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In order to obtain epoxy compounds with excellent mechanical properties without compromising other desired properties, pristine-or carboxyl-functionalized multi-walled carbon nanotube (p-MWCNT or f-MWCNT) along with polysulfide were incorporated into an amine-cured epoxy resin. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses proved the existence of carboxyl groups on the surface of f-MWCNT. Adding 0.1 wt% f-MWCNT significantly improved the tensile strength and impact strength of the epoxy nanocomposites by 104% and 47%, respectively. However, adding p-MWCNT had little effect on the mechanical properties of the nanocomposites. The glass transition temperature of the f-MWCNT/epoxy nanocomposites were also much higher than neat epoxy matrix and p-MWCNT/epoxy nanocomposites. The fracture surface morphology and dynamic mechanical analysis results indicated that the interfacial interactions between f-MWCNT and the epoxy matrix were much stronger than that of p-MWCNT, which ensured the much-improved mechanical properties.

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The purpose of the study was to reveal the differences of the flavor compounds among five Baiyunbian aged liquors by liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). In optimizing the LLE parameters, an extractant, methyl tert-butyl ether, was found which has a good extract effect and has never been used for the extraction of liquor flavor substances. Then the optimized LLE method has been applied to comprehensively analyze flavor compounds in 3-year-storage liquors (3Y), 5Y, 12Y, 15Y, and 20Y of Baiyunbian liquors combined with GC-MS. The results showed that the number and concentration of total flavor compounds also enhanced with the increase of cellaring ages. The total concentration of flavor compounds in 20Y was the highest (4543.23 mg/L), and the 3Y was the lowest (3984.96 mg/L). Among them, the significant differences among five samples were esters, alcohols, acids and nitrogen-containing compounds. Cluster analysis was used to analyze the aromas profiles by LLE-GC-MS, which revealed relationship among five samples. The results showed that the similarity of the samples was highest between 15Y and 20Y, followed by 3Y and 5Y. The characteristic flavors fingerprints of five kinds of Baiyunbian aged liquors were established by HS-GC-IMS. The results showed that the characteristic peaks in GC-IMS 3D spectra corresponding to flavor compounds can effectively characterize the sample information areas. The sectional intensities of 60 characteristic peaks in the corresponding three-dimensional spectra were selected as variables. After the principal components analysis (PCA) was used to reduce information dimensionality, it was further distinguished by HS-GC-IMS that 3Y and 5Y can be completely separated, but 15Y and 20Y were very similar and cannot be completely distinguished. The obtained results are valuable for the in-depth understanding and further study of flavors of Baiyunbian liquors.