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http://dx.doi.org/10.5658/WOOD.2014.42.5.605

Microstructure of Cured Urea-Formaldehyde Resins Modified by Rubber Latex Emulsion after Hydrolytic Degradation  

Nuryawan, Arif (Department of Wood and Paper Sciences, Kyungpook National University)
Park, Byung-Dae (Department of Wood and Paper Sciences, Kyungpook National University)
Publication Information
Journal of the Korean Wood Science and Technology / v.42, no.5, 2014 , pp. 605-614 More about this Journal
Abstract
This study investigated microstructural changes of cured urea-formaldehyde (UF) resins mixed with aqueous rubber latex emulsion after intentional acid etching. Transmission electron microscopy (TEM) was used in order to better understand a hydrolytic degradation process of cured UF resins responsible for the formaldehyde emission from wood-based composite panels. A liquid UF resin with a formaldehyde to urea (F/U) molar ratio 1.0 was mixed with a rubber latex emulsion at three different mixing mass ratios (UF resin to latex = 30:70, 50:50, and 70:30). The rate of curing of the liquid modified UF resins decreased with an increase of the rubber latex proportion as determined by differential scanning calorimetry (DSC) measurement. Ultrathin sections of modified and cured UF resin films were exposed to hydrochloric acid etching in order to mimic a certain hydrolytic degradation. TEM observation showed spherical particles and various cavities in the cured UF resins after the acid etching, indicating that the acid etching had hydrolytically degraded some part of the cured UF resin by acid hydrolysis, also showing spherical particles of cured UF resin dispersed in the latex matrix. These results suggested that spherical structures of cured UF resin might play an important role in hindering the hydrolysis degradation of cured UF resin.
Keywords
acid hydrolysis; cured urea-formaldehyde resin; microstructure; rubber latex; spherical particles; transmission electron microscopy;
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1 Abdullah, Z.A., Park, B.D. 2009. Hydrolytic stability of cured urea-formaldehyde resins modified by additives. Journal of Applied Polymer Science 114: 1011-1017.   DOI   ScienceOn
2 Bar, G., Ganter, M., Brandsch, R., Delineau, L., Whangbo, M.H. 2000. Examination of butadiene/styrene-co-butadiene rubber blends by tapping mode atomic force microscopy. Importance of the indentation depth and reduced tip-sample energy dissipation in tapping mode atomic force microscopy study of elastomers. Langmuir 16(13): 5702-5711.   DOI   ScienceOn
3 Bikaris, D.N., Papageorgiou, G.Z., Achilias, D.S. 2006. Synthesis and comparative biodegradability studies of three poly(alkylene succinate)s. Polymer Degradation and Stability 91: 31-43.   DOI   ScienceOn
4 Chuang, I.S., Maciel, G.E. 1994. NMR study of the stabilities of urea-formaldehyde resin components toward hydrolytic treatments. Journal of Applied Polymer Science 52: 1637-1651.   DOI
5 Ringena, O., Janzon, R., Pfizenmayer, G., Schulte, M., Lehnen, R. 2006. Estimating the hydrolytic durability of cured wood adhesives by measuring formaldehyde liberation and structural stability. HolzalsRoh- und Werkstoff 64: 321-326.   DOI   ScienceOn
6 Roffael, E., Huster, H.-G. 2012. Complex chemical interactions on thermo hydrolytic degradation of urea formaldehyde resins (UF-resins) in recycling UF-bonded boards. European Journal of Wood and Wood Products 70: 401-405.   DOI
7 Singh, A.P., Nuryawan, A., Park, B.D. 2013. A novel sample preparation method that enables ultrathin sectioning of urea-formaldehyde resin for imaging by transmission electron microscopy. Microscopy Research 1: 1-6.   DOI
8 Singh, A.P., Causin, V., Nuryawan, A., Park, B.D. 2014. Morphological, chemical and crystalline features of urea-formaldehyde resin cured in contact with wood. European Polymer Journal 56: 185-193.   DOI
9 Spurr, R.A., Erath, E.H., Myers, H., Pease, D.C. 1957. Curing process in phenolic resin electron-microscopic analysis. Industrial & Engineering Chemistry 49(11): 1839-1842.   DOI
