Hydrolytic Removal of Cured Urea–Formaldehyde Resins in Medium-Density Fiberboard for Recycling

Hong, Min-Kug; Park, Byung‐Dae

doi:10.1080/02773813.2017.1316741

Cited by 44 publications

(39 citation statements)

References 23 publications

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“…In both samples, the highest amount of material could be found in the water extract, followed by the acetone/water extract. These findings can most likely be attributed to the presence of UF-resins, which are readily hydrolysable in water at temperatures below 100 • C [16,17,74,75]. This assumption is further strengthened by the elemental composition of the samples before and after extraction.…”

Section: Raw Materials Characterizationmentioning

confidence: 99%

“…However, this susceptibility to hydrolysis can be used in the fractionation of MDF for recycling purposes. While the highest removal rate of cured resins can be achieved using acidic solutions [16], it is still possible to remove up to two-thirds of cured resin using only water at temperatures below 100 • C [17]. More intense reaction conditions, as they are found in steam treatments, can further improve the resin hydrolysis [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Fractionation of Waste MDF by Steam Refining

Hagel

Saake

2020

Molecules

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In view of the expected increase in available waste medium-density fiberboard (MDF) and the current insufficient and unsatisfactory disposal capacities, efficient ways of recycling the waste material need to be developed. In this study, the potential of steam refining as a method to hydrolyze the resins, isolate fibers, and obtain a hemicellulose-rich extract available for further utilization in the context of a biorefinery was assessed. Two different MDF waste samples, as well as poplar (Populus spp.) and spruce (Picea spp.) wood chips for benchmarking, were treated over a severity range from 2.47 to 3.95. The separated fiber and extract fractions were analyzed with regard to yield, content of carbohydrates, acids, degradation products, and nitrogen. A fiber fraction of more than 70% yield and an extract containing up to 30% of carbohydrates for further processing can be gained by steam-refining waste MDF. At low severities, most of the nitrogen-based compounds are solubilized. Increasing the severity leads to a decrease in nitrogen in the extract as the nitrogen compounds are converted into volatiles. A non-hydrolysable resin residue remains on the fibers, independent of the treatment severity. In comparison to the benchmark samples, the extract fraction of waste MDF shows a high pH of 8 and high amounts of acetic and formic acid. The generation of furfural and 5-hydroxymethylfurfural (5-HMF) on the other hand is suppressed. Distinct differences in carbohydrate hydrolysis behavior between waste MDF and conventional wood can be observed. Especially, the mannose-containing constituents seem to be resistant to hydrolysis reactions in the milieu created in MDF fractionation.

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Section: Raw Materials Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fractionation of Waste MDF by Steam Refining

Hagel

Saake

2020

Molecules

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“…Local stress concentration along the wood bond line in the brittle adhesives such as UF, phenolic formaldehyde (PF) and melamine-UF (MUF) is high due to high methylene crosslink density (Lubis et al, 2018) and the formation of crystalline region. Fortunately, there is possible interaction between hydroxyl groups of cellulose and methylol groups from UF resin that results in improvement of ductility of the adhesive (Fornué et al, 2011).…”

Section: Nanocellulose In Wood Adhesivesmentioning

confidence: 99%

Nanocellulose: From Fundamentals to Advanced Applications

et al. 2020

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Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

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“…UF resins are connected via methylene and ether linkages to form cross-linked thermosetting cured adhesive. Low stability of cured UF resins against hydrolysis under acidic and humid conditions causes formaldehyde release from engineered wood products bonded with UF resins (Abdullah and Park 2009;Lubis et al 2018b;Park and Jeong 2011b). The brittleness of the cured UF resins causes cracking and allows the moisture to penetrate the UF-bonded products, resulting in cured UF resins susceptible towards hydrolysis.…”

Section: Hydrolysis Of Cured Uf Adhesivementioning

confidence: 99%

The Removal of Cured Urea-Formaldehyde Adhesive towards Sustainable Medium Density Fiberboard Production: A Review

Manohar

Laksana²,

Fatriasari

et al. 2021

JSL

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Medium density fiberboard (MDF) is an engineered wood product that has density and specific gravity similar to solid wood, ranging from 600 to 800 kg/m3 of density and 0.6 to 0.8 of specific gravity. This makes MDF suitable to partially replace solid wood, particularly for interior application. Approximately over than 100 million m3 of MDF are produced in 2020, resulting in a large amount of waste MDF will be generated in the next 20 years. MDF is produced using urea-formaldehyde (UF) resins adhesive. UF resins adhesive is a poly-condensation product of urea and formaldehyde via an alkaline acid two-step reaction. Sustainable MDF production is required as the world is facing climate change and deforestation. Recycling is a way to support sustainable production in the engineered wood products manufacturing. Many attempts have been done to find ways to recycle waste MDF. The main problem is UF resins, which bond the MDF panel fibers. In order to re-manufacture the waste MDF into new recycled MDF, UF resins should be eliminated from the waste MDF before being used. The presence of UF resins in MDF can interfere with the utilization of the recycled fibers, whether it will be used as a raw material for new MDF or other composite products. This paper reviews the process of removal of cured UF resins from waste MDF panel by considering the hydrolytic stability of cured UF resins for MDF recycling, providing a comprehensive review of how cured UF resins can be removed from waste MDF and characterization of recycled fibers obtained from recycling prior to re-manufacturing of recycled MDF panel.Keywords: hydrolysis, medium density fiberboard, resin, recycling, resin removal, urea-formaldehyde

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Hydrolytic Removal of Cured Urea–Formaldehyde Resins in Medium-Density Fiberboard for Recycling

Cited by 44 publications

References 23 publications

Fractionation of Waste MDF by Steam Refining

Fractionation of Waste MDF by Steam Refining

Nanocellulose: From Fundamentals to Advanced Applications

The Removal of Cured Urea-Formaldehyde Adhesive towards Sustainable Medium Density Fiberboard Production: A Review

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