Synthesis,Structure And Properties Of Crosslinked Modified Waterborne Polyurethane Adhesives

At present,adhesives have become an important basic raw material for modern daily life and chemical production.According to the national environmental protection concept,the public's attention to green environmental protection is getting higher and higher.Waterborne polyurethane uses water as an emulsion dispersion system,which is environmentally friendly to the human body,beneficial to human health,and has good adhesion to different types of substrates.The topic of research mainly studies the influence of the preparation and properties of cross-linked modified waterborne polyurethane through the waterborne polyurethane adhesive synthesized by modifier.Using solution polymerization method,polyester polyol(PE3020),hexamethylene diisocyanate(HDI),2,2-dihydroxypropionic acid(DMPA),fenugreek gum(FG)as the main raw material,synthetic fenugreek gum Modified waterborne polyurethane(WPU)emulsion.The structure of the obtained polymer was confirmed by Fourier transform infrared spectroscopy and X-ray diffractometry to confirm that the molecular structure of the obtained polymer was consistent with the intended molecular structure of the target.The effects of FG addition on the appearance of the emulsion,particle size,morphology,water resistance,mechanical properties and thermodynamic stability were investigated.The final analysis results show that when the FG addition amount is 0.3 %,the comprehensive performance of the fenugreekmodified waterborne polyurethane is the best,and the appearance of the emulsion is translucent blue light.At this time,the rate of water absorption is13.88 %,the contact angle is 77.5°,and the fracture elongation is 440.36 %,and the tensile strength reaches 16.19 MPa.Atomic force microscopy showed that many small raised bulges appeared on the surface of the film,and the roughness of the surface increased.The thermal stability is effectively improved compared to the unmodified waterborne polyurethane.Polycaprolactone diol(PCL-1000),isophorone isocyanate(IPDI),2,2-dimethylolpropionic acid(DMPA),N-(2-aminoethyl)-2-amino Sodium ethanesulfonate(AAS)and the like are the main synthetic raw materials,and a sodium sulfamate modified aqueous polyurethane(SWPU)emulsion has been successfully prepared.The structure of the AAS molecular structure and the molecular chain of the system were cross-linked by Fourier transform infrared spectroscopy and X-ray diffractometry.The effects of the addition of AAS on the appearance of the emulsion,particle size,wettability,microstructure,mechanical properties and thermal stability were investigated.The results show that with the increase of AAS,the appearance of the emulsion shows transparent blue light,and the surface microscopic morphology of the film shows many tiny protrusions.When the amount of AAS was increased from 2 %(w)to 10 %(w),the particle size of the emulsion was decreased from 60.98 nm to 27.10 nm,and the contact angle was increased from 50 to 82.When the amount of AAS introduced was 6 %,the elongation at break was 1221.27 % and the tensile strength was 1.29 MPa.The sulfamate modified waterborne polyurethane film has a significant improvement in thermal stability compared to that before unmodified.Different content of hydroxyl terminated polybutadiene modified waterborne polyurethane was synthesized by using hydroxyl terminated polybutadiene(HTPB)as a part of soft segment.The structure of the modified waterborne polyurethane was analyzed by Fourier transform infrared spectroscopy and X-ray diffractometry.The analysis showed that the product was consistent with the target product.Furthermore,the effects of different amounts of HTPB added on the appearance of the emulsion,particle size,micro-morphology,wettability,mechanical properties and thermal stability were investigated.The results show that with the increase of HTPB content,the particle size and contact angle of the emulsion increase continuously;the texture of the film is softer;the atomic force microscopy analysis shows that the surface of the HTPB modified waterborne polyurethane film is rough and uneven.When the amount of HTPB added is 9 %,the tensile strength of the film is 2.54 MPa,the elongation at break is 597.69%,and the thermal stability is effectively improved.