| In recent years, environmental concern and restricted availability of petrochemical resource have attracted considerable attention, followed by the utilization of renewable biomass, including corn barn, because of its biodegradability, availability, and renewable nature. Liquefaction of biomass is considered to be an effective method for utilizing lignoellulosic materials.Four kinds of biomass waste (wood, hazelnut shell, rice straw and corn barn) were selected as materials. The main chemical components and liquefaction characteristics in phenol of them were firstly investigated. The factors influencing corn barn liquefaction, including reaction time, reaction temperature and the mass ratio of phenol to corn barn (liquid ratio), were analyzed. By means of GPC, HPLC, FTIR and NMR analysis, the molecular weight, bound phenol content and the structural characteristics of liquefied corn barn under different reaction conditions were investigated. The result shows that:Liquefaction efficiency of wood is better than hazelnut shell, rice straw and corn barn. The optimum condition of liquefied corn barn indicates that liquid ratio is 4:1, liquefaction temperature is 150℃and there will be recondensed residue when the liquefaction time is too long. The chemical structure of corn barn was changed greatly before and after liquefaction in phenol. Decomposition, phenolation and recondensation were all occured in liquefaction process. When increasing of the reaction time, the molecular weight distributions shift downward. Moreover, both low and high molecular weight parts are drastically diminished, and the molecular weight of liquefied product tends to homogenization.The liquefied corn barn-based epoxy resin (LCBER) was synthesized through the glycidyl etherification reaction from liquefied corn barn (LCB), which has groups of bound phenol, and epichlorohydrin under alkali conditions. The effective factors and technology of the resinification process has been studied. The structure and the molecular weight of LCBER has been analysed by many methods of instrumental analysis:FTIR,13C-NMR and GPC. The LCBER was cured with polyamide-650 (PA-650) and the thermal and mechanical properties were evaluated by TGA, DSC and lap shear strength measurement. The results showed that: the optimum conditions were obtained as molar ratio of epichlorohydrin to bound phenol of liquefaction product 20:1, molar ratio of sodium hydroxide to bound phenol of liquefaction product 4:1, reaction time 4h and reaction temperature 100℃. A highest epoxy index of 0.292 was obtained under these conditions. The distribution of retention volume of the synthesized resin (LCBER-30) from the corresponding LCB-30 is faster than the others. Before or after that, the distribution of retention volume of LCBER tends to narrow. The cured resins present good adhesive shear strength and have a highest value of 5.5 MPa. The cured resins have good thermal stability and the higher decomposition temperature at 5% weight loss (Td) is 264.5℃The waterborne dispersions of LCBER were prepared by the phase inversion emulsification technique using AEO-9 and SDS as compound emulsifier. The relationship among the critical water content of phase inversion (Rf) of LCBER, particle average size and the centrifugal stability of emulsion, and experiment condition such as HLB value of compound emulsifier, emulsifier content, emulsification temperature, stirring force was studied. The microtopography of emulsion was also observed. It shows that the factors for absorption of emulsifier and increasing its acting force with water will phase inversion from W/O to O/W easily, while under unfavourable conditions, phase inversion may occur through increasing volume fraction of water, but emulsion is very unstable. The optimum conditions were obtained as HLB value of compound emulsifier 17, emulsifier content 8%, emulsification temperature 35℃and stirring force 800rmp. The particle average size of emulsion was 1.57μm under these contions.The coating film has been prepared used home-made waterborne liquefied corn barn-based epoxy resin emulsion as base and different waterborne curing agent. The effect of emulsifier on film performance was discussed based on the film formation mechanism of double-pace waterborne epoxy resin coatings. The performance of waterborne liquefied corn barn-based epoxy resin film was further compared with different kinds of curing agent and the ratio of amine hydrogen with KINGCURE 525W60 as curing agent. The experiment results show that the emulsifier has a strong effect on physical mechanical properties of film: emulsifier residue in the film played plasticization using high concentration of emulsifier emulsion after the film formation. The curing process of film was affected by particle of low concentration of emulsifier emulsion. The physical mechanical properties of film was better than others with KINGCURE 525W60 as curing agent. The performance of waterborne liquefied corn barn-based epoxy resin film was satisfactory when the ratio of amine hydrogen with KINGCURE 525 W60 as curing agent was slightly greater than or equal to 1. |
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