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In this study, modification of LignoBoost™ softwood kraft lignin with epichlorhydrin in water-organic solvents media was realized. Lignin-based epoxy resins were obtained by two ways: acetone extraction of glycidylated lignin or glycidylation of the acetone soluble lignin fraction. The effect of glycidylation regimes on the yields of acetone soluble fractions, their functional composition and physical-chemical characteristics was investigated using wet chemistry methods, FTIR spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). The positive effect of the biphasic phase transfer catalytic system – KOH/quaternary ammonium salt – on glycidylation of both phenolic and aliphatic hydroxyl groups was testified, exemplified using a lignin-like model compound – 4-hydroxy-3-methoxylbenzyl alcohol (vanillyl alcohol). The partial substitution (up to 10%) of commercial epoxy resin on the basis of bisphenol A (Araldite® LY1564) by lignin-based epoxy resin significantly increased the viscosity of resin. Therefore, the possible practical application of lignin-containing epoxies as adhesive, mastic or crack filler instead of binder for fiber reinforced composites was considered. A tendency towards increasing Young’s modulus of cured lignin-containing epoxies, compared with the case of the reference composition, was observed. The lignin chemically incorporated into the matrix of cured commercial epoxy resin acts as a charcoal formation promoter in high temperature treatment.

The chemical composition and the structural features of macromolecular components from red grape skins (variety Touriga Nacional) have been evaluated. The results of chemical analyses revealed the following contents of the main constituents: cellulose (20.8%), hemicelluloses (12.5%), proteins (18.8%), tannins (13.8%), extractives soluble in dichloromethane (5.0%) and ash (7.8%). Cellulose of grape skins is typical cellulose I polymorph with a degree of crystallinity of 66.1% as assessed by X-ray scattering. The hemicelluloses were analyzed by neutral sugars analysis, methylation analysis and 1D/2D H-1 NMR. The water-soluble compounds (26.4%) are composed mainly of monomeric sugars (glucose and fructose) and a complex mixture of hemicelluloses, the most abundant being pectin and acetylated glucomannan. The major part of structural polysaccharides (cellulose, xylan, xyloglucan, etc.) is embedded in cuticular layer and is poorly accessible to the acid hydrolysis. The cuticular substances contributed to ca. 8.5% of grape skins and their chemical structure has been evaluated by methanolysis. The possibility of comprehensive utilization of grape skins has been discussed. (C) 2012 Elsevier B.V. All rights reserved.

The chemical composition of oleo-gum-resin from Ferula gummosa collected in the northern part of Iran has been studied. The fraction of oleo-gum-resin soluble in ethanol (ca 67 wt.%) is composed by three major fractions: (i) monoterpenes and monoterpenoids (ca 15 wt.% fraction), (ii) sesquiterpenes and sesquiterpenoids (ca 30 wt.%) and (iii) triterpenes and triterpenoids (ca 55 wt.%). The major families of terpenes and terpenoids were identified employing gas chromatography coupled with mass spectrometry detector (GC–MS). Almost 25 wt.% of oleo-gum-resin was insoluble in ethanol and, according to wet chemistry analyses, assigned to arabinogalactane structurally associated with protein complex (AGP). This arabinogalactan possessed the molecular weight of ca 30 kDa, as revealed by size exclusion chromatography, and the main backbone was constituted by β-(1 → 3)/β-(1 → 3,6)-linked d -galactopyranosyl residues ramified predominantly by terminal α- l -arabinofuranosyl and β- d -glucuronopyranosyl residues, as assessed by 1D/2D 1 H NMR.

The chemical composition of the dichloromethane extracts of several vegetal fractions of banana plant, Musa acuminata Colla var cavendish have been studied by GC–MS. Several bioactive steryl glucosides, namely campesteryl 3-β- d -glucopyranoside, stigmasteryl 3-β- d -glucopyranoside and sitosteryl 3-β- d -glucopyranoside were identified as the major components of the extracts, accounting for 838.4–1824.3 mg/kg of the plant fractions dry weight. The high abundance of these compounds might be an important contribution to the valorization of banana plant agricultural residues.

