Preparation, molecular weight determination and structure elucidation of melamine-urea-formaldehyde, melamine-methylureaformaldehyde and melamine-dimethylureaformaldehyde polymer resins with IR spectroscopy (original) (raw)
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TG-DTA study of melamine-urea-formaldehyde resins
Journal of Thermal Analysis and Calorimetry, 2008
The thermal behaviour of MUF resins from different suppliers with different content of melamine was studied, along with the 13 C NMR spectroscopic analysis of resin structure and the testing of particleboards in current production at Estonian PB factory P¬rnu Plaaditehas AS. The chemical structure of resins from DMSO-d 6 solutions was analysed by 13 C NMR spectroscopy on a Bruker AMX500 NMR spectrometer. The melamine level in different MUF resins is compared by the ratios of carbonyl carbon of urea and triazine carbon of melamine in 13 C NMR spectra. Curing behaviour of MUF resins was studied by simultaneous TG-DTA techniques on the Labsysä instrument Setaram. The shape of DTA curves characterisises the resin synthesis procedure by the extent of polymerisation of UF and MF components and is in accordance with structural data.
Syntheses and Properties of Low-Level Melamine-Modified Urea–Melamine–Formaldehyde Resins
Syntheses of urea–melamine–formaldehyde (UMF) resins were studied using 2–12% melamine levels and UF base resins that were preadvanced to various different extents. The melamine reaction was carried out at pH 6.3 with F/(U M) mole ratio of 2.1 until a target viscosity of V was reached (Gardener–Holdt) and then the second urea added at pH 8.0 to give a final F/(U M) mole ratio of 1.15. Analyses with 13 C-NMR and viscosity measurements showed that MF components react fast and the UF components very slowly in the melamine reaction. Therefore, as the extent of preadvancement of UF base resin was decreased, the reaction time to reach the target viscosity became longer and the MF resin components showed high degrees of po-lymerization. The overpolymerization of MF components resulted in increasingly more opaque resins, with viscosity remaining stable for more than a month. As the preadvance-ment of UF base resin was increased, the extent of advancement of MF components decreased, to give clearer resins, with viscosity slowly increasing at room temperature. Overall , preadvancing the UF base resin components to an appropriate extent was found to be a key to synthesizing various low-level melamine-modified UMF resins.
Jurnal Teknologi, 2003
Resin MUF yang boleh larut dalam air digunakan dengan meluas sebagai bahan pelekat dalam industri kayu, teknologi salutan, industri kertas dan merupakan bahan utama dalam penghasilan barangan dapur plastik. Sifat resin yang berbeza diperlukan dalam aplikasi yang berlainan. Sifat–sifat resin ini dipengaruhi oleh beberapa faktor iaitu nisbah mol antara formaldehid dengan melamina/urea pada setiap peringkat tindak balas dan bilangan peringkat tindak balas di mana sebatian amino ditindak balaskan. Sifat–sifat resin yang penting ialah kestabilan resin, kelarutan dalam air yang tinggi dan tempoh pengerasan yang pendek. Kajian lepas telah menghasilkan resin MUF dengan sifat–sifat ini, walau bagaimanapun ia tidak mempunyai kandungan melamina dan urea yang mencukupi, untuk menyeimbangi kos dan prestasi. Selain itu haba juga diperlukan untuk membantu memendekkan tempoh pengerasan resin. Dalam kajian ini, kesan perubahan formula ke atas sifat–sifat resin seperti kestabilan resin, kelarutan dal...
Journal of Applied Polymer Science, 2007
The preparation of an industrially used sequential formulation of a melamine-urea-formaldehyde resin was followed by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry and 13 C-NMR analysis. The analysis allowed us to identify and follow the appearance, increase, decrease, and disappearance of a multitude of chemical species during the preparation of both the initial urea-formaldehyde (UF) phase of the reaction and the subsequent reaction of melamine with the UF resin that formed. The analysis indicated that (1) the increase and decrease in the species that formed proceeded through a cycle of the formation and degradation of species occurring continuously through what appeared to be a series of complex equilibria, (2) even at the end of the reaction a predominant proportion of methylene ether bridges was still present, (3) some small proportion of methylene bridges already had formed in the UF reaction phase of the resin even under rather alkaline conditions, and (4) the addition of melamine to the UF prepolymer induced some noticeable rearrangement of methylene ether bridges to methylene bridges.
