62 documents found, page 1 of 7

Effect of spent sulfite liquor on urea-formaldehyde resin performance

Combination of urea-formaldehyde (UF) resins with technical lignins has been often reported in the literature. However, the actual implications of this approach have not been effectively addressed yet. In this work, unmodified thick spent sulfite liquor (TSSL) and hydroxymethylated TSSL (TSSLH) were incorporated in a standard UF resin in different amounts (10 and 20%) and at different stages. When 10% of TSSLH ...

Impact of the Synthesis Procedure on Urea-Formaldehyde Resins Prepared by Alkal...

In this work, two synthesis procedures for the preparation of urea-formaldehyde (UF) resins, based on the alkaline-acid process, are studied in order to better understand the chemical reactions involved. For that purpose, the number of urea loads and the methyolation temperature were varied. The molecular weight distribution of the resins was monitored by gel permeation chromatography/size exclusion chromatogra...

Introducing Flexibility in Urea-Formaldehyde Resins: Copolymerization with Poly...

Adhesives obtained by copolymerizing urea, formaldehyde, and difunctional polyetheramine with different molecular weights (230, 600, 900, and 2000 gmol(-1)) are presented as a more resilient alternative to conventional urea-formaldehyde resins. Urea and polyetheramine contents were varied and the resulting resins characterized by FTIR, C-13-NMR, and TGA. These resins were used for production of agglomerated cor...

Improving hydrophobic and oleophobic performances of highpressure laminates

High-pressure laminates are decorative materials that are widely used in furnishing and building industries. One of their major handicaps, especially in the case of high gloss laminates, is the ease of staining by fingerprints. This problem can a priori be minimized by increasing the hydrophobicity and oleophobicity of the surface. To improve hydrophobicity, the chemical composition of the resin used for impreg...

Partial replacement of melamine by benzoguanamine in MUF resins towards improve...

Statistical evaluation of the effect of urea-formaldehyde resins synthesis para...

This work discusses the optimization of different synthesis parameters for a low emitting urea-formaldehyde (UF) resin. Industrially, this resin was synthesized using the alkaline-acid process (alkaline methylolation and acidic condensation) at different values of pH, temperature (T) and final viscosity and characterized according to different analytical methods. Particleboards (PBs) were produced using differe...

Biosourced Binder for Wood Particleboards Based on Spent Sulfite Liquor and Whe...

Currently, the majority of binders used in wood particleboard (PB) manufacturing are formaldehyde-based synthetic resins. Because of the toxicity of formaldehyde, there is a strong demand for eco-friendly alternatives with similar performances and economic viability. In this work, thick spent sulfite liquor (TSSL), an industrial byproduct from sulfite pulp mills, is proposed as a binder for fully bio-based PBs....

Blocked melamine-urea-formaldehyde resins and their usage in agglomerated cork ...

Caprolactam and o-p-toluenesulfonamide are tested as chain-growth blockers for melamine-urea-formaldehyde (MUF) resins, in an attempt to reduce the crosslinking density of the cured resin and hence improve its flexibility. Agglomerated cork panels, for which flexibility is a technical demand, were produced with the modified resins and tested. The blockers were added at three different steps in the synthesis pro...

Highly flexible glycol-urea-formaldehyde resins

Urea-formaldehyde resins are successfully used in many contexts, but their tightly crosslinked thermoset structure impairs some applications, due to stiff and brittle behavior. In this work we show that copolymerization of urea and formaldehyde with glycols introduces linear flexible segments in the polymer structure, thus increasing the resilience and flexibility of the resin after curing. Glycols with differe...

Strategies to reduce formaldehyde emissions from wood-based panels: impact on p...

Formaldehyde is a common organic compound used as raw-material in several industrial applications, namely in urea-formaldehyde (UF), melamine-ureaformaldehyde (MUF) and phenol-formaldehyde resin (PF) production. These resins have been used in the manufacture of wood-based panels for decades, playing a central role within their production and properties. Since the reclassification of formaldehyde as "carcinogeni...