The vulcanized residue of styrene-butadiene rubber (SBRr) is a raw material with potential for re-addition in the production chain, adding value and reducing environmental impact. Polypropylene (PP) compounds with SBRr from the footwear industry were produced, adding styrene-(ethylene-butylene)styrene (SEBS) as compatibilizer, with 20% and 30% of styrene (St.). Addition of 30% SBRr did not compromise the processability, since the torque and ow index increased slightly. Signi cant increases in impact strength were achieved for PP/SBRr/SEBS (10% -20% St.) and PP/SBRr/SEBS (10% -30% St.), with gains of 316% and 248%, related to PP. The elastic modulus, tensile strength, elongation at break and Shore D hardness indicated greater exibility for the PP/SBRr/SEBS, especially in the copolymer with 20% St. The thermal de ection temperature (HDT) indicated that even adding high content of SBRr to PP, the HDT was not severely affected, possibly due to its crosslinked character. PP/SBRr compatibilization with SEBS (20% St.) inhibited the PP crystalline peaks, as veri ed through X-ray diffraction (XRD). Stable morphology was achieved upon 10% of SEBS addition to PP/SBRr, providing proper interfacial adhesion and ne particles, contributing to toughen PP. Acquired results are promising for the rubber recycling, aiming at the production of high-impact polypropylene for containers and furniture accessories applications.vulcanized rubber residues. In this case, the infusible rubber powder disperses within PP matrix, acting as exible ller and promoting toughening.
Costa et al.[17] evaluated the potential of waste tire rubber (SBR-styrene-butadiene) as a complementary raw material for the PP/ethylene-propylene-diene rubber (EPDM) system. The PP/EPDM/SBR compounds were prepared using a co-rotating twin screw extruder and specimens were injection molded. SBR addition to PP matrix did not result in an increase in impact strength nor in elongation at break, only a slight reduction in these properties, which is attributed to insu cient adhesion between the two phases.However, high values of impact strength were reached (> 80 J.m − 1 ), for PP/EPDM/SBR with EPDM and SBR contents around 25%. Elastic modulus and tensile strength decreased with increasing concentration of EPDM or SBR, due to increased exibility. EPDM developed improved non-adhesion between two distinct phases (PP and SBRr), leading to improved elongation at break results.Ciro et al. [18] developed PP compounds with recycled rubber (BR), in the range of 10-55% of BR weight, processed using an internal mixer. Rheometry plots displayed slight increase in torque upon BR increasing, suggesting an increase in viscosity. The increase in BR concentration reduced the elastic modulus and tensile strength, especially promoting a severe reduction in these properties at 55% BR. The thermogravimetry (TG) results showed that PP/BR compounds thermal stability decreased upon BR addition, compared to neat PP. DSC scans showed evidence that recycled rubber addition to PP affected the crystalli...
