The thermal degradation characteristics of a printed circuit board assembly (PCBA), specifically video cards from waste computers, was studied using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The video-card waste was dismantled into substrate, integrated circuits (ICs), and plastic slots for comparable investigation. The results by TGA revealed that the initial temperature at which degradation began was 300 degrees C for substrate, but it was 330 degrees C for ICs and plastic slots. For a given type of scrap, the initial temperature leading to degradation is the same under air and N2 atmosphere. However, the degradation rate was lower using air than N2 during the weight-loss stage. Further Py-GC/MS application revealed that pyrolysis products derived from substrate consisted mainly of acetone, bromotoluene, and phenol that came from the brominated epoxy resins present in substrate. Unlike substrate, the relative amounts of some products (e.g., phenol) were higher in the ICs, and cyclotetrasiloxane was released; these were released from the phenolic resins and Si mixture present in that type of waste. Benzoic acid, rather than acetone or phenol, was the main product released from plastic slots. It was proved that this scrap was a mixture of various polyesters, cracking of which predicatively generated aromatic products. The results will be useful in developing pyrolysis or starved-air incineration systems for thermosetting plastic and PCBA waste and helpful to control pollution during the treatment of this waste.
The health and survival benefits of social embeddedness have been widely documented across social species, but the underlying biophysiological mechanisms have not been elucidated in the general population. The authors assessed the process by which social isolation increases the risk...
We study the thermalization of excitations generated by spontaneous emission
Events for cold bosons in an optical lattice. Computing the dynamics described
By the many-body master equa- tion, we characterize equilibration timescales in
Different parameter regimes. For simple observables, we find reg...
We rigorously investigate the quantum dissipative dynamics of a ratchet
System described by a periodic potential model based on the Caldeira-Leggett
Hamiltonian with a biharmonic force. In this model, we use the reduced
Hierarchy equations of motion in the Wigner space representation. These
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