ABSTRACT:The lowering of ignitability and flammability of polyethylene (PE) and the production of fire-retarding materials has become an urgent problem because of the demand of fire safety. In our article, a new charring agent (CA), a derivative of triazines, was synthesized by charging 2-amino-4,6-dichloro-s-triazines and diethylenetriamine into a reactor to conduct the solution polycondensation reaction, and the synthetic conditions of monomer and CA, such as temperature, time, etc., were investigated. Both the monomer and the resulting polymer were characterized by mass spectrum (MS), Fourier transform infrared (FTIR) spectroscopy, 1 H-NMR, and elemental analysis. The intrinsic viscosities and flame-retardancy property of CA were also studied. It was found that the incorporation of ammonium polyphosphate (APP) and CA into low-density polyethylene (LDPE) has a distinct effect on thermal and flame-retardancy behavior.
The development of novel tools for studying the fouling behavior during membrane processes is critical. This work explored optical coherence tomography (OCT) to quantitatively interpret the formation of a cake layer during a membrane process; the quantitative analysis was based on a novel image processing method that was able to precisely resolve the 3D structure of the cake layer on a micrometer scale. Fouling experiments were carried out with foulants having different physicochemical characteristics (silica nanoparticles and bentonite particles). The cake layers formed at a series of times were digitalized using the OCT-based characterization. The specific deposit (cake volume/membrane surface area) and surface coverage were evaluated as a function of time, which for the first time provided direct experimental evidence for the transition of various fouling mechanisms. Axial stripes were observed in the grayscale plots showing the deposit distribution in the scanned area; this interesting observation was in agreement with the instability analysis that correlated the polarized particle groups with the small disturbances in the boundary layer. This work confirms that the OCT-based characterization is able to provide deep insights into membrane fouling processes and offers a powerful tool for exploring membrane processes with enhanced performance.
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