Preparation Of Microencapsulated Wood Preservatives And Their Decay Resistance To Wood

The forest resources in China are limited,and the contradiction between supply and demand of wood is also very prominent.Prolonging the service life of wood has become a method to alleviate the contradiction between supply and demand of wood,and the use of wood preservatives can increase the use time of wood.However,most wood preservatives pose a threat to the natural environment and human health.Therefore,people have begun to devote themselves to the research and development of natural environmental protection wood preservatives in recent years.Plant-derived organic matter has good antibacterial properties,but its anti-loss performance in wood is poor.This study aims to prepare wood preservatives with good leaching resistance and anti-fungal properties through microencapsulation technology.Poplar heat-treated extract/Si O₂ microcapsules（PSM）and vanillin/Si O₂microcapsules（VSM）were prepared respectively.The comprehensive performance of microencapsulated wood preservatives was evaluated from the aspects of morphology,structure,connection with wood,leaching resistance,anti-fungal mechanism and decay resistance.The main research results of this paper are as follows:（1）Poplar heat-treated extract/Si O₂ microcapsules（PSM）were successfully prepared using poplar heat-treated extract as core material and Si O₂ as wall material.Observation by scanning electron microscope shows that the PSM particles prepared under the preparation environment of p H=4.5 are full and retain a large number inside the wood;were 21.13%and18.77%,while the wood mass loss rates after modification by PSM prepared under the environment of p H=4 were 8.07%and 11.60%,respectively.The average flexural modulus of elasticity（MOE）and modulus of rupture（MOR）of PSM modified poplar were 11275.30 MPa and 86.37 MPa,respectively.Compared with poplar,the flexural modulus of elasticity and flexural strength increased slightly.（2）Vanillin/Si O₂ microcapsules（VSM）were successfully prepared with vanillin as the core material and Si O₂ as the wall material.VSM has a complete core-shell structure,the average particle size is between 0-0.6μm,and it is well distributed inside the wood,and the particles are full and uniform;the FTIR spectra of VSM modified poplar before and after the leaching resistance test are at 3435 cm^-1-OH The blue shift indicates that VSM and wood can be fixed by hydrogen bonding,and the leaching resistance performance is improved.After being decayed by white rot fungi and brown rot fungi,the VSM emulsion modified poplar wood specimens prepared under the reaction environment of p H=4 had good decay resistance;at the same time,VSM improved the flexural elastic modulus and Bending strength,the flexural elastic modulus and flexural strength of poplar wood modified by VSM increased by17.48%and 34.72%,respectively.（3）VSM mainly affects the growth and development of white rot fungi by cellulases（endocellulases andβ-glucosidases）,hemicellulases and ligninases activities in white rot fungi;PSM mainly inhibited cellulase（exocellulase）,hemicellulase and ligninase activities in white rot fungi to hinder their growth and development;VSM only significantly inhibited cellulase（endocellulase andβ-glucosidase）activities in brown rot fungi;PSM mainly inhibited cellulase（endocellulase,β-glucosidase）activity in brown rot fungi.（4）Both PSM and VSM could inhibit the respiratory metabolism of the two fungi.During the measurement time of 15 min,the dissolved oxygen consumption of white rot fungi and brown rot fungi treated with VSM and PSM at a concentration of 5 mg/m L was lower than that of the control group.（5）Both PSM and VSM can achieve the purpose of decay resistance by destroying the cell membrane of wood rot fungi.Compared with the control group,the conductivity of the two fungi increased after the treatment of the two microcapsules PSM and VSM,indicating that the permeability of the cell membrane increased;at the same time,the leakage of nucleic acid and soluble protein in the cell membrane was due to the two kinds of microcapsules.At the same time,the leakage of nucleic acid and soluble protein in the cell membrane increased due to the presence of the two microcapsules and their components.The results showed that two kinds of wood preservatives PSM and VSM were prepared by using microcapsule technology,poplar heat-treated wood extract and vanillin with different antibacterial abilities as core materials,and Si O₂ as wall material components.It has a good application prospect in improving the leaching resistance and the decay resistance of wood preservatives.