Creating formaldehyde free phenolic resin systems especially for indoor application is a challenging research question. We are looking for various possibilities.
Also novolak has the same problem. Commonly it is crosslinked with hexamethylenetetramine which is also a formaldehyde derivative. There are some approaches to harden novolak with 5-hydroxymethylfurfural or directly with glucose which forms 5-hydroxymethylfurfural in situ. Perhaps also glyoxal can be used to harden novolaks. Furthermore hardening of novolaks is possible with isocyanates or epoxides, but this change completely the character of the thermoset.
Shelf life is the time of storage until the viscosity becomes to high. I do not know the exact definition which increase of viscosity can be tolerated. The viscosity is increased by self-curing at storage temperature.
La tesina tipo resole es manufacturada en condicionrs alcalinas ybpir lo tanto es muy exotermica. Para evitar las emanaciones de formaldehido debe tener un buen intercambiador para que el material decreflujo retorne a menos de 60 grados Celsius. Por bioseguridad, recomiendo usar un equipo de afaorcion en la linea del tubo de venteo que sale del intercambiador de calor. Te lo explico en español porque me expreso mejor en mi idioma.
Dear all
I'm using hexamine as a curing agent for novolak type for making thermoset adhesive, but i have 2 problems:
1. It needs 200 C for curing but i can just give it 170 c temperature because of my condition
2. It is so brittle
Now how can i solve it??
I use methanol as solvent without adding acid or base like NaOH
Can any one guide me about this
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