Because fossil-based resources are constantly declining, it has become a crucial issue in both academic and industrial fields to develop biobased polymers from renewable resources. Despite excellent comprehensive properties, diglycidyl ether of bisphenol A (DGEBA)type epoxy resin suffers from nonrenewability and flammability. To overcome these shortcomings, a biobased epoxy monomer (DGEEA) derived from ellagic acid (EA) was successfully synthesized and well characterized in this study. The DGEEA monomer was cured by 4,4′diaminodiphenylmethane (DDM) to obtain a biobased epoxy thermoset, with DGEBA cured by DDM as a control sample. The cured DGEEA/DDM product showed a high glass transition temperature of 220 °C, a high tensile strength of 75.8 MPa, and a high Young's modulus of 2.7 GPa, which outperformed the conventional petroleumbased DGEBA/DDM system. Compared with the cured DGEBA/DDM system, the cured DGEEA/DDM product also exhibited an excellent intrinsic antiflammability in terms of the significantly decreased peak heat release rate (77.7 W/g versus 513.9 W/g) and the notably improved limiting oxygen index (40.0% versus 23.0%). Furthermore, the cured DGEEA/DDM product could self-extinct in the UL-94 vertical burning test (corresponding to the V-0 classification), while the cured DGEBA/DDM system burnt out eventually (no classification). The current study provides a prospective path for synthesizing biobased resin with abundant aromatic structures and makes a contribution to the generation of biobased fire-safe epoxy thermosets with exceptional comprehensive properties.
BACKGROUND:The properties and stability of emulsion rely greatly on the emulsification method and emulsifier. In this study, different emulsification methods (high-speed homogenization, ultrasonic treatment and their combination) were employed for the preparation of emulsions stabilized by soybean protein isolate (SPI) and soy lecithin (SLT) at three ratios. The microstructure, hydrodynamic average diameter, ζ-potential, creaming stability and low-field nuclear magnetic resonance relaxation behaviors of emulsions were investigated.
RESULTS:The results indicated that the influence of emulsification method was closely related to the ratio of SPI/SLT. Overall, the SPI-SLT-stabilized emulsion treated by ultrasound showed better stability and uniformity, while the combined treatment of high-speed homogenization and ultrasound was helpful in improving the uniformity and stability of SPI-stabilized Pickering emulsion. However, the SLT-stabilized emulsions all exhibited worse uniformity in terms of particle size distribution and polydispersity index.CONCLUSION: These results will be helpful for selecting an appropriate emulsification method and emulsifier to improve the stability of emulsions.
The reconstruction of the statistical analysis model of an instrument is a time-consuming and expensive process. Herein, the feasibility of spectral model calibration-transfer application to the same type of low-field nuclear magnetic resonance (LF-NMR) instrument was investigated using a one-dimensional U-net (1D U-net). Unlike conventional calibration-transfer algorithms such as direct standardization (DS), the 1D U-net network can reduce the error between the master and slave instruments through iterative cycles. The calibration-transfer ability was verified; three experiments that entailed the use of edible oil and copper sulfate (CuSO 4 ) samples were implemented. The analysis of the spectral responses and feature analysis of the edible oil samples revealed that the signal of the slave instrument calibrated using the 1D U-net most resembled the signal of the master instrument, and its relative residual value was reduced to 0.0045. Further analysis of the CuSO 4 concentration prediction showed that on the support vector regression (SVR) model constructed using the master instrument, the signal of the slave instrument calibrated by the 1D U-net was more similar to the response of the master instrument, and its root mean square error (RMSE) was only 0.01606 mmol/L. Thus, 1D U-net is a viable candidate for calibration-transfer applications to LF-NMR instruments.
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