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Pinus nigra var. laricio bark and its hot-water extracts (HWE) obtained at an analytical and pilot plant scale have been characterized in terms of phenolic extractives, condensed tannins (CTs), carbohydrates and inorganic compounds. Analytical extractions with aqueous acetone were also performed for comparison with HWE. The bark contains 35.5 g kg−1 CT, and two-thirds of it could be extracted. Analytical HWE at 75°C led to a total yield of 56.4 g kg−1. The extracts are mainly composed of phenolic compounds (50.7%) and pectins (19.7%). CTs amount to 17.9% of the extracts and are procyanidins with a mean degree of polymerization (DP) of about 9. Non-tannin phenolic oligomers also occurred in the extracts, which could be identified by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) as lignin fragments. Matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS) revealed that the CT is a flavanol derivative in methylated form. Further characterization and tailoring of the HWE properties is needed in the context of their specific application. [ABSTRACT FROM AUTHOR]

The possibility of producing binderless panels made of milled coconut husk, a largely available by-product of the coconut oil industry, has been shown in previous researches. Long pressing times and a high risk of blisters have however hindered the industrial implementation of the process. In this study, a more energy-efficient manufacturing process, involving a tailored degassing step, was developed on a laboratory scale and then validated at an industrial size (2 × 1 m2). To achieve mechanical properties close to the European and Japanese standards for fibreboards and to avoid the delamination of the boards, final densities between 900 and 1000 kg m−3 had to be targeted. Similarly, a successful board production was only possible if the moisture content of the husk was between 10 and 25%. The need for a suitable mat-forming technology to avoid the risk of warping of the panel was highlighted. [ABSTRACT FROM AUTHOR]

The hot water (HW) extraction of Norway spruce ( Picea abies [Karst.]) delivers condensed tannins and considerable amounts of other compounds. Yield and composition of the HW extracts were investigated as a function of natural weathering for up to 15 months. Total phenol monomers and oligomers were detected by Folin-Ciocaltau assay after fractionation by solid phase extraction (SPE). Procyanidins (PC) were determined by HPLC-UV after acid thiolysis and carbohydrates by HPLC combined with acid hydrolysis. Topochemistry of the bark before and after extraction was investigated by UV-microspectrometry (UMSP) and non-extractable PC analyzed by direct thiolysis on the bark. The influence of the parameters on the yield and composition of the extracts were evaluated, such as the extraction temperature, time and the addition of sodium sulfate and urea. Prolonged weathering resulted in a considerable decrease of the total extraction yield, partly because of leaching of phenolic monomers, mono- and oligosaccharides. The yield of phenolic oligomers also decreased at a moderate rate, while the yield of polysaccharides (pectins) was almost stable. Non-extractable and non-leachable compounds deposited in the cell lumens represent the majority of the phenolic extractives in spruce bark. Sequential extractions performed at increasing temperature proved to be a suitable method for the recovery of tannin-rich extracts. [ABSTRACT FROM AUTHOR]

Condensed tannins extracted from European softwood bark are recognized as alternatives to synthetic phenolics. The extraction is generally performed in hot water, leading to simultaneous extraction of other bark constituents such as carbohydrates, phenolic monomers and salts. Characterization of the extract’s composition and identification of the extracted tannins’ molecular structure are needed to better identify potential applications. Bark from Silver fir ( Abies alba [Mill.]), European larch ( Larix decidua [Mill.]), Norway spruce ( Picea abies [Karst.]), Douglas fir ( Pseudotsuga menziesii [Mirb.]) and Scots pine ( Pinus sylvestris [L.]) were extracted in water at 60 °C. The amounts of phenolic monomers, condensed tannins, carbohydrates, and inorganic compounds in the extract were determined. The molecular structures of condensed tannins and carbohydrates were also investigated (HPLC-UV combined with thiolysis, MALDI-TOF mass spectrometry, anion exchange chromatography). Distinct extract compositions and tannin structures were found in each of the analysed species. Procyanidins were the most ubiquitous tannins. The presence of phenolic glucosides in the tannin oligomers was suggested. Polysaccharides such as arabinans, arabinogalactans and glucans represented an important fraction of all extracts. Compared to traditionally used species (Mimosa and Quebracho) higher viscosities as well as faster chemical reactivities are expected in the analysed species. The most promising species for a bark tannin extraction was found to be larch, while the least encouraging results were detected in pine. A better knowledge of the interaction between the various extracted compounds is deemed an important matter for investigation in the context of industrial applications of such extracts. [ABSTRACT FROM AUTHOR]

