Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites

Flash Recycling of Graphite Anodes

The ever-increasing production of commercial lithium-ion batteries (LIBs) will result in a staggering accumulation of waste when they reach their end of life. A closed-loop solution, with effective recycling of spent LIBs, will lessen both the environmental impacts and economic cost of their use. Presently, <5% of spent LIBs are recycled and the regeneration of graphite anodes has, unfortunately, been mostly overlooked despite the considerable cost of battery-grade graphite. Here, an ultrafast flash recycling method to regenerate the graphite anode is developed and valuable battery metal resources are recovered. Selective Joule heating is applied for only seconds to efficiently decompose the resistive impurities. The generated inorganic salts, including lithium, cobalt, nickel, and manganese, can be easily recollected from the flashed anode waste using diluted acid, specifically 0.1 m HCl. The flash-recycled anode preserves the graphite structure and is coated with a solid-electrolyte-interphase-derived carbon shell, contributing to high initial specific capacity, superior rate performance, and cycling stability, when compared to anode materials recycled using a high-temperature-calcination method. Life-cycle-analysis relative to current graphite production and recycling methods indicate that flash recycling can significantly reduce the total energy consumption and greenhouse gas emission while turning anode recycling into an economically advantageous process.

The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH₃)₂R’NR]⁺, where R = C₁₂, C₁₄, C₁₆, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

A New Approach to the Assessment of the Reduction in Visibility Caused by Fires of Electrical Cables

Electricity is the most important form of household energy and one of the most important forms of energy for industry and transport. Electrical distribution in construction and transport is almost exclusively implemented using electrical cables. One of the unresolved problems associated with electrical cables is the release of smoke and the resulting reduction of visibility in case of fire in the area. In this study, a new approach was developed to assess the reduction of visibility in an area affected by an electrical cable fire. This approach is based on the determination of the critical ratio of smoke volume (in the smoke layer and exhausted from the fire compartment) to the length of the burning cable, through which the visibility of reflective and illuminated signs was reduced to a lower limit value (a standard of 10 m). The input data for this approach was the extinction area of the smoke released from one meter of burning cable and the length of the cables in the area. This approach was used to test two power cables (CHKE-V J3x1.5 and CHKE-R J3x1.5) and one signal cable J-H(St)H 1 × 2 × 0.8 with the B2ca, s1, d1, a1 fire reaction class. The smoke extinction area of the examined cables was determined using a cone calorimeter at a heat flux of 50 kW/m2. The obtained data showed that in order to maintain a visibility of 10 m for reflective signs, the critical ratio of smoke volume to length of burning cable was 7.5 m3/m. For illuminated signs, the critical ratio was 2.8 m3/m. The relationship between burning length and visibility allows the calculation of visibility in the fire compartment affected by cable fire only from cables length.

Preparation of Palladium/Silver-Coated Polyimide Nanotubes: Flexible, Electrically Conductive Fibers

A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI) nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous coating of palladium nanoparticles remain flexible after heat treatment and show the possibility for use as highly efficient catalysts. The approach developed here is applicable for coating various noble metals on a wide range of polymer matrices, and can be used for obtaining polyimide nanotubes with metal loaded on both the inner and outer surface.