scholarly journals Lignin Phenol Formaldehyde Resoles Using Base-Catalysed Depolymerized Kraft Lignin

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1162 ◽  
Author(s):  
Pia Solt ◽  
Björn Rößiger ◽  
Johannes Konnerth ◽  
Hendrikus van Herwijnen
Keyword(s):  
Phenol Formaldehyde ◽  
Lignin Content ◽  
Building Blocks ◽  
Kraft Lignin ◽  
Phenol Content ◽  
Adhesive Properties ◽  
Phenolic Resins ◽  
Adhesive Bonds ◽  
Phenolic Components ◽  
Softwood Kraft Lignin

Lignin phenol formaldehyde (LPF) resols were produced using depolymerized lignin fractions at various levels of phenol substitution (50 to 70 wt %). To produce monomeric-rich (BCD-oil) and oligomeric (BCD-oligomers) bio-based phenolic compounds, softwood kraft lignin was base-catalysed degraded. These base-catalysed depolymerized (BCD) building blocks were further used to substitute phenol in the synthesis of phenolic resins and were characterized in detail (such as viscosity, free formaldehyde and phenol content, chemical composition, curing and bonding behaviour). The adhesive properties were compared to a phenol formaldehyde (PF) reference resin and a LPF with untreated kraft lignin. The resins synthesized with the two depolymerized lignin types differ significantly from each other with increasing phenol substitution. While with LPF-BCD-oligomers the viscosity increases and the bonding strength is not effected by increasing lignin content in the resin, a reduction of these properties could be observed with LPF-BCD-oil. Furthermore, LPF-BCD-oil showed similar curing behaviour and ultimate strength as the reference LPF. Adhesive bonds made using LPF-BCD-oligomers exhibited similar strength to those made using PF. Compared to the reference resins, it has been demonstrated that modified renewable lignin based phenolic components can be an equally performing alternative to phenol even for high degrees of substitution of 70%.

scholarly journals Demethylation and other modifications of industrial softwood kraft lignin by laccase-mediators

Holzforschung ◽  
2018 ◽  
Vol 72 (5) ◽  
pp. 357-365 ◽  
Author(s):  
Miao Wang ◽  
Yadong Zhao ◽  
Jiebing Li
Keyword(s):  
Phenol Formaldehyde ◽  
Kraft Lignin ◽  
Aromatic Rings ◽  
Reaction Solution ◽  
Lower Reactivity ◽  
Diammonium Salt ◽  
Mass Increment ◽  
Modified Lignin ◽  
Softwood Kraft Lignin ◽  
Technical Lignins

Abstract Substitution of phenol in phenol-formaldehyde (PF) resin preparations by technical lignins is hindered by the inherently lower reactivity of lignin compared to phenol. Demethylation of an industrial softwood kraft lignin (SKL) to improve its reactivity is the focus of this paper. To this purpose, kraft lignin (KL) was treated with two commercial laccases, NS51002 (L1) and NS51003 (L2), for 24 h in combination with three mediators, 2,2′-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1-hydroxybenzotriazole (HBT) and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). The characterizations of the reaction solution and the resultant KL showed that methanol was released as a result of the methoxy group splitting from the aromatic rings, while such demethylation was dependent on the laccase-mediator system (LMS). The catechol structures formed, which were further oxidized to a quinone structures prone to polymerization, led to molecular mass increment. Also this reaction was LMS dependent. The same is true to the cleavage of β-O-4′ linkages, which resulted in depolymerization. The L1-ABTS, L1-TEMPO and L2-HBT combinations are the most efficient and the resulting modified lignin would be suitable to phenol substitution. Challenging is the lignin polymerization following the demethylation, especially in case of L1-ABTS, which might inhibit the reactivity of the treated lignin.

Utilization of lignin powder for manufacturing self-binding HDF

Holzforschung ◽  
2017 ◽  
Vol 71 (7-8) ◽  
pp. 555-561 ◽  
Author(s):  
Ramunas Tupciauskas ◽  
Janis Gravitis ◽  
Janis Abolins ◽  
Andris Veveris ◽  
Martins Andzs ◽  
...  
Keyword(s):  
Wheat Straw ◽  
Internal Bond ◽  
Lignin Content ◽  
Control Sample ◽  
Kraft Lignin ◽  
Modulus Of Rupture ◽  
Thickness Swelling ◽  
Medium Density Fibreboard ◽  
Dry Conditions ◽  
Softwood Kraft Lignin

Abstract The preparation of self-binding lignocellulosic fibreboards has been investigated. Different high-density fibreboards (HDF) were hot-pressed based on a mixture of grey alder (Alnus incana L. Moench) wood chips processed by steam explosion auto-hydrolysis (SE) and 15% or 25% lignin content from three different industrial sources: softwood kraft lignin (SWKL), soda wheat straw lignin (SoWhStL) and hydrolysis wheat straw lignin (HWhStL). Density, thickness swelling (TS) after immersion in water for 24 h, modulus of rupture (MOR), modulus of elasticity (MOE) and strength of internal bond (IB) of the board samples were determined. The amount (15% or 25%) and moisture content (MC) (18±1% or 5±2%) of the added lignin affected all the tested properties of the HDF except for density. However, the kind of the added lignin affects the obtained fibreboard more significantly compared to the control sample made without an admixture of lignin. In some cases, the tested values were diminished to half. The tested properties of the HDF samples produced with SoWhStL or HWhStL are compatible with standard requirements for medium-density fibreboard (MDF) for general use under dry conditions (EN 622-5, MDF), however, it depends on the lignin amount and MC.

