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This research presents pioneering work on transforming a variety of waste plastic into synthetic graphite of high quality and purity. Six recycled plastics in various forms were obtained – including reprocessed polypropylene, high-density polyethylene flakes, shredded polyethylene films, reprocessed polyethylene (all obtained from Pennsylvania Recycling Markets Center), polystyrene foams and polyethylene terephthalate bottles (both sourced from a local recycling bin). The waste plastics were carbonized in sealed tubing reactors. The study shows that this versatile process can be used on a mix of waste plastics in a variety of recycled forms to obtain a uniform graphitic carbon phase, hence addressing the challenges of separation and transportation faced by the plastic recycling industry. The conversion yield to elemental carbon for recycled plastics was improved by up to 250% by using graphene oxide (GO) additives. Five different grades of GO and graphene were used to gain insights into the interaction mechanisms between plastics and GO during pyrolysis. The effect of GO additives on carbonization was analyzed using thermogravimetric analysis / differential scanning calorimetry and ReaxFF-based reactive molecular dynamics simulations. The obtained cokes were graphitized at 2500 ℃ and the graphitic quality of the synthetic graphites was analyzed using X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The plastic waste-derived synthetic graphites exhibit remarkable graphitic quality with crystallite sizes comparable with a model graphitizable material – anthracene coke. The thin, flake-like morphology and nanostructure featuring well-stacked contiguous lamellae make these graphitic carbons highly promising candidates for energy storage applications. Based on our experiments and atomistic-scale simulations we propose interaction mechanisms between the plastic polymers and the graphenic additives that explain the chemical conversion pathways for GO-assisted waste plastic carbonization and graphitization. 

Multilayer ceramic capacitors (MLCC) play a vital role in electronic systems, and their reliability is of critical importance. The ongoing advancement in MLCC manufacturing has improved capacitive volumetric density for both low and high voltage devices; however, concerns about long-term stability under higher fields and temperatures are always a concern, which impact their reliability and lifespan. Consequently, predicting the mean time to failure (MTTF) for MLCCs remains a challenge due to the limitations of existing models. In this study, we develop a physics-based machine learning approach using the eXtreme Gradient Boosting method to predict the MTTF of X7R MLCCs under various temperature and voltage conditions. We employ a transfer learning framework to improve prediction accuracy for test conditions with limited data and to provide predictions for test conditions where no experimental data exists. We compare our model with the conventional Eyring model (EM) and, more recently, the tipping point model (TPM) in terms of accuracy and performance. Our results show that the machine learning model consistently outperforms both the EM and TPM, demonstrating superior accuracy and stability across different conditions. Our model also exhibits a reliable performance for untested voltage and temperature conditions, making it a promising approach for predicting MTTF in MLCCs. 

Transition metal dichalcogenides (TMDCs) are potential materials for future optoelectronic devices. Grain boundaries (GBs) can significantly influence the optoelectronic properties of TMDC materials. Here, we have investigated the mechanical characteristics of tungsten diselenide (WSe 2 ) monolayers and failure process with symmetric tilt GBs using ReaxFF molecular dynamics simulations. In particular, the effects of topological defects, loading rates, and temperatures are investigated. We considered nine different grain boundary structures of monolayer WSe 2 , of which six are armchair (AC) tilt structures, and the remaining three are zigzag (ZZ) tilt structures. Our results indicate that both tensile strength and fracture strain of WSe 2 with symmetric tilt GBs decrease as the temperature increases. We revealed an interfacial phase transition for high-angle GBs reduces the elastic strain energy within the interface at finite temperatures. Furthermore, brittle cracking is the dominant failure mode in the WSe 2 monolayer with tilted GBs. WSe 2 GB structures showed more strain rate sensitivity at high temperatures than at low temperatures. 

Raman spectroscopy showing the initial formation of SnSe₂followed by the stabilization of SnSe with increased growth time.