Water Extraction of Tannins from Aleppo Pine Bark and Sumac Root for the Production of Green Wood Adhesives (original) (raw)
Related papers
Wood Science and Technology, 2014
The phenolic composition of sumac root barks was studied. Colorimetric assays, FT-IR and NMR were used to examine the phenolic composition and tannins nature. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to examine the structure of the tannin oligomers. TGA analysis was used to study the thermal stability of sumac tannin extract. Analyzes showed that sumac root barks are rich in condensed tannins, especially procyanidin and prodelphinidin types. Flavonoid oligomers of dimers, trimers, tetramers, pentamers and hexamers kind were detected in MALDI-TOF-positive ion mode analysis. TGA analysis showed thermal stability of sumac tannins compared to other condensed tannin types and pomegranate hydrolyzable tannins.
Characterization of Tunisian Aleppo pine tannins for a potential use in wood adhesive formulation
Industrial Crops and Products, 2014
The phenolic composition of Tunisian Aleppo pine barks was studied. Colorimetric assays, Fourier transformed infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were used to examine Aleppo pine tannins. Analyzes showed that Aleppo pine barks are rich in condensed tannins, especially in procyanidin and prodelphinidin tannins. The reactivity to formaldehyde test (Stiasny number) showed the possible use of Aleppo pine tannins in wood adhesive formulation. Thermomechanical analysis (TMA) and strength analysis of Aleppo pine tannin/hexamin based resin showed important bonding properties.
Tannins of Deciduous Trees Bark As a Potential Source for Obtaining Ecologically Safe Wood Adhesives
Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference, 2015
The bark of deciduous trees grown in Latvia: grey alder, black alder, ash tree and goat willow were sequentially extracted using solvents of increasing polarity. The data about total content of both lipophilic and hydrophilic compounds were obtained using sequentially extraction with hexane and ethanol. The highest yields of hydrophilic extractives were found for grey alder and ash tree barks (25.7% and 25.8%, respectively). Hydrophilic extract from the both alder species contained high amount (up to 12% on bark dry mass) of condensed tannins (CT) or oligomeric proanthocyanidins, whereas CT content of extract from ach tree was negligible. The main component of ethanol-water extract from alder bark was identified using 13C NMR and MALDI–TOF MS spectroscopy as a mixture of A- and B-type oligomeric procyanidins with the epicatechin units polymerization degree of 2-7. Ecologically friendly wood adhesives were obtained on the condensed tannin basis.
Materials
Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stimulates the development of environmentally friendly adhesives. The aim of this research was to study, for the first time, the possibility of using condensed tannins (CTs)-rich extracts from grey alder (Alnus incana) and black alder (Alnus glutinosa) bark in the production of particleboards and plywood adhesives. The chemical structure, composition, and molecular weight of the CTs were identified by a 13C-NMR and TOF-MS analysis. Three innovative adhesive systems were studied: CTs-phenol-formaldehyde (CTs-PF) resin; a CTs-polyethyleneimine (PEI) adhesive system; and CTs–PEI combined with an ultra-low emitting formaldehyde resin (ULEFR)—CTs–PEI–ULEFR. The results showed that CTs-PF resin has properties close to commercial PF resin, and the formaldehyde emission was twice lower. CTs–PEI bonded particleboards corresponded to the requirements of the EN 312:2010 standard for particleboards in d...
2012
In order to reduce formaldehyde emissions from wood panels and to develop green adhesives, natural phenolic polymers of tannins and lignin have been investigated as substitutes of petrol-based chemicals used in wood panels. The potential of several wood barks, obtained from pulp mills as industrial wastes, has been evaluated for tannin extraction and further for their adhesive properties. Aqueous extractions were carried on wood barks of five different tree species on a laboratory scale – Aleppo pine barks led to the highest yield (15%) compared to spruce, Douglas fir, maritime pine and eucalyptus. Urea and sulfite used as water-additives favoured the extraction of condensed tannins, especially for spruce and Douglas fir barks. Eucalyptus barks presented the lowest tannins contents. Pyr-GC/MS of the bark extracts showed that Douglas fir and Aleppo pine tannins were mainly constituted of phenol and catechol tannins. The adhesive potential of these tannins was also established. Cookin...
Environmentally friendly wood adhesives based on chestnut (Castanea sativa) shell tannins
European Journal of Wood and Wood Products, 2016
The aim of this work was the formulation of adhesives for particleboards based on tannins extracted from industrial lignocellulosic wastes, namely chestnut shell, chestnut bur and eucalyptus bark. The interest was centred on the possibility of completely removing formaldehyde from adhesive formulations. For this, hardener alternatives to formaldehyde were used: tris(hydroxymethyl)nitromethane (TRIS), glyoxal (GLY) and hexametilentetramine (HEX). The influence of the type and concentration of the hardener and pH on adhesive gel time and pot-life were studied. A comparative structural characterization of the adhesives was performed by 13C-NMR spectroscopy. Thermomechanical analyses (TMA) tests were carried out as an indication of the final strength of the adhesive systems. Particleboards type 2 of interior use (EN 312) were manufactured with adhesives based on chestnut shell tannins alone or mixed with chestnut bur/or eucalyptus bark tannins. Free-formaldehyde was determined, and boards were prepared with TRIS, GLY and HEX tannin adhesives were classified as E0.
