Characterization of suberinic acids from birch outer bark as bio-based adhesive in wood composites

Rizhikovs, Janis; Brazdausks, Prans; Pāže, Aigars; Tupčiauskas, Ramūnas; Grīniņš, Juris; Puķe, Māris; Pļavniece, Ance; Andžs, Mārtiņš; Godiņa, Daniela; Makars, Raimonds

doi:10.1016/j.ijadhadh.2021.102989

Cited by 20 publications

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“…Infrared spectra ( Figure 4 ) for adhesive samples and feedstock (extracted BOB) showed a difference for C=O absorption bands. The band at 1734 cm −1 was attributed to esters, whereas the band at 1702 cm −1 corresponds to C=O vibration in carboxylic acids [ 24 , 25 ]; thus confirming that adhesive samples consisted mostly of depolymerized SA. Another band at 1160 cm −1 was present just for the feedstock sample.…”

Section: Resultsmentioning

confidence: 94%

“…This may suggest that 1-butanol was the least suitable solvent for BOB depolymerization. Asymmetric (2922 cm −1 ) and symmetric (2852 cm −1 ) vibrations, as well as bands at 1464, 1455, and 1374 cm −1 were another characteristic of suberin, corresponding to C–H bonds in alkyl chains [ 24 , 25 , 26 , 27 ]. The vibrations at 721 cm −1 are inherent to suberin resulting from aliphatic R 1 CH=CHR 2 structures [ 24 , 27 ].…”

Section: Resultsmentioning

confidence: 99%

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Utilization of Suberinic Acids Containing Residue as an Adhesive for Particle Boards

et al. 2022

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The birch (Betula spp.) outer bark is a valuable product rich in betulin. After removal of betulin extractives, suberin containing tissues are left. Suberin is a biopolyester built from α,ω-bifunctional fatty acids (suberinic acids), which after depolymerization together with lignocarbohydrate complex is a potential adhesive as a side-stream product (residue) from obtaining suberinic acids for polyol synthesis. In this work, we studied the utilization possibilities in particleboards of the said residue obtained by depolymerization in four different solvents (methanol, ethanol, isopropanol and 1-butanol). The adhesives were characterised by chemical (acid number, solubility in tetrahydrofuran, epoxy and ash content) and instrumental analytical methods (SEC-RID, DSC, TGA and FTIR). Based on the results of mechanical characteristics, ethanol was chosen as the most suitable depolymerization medium. The optimal hot-pressing parameters for particleboards were determined using the design of experiments approach: adhesive content 20 wt%; hot-pressing temperature 248 °C, and hot-pressing time 6.55 min.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Utilization of Suberinic Acids Containing Residue as an Adhesive for Particle Boards

et al. 2022

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“…Bio-based adhesive containing suberinic acids (SA) was obtained from birch wood outer bark, first providing ethanol extraction and then hydrolytic depolymerization in a 3% KOH water solution at 85 °C for 1 h [ 13 ]. The obtained wet SA-based adhesive with MC of ~80% (pH 2, solubility in dimethyl sulfoxide 73.0%, acid number 69.5 mg KOH/g) was mixed with fractionated (0.4–2.0 mm) birch wood particles (MC~7%) at a proportion of 21:79 by a mixer (CAT R100C, Paso Robles, CA, USA) and oven-dried at 70 °C to MC ≤ 1%.…”

Section: Methodsmentioning

confidence: 99%

“…As a reaction to the industry’s challenge related to formaldehyde emission, bio-based adhesives are on the research top, generally comprising lignin, tannins, protein, and starch [ 12 ]. A very new and promising bio-based adhesive has been revealed in the form of suberinic acids containing binder from birch wood outer bark [ 13 ] investigated for application in particleboard [ 14 ] and plywood [ 15 ]. However, very few studies have investigated the VOC profiles of binder-less and bio-adhesive-bonded particleboards.…”

Section: Introductionmentioning

confidence: 99%

Qualitative Differences and Emission Persistence of Volatile Organic Compounds from Bio-Based Particleboards

et al. 2022

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An attempt to reduce, replace, or even eliminate the synthetic resins from wood-based panels alongside broadening the array of raw lignocellulosics is still essential and attractive. Many pretreatments of lignocellulosics have been studied, among which steam explosion (SE) resulted in superior physical-mechanical properties of the obtained binder-less boards. However, the SE pretreatment leads to a relatively strong odor, which is even emitted from the obtained binder-less boards independent of the raw lignocellulosic, raising concern about the use of the boards. Emissions of volatile organic compounds (VOCs) were investigated in the framework of the study from binder-less boards obtained from different SE raw lignocellulosics and SE-untreated suberinic acids-bonded particleboard. VOCs were collected by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography–mass spectrometry (GC–MS) for 28 days with an interval of 2 weeks. The results showed that the number of detected VOCs and their chromatographic peak area varied significantly depending on the raw lignocellulosic, board density, and post-treatment (overlayering), decreasing over time. The lowest area of detected VOCs was demonstrated by the suberinic acids-bonded particleboard, while the highest area was detected from the high-density binder-less board obtained from SE hemp shives with the main compound of furfural (up to 70%) in all board types.

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“…A small shoulder of this peak also appeared at ~1730 cm −1 as the SA sample contained some esters, which also corresponded to the titrated saponification number in Table 2. The peaks at 1463 cm −1 and 1375 cm −1 indicate asymmetric and symmetric C-H deformations of the aliphatic regions, which may be characteristic of suberin [14,15]. As can be seen in Figure 7, the SA fraction, which was acidified to pH 1, contained a noticeable residue of HNO 3 .…”

Section: Preparation and Characerization Of Bio-polyolsmentioning

confidence: 99%

Suberinic Acids as a Potential Feedstock for Polyol Synthesis: Separation and Characterization

et al. 2021

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Global sustainability challenges prompt the world to modify its strategies and shift from a fossil-fuel-based economy to a bio-resources-based one and to the production of renewable biomass chemicals. Depolymerized suberinic acids (SA) were considered as an alternative resource to develop bio-polyols that can be further used in polyurethane (PU) material production. Birch (Betula pendula) outer bark was used as a raw material to obtain the SA, extracted with ethanol, and depolymerized with potassium hydroxide ethanol solution. By acidifying the filtrate to pH 5.0, 3.0, and 1.0 and drying it at 50 °C and 130 °C, 12 different SA potential feedstocks were obtained and characterized using chemical (total phenolics content, solubility in DMSO, acid, hydroxyl, and saponification number) and instrumental analytical methods (GC-MS, SEC-RID, DSC, and FTIR). Several bio-polyols were synthesized from the SA sample acidified to pH 1 and dried at 130 °C. Acid number and hydroxyl number values, the apparent viscosity and moisture content were measured. It was concluded that SA have a high enough saponification and acid value to investigate the polyol synthesis route via the esterification reaction. Moreover, SA had OH groups in their structure, which can be exploited for PU material development. The majority of SA compounds had relatively low molecular weight with <1300 Da that are suited for bio-polyol synthesis applied for rigid PU foam development. The synthesized bio-polyols had high hydroxyl number values necessary for bio-polyols to be used for rigid PU foam production.

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Characterization of suberinic acids from birch outer bark as bio-based adhesive in wood composites

Cited by 20 publications

References 20 publications

Utilization of Suberinic Acids Containing Residue as an Adhesive for Particle Boards

Utilization of Suberinic Acids Containing Residue as an Adhesive for Particle Boards

Qualitative Differences and Emission Persistence of Volatile Organic Compounds from Bio-Based Particleboards

Suberinic Acids as a Potential Feedstock for Polyol Synthesis: Separation and Characterization

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