Abstract:Thermo-mechanical (TMP) and chemo-thermo-mechanical pulping (CTMP) of UF-bonded MDF induce considerable degradation of the UF-resin in the board and lead to a conspicuous increase in the content of water extractives of the fibres. Moreover, the water extractives of the fibres have a higher pH-value and a lower buffering capacity as well as higher acetate and formate ions content than the extractives of the original board. However, the lignin content seems rather to increase than to decrease. This is possibly d… Show more
“…10, is likely due to the degradation of the aminoplastic resin in recovered boards leading to the formation of urea pre-polymers, urea and ammonia, which can react with formaldehyde and act as formaldehyde scavengers. This behaviour converges well with already known behaviour of UF resin towards hydro-thermal degradation (Roffael, Dix, Behn and Bär 2009). 10 Formaldehyde release (3 and 24 h) according to the flask method (EN 717–3) of MDF, depending on the degree of substitution of softwood TMP by recycled fibres (0, 33, 67 and 100%), the addition of PMDI (0.5 and 1.0% based on dry fibres) and the press time factor (10 and 15 s mm −1 )…”
Section: Resultssupporting
confidence: 91%
“…10, is likely due to the degradation of the aminoplastic resin in recovered boards leading to the formation of urea pre-polymers, urea and ammonia, which can react with formaldehyde and act as formaldehyde scavengers. This behaviour converges well with already known behaviour of UF resin towards hydro-thermal degradation (Roffael, Dix, Behn and Bär 2009).…”
Section: Influence Of Higher Amounts Of Recycled Fibressupporting
The work aimed to study the influence of replacing virgin wood fibres by recycled fibres, made from recovered medium-density fibreboards (MDF) by thermo-mechanical pulping, on the physical-mechanical properties and formaldehyde release of urea-formaldehyde (UF)-bonded MDF. It was found that replacement of 33% virgin fibres by recycled fibres decreased significantly the thickness swelling and water absorption of the UF-bonded MDF and mitigated the formaldehyde release. However, supplanting 33% of virgin fibres by recycled fibres had a negative impact on the internal bond strength. UF-bonded MDF with higher amounts of recycled fibres (67 and 100%) could not be produced without applying the hybrid bonding technology, i.e. adding small quantities of polymeric diphenylmethane diisocyanate to the UF resin. MDF made from 100% recycled fibres showed significantly lower thickness swelling values as well as a drastic drop in the formaldehyde release compared with boards made from virgin wood fibres.
“…10, is likely due to the degradation of the aminoplastic resin in recovered boards leading to the formation of urea pre-polymers, urea and ammonia, which can react with formaldehyde and act as formaldehyde scavengers. This behaviour converges well with already known behaviour of UF resin towards hydro-thermal degradation (Roffael, Dix, Behn and Bär 2009). 10 Formaldehyde release (3 and 24 h) according to the flask method (EN 717–3) of MDF, depending on the degree of substitution of softwood TMP by recycled fibres (0, 33, 67 and 100%), the addition of PMDI (0.5 and 1.0% based on dry fibres) and the press time factor (10 and 15 s mm −1 )…”
Section: Resultssupporting
confidence: 91%
“…10, is likely due to the degradation of the aminoplastic resin in recovered boards leading to the formation of urea pre-polymers, urea and ammonia, which can react with formaldehyde and act as formaldehyde scavengers. This behaviour converges well with already known behaviour of UF resin towards hydro-thermal degradation (Roffael, Dix, Behn and Bär 2009).…”
Section: Influence Of Higher Amounts Of Recycled Fibressupporting
The work aimed to study the influence of replacing virgin wood fibres by recycled fibres, made from recovered medium-density fibreboards (MDF) by thermo-mechanical pulping, on the physical-mechanical properties and formaldehyde release of urea-formaldehyde (UF)-bonded MDF. It was found that replacement of 33% virgin fibres by recycled fibres decreased significantly the thickness swelling and water absorption of the UF-bonded MDF and mitigated the formaldehyde release. However, supplanting 33% of virgin fibres by recycled fibres had a negative impact on the internal bond strength. UF-bonded MDF with higher amounts of recycled fibres (67 and 100%) could not be produced without applying the hybrid bonding technology, i.e. adding small quantities of polymeric diphenylmethane diisocyanate to the UF resin. MDF made from 100% recycled fibres showed significantly lower thickness swelling values as well as a drastic drop in the formaldehyde release compared with boards made from virgin wood fibres.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
