Preparation and properties of phenolated wood/phenol/formaldehyde cocondensed resin

A phenolated wood/phenol/formaldehyde cocondensed novolac-type resin was prepared with a two-stage procedure. Wood was first liquefied in the presence of phenol by using an acid catalyst to produce a phenolated wood, and after the liquefaction, formalin (i.e., formaldehyde aqueous solution) was added to conduct a cocondensation reaction for converting the remaining nonreacted phenol into resin components. It was found that this procedure can convert almost all the phenol remained after liquefaction into resin, and therefore significantly upgrades the practical value of the liquefaction technique. In addition, it can also greatly improve the thermofluidities of the phenolated wood resins and the mechanical properties of their molded products. As a result, the flow temperatures and melt viscosities of the cocondensed resins were much lower than those of the phenolated wood resins. However, these two properties were more or less similar to those of the conventional novolac resin, resulting in an excellent processability. The flexural properties of the molded products made from the cocondensed resins were much higher than those of the phenolated wood and also somewhat superior to those of the conventional novolac resin. Therefore, this preparation procedure is a prospective technique for preparing wood-based novolac resins. © 1995 John Wiley & Sons, Inc.     

Liquefaction and product identification of corn bran (CB) in phenol

The liquefaction of corn bran (CB) was successfully conducted by using three different liquefaction conditions. Among them, catalyzed liquefaction at high pressure and temperature (180–220°C) using phenol was the most effective for the liquefaction of CB. Both the phenol/CB ratio and the catalyst content affected the extent of the liquefaction. The decomposed components of CB did not show high reactivity toward phenol when liquefied without a catalyst. Thermal‐flow properties of the phenolated CB and flexural properties of the phenolated CB‐based moldings were influenced by the amount of combined phenol and were comparable to those of the commercial novolak or phenolated wood. The effect of molding time and filler content on the flexural properties is also presented. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 311–318, 2000     

Properties of compression‐molded plates made from wood powders impregnated with liquefied wood‐based novolak‐type phenol‐formaldehyde resins

Novolak‐type phenol‐formaldehyde (PF) resins with solution form were prepared by reacting phenol‐liquefied Cryptomeria japonica (Japanese cedar) wood with formalin in the presence of methanol. Wood powders of Albizzia falcate (Malacca albizzia) impregnated with these resins were air dried followed by an oven‐dried at 60°C. DSC analysis showed the PF resin existing in wood powders could be melted, and could be cured if hexamine was mixed and heated at high temperature. Compression‐molded plates made with PF resin impregnated woods had a high degree of curing reaction. However, compression‐molded plates hot‐pressed at 180°C for 8 min or 200°C for 5 min had better internal bonding strength and dimensional stability than others. Premixing hexamine with PF resin and impregnating into wood powders simultaneously could enhance the reactivity of PF resin, but it was not useful for improving the properties of compression‐molded plates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Phenolic resol resin from phenolated corn bran and its characteristics

To prepare phenolic resol resin, corn bran (CB) was liquefied in the presence of phenol and the liquefied CB was condensed with formaldehyde under alkaline condition. From NMR spectra of phenolated CB and phenolated CB–based resol resin, it was found that phenol was reacted with depolymerized CB components and the phenolated CB was methylolated by condensation with formaldehyde. Molecular weight distribution was divided into a high molecular weight zone, attributed mainly to phenolated CB, and a low molecular weight zone, which was attributed to the condensation reactants of formaldehyde and the unreacted phenol of liquefied CB. When reaction conditions became severe, a high molecular weight zone was increased. Formaldehyde/unreacted phenol of liquefied CB molar ratio most affected the change of a low molecular weight zone. To reduce the viscosity of the phenolated CB–based resol resin, a milder condensation condition was required compared with that for preparing the conventional resol resin. Properties of the resol resin were comparable to those of conventional resol resin for plywood manufacture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1365–1370, 2003     

杉木液化产物用于胶粘剂制备的研究

研究用少量的苯酚液化木材及其产物用于胶粘剂制备的方法,在硫酸催化剂作用下,用苯酚液化杉木木粉,得到木材液化产物.在液化产物中加入适量的甲醛和氢氧化钠溶液制备热固性酚醛树脂.压板测试结果表明,由木材液化产物所得树脂的干状胶合强度令人满意,但经蒸汽循环试验后,湿状胶合强度尚达不到JAS标准的要求,在下阶段工作中,需进一步研究木材液化产物胶粘剂的改性以提高其胶合耐久性.     

