Transforming vulcanized styrene–butadiene waste into valuable raw material: an opportunity for high-impact polypropylene production

Abstract

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...

Tailoring polyamide 6 to exhibit super‐tough behavior and high thermomechanical stability: The role of AES and EPDM‐MA hybridization

“…The melt flow index is widely used in industry to characterize the flow properties of polymers and evaluate their consistency. The higher the MFI, the lower the viscosity is 51 . The MFI and viscosity index (VI) results for the PA6, PA6/AES blends, and PA6/AES/EPDM‐MA systems are presented in Table 2.…”

“…The bands at 1476 and 1441 cm −1 correspond to the vibration of CH 2 groups, while the band located at 1416 cm −1 is assigned to the bending vibrations of CH 2 . The peaks at 1332, 1287, 1260, and 1198 cm −1 are from the amide group attached to the alkyl group (NHCH 2 ) 56–58 . AES shows a band associated with the stretching of the acrylonitrile group (CN) at 2238 cm −1 , a small band at 3026 cm −1 attributed to the CH stretching of the styrene aromatic ring, an intense band at 1453 cm −1 referring to the angular deformation of the CH 2 group, and bands characteristic of a monosubstituted aromatic ring at 700 and 761 cm −1 .…”

“…The higher the MFI, the lower the viscosity is. 51 The MFI and viscosity index (VI) results for the PA6, PA6/AES blends, and PA6/AES/EPDM-MA systems are presented in Table 2. PA6 had the highest MFI, indicating higher fluidity and lower viscosity.…”

“…The peaks at 1332, 1287, 1260, and 1198 cm À1 are from the amide group attached to the alkyl group ( NH CH 2 ). [56][57][58] AES shows a band associated with the stretching of the acrylonitrile group (C N) at 2238 cm À1 , a small band at 3026 cm À1 attributed to the C H stretching of the styrene aromatic ring, an intense band at 1453 cm À1 referring to the angular deformation of the CH 2 group, and bands characteristic of a monosubstituted aromatic ring at 700 and 761 cm À1 . The spectrum of EPDM-MA is characteristic of a polyolefin, with a band at 1377 cm À1 due to symmetric deformation of the CH 3 group, an intense band at 1464 cm À1 attributed to the angular deformation of the CH 2 group, and two intense bands at 2861 and 2918 cm À1 belonging to the symmetric and asymmetric stretching of the CH 2 and CH 3 groups, 35 while the maleic anhydride peak is in the range of 1700-1780 cm À1 .…”

“…[15][16][17] PA6 is a semicrystalline polymer with high toughness above its glass transition temperature (T g ), good organic media chemical resistance, low molten state viscosity, good abrasion resistance, and good mechanical and thermal properties. [18][19][20] Consequently, PA6 is one of the most relevant engineering thermoplastics that can replace metal in components and connections that require excellent mechanical, chemical, and physical properties. 21,22 Nonnotched PA6 exhibits ductile behavior under mechanical deformation, but it becomes brittle and fragile when notched.…”