| Nowadays,more and more wood-based panels or bamboo plywood are used instead of wood to alleviate the shortage of available wood,and continuous development of new adhesives.Epoxy resin has good adhesive property and strong applicability,and it can be used in many materials.However there is no research and literature on wood processing.In order to improve the application limitations and deficiencies of high temperature curing epoxy resin in some fields,and its poor toughness of the cured material,the room temperature curing system has high activity and poor product performance,the curing time of the low temperature curing system is long,and its use period of the adhesive is short.So that medium temperature curing system has become a research hotspot in the field of epoxy adhesive system due to its low curing temperature,shorter curing time and good properties of cured materials.therefore,two medium-temperature curing systems were studied in this paper,that were 2-ethyl-4-methylimidazole(EMI-2,4)as curing agent;dicyandiamide(DCD)as curing agent,2-methylimidazole(2-MI)as accelerator.The two components were modified by means of solvent exchange and melt blending respectively.The curing behavior and curing kinetics of two imidazole and epoxy systems were studied by differential scanning calorimetry(DSC),the mechanical properties,thermal stability and cross section morphology of the composites were studied by mechanical testing,thermal stability test and scanning electron microscope.Two kinds of medium temperature curing systems and glass fiber(GF)are pressed to form reinforced plastic glass fiberboard with three layers,and perform the same test as the system to verifyand select the best matching component.After that,this study manufactured the composite wood which made by hot pressing and studied its properties,and observed the cross section of wood after mechanical stretching under SEM.The results are as follows:1、With the increasing of EMI-2,4 and 2-MI,the curing temperature and curing reaction activation energy of EP system decreased gradually,which indicated that the curing rate increased with the increasing of curing agent,which could effectively promote the curing reaction of epoxy resin.The theoretical curing temperature of EMI-2,4/EP during 98-115℃ and that of 2-MI/DCD/EP system is in the range of102-127℃,which all meet the conditions of medium temperature curing system(50-130℃).2、The mechanical test results showed that when the addition of 6%(wt%)proportion of EMI-2,4,both the impact strength and the tensile strength of the curing system are the largest;and the tensile strength was greatest when the 2-MI was added to 0.4%(wt%)proportion.The elongation at break of the two components were both increased with the increase of curing agent,which indicates that the toughness was enhanced.3、The results of thermogravimetric analysis showed that added the two different curing agents could improve the stability of the curing system slightly,because of the good thermal stability of the epoxy resin.4、The SEM results showed that the curing system changed from brittle fracture to ductile fracture with the increase of curing agent;the bonding property between thetwo components of the adhesive layer and the GF is good,the adhesive could be completely permeated and dispersed into the GF,and the adhesive properties of the composite system are excellent;The fracture surface showed a drawing shape after mechanical destruction and the adhesive was completely wrapped up the wood,it showed that the modified adhesive has a strong hydrophilicity and completely permeates into the interior of the wood.5、Chose the best one from two curing systems and to formed plywood combined with wood,then tested the bonding strength of the wood and observed the wood failure rate.The results showed that the bonding strength of two systems which after boiling at 60℃ and 80℃ could both meet the requirements of superior adhesives,and the wood breaking rate could reach 100%. |
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