Journal of Applied Polymer Science, 2007
The preparation of an industrially used sequential formulation of a melamine-urea-formaldehyde resin was followed with Fourier transform infrared (FTIR). The analysis allowed us to identify the increases and decreases of the main groups in the resin and to compare this system of resin analysis with results previously obtained by 13 C-NMR analysis. The FTIR analysis, although considerably more limited than 13 C-NMR analysis, allowed us nonetheless to iden-tify and follow the appearance, increase, decrease, and disappearance of several of the main chemical groups during the preparation of the initial urea-formaldehyde (UF) phase of the reaction and the subsequent reaction of melamine with the UF resin that was formed.
Journal of Applied Polymer Science, 2009
ABSTRACT Melamine–formaldehyde–polyvinylpyrrolidone (MFP) polymer resin was prepared with 1 : 16 : 1 ratios of melamine, formaldehyde (CH2O), and polyvinylpyrrolidone amounts, respectively, by condensation polymerization at 6.9 pH. Structures were determined with IR, 1H-NMR, and 13C-NMR spectroscopies. Chemical shifts (δ, ppm) were analyzed with singlet at δ 4.5, duplet from 3.13 to 3.17 and a quartet at 1.5 to 2.2 ppm for methylene (CH2) bridging group, pyrrolidone, and polyvinyl constituents. The 3389.25, 1290.38, and 1655.28 cm−1 stretching frequencies of N, CH and COO groups, respectively, were noted on FTIR spectrum. The CN melamine units reacted with CH2O to adjoin with polyvinylpyrrolidone (PVP). An average viscosity molecular weight (v) 57,000 g mol−1 was obtained with Mark–Houwink–Sakurada equation. The chemical shift of N(CH2O)2Cpyrrolidone ring on 13C-NMR spectra was shifted toward lower magnetic field at 175.18 ppm. The resin was partially miscible with water thereby densities and viscosities of aqueous solutions were measured at 298.15 K temperature. It showed higher densities and viscosities than those of water. The resin developed exceptionally higher adhesive strengthen when its 62.29-μm uniform thin film was applied on surfaces of wooden strips. The resin showed micellar behavior at about 0.009 g/100 mL aqueous solution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Melamine salts as hardeners for urea formaldehyde resins
Journal of Applied Polymer Science, 2001
Various salts derived from melamine and organic acids were prepared and used as melamine substitutes for melamine urea formaldehyde (MUF) resins. The synthesis of these melamine salts and a detailed characterization of their stoichiometry are described. All salts form 1 : 1 or 1 : 2 stoichiometries in a homogeneous reaction. They crystallize during cooling of the hot and diluted reaction mixture. Both 13 C-NMR and 15 N-NMR data are reported and point toward the formation of real ionic structures. Most salts have higher water solubility than that of pure melamine and are tested for their ability to substitute melamine in MUF resins. The mechanical and chemical properties of plywood panels made up of traditional MUF resins and mixtures of UF resins with melamine salts are investigated.
BioResources, 2015
Melamine-urea-formaldehyde (MUF) resin was synthesized by adding melamine with a first and second portion of urea, named M1 and M2, respectively. Different allocation proportions of M1:M2 (4:0, 3:1, 2:2, 1:3, and 0:4) were used to develop five MUF (MUF-1, 2, 3, 4, and 5) resins with an F/(U+M) molar ratio of 1.05. The chemical structures, curing behaviors, and cross-section morphology of the resins were characterized. Three-ply plywood was fabricated to evaluate wet shear strength and formaldehyde emission. Results showed that when the melamine allocation proportion was increased from 0:4 to 4:0, the total methylene ether group content increased, the curing rate was elevated, and a heterogeneous cross-section of the cured resin formed, which led to a wet shear strength increase of 42.11%. When the melamine allocation proportion decreased, the free melamine content increased, the pot life was prolonged, and a highly homogeneous morphology was formed, which resulted in a decrease of 42.86% in formaldehyde emission of the resulting plywood. These results suggested that a high melamine allocation proportion, meaning that more of the MUF resin was added initially, improved the water resistance of the resulting resin, whereas a low melamine allocation proportion decreased the formaldehyde emission reduction of the resulting plywood.
Surface and Interface Analysis, 2000
The surface chemical characterization of melamine-formaldehyde (MF) resins by x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) is examined in this study. Melamine-formaldehyde resins with different molar ratios of formaldehyde to melamine are synthesized and thermally cured. From XPS measurements, quantitative information is obtained and atomic chemical concentrations show the effect of the molar ratio for the freeze-dried resins. However, the thermally cured resins display a rather similar surface elemental composition. Moreover, because the binding energy values of the main N-C-N and N-C-O groups are too close, XPS does not help to identify changes in chemical structure after curing.