Abstract
It was observed that the curing time of two-stage phenolics considerably decreased when adducts made from hexamine and some reactive phenols were formulated and used as a hardener for novolac instead of hexamine by itself. The preparative methods were studied to get adducts with high yield from hexamine and twelve kind of phenols.
The curing behavior of novolac with these adducts was studied by stroke-cure gel time test, disc-curemetry and cureastometry. The mechanism of increased cure rate of novolac with these adducts was also discussed.
Molding compounds was prepared from novolac 100 pt., hexamine 12. 5 pt., wood flour 100 pt. and. Zn-stearate 2 pt. as a reference following the usual technique. A series of compounds were also prepared under the same conditions using these adducts as a hardener of novolac to examine the effects of the adducts on the properties of cured resins. In this case, the amount of adducts used was decided upon according to the chemical composition of adducts, i. e., all compounds were prepared to contain equivalent amounts of hexamine.
The properties of compression-molded test pieces made from a series of molding compounds containing adducts were about the same order as that of the reference moldings.
However, curing rate and properties of moldings were lowered when molding compounds were prepared using the mixture consisting of equivalent amount of hexamine and phenols instead of adducts.