10 Stuligross, J., Koutsky, J.A. 1985. A morphological study of urea-formaldehyde resins. Journal of Adhesion 18: 281-299.   DOI
11 Park, B.D., Jeong, H.W. 2011a. Influence on hydrolytic degradation on the morphology of cured urea-formaldehyde resins of different formaldehyde/urea mole ratios. Journal of the Korean Wood Science and Technology 39(2): 179-186.   과학기술학회마을   DOI
12 Tohmura, S., Hse, C.Y., Higuchi, M. 2000. Formaldehyde emission and high-temperature stability of cured urea-formaldehyde resins. Journal of Wood Science 46: 303-309.   DOI   ScienceOn
13 Myers, G.E., Koutsky, J.A. 1990. Formaldehyde liberation and cure behavior of urea-formaldehyde resins. Holzforschung 44: 117-126.   DOI
14 Park, B.D., Kang, E.C., Park, J.Y. 2006. Effects of formaldehyde to urea mole ratio on thermal curing behavior of urea-formaldehyde resin and properties of particleboard. Journal of Applied Polymer Science 101: 1787-1792.   DOI   ScienceOn
15 Park, B.D., Jeong, H.W. 2011b. Hydrolytic stability and crystallinity of cured urea-formaldehyde resin adhesives with different formaldehyde/urea mole ratios. International Journal of Adhesion and Adhesives 31: 524-529.   DOI
16 Pratt, T.J., Johns, W.E., Rammon, R.M., Plagemann, W.L. 1985. A novel concept on the structure of cured urea-formaldehyde resin. The Journal of Adhesion 17: 275-295.   DOI   ScienceOn
17 Park, B.D., Jeong, H.W. 2011c. Effects of acid hydrolysis on microstructure of cured urea-formaldehyde resins using atomic force microscopy. Journal of Applied Polymer Science 122: 3255-3262.   DOI
18 Park, B.D., Causin, V. 2013. Crystallinity and domain size of cured urea-formaldehyde resin adhesives with different formaldehyde/urea mole ratios. European Polymer Journal 49: 532-537.   DOI
19 Park, B.D., Singh, A.P., Nuryawan, A., Hwang, K. 2013. MRT Letter: High resolution SEM imaging of nano-architecture of cured urea-formaldehyde resin using plasma coating of osmium. Microscopy Research and Technique 76: 1108-1111.   DOI
20 Racich, J.L., Koutsky, J.A. 1976. Nodular structure in epoxy resins. Journal of Applied Polymer Science 20: 2111-2129.   DOI
21 Depres, A., Pizzi, A. 2006. Colloidal aggregation of aminoplastic polycondensation resins: urea-formaldehyde versus melamine-formaldehyde and melamine-urea-formaldehyde resins. Journal of Applied Polymer Science 100: 1406-1412.   DOI   ScienceOn
22 Dusek, K. 1996. Are cured thermoset resins inhomogeneous? Die Angewandte Makromolekulare Chemie 240: 1-15.   DOI
23 Dutkiewicz, J. 1983. Hydrolytic degradation of cured urea-formaldehyde resin. Journal of Applied Polymer Science 28: 3313-3320.   DOI
24 Dutkiewicz, J. 1984. Preparation of cured urea-formaldehyde resins of low formaldehyde emission. Journal of Applied Polymer Science 29: 45-55.   DOI
25 Irle, M.A., Bolton, A.J. 1988. Physical aspects of wood adhesive bond formation with formaldehyde based adhesives. Part II. Binder physical properties and particleboard durability. Holzforchung 42: 53-58.   DOI
26 Ebewele, R.O., Myers, G.E., River, B.H., Koutsky, J.A. 1991. Polyamine-modified urea-formaldehyde resins. I. Synthesis, structure, and properties. Journal of Applied Polymer Science 47: 2997-3012.
27 Ferra, J.M.M., Mendes, A.M., Costa, M.R.N., Carvalho, L.H., Magalhaes, F.D. 2010. A study on the colloidal nature of urea-formaldehyde resins and its relation with adhesive performance. Journal of Applied Polymer Science 118: 1956-1968.
28 Gupta, V.B., Drzal, L.T., Adams, W.W. 1985. An electron microscopic study of the morphology of cured epoxy resin. Journal of Material Science 20: 3439-3452.   DOI   ScienceOn
29 John, W.E., Dunker, A.K. 1986. Urea-formaldehyde resin. In: Meyer B, Andrew BAK, Reinhardt RM, eds. Formaldehyde release from wood products. The American Chemical Society, pp. 76-86.
30 Motter, W.K. 1990. The formation of the colloidal phase in low mole ratio urea-formaldehyde resins. PhD Dissertation. Department of Mechanical and Materials Engineering. Washington State University, Pullman, USA.