Desenvolvimento e caracterização de compostos elastoméricos com biochar para utilização como carga em compostos elastoméricos a base de poli (Butadieno-co-estireno)

Abstract

Carbon black (NF), widely used in the rubber and tire industry, is a product of the partial combustion of fossil fuels, while biochar, a natural source, can be obtained from the pyrolysis process of different biomasses. Biochar has high potential to be applied as a substitute for carbon black, favored by its properties including a high carbon content, low ash content, in addition to being low cost, easy to store and highly energy efficient. This study investigated the use of biochar from Pinus elliottii (B), produced from the pyrolysis process, at high temperature (900 °C) and characterization of biochar modified with organosilane. Elastomeric compounds were produced using only commercial carbon black as filler (NF/B 50/0), unmodified biochar (NF/B 0/50), unmodified biochar and commercial carbon black (NF/B 25/25). The elastomeric compounds were evaluated using rheometric, physicochemical and mechanical properties before and after accelerated heat aging. The optimum vulcanization time (t90) was observed as the amount of biochar (B) in the elastomeric compounds was increased. A t90 of 13.9 minutes was obtained for the NF/B 50/0 compound, 14.6 minutes for the NF/B 25/25 compound and 15.3 minutes for the NF/B 0/50 compound. For the hardness property, an increase of 1.6% and 1.9% was observed in the NF/B 0/50 and NF/B 25/25 composites respectively when compared to the hardness of the NF/B 50/0 composite. An increasing in tear strength values was observed for NF/B 25/25 (43.45 N/mm) and NF/B 0/50 (45.88 N/mm) when compared to NF/B 0/50 (29.48 N/mm). Replacing biochar with carbon black caused a rise in DPC of 30.4% and 16.7% in the NF/B 25/25 and NF/B 0/50 composites respectively when compared to the NF/B 50/0 composite. There is a reduction in tensile strength in relation to the reference sample for the tensile strength property with the use of biochar instead of NF for both NF/B 25/25 (7.3 MPa) and NF/B 0/50 (4.2 MPa) composites when compared to the NF/B 50/0 (13.3 MPa) reference composite. The biochar was chemically modified using Triethoxymethylsilane (C7H18O3Si). A contact angle of 1140 was achieved for the modified biochar, which differs from the angle of the biochar (B) at 1090, providing evidence of a chemical modification of the biochar (resulting in greater hydrophobicity) and confirming the efficacy of the organosilane deposition technique. Analysis via Fourier-transform infrared spectroscopy (FTIR) demonstrated an absorption band at 1025 cm-1 indicating the presence of silicon in the modified biochar (MB), via Si-O-C stretching. Furthermore, scanning electron microscopy (SEM) analysis evidenced the presence of silicon within the MB samples. The findings of this investigation demonstrate the potential for the development of elastomeric compounds applying biochar (B) as a filler and confirm the chemical alteration of biochar. [resumo fornecido pelo autor]