�@�IVt��F���1�0 Sci. Both samples were left to cure in an oven at 130 °C for 1 h. After that, 0.5 g of cured samples was submerged into about 100 mL distilled water and left at room temperature for one week (Figure 9). The lignin sample used in this study was provided by POET LLC and is produced as a byproduct of bioethanol process through dilute acid pretreatment and enzymatic hydrolysis of corn stover. 2 0 obj Phenol reactions summary Questions give any two reaction that can be used to prepare phenol Aniline is treated with HNO 2 at room temperature to produce phenol. In loadings plot, each peak that is placed further from the center line has stronger influence on the model. <>>>/CropBox[0 0 612 792]/Rotate 0/MediaBox[0 0 612 792]>> Hydroxymethylation of technical lignins from South American sources with potential use in phenolic resins. More sustainable energy storage: lignin based electrodes with glyoxal crosslinking. Bio-Based Alternatives to Phenol and Formaldehyde for the Production of Resins. Graphitization of Lignin-Phenol-Formaldehyde Resins. Chemical, physical, and thermal properties of the isolated lignin, PF resin and adhesive were measured using advanced analytical techniques such as Fourier transformed infrared spectroscopy (FTIR), size exclusion chromatography (SEC), phosphorous nuclear magnetic resonance spectroscopy (31P NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The goal of our study was to formulate a 100% lignin‐based resin using an unmodified lignin that has potentially higher reactivity toward phenol. ]�o��^K.���oa��Nd�������o���տ�6v�i�c+.����寛d�i�۽QX���#������;,�������7/Ͽۿ�m�ߝ�$�;>�b�����0��,�����O����D�%Ni��Ly�5-e�q�0���6�^������C�����T{�jmH��X"�e���x�S�cu�S�UyE�/t�5�$łL5fQi��"�����-5���:e��rL�����>9��h�����_1f��wN��DC{�c�k���m�#�·�����q�k���N�]-��AD7�cA�M̱P�벹F;�������w�8#��]OWY���E6���ؔ�gc�K�ބ-H ����v=/x@���y4R���z��X[�܇�[s�OZ/^�F�3Z��*���i^gK]����a�a_�~���Yt��Lm��Y�/)z$��j�+w�u�A߷dw�yh��.Z������`w�23�Y�8l;M�.���~�߰����� )�v+{>�R�d Future opportunities for bio-based adhesives – advantages beyond renewability. In the next step, thawed resin PF (66%) and NaOH (3%) were added to the solution and stirred for a few minutes using an overhead digital mixer at 300 rpm. Tuning the Lignin-Caprolactone Copolymer for Coating Metal Surfaces. Formaldehyde is made of methanol and phenol from benzene using the cumene process.4 Fluctuations in price of phenol as a result of changes in oil price and concerns about chronic exposure of workers to phenol during the manufacturing process are the main reasons why over the last three decades many researchers have studied replacing phenol with biobased materials. Also, the lower charred residue of the original lignin sample (28.7%) in comparison with isolated lignin (32.8%) can be explained by the higher volatilization of cellulose and hemicellulose in the original lignin samples.54, TGA plots of original and isolated lignin samples in left axis and derivative TGA curves in right y‐axis. The ash contents of isolated lignins were lower than the original lignin samples as expected, due to the reduced inorganic content after the lignin purification process. PF adhesives are known to have exceptional performance such as: excellent moisture resistance, thermal resistance, chemical durability, and bonding strength.1 Depending on the molar ratio of formaldehyde to phenol (F/P) and the type of catalyst used in the reaction (acid or base), the final resin is either resols or novolacs. The hydroxyl content was calculated based on the ratio of the internal standard peak area (cyclohexanol) to integrated areas over the following spectral regions: aliphatic hydroxyls (149.1–145.4 ppm), cyclohexanol (145.3.1–144.9 ppm), and condensed phenolic units (144.6–143.3 and 142.0–141.2 ppm), syringyl phenolic units (143.3–142.0 ppm), guaiacyl phenolic hydroxyls (140.5–138.6 ppm), p‐hydroxyphenyl phenolic units (138.5–137.3 ppm), and carboxylic acids (135.9–134.0 ppm).40, 41. When water is added to benzene diazonium salt, phenol is After that, the system was cooled to the room temperature and the prepared resin was stored at −18 °C to avoid further polymerization reactions before thawing for adhesive formulation. The sulfur contents of both lignin samples (original and isolated one) were the same (0.2%) and very low. Finally, the percentage of wood failure for each lap shear specimen was calculated quantitatively with image analysis technique using ImageJ software. Add 10 mg of T. versicolor laccase to the catechol- and catechin-containing buffer. Use the link below to share a full-text version of this article with your friends and colleagues. All other reagents and chemicals were purchased from Fisher Scientific Inc. The TGA graphs (y‐axis, left) show the percentage of mass loss over the temperature range and the derivative thermogravimetric (DTG) analysis graphs (y‐axis, right) display the rate of mass loss, in which the maximum peak could be used as the degree of thermal decomposition.53 As can be seen in the TGA graph (Figure 7), the degradation temperature of carbohydrate components in the original and isolated lignin samples began at 200 and 210 °C, respectively. Image of wood failure section (left) taken from lap shear strength plywood speciemen, modified image for image analysis using photoshop (right). 81 0 obj <>stream Table 6 shows the P value of the two‐way ANOVA analysis of shear strengths of adhesives, and also the relation between the amount of adhesive that was applied, type of resin used (e.g., 100% lignin‐based (LF) or commercial resin (PRF)), and sample condition (e.g., wet or dry). First, lignin was dissolved in 1M NaOH and mixed with formaldehyde (37%) inside a three‐necked flask (Figure 1). Zinc chloride/acetamide deep eutectic solvent‐mediated fractionation of lignin produces high‐ and low‐molecular‐weight fillers for phenol‐formaldehyde resins. Impact of dilute acid pretreatment conditions on p-coumarate removal in diverse maize lines. Since all developed resins (with 20%, 50%, 80%, and 100% lignin) did not dissolve in water, only 100% lignin‐based resins were used for further characterization and adhesive formulation (Figure 9). Images of resin preparation settings. Likewise, the peaks on the bottom describe attributes enriched of the original lignin sample. Finding new markets for lignin that is produced as a byproduct during bioethanol production has the potential to significantly improve the overall economic viability of this industrial process. The gelation time of each resin was also measured following the procedure reported by Pizzi and Mittal.10 About 1 g of resin was placed in a glass test tube and immersed in a beaker filled with boiling water. Since lignin has much greater thermal stability than carbohydrates, the increase in thermal degradation temperature and the DTGmax of isolated lignin in comparison with the original sample is again due to the removal of carbohydrates through the isolation process. [Color figure can be viewed at wileyonlinelibrary.com]. Thus, it should be a more suitable biopolymer to replace phenol in formulation of phenolic resin when compared with other hardwood and softwood lignins that were used in previous studies. After dissolution, 50 μL of chromium acetylacetonate solution (5.6 mg/mL in anhydrous pyridine and deuterated chloroform 1.6:1, v/v) was added as a relaxation reagent. The results of physicochemical characteristics of original and isolated lignin samples are presented in Table 1. This study is the first to describe an adhesive formulation with 100% lignin that has mechanical strength similar to the commercially formulated phenol resorcinol formaldehyde (PRF) adhesive when cured at the same condition as the commercial formulation.