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The elastomeric composites using styrene butadiene rubber (SBR) as the polymeric matrix with two types of carbon nanofillers, carbon black and carbon nanotubes, are prepared by melt mixing with the aim to use them as sensors of organic gases for monitoring industrial environments. The prepared composites contain various amounts of conducting nanofillers and are cross-linked before examination for gas sensing. The electrical conductivity of the prepared composites is measured and the percolation threshold is calculated for both types of composites. The first aim is to determine compositions slightly above the percolation threshold for later testing of the sensing properties. Swelling/deswelling experiments have also been performed. The dispersion of conducting fillers in SBR matrix is studied by scanning and transmission electron microscopy techniques, and the mechanical properties of the pure matrix and all prepared composites are determined by tensile testing. Three organic gases, toluene, tetrahydrofuran, and n-hexane, in various mixtures with air are used to examine the ability of the prepared composites to react in their presence by changing the electrical properties. Cyclability of the sensing performance of the composites is also examined. Sensing results reveal the suitability of the prepared SBR-based materials as sensors for harmful solvents and gases widely used in industry. [ABSTRACT FROM AUTHOR]

Abstract: New types of composites were prepared using low-density polyethylene (LDPE) filled with modified organic filler, Canadian switch grass coated with polypyrrole (PPy). The grass surface was entirely covered when 10wt.% of pyrrole was used for the modification, as confirmed by scanning electron microscopy and infrared spectroscopy. LDPE composites filled with modified grass were prepared by melt mixing and their properties were compared with the properties of the composites filled with unmodified grass. The influence of crosslinking, induced by 1wt.% of peroxide, on mechanical, thermal and electrical properties of the composites was investigated. Crosslinking enhanced the tensile strength of the prepared composites in the entire range of the filler content. The Young’s modulus of the composites prepared by crosslinking is slightly lowered when compared with the uncrosslinked composites if the filler content is less than 60wt.%, for higher filler content it is increased. The conductivity of the uncrosslinked composites containing 40wt.% of grass modified by PPy was in the range 1×10−6 Scm−1, which is a value by 5 orders of magnitude higher than the conductivity of the crosslinked materials. The presence of PPy on grass surface leads to a reduction of crosslinking of the LDPE matrix. [Copyright &y& Elsevier]

Highlights: [•] The Younǵs modulus of the composites increased 13times. [•] The flexural strength of composites was improved 2 times. [•] The polarity of LDPE was significantly enhanced. [•] The adhesion of composites to the polar substrates was improved. [ABSTRACT FROM AUTHOR]

Lignin/polypyrrole composites were prepared by single-step coating of water-insoluble kraft lignin with polypyrrole. The polymerization of pyrrole was performed with and without the presence of methyl orange, leading to the formation of polypyrrole films of two different morphologies, globular and nanotubular, respectively, on the lignin surface. Such composites were converted to double-carbon composites enriched in inert atoms by pyrolysis in nitrogen atmosphere at 650 °C. The carbonization process was followed by thermogravimetric analysis and confirmed by Raman spectroscopy. The properties of all composites were investigated by FTIR spectroscopy, XPS, EPR, SEM, specific surface area and electrical conductivity measurements. Electrochemical properties were analyzed in terms of their capacitive behavior mainly in acidic solutions, but also in neutral and alkaline media. [ABSTRACT FROM AUTHOR]

Polysulfone-supported silver nanoparticles (Ag@PSF) were obtained by a combination of polymer nanoprecipitation and redox synthesis of silver, in the presence of two siloxane-based stabilizing agents, and were incorporated into a PDMS matrix. Soft elastic composites (PDMS-Ag@PSF) were obtained and were investigated by dielectric relaxation spectroscopy and tensile measurements, in comparison with similar materials containing either PSF particles or AgNPs. The mechanical properties of the composites are tunable by composition, depending quasi-linearly on the Ag content. A PDMS-Ag@PSF film with 0.8 wt% Ag, having Y = 0.12 MPa, maximum strain 550% and E BD = 36 V μm−1 exhibited electrical actuation of 8% lateral strain at 22 V μm−1. Apparent piezoelectric coefficient d 33 values of ~15 pm V−1 were measured by piezoresponse force microscopy for the composites with Ag@PSF, showing a synergistic effect of the fillers' components. In addition, the materials exhibited antibacterial and antifungal activity and low bioadhesion. Based on their properties, the highly stretchable composites can be regarded as candidates for applications like actuators, sensors or micro/nanogenerators in biomedical field. Image 1 • Polysulfone-supported silver nanoparticles stabilized with siloxane surfactants. • PDMS-Ag@PSF composites with tunable mechanical and dielectric properties. • Electric actuation response of 8% lateral strain at 22 V/μm. • Apparent piezoelectric coefficient d 33 of 15 pm V-1 measured by PFM. [ABSTRACT FROM AUTHOR]