In this case, it is present in LPF and it becomes more intense with increasing percentage of lignin in LPF resin from 35% to 50%. DOI: 10.1002/app.2119, Alonso, M. V., Oliet, M., Rodriguez, F., Astarloa, G., and Echeverria, J. M. (2004). Wolfgang Hesse "Phenolic Resins" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. The increase in viscosity of lignin-phenol formaldehyde resin with higher percent substitutions can be attributed to incorporation of high lignin content with a high molecular weight compared to phenol in the modified phenolic resins. It was developed by the Belgian-American chemist Leo Baekeland in Yonkers, New York, in 1907. The base material choice depends on the intended application of the finished product. Développement de Nouveaux Adhésifs Bases sur des Dérivés de la Lignine, Ph.D. Dissertation, UMI Dissertation Services. Finally, 10 mL of a hydroxylamine-hydrochloride solution (10%, w/w) was added. The results of the characterization of modified phenolic resins, including pH, gel time, viscosity at 25 °C, solids content, and free formaldehyde, are recorded in Table 1 together with the experimental conditions. Analysis of variance (Table 5) showed that viscosity was significantly influenced by all the studied parameters, and the cross-terms (L(%))*[F/(P+L)] and[F/(P+L)]*[S/(P+L)] at the p=0.05 significance level. Gardziella, A., Pilato, L.A., Knop, A. “Lignocellulosic ethanol residue-based lignin-phenol-formaldehyde resin adhesive,” International Journal of Adhesion and Adhesives 40, 11-18. At this point the resin is a 3-dimensional network, which is typical of polymerised phenolic resins. Supplied into the commercial formaldehyde market, it’s also vertically integrated as a raw material into phenolic resin and amino resins production. “Characterization and structural modification of ammonic lignosulfonate by methylolation,” Journal of Applied Polymer Science 82(11), 2661-2668. Phenol-formaldehyde resin is "like" a one-way street; once formed, it cannot be turned back into the starting points & get additives from it according to our present knowledge. The obtained resins were cooled and stored at lower temperature pending to analysis. Sellers, T., Lora, J. H., and Okuma, M. (1994). The partial substitution of phenol by fillers or extenders is one way to reduce the price of these resins. 2001).The band observed at 1386 cm-1 in LPF is attributed to lignin, which is assigned to C-O of syringyl unit present in lignin. It has great moisture resistance, low cost and good thermal and flame resistance. (2006). The resin fully polymerizes (cures) during this process forming the thermoset polymer matrix. Lignins are currently produced by several pulping and ethanol processes, but only lignosulfonates and kraft lignin are available in large quantities (Gosselink et al. 2004; Vishtal and Kraslawski 2011). Experimental Conditions and Properties of Synthesized Modified Phenol Formaldehyde Resins. Estimated response surface for gel time at [F/(P+L)]=2.2, L(%) vs.[S/(P+L)]. For each studied variable, the analyses of variances were performed, and all the hypothesis tests were carried out at 95% confidence level. (2016). The feature common to all composite processes is the combining of a resin, a curing agent, some type of reinforcing fiber, and in some cases a solvent. The base material choice depends on the intended application of the finished product. Structure of PF resin and lignin (Forss and Fuhrmann 1979). 2017). 5) shows that for [S/(P+L)]=1.2 molar ratio, the viscosity increased with increase of lignin content (in lower [F/(P+L)] region) and [F/(P+L)] molar ratio. Fernández-Rodríguez, J., Erdocia, X., Sánchez, C., González Alriols, M., and Labidi, J. (eds. 2006; Ghorbani et al. Novolacs have multiple uses as tire tackifier, high temperature resin, binder for carbon bonded refractories, carbon brakes, photoresists and as a curing agent for epoxy resins. DOI: 10.15376/biores.6.3.3515-3525, Hoareau, W., Oliveira, F. B., Grelier, S., Siegmund, B., Frollini, E., and Castellan, A. In industrial practice, there are two basic methods for making the polymer into useful resins. 2016). The bands in the region of 850to750 cm-1 are due to the trisubstituted benzene ring and confirm the formation of a three dimensional network structure. Similarly, these bands are also present in LPF with 35% and 50% of lignin. Table 1. 