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Author Question: What are the structural features in the melamine monomer that lead to the very high hardness of ... (Read 10 times)

penza

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on: Aug 19, 2018
What are the structural features in the melamine monomer that lead to the very high hardness of cured melamine resins?
 
  What will be an ideal response?

Question 2

Compare the processing differences of resole and novolac resin. What is meant by one-stage and two-stage resins?
 
  What will be an ideal response?


Carliemb17

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Reply #1 on: Aug 19, 2018
Answer to Question 1

The melamine monomer has three amine groups attached to the ring, with each amine group containing a nitrogen and two hydrogens. Each of these nitrogens is capable of being a crosslinking site. Therefore, the hardness in melamine plastics comes from the very high crosslink density that is possible because of the multiple crosslink sites.

Answer to Question 2

Resole and novolac resins are both types of phenolics. The resole resins are linear polymers that are cured simply by heating, while the novolacs must have a hardener added to them and then heated to cure. The resoles are, therefore, one-stage polymers, meaning that only one step is needed to complete the crosslinking, whereas the novolacs are two-stage polymers.


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