Poly (Lactic Acid) (PLA) / Ground Tire Rubber (GTR) Blends Using Peroxide Vulcanization

Poly (Lactic Acid) (PLA) / Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared as a route to recycle wastes rubber from the automotive industry. The GTR were exposed to grinding and exhibited mechanical damage, traduced at the rubber network scale by chains scission and/or chemical cross-links breakage. Such damage is accompanied by a decrease of 80% of the rubber chains network density of the initial tire buffing but found independent on the type of grinding (cryogenic, dry ambient) or on the GTR size (from <400 µm to <63 µm). Moreover, the finest sieved GTR contain the largest the amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. The melt-blending of these finest GTR particles obtained by cryo-grinding at an amount of 15 wt.% and in presence of the crosslinking agent (DCP), resulted in an optimum improvement of the ductility, energy at break and impact strength of the PLA/GTR blends as compared to neat PLA, while maintaining its stiffness. The results were attributed to (i) the good dispersion of the fine GTR particles into the PLA matrix, (ii) the partial re-crosslinking of the GTR particles and co-crosslinking at PLA/GTR interface and (iii) the presence of reinforcing carbon black into the GTR particles and clay particles dispersed into the PLA matrix.

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Poly (Lactic Acid)/Ground Tire Rubber Blends Using Peroxide Vulcanization

Polymers ◽

10.3390/polym13091496 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1496

Author(s):

Nicolas Candau ◽

Oguzhan Oguz ◽

Noel León Albiter ◽

Gero Förster ◽

Maria Lluïsa Maspoch

Keyword(s):

Lactic Acid ◽

Impact Strength ◽

Crosslinking Agent ◽

Mechanical Damage ◽

Tensile Modulus ◽

Poly Lactic Acid ◽

Tire Rubber ◽

Ground Tire Rubber ◽

Clay Particles ◽

Rubber Blends

Poly (Lactic Acid) (PLA)/Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared with the following aims: propose a new route to recycle wastes rubber from the automotive industry and improve the toughness and impact strength of the inherently brittle bio-based PLA. The GTR were subjected to two types of grinding process (cryo- and dry ambient grinding). Swelling measurements revealed the grinding to be associated with a mechanical damage of the rubber chains, independently on the type of grinding or on the GTR size (from <400 µm to <63 µm). Moreover, the finest GTR contains the largest amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. Indeed, the use of the finest cryo-grinded GTR in the presence of DCP showed the least decrease of the tensile strength (−30%); maintenance of the tensile modulus and the largest improvement of the strain at break (+80%), energy at break (+60%) and impact strength (+90%) as compared to the neat PLA. The results were attributed to the good dispersion of both fine GTR and clay particles into the PLA matrix. Moreover, a possible re-crosslinking of the GTR particles and/or co-crosslinking at PLA/GTR interface in presence of DCP is expected to contribute to such improved ductility and impact strength.

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Conductivity and mechanical properties of carbon black-reinforced poly(lactic acid) (PLA/CB) composites

Iranian Polymer Journal ◽

10.1007/s13726-021-00973-2 ◽

2021 ◽

Cited By ~ 1

Author(s):

Jipeng Guo ◽

Chi-Hui Tsou ◽

Yongqi Yu ◽

Chin-San Wu ◽

Xuemei Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Lactic Acid ◽

Carbon Black ◽

Poly Lactic Acid

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Devulcanization of ground tire rubber: microwave and thermomechanical approaches

Scientific Reports ◽

10.1038/s41598-020-73543-w ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Dániel Ábel Simon ◽

Dávid Zoltán Pirityi ◽

Tamás Bárány

Keyword(s):

Microwave Treatment ◽

Chain Scission ◽

Polymer Chains ◽

Tire Rubber ◽

Ground Tire Rubber ◽

Elongation At Break ◽

Link Density ◽

Cross Links ◽

Cross Link Density ◽

Internal Mixer

Abstract We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx’s analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such a trend. Mechanical properties improved with increased vulcanizing agent contents. The examined properties of the samples improved even further with the use of thermomechanically devulcanized samples. Horikx’s analysis showed that this is attributable to moderate polymer chain scission.

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