2015; Fernandez-Rodriguez et al. 2018). A slow cure lead to longer pressing time, and therefore the manufacture of the plywood must be expensive. where X1, X2, and X3 are the values of L(%), [F/(P+L)], and [S/(P+L)], respectively after normalization to the interval [-1,1]. Results obtained were discussed according to the requirements for adhesives utilization in plywood manufacture, and the optimum operating conditions were selected. This is why novolacs (F:P <1) do not harden without the addition of a crosslinking agents, and why resoles with the formula F:P >1 will. Peng, W. (1994). 2000; Zhang et al. (2017) confirm a similar trend of increasing viscosities of lignin-based phenolic resins with increasing lignin replacement (Cheng et al. DOI:10.15376/biores.11.3.6867-6879. The rate of the base-catalysed reaction initially increases with pH, and reaches a maximum at about pH = 10. Phenolic laminates are made by impregnating one or more layers of a base material such as paper, fiberglass, or cotton with phenolic resin and laminating the resin-saturated base material under heat and pressure. Phenolic resins are used in adhesives, coatings, and molding compounds. Exterior plywood, oriented strand boards (OSB), engineered laminated composite lumber (LCL) are typical applications. The results obtained for solid content were between 41 and 45%. Phenol-formaldehyde resins, as a group, are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed. 7. The prepared resins were characterized according to gel time, solids content, viscosity, and free formaldehyde.The values for these parameters must be in agreement with commercial resins specifications applied for plywood. The initial reaction in all cases involves the formation of a hydroxymethyl phenol: The hydroxymethyl group is capable of reacting with either another free ortho or para site, or with another hydroxymethyl group. In this research work, modified phenol-formaldehyde resins were prepared using hydroxymethylated alkaline rice straw lignin as a substitute for petroleum-based phenol in the range of 20 to 50% by weight. DOI: 10.1016/j.ijadhadh.2015.10.010, Zhang, W., Ma, Y., Xu, Y., Wang, C., and Chu, F. (2013). 2015; Ma et al. TCC phenolic resins are found in a myriad of industrial products. “Sustainable bio-based phenol-formaldehyde resoles using hydrolytically depolymerized kraft lignin,” Molecules 22(11), 1850. 1994; Alonso et al. The analysis of variance (Table 4) showed that, at the p=0.05 significance level, gel time was significantly influenced by [S/(P+L)] and L(%) together with the cross-terms L(%)*[S/(P+L)], [F/(P+L)]*[S/(P+L)], and L(%)*[F/(P+L)]*[S/(P+L)]. and Duramold. Fig. None reported. Synthetic resin bonded paper, made from phenolic resin and paper, is used to make countertops. This highest wave-number zone do not offer any difference among the three resins analyzed. The binding agent in normal (organic) brake pads, brake shoes, and clutch discs are phenolic resin. Fig. Since formaldehyde exists predominantly in solution as a dynamic equilibrium of methylene glycol oligomers, the concentration of the reactive form of formaldehyde depends on temperature and pH. Formaldehyde is to be commercially manufactured on an industrial scale from methanol and air in the presence of a sliver catalyst or the use of a metal oxide catalyst. DOI: 10.1016/j.biombioe.2011.02.001, Nada, A. M. A., Elsaied, H., Ibrahem, A. “Lignins for phenol replacement in novolac-type phenolic formulations. Free formaldehyde was determined by the hydroxylamine hydrochloride method with end-point titration (ISO 9397). A very fast cure can cause the lost of the final properties of the board. The sodium hydroxide (0.1 N) was used to adjust the pH to 3.5. The fitted model for gel time gave an R2 value of 99.38% and a standard deviation of residuals (SDR) of 0.18. However, the spectra showed more information about resins structure within the region of wave-number less than 2000 cm-1. (2006). The modeled response surface (Fig. Furthermore, Marbun et al. Sellers, T, Jr., (1995). “Reactivity enhancement of organosolv lignin by phenolation for improved bio-based thermosets,” European Polymer Journal, 67, 1-11. The process may be carried out as follows; • A mixture of phenol and formaldehyde are allowed to react in the presence of a catalyst i.e.Oxalic acidandsodium hydroxide. Table 4. Novolaks (or novolacs) are phenol-formaldehyde resins with a formaldehyde to phenol molar ratio of less than one. “Lignin-based polycondensation resins for wood adhesives,” Journal of Applied Polymer Science 103(3), 1690-1699. The modeled response surface (Fig. In the case of free formaldehyde content, within the range of the three studied variables, the obtained values for formaldehyde content were lower than 0.2%, which is the maximum value acceptable for environmental reasons. This spectrum is characterized by a broad band of OH stretching located at 3415 cm-1, which is attributed to the hydroxyl groups in phenolic and aliphatic structures, and the bands at 2933 cm-1and 2849 cm-1, arising from CH stretching in the aromatic methoxyl groups and the methyl and meythylene groups of the side chains. (2008). “Lignin depolymerization for phenolic monomers production by sustainable processes,” Journal of Energy Chemistry 26(4), 622-631. 