypropylene (PP) ranks third in the plastic manufacturing field [1], being intensely processed for auto components, fittings, pipes, cables, packaging, electronic items and fibers for concrete reinforcing.Generally, PP shows a low impact, especially at low temperatures, and low strength
The design of composites based on post-consumer recycled polypropylene, synthesized styrene-butadiene/styrene-isoprene block-copolymers with 30 wt% styrene content (SBS and SIS, respectively) using the anionic sequential polymerization and glass bubbles (GB) by melt allowing, and their processability, mechanical and thermal properties, are analyzed. These post-consumer recycled PP/elastomer/GB composites were characterized by optical microscopy, processability on a Brabender Plastograph, mechanical measurements (density, tensile properties, dynamic mechanical analysis (DMA), hardness, impact), and thermal analyses (differential scanning calorimetry (DSC), thermogravimetric (TG), heat deflection temperature (HDT), and VICAT softening temperature). These analyses revealed that by introduction of SBS or SIS block copolymers and glass bubbles into rPP, the additional properties to impact strength and elongation were obtained in comparison with previous studies, in terms of improving density and melt processability
The melt processability of post-consumer rPP loaded with thermoplastic elastomers and glass bubbles is investigated by means of torque (TQ), melt viscosity (η) and power (P) measurements from torque-time curves—Table 3

Summary

Introduction

Polypropylene (PP) ranks third in the plastic manufacturing field [1], being intensely processed for auto components, fittings, pipes, cables, packaging, electronic items and fibers for concrete reinforcing.Generally, PP shows a low impact, especially at low temperatures, and low strength. By adding titanate coupling agent and talc (30%–40%), the melt flow index and toughness of PP increased [10]. Thermoplastic elastomers, such as ethylene propylene-rubber (EPR) [11,12], ethylene–propylene–diene. Spectral presented the FTIR (=C-H group of butadiene), 960 cm−1 (-CH=CH- group of butadiene), 835 cm−1 and 887 cm−1 (isoprene) spectrum for the post-consumer rPP/SBS/GB20 blend consist in the decrease of intensity of bands at [48,49], in the 1576–1375 cm−1 region (stretching vibration of aromatic C=C bond), 2848 cm−1 (-CH2−1 compared −1 (-CH3 group).

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Conclusion