| As a kind of non-polluting, renewable resources, peanut shells are inexpensive and abundant by-products of peanut industry. In recent years, with the transformation of development concept and mode, the use of agricultural and forestry waste get more attention of people.Through series of study, peanut shells can be widely used to develop high value-added products.Compared with other utilizations, wood-based panel adhesive has more advantages and prospects, which provides a reference for the use of peanut shells.This article selects peanut shell as raw material, phenol as liquefaction solvent, sulfuric acid as catalyst, liquefied peanut shells to get insoluble-lignin and holocellulose, residue rate as macro physical indicators, formaldehyde combining power and unbound phenol as chemical indicators, liquid-solid ratio, catalyst content, liquefaction temperature and liquefaction time these four factors influence on liquid content indicators, and four factors affecting liquefaction index is obtained by the orthogonal experiment of order and the best technological conditions, under the optimum process conditions are verified experiment.Using SEM observe surface topography, use FTIR analysis functional characteristics, finally using GC-MS analyses the chemical composition of liquefied content.Liquid content as additive, join to UF resin adhesives used for manufacturing plywood improving the bonding strength, reducing the formaldehyde relase by using the method of plasma processing to achieve the purpose of reduce the amount of glue.The results show that:(1)In peanut shell liquefaction system, given a certain range, the residue ratio with increase of liquid-solid ratio, catalyst dosage, temperature rise, the longer time, residue rate of a downward trend.Minimum residue rate set of conditions for: liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature as 180?, liquefaction time as 80 min, the residue rate was 19.1%. Set of conditions for maximum residue rate: liquid-solid ratio as 2:1, catalyst content is 6%, the liquefaction temperature as 140?, liquefaction time as 60 min, residue rate was 41.7%. Strongest formaldehyde in combination conditions is : liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature as 160?, liquefaction time as 80 min, formaldehyde in combination with a quantity of 0.68g/g. Weakest formaldehyde in combination conditions as follows: the liquid-solid ratio as 2:1, catalyst content is 8%, the liquefaction temperature is 160 ?, liquefaction time is 100 min, formaldehyde in combination with a quantity of 0.47g/g. For maximum free phenol content condition: liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature is 160?, liquefaction time as 100 min, unbound phenol content of 37.28%. Minimum unbound phenol content conditions as follows: liquid-solid ratio as 2:1, catalyst content is 6%, the liquefaction temperature as 140 ?, liquefaction time as 60 min, unbound phenol content of 24.4%.(2)In insoluble-lignin liquefaction system, the residue ratio with increase of liquid-solid ratio, catalyst dosage, temperature rise, the longer time, residue rate of a downward trend.Minimum residue rate set of conditions for: liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature as 180?, liquefaction time as 80 min, the residue rate was 4.8%. Set of conditions for maximum residue rate: liquid-solid ratio as 2:1, catalyst content is 6%, the liquefaction temperature as 140?, liquefaction time as 60 min, residue rate was 26.8%. Strongest formaldehyde in combination conditions is : liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature as 160?, liquefaction time as100 min, formaldehyde in combination with a quantity of 0.72g/g. Weakest formaldehyde in combination conditions as follows: the liquid-solid ratio as 2:1, catalyst content is 6%, the liquefaction temperature is 140?, liquefaction time is 60 min, formaldehyde in combination with a quantity of 0.50g/g. For maximum unbound phenol content condition: liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature is 180?, liquefaction time as 80 min, unbound phenol content of 32.61%. Minimum unbound phenol content conditions as follows: liquid-solid ratio as 2:1, catalyst content is 6%, the liquefaction temperature as 140?, liquefaction time as 60 min, unbound phenol content of 20.66%.(3)In holocellulose liquefaction system, the residue ratio with increase of liquid-solid ratio, catalyst dosage, temperature rise, the longer time, residue rate of a downward trend.Minimum residue rate set of conditions for: liquid-solid ratio as 5:1, catalyst content is 10%, the liquefaction temperature as 180?, liquefaction time as 60 min, the residue rate was 29.1%. Set of conditions for maximum residue rate: liquid-solid ratio as 3:1, catalyst content is 6%, the liquefaction temperature as 140 ?, liquefaction time as 60 min, residue rate was 50.4%. Strongest formaldehyde in combination conditions is : liquid-solid ratio as 4:1, catalyst content is 10%, the liquefaction temperature as 180?, liquefaction time as 60 min, formaldehyde in combination with a quantity of 0.53g/g. Weakest formaldehyde in combination conditions as follows: the liquid-solid ratio as 3:1, catalyst content is 8%, the liquefaction temperature is 160?, liquefaction time is 100 min, formaldehyde in combination with a quantity of 0.37g/g. For maximum unbound phenol content condition: liquid-solid ratio as 5:1, catalyst content is 10%, the liquefaction temperature is 160?, liquefaction time as 100 min, unbound phenol content of 41.62%. Minimum unbound phenol content conditions as follows: liquid-solid ratio as 3:1, catalyst content is 6%, the liquefaction temperature as 140?, liquefaction time as 60 min, unbound phenol content of 33.12%.(4)Observation through SEM, liquefied peanut shells and acid-insoluble lignin appears uniform particle, but grain of liquefied acid-insoluble lignin is bigger, liquefaction of holocellulose in clumps, a large number of residue arrangement disorderly. Analysed by FTIR, degradation reaction happened in peanut shells, acid-insoluble lignin and holocellulose liquefaction, generates large amount of phenolic compounds. Liquefaction compositions analysed by GC-MS, phenolic compounds are rich in three kind of liquefied products, active sites are rich in the presence of large amounts in phenolic compounds.(5)Liquefied peanut shells, acid-insoluble lignin and holocellulose has good modification effect of urea-formaldehyde resin adhesive, liquefied peanut shells modification effect is best, followed by liquefied acid-insoluble lignin, finally liquefied holocellulose.(6)Liquefied content as additive with plasma treatment is able to improve the bonding strength of plywood and satisfy the national class?standard, formaldehyde release meet the requirements of E1 grade. Cypress wood veneer, after treated with plasma, the contact angle of UF decreased by 30%-40%, significantly improve wettability. Plasma treatment of veneer surface inspired a large number of nanoscale etching, is conducive to the formation of the gel nail, also is advantageous to the gum drops on the surface veneer uniform flattening. Hydroxy, carboxyl and carbonyl oxygen and some other functional groups, improves the surface activity of veneer, and benefits bonding performance of veneer. |
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