Study And Characterization Of Amf Copolymerized Resin Wood Adhesive Based On Starch Hydrolyzate

In this paper,AMF resin and Eucalyptus wood were used to prepare plywood.The physical and chemical properties of AMF resin,the synthesis process of plywood and the characterization of AMF resin were studied.Using Excel,the molar ratio of formaldehyde to melamine(Mf/Mm)and the mass ratio of starch hydrolyzate to melamine m(A)/m(M)were used to optimize the resin performance.Fourier transform near-infrared spectroscopy(NIR)was used to rapidly detect and analyze its viscosity,and Fourier transform infrared spectroscopy(FT-IR)was used to analyze the structure of different AMF resin systems.The contact angle meter was used to study the wettability of AMF resin on the surface of plywood and the effect of hot pressing process on the wettability of the resin.The main conclusions of the paper are as follows:(1)In the process of synthesizing AMF resin,it is tested for the storage period,and it was initially confirmed that the molar ratio of formaldehyde to melamine was 1.6 to 2.2.When the molar ratio of formaldehyde to melamine(Mf/Mm)is between 1.6 and 2.2,the solid content is relatively stable as the Mf/Mm increases,and the viscosity tends to decrease.The storage period of resin showed a trend of rising first and then decreasing,ranging from 8d to 25d.The change of Mf/Mm does not affect the pH of the resin.(2)The performance of the AMF resin can be improved by the preferred molar ratio(Mf/Mm)and the mass ratio m(A)/m(M).The technical synthetic resin with Mf/Mm =1.8 and m(A)/m(M)=60%is selected and its wet board bonding strength reaches 0.9752 MPa,which exceeds the national I standard for plywood and the formaldehyde emission is 1.26 mg/L,reaching the E1 standard.(3)AMF resin near-infrared spectra database was generated by collecting NIR near-infrared spectrograms and using standard experimental methods to measure the viscosity(25℃)of AMF resin.Then using the PLS method,through cross-validation,it was determined that the dimension is 3,the model R2=92.27,RMSECV = 4.92,Bias = 5.671,and the regression curve:y = 0.9187x+5.6726,and the model is verified.(4)FT-IR analysis results show that the absorption peak of AMF-30%resin is the strongest and the absorption peak of AMF-50%resin is the weakest.The absorption peak at peak position 3 is attributed to the stretching vibration of C-O-C bond,the absorption peak at position 7 belongs to the coupling vibration peak of O-H and N-H,and the intensity of the two vibration peaks are higher than those of other peak positions;The mass ratio m(A)/m(M)is in the range of 30%to 50%.With the gradual increase of the starch hydrolysate,the amount of amide in the resin structure decreases.(5)As the amount of starch hydrolysate increases,the wettability of the resin on the surface of the plywood rises rapidly and then slowly declines.When the mass ration(A)/m(M)is 40%,the wettability of the resin on the plywood is the best.The viscosity of AMF resin decreases with increasing temperature,and the wettability on the surface of the plywood is better.(6)At 20℃,the equilibrium contact angles of AMF-20%and AMF-30%resins are basically the same,and the contact angle change rate is also very close.At 70℃,the equilibrium contact angle of AMF-20%resin is greater than AMF-40%of the equilibrium contact angle,the permeability k of the two is almost the same.(7)As the temperature rises,the fitted curve changes from flat to steep.The time when the contact angle reaches the equilibrium state is gradually shortened,the initial contact angle and the equilibrium contact angle are reduced,and the wettability becomes easier.When the AMF-30%resin was at 50℃,the initial contact angle was 87.2° and the equilibrium contact angle was 50.3°.The contact angle change rate was 42.32%,and the wettability was the best.