2006, 2007; Hu et al.2011;Mancera et al. “Alkali lignin depolymerization under eco-friendly and cost-effective NaOH/urea aqueous solution for fast curing bio-based phenolic resin,” Industrial Crops and Products 120, 25-33. The former of these two gives a complete reaction of oxygen. [7], Except where otherwise noted, data are given for materials in their, Crosslinking and the formaldehyde/phenol ratio, A. Gardziella, L.A. Pilato, A. Knop, Phenolic Resins: Chemistry, Applications, Standardization, Safety and Ecology, 2nd edition, Springer, 2000. One reacts phenol and formaldehyde directly to produce a thermosetting network polymer, while the other restricts the formaldehyde to produce a prepolymer known as volcano which can be moulded and then cured with the addition of more formaldehyde and heat. Phenolic laminates are made by impregnating one or more layers of the base material such as paper, fiberglass or carbon with phenolic resin and laminating the resin saturated base material under heat and pressure. Table 5.Analysis of Variance for Viscosity at 25 °C, Fig. When the molar ratio of formaldehyde:phenol reaches one, in theory every phenol is linked together via methylene bridges, generating one single molecule, and the system is entirely crosslinked. Faix, O. (2004). DOI: 10.3390/molecules22111850, Tachon, N., Benjelloun-Mlayah, B., and Delmas, M. (2016). Chemical Reaction Phenol Formaldehyde resins are prepared by reaction of phenol with formaldehyde in the presence of acidic or basic catalyst. These bands are assigned to C=O stretching in unconjugated ketone and carbonyl bond in ester group or in conjugated p-substituted aryl ketone, respectively (Khan and Ashraf 2005).The absorption bands at 1600 cm-1 and 1500 cm-1are assigned to aromatic ring vibrations. “Optimization of experimental variables to modify lignin fromEucalyptus globulus under alkaline catalysis,” BioResources 11(1), 1828-1842. A., and Yousef, M. A. A glass flask equipped with a condenser, a thermometer, and an overhead stirrer was charged with the above solution, and then formaldehyde aqueous solution was added according to the molar ratios of formaldehyde to lignin of1.0. Different modified phenol formaldehyde resins were prepared and characterized using alkaline rice straw lignin structurally modified by hydroxymethylation reaction. Formaldehyde is made of methanol and phenol from benzene using the cumene process. In place of phenol itself, they are often produced from cresols (methylphenols). US3969321A US05/510,875 US51087574A US3969321A US 3969321 A US3969321 A US 3969321A US 51087574 A US51087574 A US 51087574A US 3969321 A US3969321 A US 3969321A Authority US United States Prior art keywords phenol polymer resin formaldehyde aldehyde Prior art date 1973-10-03 Legal status (The legal status is an assumption and is not a legal conclusion. Intratec offers professional, easy-to-understand reports examining Phenol-Formaldehyde Resins production. Another use of phenolic resins is the making of Duroplast, used in the Trabant automobiles. The modified phenol formaldehyde LPF2 and LPF10 with lignin content of 50% and 35%, respectively, were selected to be tested for plywood manufacturing because of their suitable gel time and low free formaldehyde content. Formation of phenol-formaldehyde resins. All these bands match well with the literature values (Faix 1992). 2016). DOI: 10.1002/app.1983.070280209. The reaction was monitored by measuring the viscosity at 25ºC with viscosimeter and halted when the resin viscosities reached 300 to 400 mPas. This resin is also produced by substituting methylphenols in place of phenols. The low values of free formaldehyde found for the formulated modified phenolic resins are in the same range of those reported in a previous study that reported values 0.02% and 0.12 % (Vazquez et al. DOI: 10.1080/02773819909349617. studied the effect of benuang (Octomeles sumatrana BN) and duabanga (Duabanga moluccana DB) barks as the filler for phenol-formaldehyde resin (PF) in glulam production. 