Halogenated Polyhydrocarbons with Aromatic Rings in the Backbone

2 HALOGENATED POLYHYDROCARBONS WITH AROMATIC RINGS IN THE BACKBONE 

The polymers from this group show excellent thermal stability when they do not contain hydrogens, for example, when they are perfluorinated. Compounds having both hydrogen and a halogen (such as fluorine) eliminate the hydrohalogenated acid (HF, HCI, etc.) at lower temperatures. Some literature reports on thermal decomposition for this group of compounds are indicated in Table 8.2.1 [1]. 

3 THERMOSETTING PHENOLIC RESINS AND RELATED POLYMERS - General aspects 

Thermosetting phenolic resins include a number of polymers, the most common being obtained from the condensation of phenol with formaldehyde. The OH group on the benzene ring increases the reactivity in the o- and p- positions leading to three reactive centers for the phenolic component, while formaldehyde acts as having two active centers that can lead to a fully crosslinked polymer. The process may take place in neutral or alkaline conditions when in the first stage of the reaction, compounds known as methylol derivatives are formed. The condensation of phenol with formaldehyde occurs randomly at ortho- or para- position of the phenol, as shown below  

The methylol derivatives under mild heating for a limited time further react forming fusible polymers that are not yet fully crosslinked, as shown below  

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