I would like to know if there is a methodology to quantife lignin in phenolic resins (resol). I want to clairy some hypothesys during the synthesis of phenolic resins with lignin:
1) If all the lignin added in the synthesis of phenolic resins (resol), is structural linked in the network of phenolic resin;
2) If part of lignin is not linked in the structure of the resin and it's like a filler
Best regards,
Gustavo
Dear Gustavo R. O. A. Tanobe, lignine contain phenolic in addition to other reactive groups with formaldehyde. It is highly expected to react, since many studies are investigating the replacement of phenol with lignin. Please have a look at the following document. My Regards
https://doi.org/10.1163/156856100743167
You can also use ASTM D 1106 protocol for calculation of acid-insoluble lignin
Dear Gustavo R.O.A. Tanobe
I totally agree with dear Abdelkader Bouaziz.
Just as a part of urea does not react in formaldehyde with urea, and a part of formaldehyde is present, an unreacted part may be found in the lignin-formaldehyde adhesive.
After the synthesis, it is correct to think of dissolved unreacted lignin as a filler material. The thermoplastic structure of lignin will contribute to adhesion and enhance mechanical properties.
However, finding this with acid-insoluble lignin will technically lead you to an error, because after the glue hardens, the formaldehyde amount will be added in a 3-dimensional structure.
best regards
Article Use of lignins in phenolic resins: 1. Preparation of novolac...
After synthesis, we need to characterize the following properties:
-Molecular weight (GPC)
- Compositional analysis (HPLC, measuring carbohydrate content)
- TGA and DSC (thermal properties, thermal stability, and Tg)
- Hydroxyl content (31P NMR)
- HSQC NMR (provides information about the structure of lignin, mainly interunit linkages)
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