The aim of this study was to determined the quality of mahogany (Swietenia mahagony) tannin extract as an adhesive for plywood. The mahogany tannin extract was copolymerized with phenol and formaldehyde became TPF adhesive. Then, the plywood was made from mangium (Acacia mangium) and sengon (Paraseriathes Falcataria) with dimensions 30 × 30 × 0.6 (cm3) in the length, width, and thickness, respectively. Pressing was carried out using the cold press method for 11 minutes and then followed by the hot press method for 10 minutes at a temperature of 110oC with a specific pressure of 1.47 MPa. Phenol formaldehyde and urea formaldehyde adhesives were used as a comparison and 5 replicates were made for each plywood. The physical and mechanical were tested according to JAS 233:2003. The result showed that TPF had an equal quality with the synthetic adhesive in dry conditions. Moreover, all of plywood from sengon wood categorized as F**** the lowest and the best.
Properties of Pine Bark Tannin-based Adhesive Produced with Various Hardeners
BioResources, 2018
Tannin-based adhesives are alternative bio-based products that can be used in the wood panel industry instead of synthetic adhesives that contain formaldehyde. For the production of these adhesives, formaldehyde is utilized generally as a hardener as in its synthetic counterparts. In this study, adhesive formulations were prepared using eight different hardeners and tannin powder from Turkish red pine (Pinus brutia) barks. While the shortest gel time values in the adhesive formulations were identified in the samples prepared with formaldehyde and paraformaldehyde, the longest gel time was obtained in the formulation prepared with tris(hydroxymethyl)nitromethane. As a result of the dry bonding tests, the values closest to the commercial UF adhesive were found in descending order as paraformaldehyde, formaldehyde, hexamine glyoxal, and poly[(phenyl isocyanate)-co-formaldehyde] (pMDI). According to the wet bonding strength test results, the adhesive samples in which furfural, tris(hydroxymethyl)nitromethane, and benzaldehyde were used as hardeners did not achieve wet bonding strength. As a result of thermogravimetric analysis (TGA), commercial UF adhesive samples had dramatically lower thermal stability than all of the formulations prepared with tannin. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectral analysis revealed that new chemical bonds were established between the tannin and hardeners.
Effect of Extraction Solvent on Tannin-Formaldehyde Adhesives for Plywood Production
Journal of Energy and Natural Resource Management, 2018
Pine bark is a good source of natural polyphenolic compounds for wood adhesives. The objective of this study was to obtainthe most suitable solvent for extracting pine tannins in the preparation of tannin-formaldehyde plywood adhesives. Aqueousacetone, aqueous ethanol, aqueous NaOH and water as solvents were used to obtain crude tannins from pine bark. Thetannin content, sugar content and Stiasny number of the extracts were determined. Using the extracts from the solventextractions, synthesis of tannin-formaldehyde resin was carried out. Plywood panels were made using the synthesized resinsand the quality of the resins in plywood application determined. The quality of tannin-formaldehyde resins produced from thetannins were generally in close agreement with the chemical characteristics of the extracts obtained from the various solventextractions. The aqueous NaOH extraction although gave very high tannin yield (16.1%), its associated high sugar content(33.8%) and very low Stiasny nu...
Wood Science and Technology, 2012
MALDI-TOF, HPLC-ESI-TOF and 13C-NMR techniques were used to analyse the structure of non-purified aqueous chestnut shell tannin extracts. In addition, the influence of the extraction agent (water or aqueous solutions of Na 2 SO 3 and/or NaOH) on tannin structure was analysed by MALDI-TOF in order to select the extract with the best properties for wood adhesives. Using HPLC-ESI-TOF, catechin/epicatechin, gallocatechin/epigallocatechin, dicatechin structures, dicatechin structures without a hydroxyl group, galloyl-glucoses and ellagic acid were identified as the main monomeric components in the aqueous extract. 13C-NMR and MALDI-TOF spectra revealed that extracts are mostly composed of procyanidin and prodelphinidin structures although prorobinetidins might be also present. MALDI-TOF spectrometry was used to identify the extract oligomeric components. Extractions with Na 2 SO 3 and/or NaOH produced changes in the predominant structures in the extracts and on the amount of sugar units linked to the flavonoid structures, which decreased in the presence of Na 2 SO 3. Extract obtained using low Na 2 SO 3 and NaOH concentrations (1.5 and 0.75 %, respectively) was selected as more suitable for wood adhesive preparation.