Preparation And Performance Characterization Of Alkali Lignin Based Rigid Polyurethane Foam

With foam formation once,two kinds of alkali lignin based rigid polyurethane foams (RPUF) were prepared with respectively adding the refined alkali lignin or modified alkali lignin.The refined alkali lignin and modified alkali lignin were obtained from wheat straw alkali lignin as raw material refined and modified by 3- chloro- 1,2-epoxypropane.By using single- factor analysis and multi-factors orthogonal test,the effects of polyether polyol, isocyanate index,the catalyst system and the dosage of foam stabilizer on the reaction conditions were investigated and optimized.The optimum ratios of reactant materials were 40 parts of PEG,48 parts of PAPI,0.5 parts of silicone oil,3 parts of n-pentane and 0.03 parts of triethylenediamine as well as 1.15 of isocyanate index.In the experiments,two kinds of alkali lignin based rigid polyurethane foams were synthesized by polymeric phenyl methane-diisocyanate (PAPI) with refined alkali lignin and modified alkali lignin to be instead of 5%-40% of the polyether glycol in weight.The mechanical performance,apparent density,thermal stability and aging resistance for prepared RPUF were separately tested.The results show that the adding range of lignin for alkali lignin based RPUF was from 10%to 20%.The addition of 15%refined and modified lignin could be applied in practice.All kinds of indexes of products can be reached the industrial requirements with better performance.The guaiacol and vanillin are model material as alkali lignin.FTIR showed that all the two models could react with PAPI to gernerate carbamic ester,but the reaction was not completely,which reflected in the other performance evaluation.For refined alkali lignin RPUF and modified alkali RPUF,the mechnical properties and thermal stability of modified alkali lignin RPUF are better than those of refined alkali lignin RPUF.The lignin based RPUF should be ideal insulation materials.The high temperature resistant properties of RPUF are excellently,furthermore,the thermal stability of modified alkali lignin RPUF was better than that of refined alkali lignin RPUF.The results of aging resistance test show that the influence of addition of lignin was not significant on the natural aging resistance of synthesized RPUF in a short time(three months),but having obvious effect on UV aging and hot alkali resistant properties.The ability of alkali resistance for modified alkali lignin RPUF was improved.