30 сентября, 2015 
Malyar The various components and raw materials of the resins can be determined using different chemical methods (Table 19). The content of total formaldehyde is accessible by hydrolysis of an aminoplastic resin; this process, however, is not possible for PF resins. Urea can be determined in the easiest way from the resin nitrogen content. However, other possible
Component urea
melamine
phenol
formaldehyde (total formaldehyde, methylol groups) alkali (free alkali, total alkali, ash)
Analysis of residual monomers free formaldehyde
unreacted urea free phenol
Molar ratios F/U for a straight UF resin
F/M for an MF resin F/(NH2)2 for an MUF resin F/P or F/P/NaOH for a PF resin
sources of nitrogen have to be taken into account. Melamine is measured via a UV method after hydrolysis in dilute hydrochloric acid. The content of phenol and of the total formaldehyde in PF resins can only be determined by NMR. Residual monomers such as free formaldehyde, unreacted urea, and residual phenol or methanol as a residual product of formaldehyde production can be determined by various methods, e. g., free phenol via high performance liquid chromatography (HPLC).
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