Abstract Due to the technical evolution of tires, currently most automotive tires do not have an inner tube. However, truck, motorcycle and bicycle tires still use tires with inner tubes, mostly made of synthetic elastomeric material, which guarantees good potential for air restriction or longer periods for tire pressure failure. This work aims to study changes in the mechanical properties of a truck inner tire, after its exposure to gamma rays, to promote the subsequent recycling of the material. The choice of ionizing radiation is due to its ability to modify the structure and properties of materials, in addition to its applicability in recycling/recovering rubber. For the characterization of the samples, doses of 5, 10, 15, 20, 25 and 30 kGy were applied, and after irradiation as a sample, they were tested using the following characterization methods: traction and elongation at break, hardness, thermal aging and elemental analysis. Observed that is a decrease in the values of the mechanical properties of the samples after irradiation, mainly at doses greater than 10 kGy.

Abstract High performance polymeric materials such as poly-ether-ether-ketone (PEEK) are increasingly being used for challenging tribological applications in order to replace metal parts in vehicle engines and transmissions. The tribology of natural PEEK, under oil-lubricated conditions, was studied for different metal counterbody finishes. Two different finishing processes were selected for this study: turning and polishing. The test system used was a tri-pin on disc, with pins made of PEEK and counterbodies made of steel, and then dipped in ATF Dexron VI oil. The conclusion was that the wear rate generated by turning was about seven times as high as the wear rate generated by polishing. The friction coefficient displayed a direct correlation with the lubrication regime, and the level of counterbody roughness. On average, the friction coefficient on the hydrodynamic regime for polishing was more than 3 times lower than the friction coefficient in the boundary regime for turning.

Abstract The tribological properties of poly-ether-ether-ketone (PEEK) containing 30% of carbon fiber were studied in an oil-lubricated environment and different surface finishing of the metallic counterbody. Four different finishing processes, commonly used in the automotive industry, were chosen for this study: turning, grinding, honing and polishing. The test system used was tri-pin on disc with pins made of PEEK and counterbody made of steel; they were fully immersed in ATF Dexron VI oil. Some test parameters were held constant, such as the apparent pressure of 2 MPa, linear velocity of 2 m/s, oil temperature at 85 °C, and the time - 120 minutes. The lubrication regime for the apparent pressure of 1 MPa to 7 MPa range was also studied at different sliding speeds. A direct correlation was found between the wear rate, friction coefficient and the lubrication regime, wherein wear under hydrodynamic lubrication was, on average, approximately 5 times lower, and the friction coefficient 3 times lower than under boundary lubrication.

Um estudo comparativo envolvendo técnicas de análise por espectroscopia no infravermelho com transformada de Fourier (FTIR) de transmissão, reflexão e fotoacústica é apresentado com análise de poliamida-6. O potencial e as limitações destes métodos são investigados para analisar as alterações espectrométricas que ocorrem no interior e na superfície da poliamida-6, reciclada, e irradiada na presença de oxigênio, com feixe de elétrons de 1,5 MeV, na dose de 500 kGy. As técnicas mostram-se sensíveis para detectar pequenas mudanças de estruturas que ocorrem na poliamida-6 reciclada e irradiada. Os espectros sugerem formação de grupos --OH, HOC=O-, e -C=O, e mudanças estruturais relacionadas com grupos NH e -CN-C=O. Basicamente, as mesmas alterações espectrométricas são observadas com o uso das técnicas, sendo mais evidenciadas no interior das amostras pela espectroscopia-FTIR de transmissão, e na sua superfície, pela microscopia-FTIR.

A comparative study involving transmission, reflection and photoacoustic FTIR techniques is presented with analysis of polyamide-6. The potential and limitations of these methods are investigated by analyzing structural variations that take place at the surface in the bulk in recycled and irradiated polyamide-6 with a 1.5 MeV electron beam with a 500kGY dose, in the presence of O2. FTIR techniques appear to be sensitive in detecting small structural changes that occur in recycled and irradiated polyamide-6. The analysis of samples indicated the formation of --OH, HOC=O-, - C=O groups. Also, small structural changes were detected which are characterisitic of NH and --CN-C=O groups. Transmission techniques show better the structural changes in the bulk, and microscopy-FTIR appears to be more sensitive in detecting what occurs at the sample surface.