Characterization of different tannins for possible industrial resin production
Liang, Shujun (2022)
2022
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2022090557506
https://urn.fi/URN:NBN:fi-fe2022090557506
Tiivistelmä
Tannins are the fourth most abundant component in plant material after cellulose, hemicellulose, and lignin, and have received extensive attention due to their high content of phenolic and carboxyl groups. The earliest use of tannins can be traced back to the Neolithic Age for leather making. Although many researchers have tried to describe tannins in detail, the properties obtained from different sources by different analytical methods vary greatly. In order to tailor the commercial use of tannins, it is very important to characterize tannin samples before commercial applications.
In this thesis, six kinds of tannins were extensively characterized with various methods to explore the differences between different industrial processed tannins, and their feasibility as a substitute for petroleum-derivative phenol in the production of resins.
First, the physical properties of the tannins were determined, including pH, moisture content, ash content and elemental analysis. The elemental analysis was performed on crude tannins and tannin ash using SEM-EDS. In this thesis, DSC and TGA characterization of crude tannins were performed to provide thermogravimetric information. In addition, GPC and FT-IR methods were used to determine the molar mass and functional groups of tannins, respectively.
Secondly, in order to investigate the composition of tannins in addition to moisture and ash content, ASE with six solvents of increasing polarity was used to sequentially extract the crude tannins, and the extracts were analyzed by SEC-MALS. Acid hydrolysis and methanolysis combined with GC analysis techniques were used to determine the composition of cellulose and non-cellulosic polysaccharides in crude tannins and short column GC combined with GC-MS was used for qualitative and quantitative analysis of the extracts.
Finally, pyrolysis-GC MS and different NMR analysis techniques including 13C, HSQC and 31P NMR were used to determine the structure of the tannin molecules.
The results show that the different methods described above can effectively characterize the obtained tannin samples and provide information for their possible industrial application.
In this thesis, six kinds of tannins were extensively characterized with various methods to explore the differences between different industrial processed tannins, and their feasibility as a substitute for petroleum-derivative phenol in the production of resins.
First, the physical properties of the tannins were determined, including pH, moisture content, ash content and elemental analysis. The elemental analysis was performed on crude tannins and tannin ash using SEM-EDS. In this thesis, DSC and TGA characterization of crude tannins were performed to provide thermogravimetric information. In addition, GPC and FT-IR methods were used to determine the molar mass and functional groups of tannins, respectively.
Secondly, in order to investigate the composition of tannins in addition to moisture and ash content, ASE with six solvents of increasing polarity was used to sequentially extract the crude tannins, and the extracts were analyzed by SEC-MALS. Acid hydrolysis and methanolysis combined with GC analysis techniques were used to determine the composition of cellulose and non-cellulosic polysaccharides in crude tannins and short column GC combined with GC-MS was used for qualitative and quantitative analysis of the extracts.
Finally, pyrolysis-GC MS and different NMR analysis techniques including 13C, HSQC and 31P NMR were used to determine the structure of the tannin molecules.
The results show that the different methods described above can effectively characterize the obtained tannin samples and provide information for their possible industrial application.