@article {1864, title = { Effects of Broussonetiapapyrifera leaf cutting modes on bonding performance of its protein-based adhesives }, journal = { EUROPEAN JOURNAL OF WOOD AND WOOD PRODUCTS }, volume = {78}, year = {2020}, pages = {461-470}, abstract = {

Broussonetiapapyrifera leaf protein was used as a biomass feedstock to prepare wood adhesives, and the influence of cutting modes (cutting frequencies and cutting heights) on leaf protein content and reactivity was studied in this paper. Bonding performance of Broussonetiapapyrifera leaf protein-based adhesives were evaluated by shear strength of plywood. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), and scanning electron microscope (SEM) were used to analyze them. The results indicated that: (1) the leaf protein content gradually increased as the cutting height increased, but it presented a decreasing trend as the cutting frequency increased. When the cutting frequency is two times per year and the cutting height is 30 cm, this leaf protein-based adhesive exhibited the best bonding strength with 0.75 MPa. (2) Cutting frequency and cutting height have no significant correlations to the reactivity of leaf protein with the crosslinker. (3) DSC and FTIR indicated that both leaf protein content and reactivity appeared to exert an influence on the bonding properties of the protein adhesives, and the latter is more pronounced. (4) TG and SEM analyses indicated that under different cutting modes, leaf protein content, especially protein reactivity, had a great effect on the thermal properties of the adhesives. (5) Contact angle analysis showed that Broussonetiapapyrifera leaf protein-based adhesives had good wettability on wood surfaces. Under different cutting modes with the difference of leaf protein content and reactivity, the crosslinking degree of the adhesives with crosslinker and compactness of the cured adhesives were different and thus affect their bonding strength and water resistance.

}, author = {Z.G. WU and X.D. XI and A. PIZZI and Y.F. XIA and Q.X. ZHAO and H. LEI and J.K. LIANG} } @article {1836, title = { EFFECTS OF HEAT-TREATMENT ON BONDING PERFORMANCE OF BETULA ALNOIDES }, journal = { WOOD RESEARCH }, volume = {64}, year = {2019}, pages = {1045-1054}, abstract = {

Heat-treatment woods of Betula alnoides were prepared by using vapor as the heat-conducting medium. Effects of heat-treatment time and heat-treatment temperature on equilibrium moisture content, density, pH value, contact angle and bonding performance of Benda alnoides were discussed in this paper. The results indicated that: (1) With the increase of heat-treatment temperature, the equilibrium moisture content, density and pH value of Betula alnoides decreased gradually. (2) With the increase of heat-treatment temperature, the contact angle of Betula alnoides increased from 70.08 degrees to about 100 degrees, resulting in the reduction of bonding strength gradually. Bonding strength of Betula alnoides after heat-treatment was related with the used adhesive. Bonding strength of different adhesives decreased to different extents. The bonding strength of Betula alnoides wood with polyvinyl acetate (PVAC) resin was generally higher than that of melamine-urea-formaldehyde (MUF) resin. The former were 6.35-4.56 MPa, and the latter were 5.60-3.00 MPa. (3) Heat-treatment time influenced equilibrium moisture content, density, contact angle, pH value and bonding strength of Betula alnoides less than heat-treatment temperature. (4) Heat-treatment could affect strength and surface performance of Betula alnoides greatly and the processing medium should be extended.

}, author = {Z.G. WU and S.C. CHEN and M.F. TIAN and L.F. LI and L.P. YU and X.D. XI and J.K. LIANG and B.G. ZHANG and H. LEI and J. ZHANG and T.A. CHEN} } @article {1825, title = { Non-isocyanate polyurethane adhesive from sucrose used for particleboard }, journal = { WOOD SCIENCE AND TECHNOLOGY }, volume = {53}, year = {2019}, pages = {393-405}, abstract = {

Sucrose-based non-isocyanate polyurethanes (S-NIPU) were synthesized by the already codified reaction of sucrose, dimethyl carbonate and hexamethylene diamine and used for the first time as adhesives for bonding particleboard. To decrease the NIPU adhesive curing temperature, a silane coupling agent was used as a crosslinking promoter. The performance of particleboards prepared at a press temperature of 230 degrees C, 200 degrees C and 180 degrees C and a press time of 8 min, 10 min and 12 min was tested and evaluated. The structure of the oligomers obtained was detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Thermomechanical analysis and differential scanning calorimetry were also used to analyze their behavior. The particleboards bonded with the S-NIPU adhesive at 230 degrees C showed excellent properties, which, however, decreased as the press time was reduced. The silane coupling agent used as a crosslinking promoter significantly reduced the curing temperature of the adhesive and allowed to obtain good bonding at a lower press temperature. The results obtained confirmed that coupling the S-NIPU adhesive with a silane used as a crosslinking promoter can yield sufficiently improved results to function as a suitable adhesive for particleboard, medium density fiberboard and other types of particulate wood panels. It was also the first time that a NIPU adhesive was used for wood bonding.

}, author = {X.D. XI and Z.G. WU and A. PIZZI and C. GERARDIN and H. LEI and B.G. ZHANG and G.B. DU} } @article {1765, title = { AN ECO-FRIENDLY UREA-FORMALDEHYDE RESIN: PREPARATION STRUCTURE AND PROPERTIES }, journal = { WOOD RESEARCH }, volume = {63}, year = {2018}, pages = {45-56}, abstract = {

The preparation, structures and properties of UF resin prepared with concentrated formaldehyde at a low molar ratio F/U=1.1 were studied in this paper. According to the results obtained from C-13-NMR, FT-IR and DMA, UF resin prepared with concentrated formaldehyde showed better mechanical properties and heat resistance and lower formaldehyde emission responsible for its high degree of polycondensation and crosslinking than that of UF prepared with common formaldehyde, but its stability was so bad due to its high content of ether bridges. However, it was stated that adding hydrolyzed soy protein to this UF resin at the first alkali preparation stage of \"alkali-acid-alkali\", its stability got improved due to the increase of methylene bridges, which was the key contribution to polycondensation.

}, author = {Z.G. WU and X.D. XI and L.P. YU and L. SU and H. LEI and G.B. DU and Z.W. YIN} }