Bonding of recycled fibres with urea-formaldehyde resins

Roffael, E.; Behn, C.; Schneider, T.; Krug, Detlef

doi:10.1080/20426445.2015.1131918

Cited by 21 publications

(21 citation statements)

References 12 publications

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“…Lately, there has been a growing interest in utilizing oligosaccharides in different applications such as biodegradable oxygen barrier films [38][39][40], emulsifiers [41][42][43][44][45][46][47], thermoplastics [48], hydrogels [49], coatings, or adhesives [50]. The remaining fibrous fraction, on the other hand, might be suitable for production of new fiberboards [51][52][53][54][55][56][57], cellulose nanocrystals [58,59], bioethanol [60,61], biogas, and bio-oil using pyrolysis [62,63]; however, utilization as reinforcement and filler material in wood-plastic compounds (WPCs) [64][65][66] and particleboards [67] has also been proposed.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

Fractionation of Waste MDF by Steam Refining

Hagel

Saake

2020

Molecules

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“…It revealed that a combination of steam explosion, chemical impregnation, and hammer milling process could be applied to isolate the recycled fibers (Wan et al 2014). However, the recycled fibers still contain cured UF resin and release a high formaldehyde emission from the re-manufactured panel (Roffael et al 2016). Moreover, it has been reported that replacement virgin fibers by recycled fibers over 20% reduced the internal bond strength of the MDF panel (Lubis et al 2018a).…”

Section: Properties Of Recycled Fibersmentioning

confidence: 99%

“…A lot of fines chips are generated during the disintegration process. Moreover, the recycled chips still contain the residues of the cured resin and exhibit a high formaldehyde emission from the re-manufactured panel (Roffael et al 2016). A combination of mechanical and hydrothermal disintegration can reduce the amount of cured resin in the recycled chips.…”

Section: Properties Of Recycled Fibersmentioning

confidence: 99%

“…It means the recycled fibers have high interference for bonding with UF resin in MDF manufacturing. It has been reported that the utilization of recycled fibers over 20% reduced the internal bond strength of the MDF panel (Lubis et al 2018a;Roffael et al 2016). However, further treatment of recycled fibers with chemical treatment using a combination of the aqueous solution of Na2SO3 and NaOH could increase the internal bonding strength by 16% (Mantanis et al 2004).…”

Section: Acid Buffering Capacity = (V1 X N Of Base X V2 X 100)/(v3 X W) (Meq/100g Od Fiber)mentioning

confidence: 99%

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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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“…The reuse of the separated waste MDF fibers in production of new MDF is the most apparent possible recycling pathway. However, due to a combination of effects such as fiber shortening, changes in the chemical compositions of the fibers and resin residues found on their surface, a deterioration of the mechanical properties in comparison with MDF made from fresh wood can be observed when using hydrothermal or steam-based fractionation processes [19][20][21][22][23][24]. Recently, Moezzipour et al [25] have reported that such negative effects on the fibers can be reduced using electrical heating instead of hydrothermal treatments, leading to improved mechanical properties of the newly produced MDF.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

Hagel

Joy

Cicala

et al. 2021

Waste Biomass Valor

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Currently, most of the collected waste medium-density fiberboards (MDF) is incinerated or landfilled, as economically viable recycling methods are yet to be developed. By steam refining waste medium-density fiberboards (MDF), it is possible to hydrolyze the incorporated resins and isolate a high yield fiber fraction. Further refining of the steam treated fibers might enable the fibers to be utilized in applications such as paper packaging, facilitating a cascading use of the waste material stream. To this end, intimate knowledge of the material is needed. In this study, the steam refined fibers of two waste MDF samples containing differing amounts of softwood and hardwood underwent refining and beating. The resulting fibers were characterized regarding their morphology and paper test sheets were produced to evaluate their strength (compression-, tensile- and tear-strength). Distinct differences in response to refining between the MDF samples were apparent. For the sample with the higher hardwood share an increase in strength properties with increasing steam treatment severities could be observed and it was possible to produce test sheets with comparable compression strength to recycled pulp for industrial corrugated paperboard. For the sample with a higher share of softwood, the steam treatment severity did not show any influence on fiber morphology or paper properties, and the resulting paper strength was low in comparison to the other steam refined waste MDF sample. Graphic Abstract

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Bonding of recycled fibres with urea-formaldehyde resins

Cited by 21 publications

References 12 publications

Fractionation of Waste MDF by Steam Refining

Fractionation of Waste MDF by Steam Refining

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

Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

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