The Use of South African Spent Pulping Liquor to Synthesize Lignin Phenol-Formaldehyde Resins

2020 ◽  
Vol 70 (4) ◽  
pp. 503-511
Author(s):  
Priyashnie Govender ◽  
B. M. Majeke ◽  
Abiodun Oluseun Alawode ◽  
Johans F. Gorgens ◽  
Luvuyo Tyhoda
Keyword(s):  
South African ◽  
Bonding Strength ◽  
Phenol Formaldehyde ◽  
Black Liquor ◽  
Kraft Lignin ◽  
Curing Temperature ◽  
Scanning Calorimetry ◽  
Adhesive Properties ◽  
Bonding Performance ◽  
Bonding Properties

Abstract This study aims to investigate the potential of using lignin sourced from South African black liquor as a total phenol substitute in phenol-formaldehyde resins (PFRs), with a particular focus on bonding strength and curing properties. Four South African pulping-based lignins were used to synthesize these lignin-phenol formaldehyde resins (LPF100 resins), namely Eucalyptus Kraft lignin, Pine Kraft lignin, Bagasse Soda lignin, and Bagasse Steam Exploded lignin. Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry were used to determine structural and curing properties. These resins were then used directly (unmodified) as adhesives to test shear bonding strength (R0 LPF100 adhesives). To improve the bonding properties of the unmodified LPF100 adhesives, the LPF100 resins were modified via the addition of a crosslinker (hexamine) as well as a hardener (either glyoxal, R1, or epichlorohydrin, R2). All R0 LPF100 adhesives fell below the GB/T 17657-2013 plywood standard of ≥0.7 MPa, with the Bagasse Soda LPF100 adhesive recording the highest bonding performance of 0.5 MPa, and the lowest curing temperature of 68°C. From the modified adhesives, the best performing were the Pine Kraft (R1) and the Eucalyptus Kraft (R2) LPF100 adhesives, recording 1.4 and 1.3 MPa, respectively. The curing temperatures of both these resins were 71°C and 80°C, respectively. Ultimately, the results of this study indicated that favorable adhesive properties may be obtained with the use of South African pulping-based lignins as a 100 percent phenol substitute in PFRs.

Preparation and Characterization of Lignin from Malaysian Coconut Coir Husk (CCH) as a Potential Precursor in Phenol-Formaldehyde (Phenolic) Resins for the Plastics Industry

2016 ◽  
Vol 1133 ◽  
pp. 583-587 ◽  
Author(s):  
Nur Fatin Nabila Saari ◽  
Dalina Samsudin ◽  
Nor Mazlina Abdul Wahab ◽  
Noor Aishatun Majid ◽  
Rusli Daik ◽  
...  
Keyword(s):  
Phenolic Resin ◽  
Phenol Formaldehyde ◽  
Lignin Content ◽  
Natural Fibre ◽  
Phenol Formaldehyde Resin ◽  
High Yield ◽  
Formaldehyde Resin ◽  
Phenolic Resins ◽  
Coconut Coir ◽  
The Fourier Transform

Coconut coir husk (CCH) was chosen to extract it lignin due to high lignin content comparable with other natural fibre. The lignin was extracted and its utilization in production of phenolic resin was investigated. The percentage extracted lignin obtained in this studied was 38.1% which indicated the high yield of lignin. Two phenolic resins were prepared, which are phenol-formaldehyde resin and lignin-formaldehyde resin. The functional group present in the lignin and both phenolic resins were further analyzed using the Fourier Transform Infrared Spectroscopy (FTIR). The findings from the infrared spectra of the lignin-formaldehyde resin were similar to the phenol-formaldehyde resin. These indicate that lignin can be partially used as phenol in phenolic resin synthesis.

scholarly journals Metabolite Differences of Polyphenols in Different Litchi Cultivars (Litchi chinensis Sonn.) Based on Extensive Targeted Metabonomics

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1181
Author(s):  
Nonghui Jiang ◽  
Huili Zhu ◽  
Wei Liu ◽  
Chao Fan ◽  
Feng Jin ◽  
...  
Keyword(s):  
Main Part ◽  
Ultra Performance Liquid Chromatography ◽  
Total Phenol Content ◽  
Phenol Content ◽  
Polyphenol Content ◽  
Reference Information ◽  
Phenolic Components ◽  
Early Maturing ◽  
Litchi Fruit ◽  
First Time

Litchi is an important fruit cultivated in tropical and subtropical areas with high nutritious and delicious flavor and the pulp is the main part of the fruit consumed. Previous studies found that litchi had high total phenol content and antioxidant activity, but most of them focused on the identification of single or a few phenolic components with a low throughput test, and the metabolic differences of cultivars are still unknown to a some extent. In this study we used widely targeted metabolome based on ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) to analyze the polyphenol metabolites of five different genotypes of mature litchi fruit. A total of 126 polyphenol metabolites in eight categories were identified to reveal the composition and differences of polyphenol; 15 common differential metabolites and 20 specific differential metabolites to each cultivar were found for the first time. The results infer that flavonoids, flavonols, hydroxycinnamoyls and catechins are the main polyphenol metabolites of litchi pulp. Cluster analysis showed that there were three groups of polyphenols from high to low; early maturing Feizhixiao is a kind of high polyphenol content cultivars, especially in catechins, anthocyanins, flavonols, quinic acids and hydroxycinnamoyls. The polyphenols in the flesh of mature litchi are rich, and there are significant differences among cultivars; there was a level of correlation between the contents of phenolics and the maturity of litchi cultivars; the content of phenolics in early maturing litchi cultivars appeared higher than those of mid- to late-maturing cultivars. This experiment will provide significant reference information for cultivation, breeding, processing and consumption.

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