Condensed tannins extracted from the bark of softwoods have been proven to be suitable compounds in the formulation of environmentally friendly adhesives and resins. Their chemical structure has been shown to significantly influence their properties and possible applications. Condensed tannins extracted from the bark of Norway spruce ( Picea abies [Karst.]) and Silver fir ( Abies alba [Mill.]) still lack a detail characterization of their chemical structure. In an effort to address this deficiency, barks from these species were collected and extracted in water at 60 °C. The dried extracts were analyzed by MALDI-TOF mass spectrometry to identify the building blocks and to determine the degree of polymerization of the tannin oligomers. The condensed tannins extracted from spruce bark at the used conditions were mainly composed of procyanidins with a polymerization degree up to 13. Silver fir extracts revealed a predominance of prodelphinidins with a polymerization degree up to 9. The presence of less common building blocks such as stilbene glucosides and flavan-3-ols gallates was also hinted. Different curing times and viscosities in resin formulations are expected between the two studied species, as well as in comparison to the most known and available tannins from tropical species. [ABSTRACT FROM AUTHOR]

Abstract: The use of interface models for the full simulation of fracture processes in polymer–matrix composites is discussed in the present paper. To this end, a numerical model accounting for both the elasto-plastic behaviour of the material surrounding an interlaminar crack in thermoplastic–matrix composites and the fracture behaviour of the material inside the fracture zone was developed. An attempt to separate decohesion from other main dissipative effects such as plasticization of the matrix has been made. The material behaviour observed by applying a toughening technique known as “interleaving” was explained by the evolution of process and plastic zones in the interlaminar region. An indirect identification procedure of the interface behaviour based on fracture testing of the neat resin was proposed, but the agreement with the experimental composite response was not completely satisfactory. [Copyright &y& Elsevier]

• Plant extractives from alpine forests offer highly variable compositions. • Condensed tannins can be recovered from several tissues of different tree species. • Condensed tannins have been identified in almost all highly antioxidant extracts. • A combination of phenolic monomers could be a cause of some antioxidant extracts. Tree species typical of the alpine forests can be valued not only as sources of timber, but also as raw tissues for the recovering of extractives with significant antioxidant activity (AA). To improve knowledge about the extractive content in these trees and to investigate whether there is a correlation between extract composition and AA, heartwoods, sapwoods, barks, knotwoods, twigs and needles of seven of the most common tree species from the alpine region were extracted with different solvents by Accelerated Solvent Extraction (ASE). The extracts were characterized by GC–MS for fatty and resin acids, TD-GC/MS for terpenes, HPLC-UV for phenolic monomers and condensed tannins (CT), and GC-FID for mono- and polysaccharides. The AA of the extracts were thereafter estimated using the DPPH assay. The exact composition of extractives derived was highly characteristic of each specific plant tissue, and some general trends were observed. The richest tissues in extractives (18.6–39.0% on dry tissue) were barks and needles. However, sapwoods showed a very low presence of extractives (5.2–7.5%). The main extractable compounds from bark were CT and polysaccharides, while phenolic monomers and monosaccharides represented the majority of needle extractives. Terpenes were mostly detected in twigs. The composition of extractives for heartwoods and knotwoods were more scattered and closely associated to the tissues. A significant correlation between the extract composition and their AA was demonstrated by a multiple linear regression analysis (p -value <0.001). The most effective compounds contributing to the high AA of the extracts were CT. Plant tissue rich in condensed tannins like European oak heartwood, Scots pine bark and Norway spruce bark, should therefore be considered as the most suitable sources for natural antioxidants from the alpine region. However, the findings need to be validated with further antioxidant assays. [ABSTRACT FROM AUTHOR]

The study is aimed to determine the resistance of fibreboards made of milled coconut (Cocos nucifera [L.]) husk and bonded with tannin adhesive (Coconut Fibreboards - CFB) against wood-destroying insects and fungi under laboratory and field conditions. Marine plywood (MPW) samples were included in the tests for comparison. Results showed that CFB had higher resistance to insect and fungi than MPW. After four months of laboratory exposure to subterranean termites CFB had only few signs of nibbling with weight losses of 3.5%. MPW showed instead weight losses of 95%. CFB exposed for 12 months to drywood termite were damaged between 0.0% and 6.0%. MPW damage was within 21.0% and 65.0% within the same period. Wood decay fungi caused weight loss of 7.8% in CFB, while weight losses between 55.4% and 88.0% were observed in MPW. The potential of CFB for applications as ceiling and wall cladding in the Philippines was therefore suggested. [ABSTRACT FROM AUTHOR]