Study On Laccase Pretreatment Wheat Straw Technique And Self-bonding Fibreboard Preparation

In this study, straw clean pulping and bleaching technology was employed to modify its interfaces. Laccase water bath and spray were employed for pretreatment of modified straw chips to explore the manufacturing for straw self-bonding fibreboard. Therefore, this project is to assess the effects of parameters of pretreatment and hot pressing to the properties the products. The products were characterized by FTIR spectroscopy to investigate the mechanism of self-bonding fibreboard with the effect of laccase. The specific results include are shown as following:(1) With Laccase as the activating agent, surface properties of straw fibers can be changed by application of enzyme through either water-bath or spray approach, so as to realize self-bonding of straw fiberboards. Certain amount of lignocellulose added helps improve strength of self-bonding fiberboards.(2) Pretreated by water bath, laccase is found to be better for the internal bonding (IB) than spray approach. The amount of laccase is an important factor attributing to the results of products.Under experimental condition, parameters of water-bath approach are as follows:laccase dosage43.6-58.1U/g, wood fiber’s quantity20%, processing temperature50～70℃, processing time120-180min. And those of spray approach are:laccase dosage43.6-58.1U/g, wood fiber’s quantity20%, processing temperature50～70℃, processing time180min.(3) Hot-pressing process has significant influence on properties of wheat straw fiberboards. Hot-pressing temperature is the major influencing factor, while water content plays secondary role of impact. Parameters of hot-pressing regard to water-bath approach under optimized experimental condition are as follows:temperature170℃, water content13%, pressure3-4MPa, duration20-25min. The optimized experimental protocol for spray approach with material and method as follow: hot-pressing temperature170℃, moisture content13%, hot-pressing pressure4MPa, hot-pressing time25min. Under the same condition, the MOE/MOR of water-bath approach reaches25.53MPa/2980MPa in comparison with23.63MPa/2420MPa by spray approach.(4) Primary exploration of the mechanism shows that Laccase is capable to increase surface activity of fibers and facilitate degradation of lignin into monose that causes condensation polymerization. The reaction enhances chemical bonds and hydrogen bonds, creating the matters similar to adhesives that make self-bonding possible.