Reinforcing novolac phenol formaldehyde resin

HMMM can also be used with reinforcing novolac phenol formaldehyde resins to harden a cured rubber compound. For example, these reactive PF resins might be used in the bead area or the tread compound of a tire in order to increase hardness. 

Most processors of fiber-reinforced composites choose a phenol formaldehyde (phenoHc) resin because these resins are inherently fire retardant, are highly heat resistant, and are very low in cost. When exposed to flames they give off very Htde smoke and that smoke is of low immediate toxicity. PhenoHc resins (qv) are often not chosen, however, because the resole types have limited shelf stabiHty, both resole and novolac types release volatiles during their condensation cure, formaldehyde [50-00-0] emissions are possible during both handling and cure, and the polymers formed are brittle compared with other thermosetting resins. 

Novoloid fiber A phenolic fiber made by cross-linking a melt-spun novolac resin with formaldehyde. Novoloid fibers have good flame resistance, can serve at temperatures to about 220°C, and are used as reinforcement in a range of thermosetting matrices. 

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