3) shows that for L=35%, the pH increased with increase of (S/PL) molar ratio. In any case, the final pH of the synthesized resol resins can be corrected by addition of base or acid solution. Ma, Z., Li, S., Qiao, W., and Ren, S. (2016). Some of the lignins that have been used in phenolic resins are derived from annual plants such as flax (Tejado et al. FTIR spectrum of lignin raw material. Article submitted: October 11, 2011; Peer review completed: January 8, 2012; Revised version received and accepted: August 12, 2018; Published: September 7, 2018. Bands at 2937 cm-1 and 2846 cm-1 are the consequence of in-plane and out-of-plane stretching of aliphatic -CH2-. Previous research findings from Cheng et al. In PF the band at 1474 cm-1 is assigned to -CH- deformation in -CH2– groups. They were near to the range of values of the commercial resins used for plywood production, which ranges from 45to47% (Alonso et al. “Use of a methylolated softwood ammonium lignosulfonate as partial substitute of phenol in resol resins manufacture,” Journal of Applied Polymer Science 94(2), 643-650. Phenol formaldehyde resin (resole type) is the most useful thermosetting resin for the manufacture of wood-based panels such as plywood, particleboard, and fiberboard (Nimz 1983; Sellers 1995; Gardziella et al. Resoles are major polymeric resin materials widely used for gluing and bonding building materials. Moreover, the band at 1474 cm-1is not very intensive in both LPF, which indicates that methylolated lignin molecule incorporates hydroxymethyl groups in the LPF (Nada et al. © 2020 NC State University. In one method, an excess of formaldehyde is reacted with phenol in the … It is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. (2016). 7. The negative charge is delocalised over the aromatic ring, activating sites 2, 4 and 6, which then react with the formaldehyde. for Plastics, Phenolic Resins, Determination of Free Formaldehyde Content by Hydroxylamine Hydrochloride Method. They are formed through the reaction of phenol with formaldehyde, followed by cross-linking of the polymeric chains. The parameters used to characterize the modified phenol-formaldehyde resins were: free-formaldehyde, gel time, viscosity, pH, and solid content. DOI: 10.1016/j.indcrop.2012.10.033, Diop, A., Jradi, K., Daneault, C., and Montplaisir, D. (2015). (2007). At a temperature greater than 90 °C, it forms methylene and dimethylene amino bridges. 1 injured. Bakelite was patented on December 7, 1909. DOI: 10.15376/biores.11.1.1828-1842, Pang, B., Yang, S., Fang, W., Yuan, T. Q., Argyropoulos, D. S., and Sun, R. C. (2017). 1 to the Experimental Data for pH (Y1), Gel time (Y2), and Viscosity (Y3), Fig. The polymerization is brought to completion using acid-catalysis such as sulfuric acid, oxalic acid, hydrochloric acid and rarely, sulfonic acids. By contrast, organosolv lignin, hydrolysis lignin, and soda lignin are produced in minor quantities. 2004). FTIR spectroscopy analysis showed that the spectra of LPF resins were structurally similar to that of the unmodified PF resin. In the PF, a band at 3373 cm-1was observed, which shows the presence of OH groups. 1999). Consumers most commonly encounter this substance in the context of a packaged product which includes it, such as MDF, a wood product commonly used in construction. They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives. Phenolic resin is used as a binder in loudspeaker driver suspension components which are made of cloth. The analysis of variance reported in Table 3, showed that pH was significantly influenced only by (S/PL) at the p=0.05 significance level. “Isolation and characterization of lignin from the oak wood bioethanol production residue for adhesives,” International Journal of Biological Macromolecules 72, 1056-1062. In any case, the high free formaldehyde content can be lower than the desired value by urea addition. 2016; Norambuena et al. The reaction of phenol or substituted phenol with an aldehyde, such as formaldehyde, in the presence of an acidic or basic catalyst is used to prepare phenolic resins. Available Variants : Resin for Magnesia-Carbon Bricks - PROREZ 7015; Resin for Blast Furnace Tap-hole Mass - PROLAC ABC None reported. Phenolic resins are found in myriad industrial products. A polymeric compound obtained by polycondensation of a phenolic compound and an aldehyde compound under acidic or basic conditions generally refers to a resin synthesized from phenol and formaldehyde, and is called a phenol-formaldehyde resin (PF). Nimz, H.H. Elements. The higher or lower values indicate a slow or fast curing reaction, respectively. The Dutch painting forger Han van Meegeren mixed phenol formaldehyde with his oil paints before baking the finished canvas, in order to fake the drying out of the paint over the centuries. 