Synthesis and Characterization of an Environmentally Friendly Phenol–Formaldehyde Resin Modified with Waste Plant Protein

Abstract

To develop a lower-cost, excellent-performance, and environmentally friendly phenol–formaldehyde (PF) resin, soybean meal was used to modify PF resin, and soybean meal–phenol–formaldehyde (SMPF) resins were prepared. This reveals the effect of soybean meal on the structural, bonding, and curing properties of PF resin, which are very important for its applications in the wood industry. The resins’ physicochemical properties and curing performance were investigated, showing that SMPF resins have higher curing temperatures than PF resin. The Fourier transform infrared spectroscopy results indicated that a cross-linking reaction occurred between the amino groups of soybean protein and the hydroxymethyl phenol. Moreover, with the addition of soybean meal, the viscosity of SMPF increased while the gel time decreased. It is worth mentioning that SMPF-2 resin has favorable viscosity, short gel time, low curing temperature (135.78 °C), and high water resistance and bonding strength (1.01 MPa). Finally, all the plywoods bonded with SMPF resins have good water resistance and bonding strength, which could meet the standard (GB/T 17657-2013, type I) for plywood. The optimized SMPF resins showed the potential for application to partially replace PF resin in the wood industry.

Optimization of Isocyanate Content in PF/pMDI Adhesive for the Production of High-Performing Particleboards

“…Overall, the thermal degradation process of PF resin includes three main degradation stages: post-curing, thermal reforming, and ring stripping [ 60 , 61 ]. Based on the analysis of TG/DTG curves, three mass-loss stages can be noted: a first in the temperature range up to 270 °C, a second between 270 and 450 °C, and a third between 450 and 550 °C.…”

“…Despite the recorded improvement in the reactivity of PF/pMDI hybrid resin, we also noticed that the introduction of pMDI in the amount ranging from 5 to 15% resulted in a gradual decrease in resin's thermal stability, especially at temperatures exceeding 300 °C (Figure 3, Table 4). Overall, the thermal degradation process of PF resin includes three main degradation stages: post-curing, thermal reforming, and ring stripping [60,61]. Based on the analysis of TG/DTG curves, three mass-loss stages can be noted: a first in the temperature range up to 270 • C, a second between 270 and 450 • C, and a third between 450 and 550 • C. In the first stage of pyrolysis, usually occurring below 270 • C, a mass loss mainly related to the release of free formaldehyde, phenol, oligomer, and water introduced with PF resin and resulting from the progressing cross-linking reaction can be observed.…”

The Observation of Creep Strain Distribution in Laminated Veneer Lumber Subjected to Different Loading Regimes

“…As displayed in Figure 4b, the hysteresis of transient deformation into viscoelastic deformation was obvious for all chosen creep stress levels, suggesting the substantial plastic deformation of LVL subjected to edge-wise bending creep [36][37][38]. The brittle fracturing of PF adhesive can be a major trigger for the plastic deformation of LVL due to the direct contact at the wood-adhesive interface and loading plane in the edge-wise bending of LVL [39]. The creep compliance of edge-wise bent LVL at 50% of the ultimate strength was ~0.3 MPa −1 , which was lower than that corresponding to flat-wise bending creep by an order of magnitude.…”

Recent progress of biomass in conventional wood adhesives: a review

“…The results demonstrated that the PF resin-modified soy protein adhesive had improved water resistance, indicating that the PF resin reacted with soy protein. Li et al 120 prepared environmentally friendly PF resins with exceptional water resistance and bonding strength utilizing soybean meal as a cost-effective substitute. The results showed that all plywoods bonded with soybean meal–phenol–formaldehyde (SMPF) resins had good water resistance and bonding strength, and could meet the standard (GB/T 17657-2013, type I) for plywood.…”