Preparation of Soy-Based Adhesive Enhanced by Waterborne Polyurethane: Optimization by Response Surface Methodology

Response surface methodology was used to optimize the preparation conditions of soy-based adhesives (SBAs) in this work. The parameters such as the effects and interactions of waterborne polyurethane (WPU) addition level (X1), temperature (X2), and time (X3) on wet shear strength (Y) were investigated. The regression model for SBA preparation was significant (p=0.0034<0.05). The coefficient of determination (R2) of this model was to be 0.9256. According to the results, WPU addition level (X1) had a significant influence on the wet shear strength, whereas reaction temperature (X2) and reaction time (X3) were not significant. The optimal preparation conditions of SBA were 12 wt.% WPU addition level for 101 min at 76°C. Under the optimal conditions, the wet shear strength was 1.07 ± 0.08 MPa, which was in good agreement with the model predicted value. An analysis of FTIR spectra of WPU, soy flour, and soy-based adhesive further confirmed the validity of the model

Effects of wood fiber size on the performance of biodegradable foam

Biodegradable foam for cushion packing materials was prepared with wood fiber and starch through mold foaming. This study investigated the effect of wood fiber size and content on the mechanical properties of the foam. The results showed the size and content of the wood fiber bearing significant influences on the density, compressive strength, and tensile strength of the resultant foams. Lower size of wood fiber aided in better foaming, and a 40 wt% of 125–180 μm wood fiber yielded the best mechanical properties among the blends investigated. The behavior of the foaming agent was a function of the foaming temperature, and 150 °C was deemed as the optimum temperature for foaming. The compressive strength increased with an increase in wood fiber fraction, whereas the tensile strength decreased with increased wood fiber fraction. Overall, physical and mechanical properties of the biodegradable foams developed herein showed potential as cushion packing materials

Study on the Retention and Distributions of the Copper-Based Preservative in Standing Tree Chinese Fir (Cunninghamia lanceolata)

In spite of some studies about the wood permeability and its improving measures, some progress has been made to study the diffusion and transmission of preservative solutions in standing trees. In the present study, copper- (Cu-) based preservative with other reagents is injected into the standing tree Chinese fir using sap-flow method. The chemical compositions of the retreated woods are analyzed with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The samples from different height positions are analyzed with scanning electron microscope (SEM) and atomic absorption spectroscopy (AAS) to obtain microstructures and preservative retention, respectively. The results indicate that the preservative solutions with lower concentrations are more conducive to diffusion and transmission in the wood. Moreover, the preservative retention at different height position has a greater concentration gradient for composite preservative solutions than those of the single preservative solutions. Solidified preservative particles are observed in xylem rays with SEM. The results of the present study provide some useful information for the functional design of the target wood products

Curing Dynamics of Soy Flour-Based Adhesives Enhanced by Waterborne Polyurethane

In this paper, thermogravimetric (TG) analysis was carried out to make clear the curing properties of soy flour-based adhesives (SFAs) enhanced by waterborne polyurethane (WPU) with different addition levels. The kinetic parameters were evaluated by a thermal dynamics method, including activation energy and preexponential factor. In addition, the structure characteristics of both soy flour and modified soy flour-based adhesives were tested by Fourier transform infrared spectroscopy (FTIR). The results revealed that the FTIR spectra of pristine soy flour-based adhesives were different from those of soy flour after alkali treatment and waterborne polyurethane modification. Furthermore, there were four main degradation phases in the derivative thermogravimetric (DTG) curves of modified soy-based adhesives while there were two phases of a defatted soy flour sample. The kinetics analysis demonstrated that the curing process could be described as a consecutive first-order curing process. Moreover, with the addition level of WPU growing, the apparent activation energy of each phase of the curing process was increasing compared with that in pristine soy-based adhesives