2004). In the early studies related to the use of lignin for phenolic resins manufacturing, different types of unmodified lignins, which were obtained directly from the pulping liquor, were investigated. R. S. Skinner, M. T. Skubiak, and D. H. Wetherell. (2000). ), Springer, Berlin., Heidelberg, 83-109. “Structural modification and characterization of lignosulfonate by a reaction in an alkaline medium for its incorporation into phenolic resins,” Journal of Applied Polymer Science 102(4), 3286-3292.DOI: 10.1002/app.24744, El Mansouri, N. E., Pizzi, A., and Salvado, J. “The isolation and characterization of lignin of kenaf fiber,” Journal of Applied Polymer Science 114(3), 1896-1901. The process of polymerizing the compound is completed by adding acidic catalysts like sulfuric acid, oxalic acid, or sulfonic … 2007, 2008), or kenaf (Yan2009), and agricultural waste such as sugar cane bagasse and wheat straw (Hoareau et al. The molar ratios of sodium hydroxide to phenol-modified alkaline lignin and the formaldehyde to phenol-modified alkaline lignin were from 1.0 to 1.4, and 1.8 to 2.6, respectively. Paper phenolics are used in manufacturing electrical components such as punch-through boards, in household laminates, and in paper composite panels. All rights reserved. 2013; Zhao et al. Phenol-formaldehyde resins are heat-resistant and waterproof, though somewhat brittle. Phenolic Resins: Chemistry, Applications, Standardization, Safety and Ecology. The structural differences and similarities between the prepared resins were determined by FTIR spectroscopy. Higher end billiard balls are made from phenolic resins, as opposed to the polyesters used in less expensive sets. The modeled response surface (Fig. Liquid RESI-SHELL ® resins are used in the production of foundry shell molds and cores by the warm air sand process. 2013; Siddiqui et al. This product is used in a wide variety of settings and industries, and is one of the oldest synthetic resins around. There are two main production methods. release of phenol and formaldehyde from process vessel. Preparation and Characterization of Phenol-Formaldehyde Resins Modified with Alkaline Rice Straw Lignin, Nour-Eddine El Mansouri,b,c,* Qiaolong Yuan,a and Farong Huanga,*, Keywords: Adhesives; Hydroxymethylation; Lignin; Phenol formaldehyde; Wood panels. Novolac is a type of formaldehyde phenol resin. ), Wood Adhesives Chemistry and Technology, Marcel Dekker, New York, pp. However the second type of catalyst achieves almost complete methanol conversion. The used apparatus for gel time determination operates in accordance with ISO 9396 B. Phenolic resins account for a large portion of phenol production. Thus, the main objective of this work is to prepare and characterize a modified phenol-formaldehyde resins using hydroxymethylated alkaline lignin from rice straw as a substitute of petroleum-based phenol. [1][2] There are many variations in both production and input materials that are used to produce a wide variety of resins for special purposes. 2011b). Lignin is a good candidate to replace phenol in the phenol formaldehyde resins’ formulation because (a) its polyphenolic structure is similar to that of phenolic resin (Fig. Phenol and formaldehyde are charged into the kettle in specified quantaties. The Manufacturing Process A. The high crosslinking gives this type of phenolic resin its hardness, good thermal stability, and chemical imperviousness. The modified phenol formaldehyde resins were dissolved in isopropanol-water mixture (2:1, v/v) and hydrochloric acid was added until pH was in the range 2 to 3. DOI:10.1016/j.ijbiomac.2014.10.020, Khan, M. A., and Ashraf, S. M. (2005). August 28, 1989 NY Manufacture of phenolic resins; release of phenol and phenolic resin from process vessel; “operator error” cited as cause. POLYTONETM PF 132 C is a phenol – formaldehyde resin to be mixed with Hexa or Part 2 Catalyst.POLYTONETM PF 132 C (Part 1 + 2) effortlessly penetrates and adheres to the structure of many organic and inorganic fillers and reinforcements which makes it an ideal candidate for various end uses. Being thermosets, hydroxymethyl phenols will crosslink on heating to around 120 °C to form methylene and methyl ether bridges through the elimination of water molecules. DOI: 10.1016/j.jechem.2017.02.007. In fact, the incorporation of a large amount of lignin with a high molecular weight is the main reason for increasing the molecular weight of final resin, thus resulting in higher viscosities for lignin-phenol formaldehyde resins. July 25, 1989 VA Specialty paper manufacturing; release of phenolic resin and methanol from process vessel. “Structure-property relationships for technical lignins for the production of lignin-phenol-formaldehyde resins,” Industrial Crops and Products 108, 316-326. 