The Fundamental Research On Lignin-Based Foam Material

Natural reproducible material——lignin (derivant), which has the characteristic of amorphism structure of polyphenolic three-dimensional reticulation, was blended, polymerized and foamed with common polymer material under the help of"863"Plan Item (NO. 2002AA322050). Different foam condition, product properties and degradable properties were researched and following results were obtained.(1) The viscidity of high-purified lignin/LDPE-EVA blend induces that pseudoplastic fluid. The rheological properties such as maximum torque, balanceable torque and plastic time are influenced with the content of lignin, the content of compatibilizer, temperature, LDPE/EVA. The optimal blend can be obtained under the conditions of 20 parts lignin blending with 55/45 LDPE-EVA with 10 parts compatibilizer at 150℃.(2) The blend has following properties with 10 parts compatibilizer. The tensile intensity and elongation at break reach 35.66MPa and 23.58%, respectively, improving by 26.6% and 65.7% respectively compared with 0 part compatibilizer; The characteristic absorption peak of carbonyl at 1725～1800cm-1 disappear and the characteristic absorption peak of hydroxide at 3438～3440cm-1 increase induce the formation of hydrogen bond; The decalescence peak of blend increase by 2℃compared with the blend containing 0 part compatibilizer near 100℃; Lignin can be dispersed homogeneously to avoid reuniting of lignin particle.(3) Lignin/LDPE-EVA foam can be obtained through blend, particle- making and moulding process. The tensile intensity, elongation at break and stress intensity were 0.6～0.9MPa, 40～60% and less than 0.1MPa respectively while 20 parts lignin blend with 55/45 LDPE-EVA containing 10 parts compatibilizer, 1 part crosslink agent and 2 parts foam agent.(4) The hydroxide value and viscidity of lignin-based polyhydric alcohol are 450～550mgKOH/g and 500～1000mPa.s respectively while 20 parts lignosulfonate calcium dissolves in common polyhydric alcohol for 2 hours. The FTIR of lignin-based polyhydric alcohol shows new characteristic peak of carbonyl is formed and the characteristic peak of aromatic ring and polyether at 1600cm-1 and 1110cm-1 respectively, which induce there is linkage of chemical bond.(5) 9～10Kg/m3 of foam density and 13.7～15kPa of stress intensity have been obtained with 1.2% L580, 0.4% An when An/Sn is 2:1 and 1.1 isocyanate index. The FTIR of lignin-based polyurethane shows the characteristic peak of–NH- in 1535cm-1 and the aromatic groups for lignin and MDI have been appeared. The lignin-based PU foam aperture is bigger than common PU foam and the framework of lignin-based PU is thicker than common PU, which is obtained by digital photos.(6) The lignin-based foam has been degraded obviously under the effect of controlled compost. The buffer phase for sample degradation have been decreased compared with PE from 14 days to 7～8 days, still more than starch(3 days). The amount of CO2 for lignin-based mould foam is 1～2g more than lignin-based PU foam because of different exist form of lignin.The fundamental research on the modified lignin-based foam is meaningful in taking use of natural reproducible lignin resource and developing new degradable foam material.