The effect of polyester recycled tire fibers mixed with ground tire rubber on polyethylene composites. Part I

Abstract

The effect of polyester recycled tire fibers (RTFs) mixed with ground tire rubber (GTR) in linear low-density polyethylene (LLDPE) with and without styrene–ethylene–butylene–styrene-grafted maleic anhydride was studied. In particular, different RTF contents (10, 25, and 50 wt%) and compounding screw speed (110, 180, and 250 r min−1), as well as temperature profiles (extrusion and injection molding) were used to optimize the processing conditions. In this first part, a complete physical and morphological analysis for the RTF fibers and GTR particles was performed. The results show that the compatibilized compounds have lower RTF length and GTR particle size but better distribution of rubber particles in the LLDPE matrix. Overall, lower processing temperatures used in both extrusion and injection molding showed better interfacial adhesion between the components due to higher shear and mechanical energy imparted on the different particles.

Rheological characterization of polyethylene/polyester recycled tire fibers/ground tire rubber composites

“…On the other hand, the addition of a compatibilizer like SEBS‐ g ‐MA improves the interaction due to the reactivity of the MA groups having strong polarity and resulting in lower surface tension and increased interfacial adhesion between the phases. Furthermore, as seen in Figure (c), samples E‐250 and I‐250 produced with HT profiles have lower shear storage modulus than LC‐502 related to the degradation of rubber particles as well as the matrix . However, less degradation occurred in sample I‐250 compared to E‐250 due to lower material residence time in injection molding at HT profile …”

“…This is associated with the presence of RTF and the interface which is increasing with RTF content. On the other hand, increasing the mixing speed at constant filler content [Figure (b)] decreased the RTF aspect ratio and GTR sizes (because of higher shear). Hence, due to larger surface area created, smaller rubber particles impart higher elasticity .…”

“…It has a melting temperature of 124 °C, a melt index of 22 g/10 min (230 °C/5 kg), and a density of 0.91 g/cm 3 . More details on the materials can be found in our previous studies …”

“…Finally, the samples were cut directly from the injection molded parts for each characterization. Tables present an overview of the experimental conditions and more details can be found in our previous publications …”

“…Since rheological characterizations are known to be useful tools to investigate the relationships between structural properties (morphology), processability, and mechanical behavior, this work investigates the rheological properties in both the melt and solid states for RTF/GTR filled linear low density polyethylene (LLDPE) composites. In the first parts of this study, the morphological and mechanical properties were reported for three different processing parameters including RTF/GTR content (total filler content), compounding screw speed (resulting in different final particle sizes), and different temperature profiles (above and below PET melting temperature). Here, shear rheology is combined with DMA to get more information on the effect of morphology and interfacial adhesion between the phases and better explain the mechanical results reported in previous papers.…”