A series of self-crosslinked acetic acid lignincontaining polyurethane (LPU) membranes were prepared based on 4,4-diphenyl methane diisocyanate (MDI),polyethylene glycol (PEG),acetic acid lignin (AL),aminopropyltriethoxy silane (APTS) and trimethylol propane (TMP).A fundamental investigation of the influence of AL,APTS and TMP on LPU was conducted to elucidate the effect of phase behavior,hydrogen bonding and crosslinking density on microstructure,thermal stability,mechanical properties and water resistance of the LPU.It was found that the crosslinking density increased with addition of AL,TMP and APTS.The results from environmental scanning electron microscope (ESEM) indicated that the surface morphology of membranes became smoother and more homogeneous when the crosslinking density was higher.FT-IR spectra demonstrated that the hydrogen bonding interaction between -NH and -C=O of urethane was destroyed due to the addition of APTS,while the interactions between NH and Si-O-Si and/or -C=O in urea was enhanced,indicating better compatibility between APTS and LPU at the optimum amounts of APTS and TMP.These results were in agreement with the results from thermal stability,mechanical properties and water resistance,i.e.,LPU with 1％ TMP and 2％ APTS was endowed with best tensile strength,thermal stability,rubbery modulus and water resistance.
Haihua Wang Yonghao Ni Mou Jing Zehua Liu M.Sarwar Jahan
Key laboratory of Auxiliary Chemistry & Technology for Chemical Industry,Ministry of Education.Shaan Limerick Pulp and Paper Center,University of New Brunswick,Fredericton,NB,Canada E3B 5A3 Key laboratory of Auxiliary Chemistry & Technology for Chemical Industry,Ministry of Education.Shaan Tianjin Key Laboratory of Pulp and Paper,Tianjin University of Science and Technology,Tianjin 300457 Pulp and Paper Research Division,BCSIR Laboratories,Dhaka,Dhaka 1205.