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This work investigates five reactions between melamine (M) and formaldehyde (F) at pH ¼ 9.0, and with initial F : M ratios of 2. The samples were analyzed by size exclusion chromatography (SEC), volumetric techniques, and (1H and 13C) NMR. Condensation was quantified by the SEC measurements. In the experiments at 38 and 48C, condensation was almost negligible, and the reversibility of methylolation reactions determined that equilibriums were reached in the ratios between primary, secondary, and tertiary amines. In the experiments at 60, 70, and 90C, condensation was significant, but in all cases, the mass fraction of single-ringed species was larger than that of species with two or more rings per molecule. The following were estimated by combining the SEC and volumetric measurements: number-average molecular weights, and average functionalities of reactive Hs, methylols, methylene bridges, and ether bridges. The dissolution of M in water was essentially instantaneous. The measurements are employed in the next article of this series for adjusting a novel mathematical model¼ 9.0, and with initial F : M ratios of 2. The samples were analyzed by size exclusion chromatography (SEC), volumetric techniques, and (1H and 13C) NMR. Condensation was quantified by the SEC measurements. In the experiments at 38 and 48C, condensation was almost negligible, and the reversibility of methylolation reactions determined that equilibriums were reached in the ratios between primary, secondary, and tertiary amines. In the experiments at 60, 70, and 90C, condensation was significant, but in all cases, the mass fraction of single-ringed species was larger than that of species with two or more rings per molecule. The following were estimated by combining the SEC and volumetric measurements: number-average molecular weights, and average functionalities of reactive Hs, methylols, methylene bridges, and ether bridges. The dissolution of M in water was essentially instantaneous. The measurements are employed in the next article of this series for adjusting a novel mathematical model1H and 13C) NMR. Condensation was quantified by the SEC measurements. In the experiments at 38 and 48C, condensation was almost negligible, and the reversibility of methylolation reactions determined that equilibriums were reached in the ratios between primary, secondary, and tertiary amines. In the experiments at 60, 70, and 90C, condensation was significant, but in all cases, the mass fraction of single-ringed species was larger than that of species with two or more rings per molecule. The following were estimated by combining the SEC and volumetric measurements: number-average molecular weights, and average functionalities of reactive Hs, methylols, methylene bridges, and ether bridges. The dissolution of M in water was essentially instantaneous. The measurements are employed in the next article of this series for adjusting a novel mathematical modelC, condensation was almost negligible, and the reversibility of methylolation reactions determined that equilibriums were reached in the ratios between primary, secondary, and tertiary amines. In the experiments at 60, 70, and 90C, condensation was significant, but in all cases, the mass fraction of single-ringed species was larger than that of species with two or more rings per molecule. The following were estimated by combining the SEC and volumetric measurements: number-average molecular weights, and average functionalities of reactive Hs, methylols, methylene bridges, and ether bridges. The dissolution of M in water was essentially instantaneous. The measurements are employed in the next article of this series for adjusting a novel mathematical modelC, condensation was significant, but in all cases, the mass fraction of single-ringed species was larger than that of species with two or more rings per molecule. The following were estimated by combining the SEC and volumetric measurements: number-average molecular weights, and average functionalities of reactive Hs, methylols, methylene bridges, and ether bridges. The dissolution of M in water was essentially instantaneous. The measurements are employed in the next article of this series for adjusting a novel mathematical model