1997; Alonso et al. This variable is of interest because of its influence on the resin storage life. DOI: 10.15376/biores.6.3.2647-2662, El Mansouri, N.-E., Yuan, Q., and Huang, F. (2011b). “Development and characterization of a lignin-phenol-formaldehyde wood adhesive using coffee bean shell,” Journal of Adhesion Science and Technology 19(6), 493-509. “Co-ordination network for lignin – Standardisation, production and applications adapted to market requirements (EUROLIGNIN),” Industrial Crops and Products 20(2), 121-129. “Waste liquors from cellulosic industries.4. (1983). “Characterization and phenolation of biorefinery technical lignins for lignin-phenol-formaldehyde resin adhesive synthesis,” RSC Advances 4(101), 57996-58004. “Modification of ammonium lignosulfonate by phenolation for use in phenolic resins,” Bioresource Technology 96(9), 1013-1018.DOI: 10.1016/j.biortech.2004.09.009, Cheng, S., Yuan, Z., Leitch, M., Anderson, M., and Charles, C. (2013). They were at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins and fiberglass cloth, as with fire-resistant FR-4 circuit board materials. Among all of the modification treatments that increase reactive sites in lignin, the phenolation and hydroxymethylation modifications are the most studied and effective for formulation of phenolic resins (Nada et al. Phenolic resins are found in myriad industrial products. “Methods to improve lignin’s reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review, “BioResources 6(3), 3515-3525. This is done by reacting resorcinol with formaldehyde. “Organosolv wheat straw lignin as a phenol substitute for green phenolic resins,” BioResources 11(3), 5797-5815. 1 Introduction . The most common application of Phenol-Formaldehyde Resins is in adhesives for bonding wood products, especially those desired for exterior plywood. Production of Phenol-formaldehyde Adhesives from Catalytic Pyrolysis Oil Angela M. Akude Utah State University Follow this and additional works at: Part of the Biological Engineering Commons Recommended Citation Akude, Angela M., "Production of Phenol-formaldehyde Adhesives from Catalytic Pyrolysis Oil" (2017). DOI: 10.1002/app.1987.070330824. “Modification of lignins for use in phenolic resins,” ACS Symposium Series 385, 55-67. DOI: 10.15376/biores.10.3.4933-4946, El Mansouri, N. E., Farriol, X., and Salvado, J. The reactive species is the phenoxide anion (C6H5O−) formed by deprotonation of phenol. Base-catalysed phenol-formaldehyde resins are made with a formaldehyde to phenol ratio of greater than one (usually around 1.5). Pulp and Paper Fundamental Research Symposia Proceedings. The alkaline lignin (AL) used for the preparation of hydroxymethylated lignin was supplied by South China University of Technology, Guangzhou, China. RESI-SET ® liquid resins are specifically designed for the foundry no-bake process.. 2. Diagram of the experimental protocol. (2005). Fig. In PF the band at 1155 cm-1 and 1015cm-1 are characteristic for in-plane deformation of aromatic C-H, whereas the band at 1154 cm-1in LPF is attributed to C-H stretching in a syringyl unit and is attributed to presence of lignin. The statistical analysis was carried out by using Statgraphics 18 Centurion. Figure 6 shows the FTIR-spectrum of lignin raw material used for resins preparation. 2011; Jung et al. Urea-formaldehyde is the resin most commonly used for particleboard manufacture. Overall, the viscosity values obtained are between 330 and 790 (mPas), and most of the prepared resins have viscosities within the range of 275to425 (mPas) suitable for use in plywood manufacture (Alonso et al. The pellets were prepared with a mixture of 300 mg potassium bromide and 5-10 mg of analyzed samples. II. The bands at 1455 cm-1 and 1425 cm-1 are due to the asymmetric C-H deformation in –OCH3 groups. Forss, K. G., and Fuhrmann, A. 10.1021/bk-1989-0385.ch005, Alonso, M. V., Rodriguez, J. J., Oliet, M., Rodriguez, F., Garcia, J., and Gilarranz, M. A. 2017).There are several modification methods such as demethylation, reduction, oxidation, and hydrolysis that have been studied to improve the reactivity of lignin as well as to produce phenolic compounds from lignin (Hu et al.

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