Ground tire rubber (GTR) was devulcanized by microwaves at the same heating rate (constant power) and different times of exposure. The devulcanized rubber (DV-R) and untreated GTR were characterized physically and thermally. Composite materials were prepared from different proportions of the GTR, which was used as a filler, and the DV-R, which was used as part of the styrene butadiene rubber (SBR) matrix, and by varying the exposure time of the microwave power. These composites were compared with a control sample that was prepared from virgin SBR. The sol content (soluble part) and Fourier transform infrared spectroscopy (FTIR) analyses of the devulcanized samples were examined to define the efficiency of devulcanization. The cure characteristics and tensile properties of the SBR composites were researched. In this study, it was found that using DV-R as part of the rubber matrix produced much better properties than using GTR as a filler, thereby showing the significant benefits of microwave devulcanization. At the DV-R content of 50 phr, the elongation at break of the DV-R 5 min/SBR composites increased to 445.06% from 217.25% for the GTR/SBR composites, i.e., the elongation at break was enhanced by 105% by the devulcanization of GTR. Scanning electron microscopy (SEM) photographs displayed a better interface coherence between the DV-R 5 min and SBR matrix than the GTR/SBR composites.

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Abstract. Pyrolytic carbon black (CBp) and pyrolytic oil (Op) made from used tires were used in natural rubber (NR)/ styrene-butadiene rubber (SBR) blends. The effects of CBp and Op on the processing properties, the mechanical properties and the dynamic mechanical properties of the NR/SBR blends were investigated and compared with a control sample that was prepared with N550 and commercial process oil. It was found that the effect of CBp on the processing properties of the NR/SBR blends was similar to that of N550. With the increase of the CBp content, the curing properties of the NR/SBR blends changed little. The reinforcing effect of CBp was inferior to that of N550. With the increase of the CBp content, the tensile strength, tear strength and modulus at 100% elongation of the NR/SBR vulcanizates decreased significantly. Dynamic mechanical properties of the NR/SBR blends were also affected and all samples comprising CBp have a higher tan ! than control sample. It is suggested that the low surface area and high ash content of CBp strongly effects all of these property changes of the NR/SBR blends. The morphology and distribution of the carbon black particles are studied using a scanning electron microscope. It was also found that with the increase of the Op content, the properties of the NR/SBR blends were strongly affected due to the high sulfur content of Op, which produced a high crosslinking density.

This article investigates the impact of addition various types of nanoparticles with different structural, dimensional, and morphological properties on the interphase region formed between the particle/matrix and the curing behavior of the epoxy affect the nanocomposite material properties. For this purpose, epoxy nanocomposites (NCs) were produced by adding multi-walled carbon nanotube (MWCNT) and alumina (Al2O3) nanoparticles (NPs) into the epoxy matrix at different rates (0.5–2.0 wt.%). The effects of the particle/matrix interaction on the properties of the composite have been revealed by chemical, thermal, mechanical analyzes and microstructure investigations. An increase in the absorption density, which reveals the physical interaction of nanoparticles with the epoxy matrix, was observed in Fourier-transform infrared spectroscopy. Absorption vibration peak intensities in nanocomposite samples were at most 1.0 wt.% Al2O3 and 1.25 wt.% CNT added nanocomposites. It was observed that the Tg value increased depending on the number of nanoparticles. The addition of Al2O3 increased Tg values more than CNT. Besides, the mechanical properties of NCs were determined by tensile tests. The highest increase in mechanical properties was achieved by adding 1.25 wt.% CNT and 1.0 wt.% Al2O3, respectively. Mechanical properties tended to decrease at higher addition rates. The shape, size, amount, and distribution of nanoparticles added into the epoxy matrix directly affected the NCs' properties. It has been determined that homogeneously dispersed spherical Al2O3 nanoparticles are more effective than fiber-shaped CNTs in the properties of NCs.

In this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR) and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant power while varying the microwave exposure time. Devulcanized rubber (DV-R) and untreated GTR were revulcanized by mixing with SBR at different rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests were conducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experimental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samples for comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcanization functionalization of ground tire rubber. In general, DV-R/SBR composites exhibited improvement in both mechanical and tribological properties. However, the enhanced compatibility of DV-R resulting from the specific chemical coupling of DV-R with SBR was crucial for the mechanical, friction and wear properties.