Infrarotspektroskopische Untersuchungen an Harnstoff‐Formaldehyd‐Feststoffen

Schmolke, R.; Dietrich, K.; Nastke, R.; Kunath, D.; Teige, W.

doi:10.1002/actp.1987.010381007

Cited by 4 publications

(1 citation statement)

References 14 publications

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“…Uočeno je da molski odnos F/U ispod 1,25 favorizuje nastajanje linearnih lanaca metiloluree, dok se pri većem molskom odnosu stvaraju etarske veze. Pored toga, u jako kiselim uslovima uočeno je stvaranje cikličnih, uronskih struktura [35]. Metoda IR spektroskopije korišćena je i za proučavanje mehanizama toplotne degradacije kod UF polikondenzacionih produkata, pri čemu je uočeno je da se tokom zagrevanja do 500 o C toplotna degradacija odvija u četiri sekvence.…”

Section: Metoda Infra-crvene Spektroskopijeunclassified

Curing of urea-formaldehyde adhesive for particleboards in the presence of some domestic wood species

Popović¹

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In this doctorate dissertation, the influence of beech, fir and poplar wood species on curing kinetics of commercial urea-formaldehyde (UF) adhesive was investigated. With this objective, the following thermal analysis methods were utilized: differential scanning calorimetry (DSC), dielectric analysis (DEA) and dynamical mechanical analysis (DMA). DSC measurements were obtained in dynamical scanning regime with the heating rates (β) of 5; 10; 15 i 20 o C/min. Test samples consisted of pure UF adhesive, UF adhesive / wood flour mixes and UF adhesive / wood extractives mixes of selected wood species. Catalyst (NH 4 Cl) addition was 0.2% (per oven dry weight) for all test samples. Results of peak temperature (T p ), enthalpy of reaction (ΔH), and activation energy (E a ) were analyzed for each UF adhesive system. In addition, the isoconverzional models of Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) were applied on the DSC test data.DEA tests proceeded in the isothermal regime in the real hot pressing conditions using veneer samples of the selected wood species as adherents. UF adhesive was applied with the NH 4 Cl addition of 0.2% (per oven dry weight). Press temperatures were 120; 140 i 160 o C. Dielectric parameters were recorded through IDEX sensor applied on the bond line of veneer samples and connected to LCR meter. Degree of reaction (α) was obtained on the basis of electric conductivity. DMA rheological tests were performed in the sinusoidal shear stress regime at the temperature of 80 o C. Test samples consisted of pure UF adhesive and the UF adhesive / wood extractives mixes. Two separate sample series were used, one with the NH 4 Cl addition of 0.2% (per oven dry weight) and the other without catalyst addition. Gel time was determined at the crossover of the storage modulus (G') and loss modulus (G"), resulting in the loss factor tanδ=1.Results of DSC and DMA tests on UF adhesive / wood extractive mixes, showed significant influence of pH value and acid buffer capacity of selected wood species on kinetics of curing reaction. Lower values of said chemical characteristics of a given extractive, resulted in decrease of peak temperature and activation energy, as well as in shorter gel time for a corresponding mixture. Both, DSC measurements of UF adhesive / wood flour mixtures and DEA results of UF adhesive cure in the hot pressed veneer samples, have showed significant influence of wood anatomy structure on curing behavior of UF adhesive.

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Section: Metoda Infra-crvene Spektroskopijeunclassified

Curing of urea-formaldehyde adhesive for particleboards in the presence of some domestic wood species

Popović¹

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Strukturcharakterisierung von Polymeren mit physikalischen Methoden

Fink¹,

Geiß²,

Walenta³

et al. 1989

Acta Polymerica

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Die kombinierte Anwendung der IR‐ und NMR‐Spektroskopie, der Röntgenklein‐ und ‐weitwinkelstreuung und elektronenmikroskopischer Methoden wird an ausgewählten Beispielen von Polymerfestkörpern demonstriert. Neuere Ergebnisse zu PE‐Strukturen einschließlich hochfester/hochmoduliger Fasern, zur strukturellen Erklärung von PVDF‐Polarisationseffekten sowie zu Strukturveränderungen der Cellulose infolge Natronlaugebehandlungen werden vorgestellt. Die Schlüsselrolle der IR‐Spektroskopie für die Analyse chemischer Strukturen wird an Beispielen aufgezeigt.

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Analytik und Prüfverfahren für Bindemittel und Holzwerkstoffe

Dunky

Niemz

2002

Holzwerkstoffe Und Leime

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Infrarotspektroskopische Untersuchungen an Harnstoff‐Formaldehyd‐Feststoffen

Cited by 4 publications

References 14 publications

Curing of urea-formaldehyde adhesive for particleboards in the presence of some domestic wood species

Curing of urea-formaldehyde adhesive for particleboards in the presence of some domestic wood species

Strukturcharakterisierung von Polymeren mit physikalischen Methoden

Analytik und Prüfverfahren für Bindemittel und Holzwerkstoffe

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