The chemical composition of maritime pine (Pinus pinaster) bark and of alkaline bark extracts has been investigated with bark from trees grown in Portugal. Bark is composed of lignin and polyphenolics (ca. 44%), polysaccharides (ca. 39%), dichoromethane, ethanol and water extractives (ca. 17%) and ashes (ca. 1%). The lignin content determined by the Klason method, after the extraction of polyphenolics (tannin-rich fraction) from the bark by alkali solution, is 33.2%. Cellulose content is about 24%. Hemicelluloses (about 15% of bark dry weight) are suggested to be predominantly composed of arabinoglucuronoxylans and minor amounts of galactoglucomanans. The bark lignin is composed by p-hydrophenylpropane and guaiacylpropane units in proportions of 20:80. The condensed tannins are constituted mainly by catechin-type structural units. The direct extraction of bark with aqueous alkaline solutions yields extracts which contain sugars, lignin and condensed tannins. The number average molecular weights (Mn) of alkaline extracts are in the range 1000–1500. The composition and Mn of extracted substances depends on the alkaline extraction conditions.

Arundo donax plants were manually separated into fractions of different morphological regions (internodes, nodes and foliage) at different stages of maturity and submitted to chemical composition studies. General chemical composition was determined by established methods. The polysaccharides were fractionated by successive extractions of holocellulose with aqueous KOH solutions. The sugar composition was determined by hydrolysis of polysaccharides followed by GC analysis of neutral sugars as alditol acetates and spectrophotometric determination of uronic acids. In situ lignins, milled wood lignins (MWL) and dioxane lignin were characterised by permanganate oxidation followed by GC and GC-MS analysis of the methylated oxidation products and by quantitative 13C NMR spectroscopy. The results of general chemical analysis evidenced the different relative abundance of holocellulose, lignin, proteins, extractives and ashes in internodes, nodes and foliage, at different stages of maturity. In internodes, nodes and foliage about 70–80% of hemicelluloses (21–30% o.d. material) were easily extracted with 5% KOH aqueous solutions. The analysis of hemicelluloses indicated that they are constituted mainly by arabinoglucuronoxylans with a xylose:arabinose:uronic acid ratio of 91–93:5–7:2 for internodes. The high content of xylose in Arundo donax stem (24–27% o.d. material) and the easy extraction of hemicelluloses opens new perspectives for the use of this reed as a source of pentosans. The results obtained by the permanganate oxidation method indicated that Arundo donax lignins are essentially H-G-type with approximate H:G:S proportions of (32–36):(59–61):(5–8) in internodes. The H units are constituted mainly by esterified p-coumaric acid. These results were confirmed by quantitative 13C NMR spectroscopy of isolated dioxane lignin. The quantity of condensed structures in in situ lignin decreases from the older to the younger parts of the stems and is much higher in nodes than internodes.

Different morphological regions of Hibiscus cannabinus plants grown in Portugal were submitted to chemical composition studies. General chemical composition was determined by established methods. The polysaccharides were fractionated by successive extractions of holocellulose with aqueous KOH solutions. The sugar composition was determined by hydrolysis of polysaccharides followed by gas chromatography (GC) analysis of neutral sugars and spectrophotometric determination of uronic acids. In situ lignins and milled wood lignins (MWL) were characterised by permanganate oxidation followed by GC and GC-MS (mass spectrometry) analysis of the methylated oxidation products. The results of general chemical analysis have evidenced the different relative abundance of holocellulose, lignin, proteins, extractives and ashes in bark, core and foliage, at different stages of maturity. About 70–80% of the core hemicelluloses (about 20% o.d. material) was easily extracted with 5% KOH aqueous solutions against 60–70% (about 15% o.d. material) for the hemicelluloses of the bark. This hemicellulose fraction was composed mainly by glucuronoxylans with high content of uronic acids (xylose: uronic acid: 3–5: 1 for bark and 5–10: 1 for core). The hemicellulose fraction extracted with 24% KOH aqueous solutions was composed mainly by glucuronoxylans (80–90%) and glucomannans (10–15%). The results obtained by the permanganate oxidation method indicated that kenaf lignins are H-G-S type with approximate H: G: S molar proportions of (9–13): (55–60): (27–34) in bark and (14–20): (57)-(74): (12–23) in core, which evidences a high content of H and G units and a relatively low content of S units when compared with traditional dicotyledons. The relative proportion of H, G and S units as well as the structural features of lignins depends on the stage of maturity and on the morphological region of the plant. Kenaf lignins present a lower degree of condensation when compared with traditional wood lignins.