Editing Epoxy (section)

=== Novolaks ===
[[file:Epoxyphenol-Novolak.svg|thumb|General structure of epoxyphenol novolak with ''n'' usually in the range from 0 to 4. The compound is present in the form of various [[Structural isomer|constitutional isomers]].]]

[[Novolak]]s are produced by reacting [[phenol]] with [[methanal]] ([[formaldehyde]]). The reaction of [[epichlorohydrin]] and [[novolak]]s produces novolaks with [[Glycidol|glycidyl residues]], such as epoxyphenol novolak (EPN) or epoxycresol novolak (ECN). These highly viscous to solid resins typically carry 2 to 6 epoxy groups per molecule. By curing, highly cross-linked polymers with high temperature and chemical resistance but low mechanical flexibility are formed due to the high functionality, and hence high crosslink density of these resins.<ref name="Ullmann">{{cite book |doi=10.1002/14356007.a09_547.pub2 |chapter=Epoxy Resins |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2005 |last1=Pham |first1=Ha Q. |last2=Marks |first2=Maurice J. |isbn=978-3-527-30385-4 }}</ref>