Resol‐type phenolic resin from liquefied phenolated wood and its application to phenolic foam

A liquefied wood‐based resol resin was prepared with excellent yield by a reaction of liquefied wood and formaldehyde under alkaline conditions. The effects of various reaction parameters on the extent of the yield of the resol resin, unreacted phenol content, and viscosity were investigated. Milder resol resinification conditions were required as compared to those used in conventional methods. The liquefied wood‐based resol resin was successfully applied to produce phenolic foam using appropriate combinations of foaming agents. Diisopropyl ether with a relatively higher boiling temperature was suitable for the foaming of liquefied wood‐based resol resin. Hydrochloric acid and poly(ethylene ether) of sorbitan monopalmitate were used as a catalyst and a surfactant, respectively. The obtained foams showed satisfactory densities and compressive properties, comparable to those of foams obtained from conventional resol resin. Foams with low density were obtained by the blending of liquefied wood‐based resol resin and conventional resol resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 468–472, 2002; DOI 10.1002/app.10018     

Preparation and properties of phenolated corn bran (CB)/phenol/formaldehyde cocondensed resin

Corn bran (CB) was liquefied in the presence of phenol at high temperature (200°C) under high pressure (>1 atm) and the obtained liquefied products were reacted with formaldehyde to get phenolated CB/phenol/formaldehyde resins with excellent yields. The properties of the cocondensed resins were examined and compared with the liquefied products before the cocondensation. Little difference was observed in thermofluidity before and after the cocondensation, whereas the thermosetting properties and the flexural properties of the molded products were enhanced. These properties were comparable with those of liquefied resins from corn starch (CS) and those of commercial novolak resin. Moreover, no significant differences were found in the properties of the liquefied products and the thermosetting resins therefrom after removal of the solid residue and neutralization salt. It became apparent that the condensation reactions between formaldehyde and the unreacted phenol in the liquefied products enhance the physical properties of the liquefied products from CB, making possible the total utilization of the liquefied products. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2901–2907, 2000     

Synthesis and cure kinetics of liquefied wood/phenol/formaldehyde resins

Wood liquefaction was conducted at a 2/1 phenol/wood ratio in two different reactors: (1) an atmospheric three‐necked flask reactor and (2) a sealed Parr reactor. The liquefied wood mixture (liquefied wood, unreacted phenol, and wood residue) was further condensed with formaldehyde under acidic conditions to synthesize two novolac‐type liquefied wood/phenol/formaldehyde (LWPF) resins: LWPF1 (the atmospheric reactor) and LWPF2 (the sealed reactor). The LWPF1 resin had a higher solid content and higher molecular weight than the LWPF2 resin. The cure kinetic mechanisms of the LWPF resins were investigated with dynamic and isothermal differential scanning calorimetry (DSC). The isothermal DSC data indicated that the cure reactions of both resins followed an autocatalytic mechanism. The activation energies of the liquefied wood resins were close to that of a reported lignin–phenol–formaldehyde resin but were higher than that of a typical phenol formaldehyde resin. The two liquefied wood resins followed similar cure kinetics; however, the LWPF1 resin had a higher activation energy for rate constant k₁ and a lower activation energy for rate constant k₂ than LWPF2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Phenol–formaldehyde‐type resins made from phenol‐liquefied wood for the bonding of particleboard

Liquefaction of southern pine wood in phenol in 30–40 : 70–60 weight ratios resulted in homogeneous liquefied materials, which were directly used to synthesize phenol–formaldehyde (PF)‐type resins. The synthesized resins showed good physical and handling properties: low viscosity, stability for storage and transportation, and resin applicable by a common sprayer. Particleboard panels bonded with the synthesized resins showed promising physical properties and significantly lower formaldehyde emission values than those bonded with the urea–formaldehyde resin control. One deficiency observed for the synthesized resins was lower internal bond values, which might be overcome the use of a hot‐stacking procedure. Overall, the process of wood liquefaction with limited amounts of phenol as a solvent was shown to have the potential of providing practical, low‐cost PF‐type resins with very low formaldehyde emission potentials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Resinification of NaOH-catalyzed phenolated wood–phenol mixture with formalin for making molding materials

