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.
Enzymatic features of DNA polymerase that account for its inability to copy one of the DNA strands a
The brain. (a) Superior (top) view. (b) Sagittal view of a sectioned brain to reveal internal featur
This graphic illustrates the original systems model of politics advanced by David Easton. Politics
Prolonged abuse leads to production of stress hormones that can lead to a cascade of effects ...
Structural classes of neurons.
Structural basis for Ras activation by GTP