Thermoplastic polymers as modifiers for urea–formaldehyde wood adhesives. III.In situ thermoplastic-modified wood composites

2007 ◽  
Vol 107 (5) ◽  
pp. 3200-3211 ◽  
Author(s):  
S. Das ◽  
L. M. Matuana ◽  
P. Heiden
Keyword(s):  
Urea Formaldehyde ◽  
Wood Composites ◽  
Thermoplastic Polymers ◽  
Wood Adhesives ◽  
Modified Wood

scholarly journals Particleboards from Recycled Thermally Modified Wood

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1462
Author(s):  
Ján Iždinský ◽  
Zuzana Vidholdová ◽  
Ladislav Reinprecht
Keyword(s):  
Mechanical Properties ◽  
Urea Formaldehyde ◽  
Brown Rot ◽  
Decay Resistance ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Negative Effect ◽  
Serpula Lacrymans ◽  
Thermally Modified Wood ◽  
Modified Wood

In recent years, the production and consumption of thermally modified wood (TMW) has been increasing. Offcuts and other waste generated during TMWs processing into products, as well as already disposed products based on TMWs can be an input recycled raw material for production of particleboards (PBs). In a laboratory, 16 mm thick 3-layer PBs bonded with urea-formaldehyde (UF) resin were produced at 5.8 MPa, 240 °C and 8 s pressing factor. In PBs, the particles from fresh spruce wood and mixed particles from offcuts of pine, beech, and ash TMWs were combined in weight ratios of 100:0, 80:20, 50:50 and 0:100. Thickness swelling (TS) and water absorption (WA) of PBs decreased with increased portion of TMW particles, i.e., TS after 24 h maximally about 72.3% and WA after 24 h maximally about 64%. However, mechanical properties of PBs worsened proportionally with a higher content of recycled TMW—apparently, the modulus of rupture (MOR) up to 55.5% and internal bond (IB) up to 46.2%, while negative effect of TMW particles on the modulus of elasticity (MOE) was milder. Decay resistance of PBs to the brown-rot fungus Serpula lacrymans (Schumacher ex Fries) S.F.Gray increased if they contained TMW particles, maximally about 45%, while the mould resistance of PBs containing TMW particles improved only in the first days of test. In summary, the recycled TMW particles can improve the decay and water resistance of PBs exposed to higher humidity environment. However, worsening of their mechanical properties could appear, as well.

scholarly journals Lignosulphonates as an Alternative to Non-Renewable Binders in Wood-Based Materials

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4196
Author(s):  
Sofia Gonçalves ◽  
João Ferra ◽  
Nádia Paiva ◽  
Jorge Martins ◽  
Luísa H. Carvalho ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Aromatic Ring ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Value Added ◽  
Wood Adhesives ◽  
Renewable Source ◽  
Pressing Time ◽  
Value Added Products ◽  
Total Market

Lignin is a widely abundant renewable source of phenolic compounds. Despite the growing interest on using it as a substitute for its petroleum-based counterparts, only 1 to 2% of the global lignin production is used for obtaining value-added products. Lignosulphonates (LS), derived from the sulphite pulping process, account for 90% of the total market of commercial lignin. The most successful industrial attempts to use lignin for wood adhesives are based on using this polymer as a partial substitute in phenol-formaldehyde or urea-formaldehyde resins. Alternatively, formaldehyde-free adhesives with lignin and lignosulphonates have also been developed with promising results. However, the low number of reactive sites available in lignin’s aromatic ring and high polydispersity have hindered its application in resin synthesis. Currently, finding suitable crosslinkers for LS and decreasing the long pressing time associated with lignin adhesives remains a challenge. Thus, several methods have been proposed to improve the reactivity of lignin molecules. In this paper, techniques to extract, characterize, as well as improve the reactivity of LS are addressed. The most recent advances in the application of LS in wood adhesives, with and without combination with formaldehyde, are also reviewed.

Nanocellulose-modified Wood Adhesives

2014 ◽  
pp. 253-264 ◽  
Author(s):  
Wolfgang Gindl-Altmutter ◽  
Stefan Veigel
Keyword(s):  
Wood Adhesives ◽  
Modified Wood

Influence of Nanoclay on Phenol-Formaldehyde and Phenol-Urea-Formaldehyde Resins for Wood Adhesives

2010 ◽  
Vol 24 (8-10) ◽  
pp. 1567-1576 ◽  
Author(s):  
H. Lei ◽  
G. Du ◽  
A. Pizzi ◽  
A. Celzard ◽  
Q. Fang
Keyword(s):  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Wood Adhesives

Influence of nanoclay on urea-formaldehyde resins for wood adhesives and its model

2008 ◽  
Vol 109 (4) ◽  
pp. 2442-2451 ◽  
Author(s):  
Hong Lei ◽  
Guanben Du ◽  
Antonio Pizzi ◽  
A. Celzard
Keyword(s):  
Urea Formaldehyde ◽  
Wood Adhesives

scholarly journals Fabrication and Spectral Properties of Wood-Based Luminescent Nanocomposites

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Xianjun Li ◽  
Yun Li ◽  
Yongfeng Luo ◽  
Qunying Mou ◽  
Xingong Li ◽  
...  
Keyword(s):  
Blue Light ◽  
Conventional Method ◽  
Spectral Properties ◽  
Urea Formaldehyde ◽  
Broad Band ◽  
Green Emission ◽  
Formaldehyde Resin ◽  
Luminescent Materials ◽  
Bluish Green ◽  
Modified Wood

Pressure impregnation pretreatment is a conventional method to fabricate wood-based nanocomposites. In this paper, the wood-based luminescent nanocomposites were fabricated with the method and its spectral properties were investigated. The results show that it is feasible to fabricate wood-based luminescent nanocomposites using microwave modified wood and nanophosphor powders. The luminescent strength is in positive correlation with the amount of phosphor powders dispersed in urea-formaldehyde resin. Phosphors absorb UV and blue light efficiently in the range of 400–470 nm and show a broad band of bluish-green emission centered at 500 nm, which makes them good candidates for potential blue-green luminescent materials.

scholarly journals Research Progress of Wood-Based Panels Made of Thermoplastics as Wood Adhesives

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 98
Author(s):  
Xianfeng Mo ◽  
Xinhao Zhang ◽  
Lu Fang ◽  
Yu Zhang
Keyword(s):  
Production Efficiency ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Raw Material ◽  
Research Progress ◽  
Formaldehyde Resin ◽  
Wood Adhesives ◽  
Bonding Structure ◽  
Existing Problems ◽  
Thermoplastic Resins

When thermoplastic resins such as polyethylene (PE) and polypropylene (PP) are selected as wood adhesives to bond wood particles (fibers, chips, veneers) by using the hot-pressing technique, the formaldehyde emission issue that has long existed in the wood-based panel industry can be effectively solved. In this study, in general, thermoplastic-bonded wood-based panels presented relatively higher mechanical properties and better water resistance and machinability than the conventional urea–formaldehyde resin-bonded wood-based panels. However, the bonding structure of the wood and thermoplastic materials was unstable at high temperatures. Compared with the wood–plastic composites manufactured by the extruding or injection molding methods, thermoplastic-bonded wood-based panels have the advantages of larger size, a wider raw material range and higher production efficiency. The processing technology, bonding mechanism and the performance of thermoplastic-bonded wood-based panels are comprehensively summarized and reviewed in this paper. Meanwhile, the existing problems of this new kind of panel and their future development trends are also highlighted, which can provide the wood industry with foundations and guidelines for using thermoplastics as environmentally friendly adhesives and effectively solving indoor pollution problems.

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