NaOH-catalyzed phenolated wood-phenol-formalin co-condensed novolak type resin was prepared in two stages. Birch wood meal was first phenolated by using NaOH as a catalyst at an elevated temperature (i.e. 250 °C), and then formalin solution together with oxalic acid was added to the phenolated wood-phenol mixture obtained. The relationships among reaction parameters and phenolation/ resinification yields, flow properties of the resinified phenolated wood, and the physico-mechanical properties of the resinified phenolated wood-based molding materials were studied. The yields obtained due to resinification of the phenolated wood were found to depend, greatly, on the phenol-formalin molar ratio. Moreover, the melt flow properties (i.e. flow properties and viscosity) of the resinified NaOH-catalyzed phenolated wood reached or slightly exceeded those of commercial novolak resin and was greatly improved in comparison to the NaOH-catalyzed phenolated wood-based molding materials alone. Furthermore, the flexural properties of the resinified phenolated wood-based molding materials were determined to be much similar to or better than those of commercial novolak resin-based molding materials and much greater than those of NaOH-catalyzed phenolated woodbased molding materials alone. On the other hand, the resinified phenolated wood-based molding materials were more hydrophobic and biodegradable than those of commercial novolak resin-based molding materials and less hydrophobic and biodegradable than NaOH-catalyzed phenolated woodbased molding materials alone.     

Properties of phenol‐formaldehyde resins prepared from phenol‐liquefied lignin

In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H₂SO₄) or hydrochloric acid (HCl) as the catalyst. The phenol‐liquefied lignins were used as raw materials to prepare resol‐type phenol‐formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol‐liquefied lignin‐based PF resins had shorter gel time at 135°C and had lower exothermic peak temperature during DSC heat‐scanning than that of normal PF resin. The thermo‐degradation of cured phenol‐liquefied lignin‐based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol‐liquefied lignin‐based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Liquefaction of wood in the presence of phenol using phosphoric acid as a catalyst and the flow properties of the liquefied wood

The liquefaction of wood in the presence of phenol using phosphoric acid as a catalyst and the flow properties of the obtained liquefied wood were investigated. It was found that phosphoric acid is a satisfactory catalyst for liquefying wood. The amount of phenol that reacts with the liquefied wood components (i.e., combined phenol) increases with an increase in liquefaction temperature, liquefaction time, catalyst content, or liquid ratio. By removing the free phenol, the resulting liquefied woods become novolaclike resins. The measurements of the flow properties of these liquefied woods reveal that the melts of liquefied woods behave as pseudoplastics and their flows obey the Ostwald de Waele power law equation. The amount of combined phenol within the liquefied wood and the presence of filler in the liquefied wood have great influence on their flow properties. The flowing temperature, activation energy, and zero shear viscosity of the liquefied woods show tendencies to increase with an increase in combined phenol. © 1994 John Wiley & Sons, Inc.     

Polyurethane foams from alkaline lignin‐based polyether polyol

As a byproduct produced during biorefining, alkaline lignin (AL) possesses multiple benzene ring and phenol hydroxyl groups with high chemical reactivity, and is renewable and cheaper than petrochemical products. Here, AL was liquefied in polyethylene glycol‐400/glycerol and subsequently used to prepare polyurethane foams (PUFs). The results showed that the AL could be almost completely liquefied. The resulting lignin‐based polyether polyol (LPP) exhibited physicochemical properties similar to a commercial polyether polyol (PP). The PUFs made from LPP presented better thermal stability and higher compressive strength than those PUFs obtained from commercial PP, suggesting this could be a viable commercial application for AL. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43261.     

Reduction of Formaldehyde Emission from Particleboard by Phenolated Kraft Lignin

The aim of this study was the reduction of formaldehyde emission from particleboard by phenolated Kraft lignin. For this purpose, the lignin was extracted from black liquor and then modified by phenolation. During the urea formaldehyde (UF) resin synthesis different proportions of unmodified and phenolated Kraft lignins (10%, 15%, and 20%) were added at pH = 7 instead of the second urea. Physicochemical properties and structural changes of resins so prepared, as well as the internal bond (IB) strength and formaldehyde emission associated with the panels bonded with them were measured according to standard methods. The Fourier transform infrared (FTIR) analysis of lignin indicated that the content of O–H bonds increased in phenolated lignin while the aliphatic ethers C–O bonds decreased markedly in the modified lignin. Since both synthesis of UF resins and lignin phenolation are carried out under acid conditions, phenolation is an interesting way of modifying lignin for use in wood adhesive. The panels bonded with these resins showed significantly lower formaldehyde emission compared to commercial UF adhesives. The UF resin with 20% phenolated lignin exhibited less formaldehyde release without significant differences in internal bond strength and physicochemical properties compared to an unmodified UF resin. XRD analysis results indicated that addition of phenolated lignin decreased the crystallinity of the hardened UF resins.     

核桃壳液化产物制备木材胶粘剂的研究

研究了核桃壳苯酚液化产物制备的酚醛树脂类木材胶粘剂及性能。结果表明,核桃壳经酸催化苯酚液化一段时间后,液化混合液的残渣率、游离苯酚和可被溴化物质量分数分别为22.11%、18.00%和33.10%,利用此液化混合液替代苯酚,所制备的酚醛树脂类胶粘剂能够满足混凝土模板用胶合板生产的要求。     

Adhesives from Waste Paper by Means of Phenolation

Recently the effective use of woody materials has been of interest from the viewpoint of forestry preservation. Newsprint is one of the most abundant of woody materials which are discarded into the environment after use. They would be, however, easily recovered from the market.

