1. What is the difference between acid and base catalyst Phenolic polymers? How to
prepare prepolymers and how to make crosslinked Phenolic polymers?
Solution:
1. Base/alkaline catalyst phenolic polymers are result from strong base-catalyzed
polymerization that yields resole prepolymers also known (resole phenolics).
Whereas Acid catalyst phenolic polymers are results from reaction which is
accomplished by heating 2-4 hr at reflux temperature in presence of an acid
catalyst (1-2%) also known as Novolac Phenolics.
2. Base catalyst phenolic polymers produced via B-staging (system close to gel point
Pc) while Acid catalyst phenolic polymers are made by pre-polymerization.
3. Resole phenolics / base catalyzed phenolic polymers are methylol-bearing groups
increasing phenol reactivity whereas Novolac phenolic / acid catalyst phenolic
polymer are non-methylol bearing groups.
4. Resole phenolics typically have a shelf life of less than 1 year (and < 60 days)
while Novolacs have an infinite shelf life.
5. During curing process, base catalyst phenolic polymers split off water while acid
catalyst phenolic polymers split off ammonia.
6. Acid catalyst phenolic polymers are twice dimensionally stable than base catalyst
phenolic polymers.
7. Resole phenolics are typically casting and bonding polymers, whereas molding
compounds are made from Novolac phenolics. Of course, some molding
compounds can be made from resole phenolics.
8. Base catalyzed phenolic polymers are usually liquids whereas acid catalyzed
phenolic polymers are solids. [1]
prepare prepolymers and how to make crosslinked Phenolic polymers?
Solution:
1. Base/alkaline catalyst phenolic polymers are result from strong base-catalyzed
polymerization that yields resole prepolymers also known (resole phenolics).
Whereas Acid catalyst phenolic polymers are results from reaction which is
accomplished by heating 2-4 hr at reflux temperature in presence of an acid
catalyst (1-2%) also known as Novolac Phenolics.
2. Base catalyst phenolic polymers produced via B-staging (system close to gel point
Pc) while Acid catalyst phenolic polymers are made by pre-polymerization.
3. Resole phenolics / base catalyzed phenolic polymers are methylol-bearing groups
increasing phenol reactivity whereas Novolac phenolic / acid catalyst phenolic
polymer are non-methylol bearing groups.
4. Resole phenolics typically have a shelf life of less than 1 year (and < 60 days)
while Novolacs have an infinite shelf life.
5. During curing process, base catalyst phenolic polymers split off water while acid
catalyst phenolic polymers split off ammonia.
6. Acid catalyst phenolic polymers are twice dimensionally stable than base catalyst
phenolic polymers.
7. Resole phenolics are typically casting and bonding polymers, whereas molding
compounds are made from Novolac phenolics. Of course, some molding
compounds can be made from resole phenolics.
8. Base catalyzed phenolic polymers are usually liquids whereas acid catalyzed
phenolic polymers are solids. [1]