The application of phenolation to cellulosic materials is one possibility for the utilization of waste papers. Phenolation is a newly-established method by which lignocellulosic materials are completely converted to substances soluble in some polar organic solvents.

Waste newsprint is subjected to phenolation in the presence of an acidic catalyst. The phenolated product was then methylolated in order to prepare alkaline curable adheisve resins. The chemical characteristics of the phenolated products were studied and the properties of plywood adhesives from them were evaluated. The results indicated that cellulose decomposed and reacted with phenol, producing complicated compound having a phenolic moiety during phenolation and that the compound reacted with formaldehyde, leading to resinous substance which could be thermoset.

The adhesives from the resins of phenolated newsprint provided comparable properties to a commercial phenolic resin in cure behavior, resin viscosity and tensile bond strength. The products of cellulose phenolation, therefore, are expected to be a source of wood adhesives comparable with phenolic resins.     

Kinetics of wood phenolysis in the presence of HCL as catalyst

Monarch birch wood (Betula maximowiczina Regel) wastes were phenolated in the presence of HCl as a catalyst at 60–150°C for various reaction times. Typical kinetic parameters along with percent reacted wood and phenol were determined by using kinetic models. In addition, according to the transition‐state theory the activation parameters of wood phenolysis was determined. The percent reacted wood wastes depicted that about 90% of the wood could be liquefied into phenol at a temperature of 150°C. However, about 30% of phenol was found to react with wood components. The kinetic studies showed that wood phenolysis with HCl catalyst at 60–150°C obviously followed a bimolecular type of second‐order reaction. Activation energy was found to be 13.438 kJ mol^?1 from an Arrhenius plot. Furthermore, the findings related with activation enthalpy showed that the wood phenolysis had dominantly endothermic reaction nature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1098–1103, 2002     

A KINETIC STUDY OF SULFURIC ACID-CATALYZED LIQUEFACTION OF WOOD INTO PHENOL

The powders of monarch birch wood (Betula maximowiczina Regel) were liquefied into phenol using sulfuric acid as a catalyst at various temperatures and reaction times. Typical kinetic parameters of the degrading reaction of wood in the presence of phenol and the acid were determined using typical kinetic models. In addition, the activation parameters of the liquefaction of wood were determined according to transition-state theory. The results of showed percent liquefied wood that about 100% of the wood could be liquefied into phenol at a temperature of 150°C for about 2 h. However, about 68% of phenol was found to react mainly with wood components along with sulfuric acid and phenol itself. The kinetic studies showed that the liquefaction of wood into phenol using sulfuric acid obeyed a bimolecular type second-order reaction and Arrhenius law. The activation energy of the liquefaction was 68.5 kJ mol^-1. Furthermore, the findings related with activation enthalpy showed that the liquefaction of wood possessed a primarily endothermic reaction nature.     

A KINETIC STUDY OF SULFURIC ACID-CATALYZED LIQUEFACTION OF WOOD INTO PHENOL

The powders of monarch birch wood (Betula maximowiczina Regel) were liquefied into phenol using sulfuric acid as a catalyst at various temperatures and reaction times. Typical kinetic parameters of the degrading reaction of wood in the presence of phenol and the acid were determined using typical kinetic models. In addition, the activation parameters of the liquefaction of wood were determined according to transition-state theory. The results of showed percent liquefied wood that about 100% of the wood could be liquefied into phenol at a temperature of 150°C for about 2 h. However, about 68% of phenol was found to react mainly with wood components along with sulfuric acid and phenol itself. The kinetic studies showed that the liquefaction of wood into phenol using sulfuric acid obeyed a bimolecular type second-order reaction and Arrhenius law. The activation energy of the liquefaction was 68.5 kJ mol^?1. Furthermore, the findings related with activation enthalpy showed that the liquefaction of wood possessed a primarily endothermic reaction nature.     

竹材酚醇液化及其甲醛树脂的FT-IR分析

采用傅立叶红外光谱法分析了竹刨花在苯酚与聚乙二醇-400溶剂作用下酸催化液化产物的化学结构,以及液化物甲醛树脂的结构特征。分析表明:在液化过程中木质素、纤维素和半纤维素都发生了不同程度的降解,产生了很多的小分子物质;并且同时加入两种液化试剂,可以使竹刨花发生两种不同的液化反应。