Construction Of Interpenetrating Network Structure In Wood And Study Of Its Performances

The decay and mildew of wood or bamboo are related to their splitting property.Splitting of wood or bamboo not only breaks their integrity,affects their appearance,but also provides good paths and chances for the invasion of water,light,dust,fungi and insects,thus leading serious deterioration and collapse.In order to solve the problems of splitting,mildew and decay,new research results in medical polymers were draw to construct the interpenetrating polymer networks(IPN)in wood or bamboo.The IPN will also be used as drug carriers to protect wood and bamboo from mold and decay fungi.Two or more water-soluble monomers or polymer are firstly injected into the internal of wood or bamboo.These monomers or polymer can inflate cell cavity and cell wall,and then crosslink to form insoluble,infusible,intertwined,interpenetrating polymer network(IPN)structure which can help to solve the splitting properties of wood or bamboo.Meanwhile,if the decay or mold resistant chemicals are added to the IPN structure,performance of active ingredients will be loaded and control released,improving the efficiency of resisting effects against decay or mold.The main results are as follows:(1)Polyacrylate/polyethylene glycol(PAA/PEG)polymer alloy with semi-interpenetrating network(SIPN)structure was prepared by one-step polymerization.The swelling performances of polymer with the given amount of crosslinking agent was studied.The results showed that within a certain range,increasing amount of crosslinking agent decressed the swelling properties of the polymer while strength increased.The prepared SIPN polymer alloy was characterized by infrared spectroscopy(IR),scanning electron microscope(SEM)and transmission electron microscope(TEM).PEG was continuously dispersed in PAA to form a phase-separate structure.To improve the dimensional stability of wood,Populus tomentosa wood was impregnated with acrylic acid,PEG,initiator and crosslinker under vacuum then in situ polymerized.The dimensional stability tests of wood via three wet-dry cycles showed that the treated wood had lower shrinkage and expansion.Through indoor and comprehensive experiments it is known that,after loading drug,the mildew resistance of wood or bamboo treated by PAA/PEG SIPN is improved.(2)Chitosan/Polyvinyl alcohol(CTS/PVA)alloy with IPN structure was prepared by one-step polymerization,also,its effect on the swellable of polymer with the amount of crosslinking agent was studied.The results showed that the crosslinking agent can decrease the swelling properties of the polymer.The prepared IPN polymer alloy was characterized by SEM.It showed that PVA was continuously dispersed in CTS to form a phase-separate structure.The dimensional stability tests of wood or bamboo via three wet-dry cycles showed that the treated wood or bamboo had lower shrinkage and expansion.Through indoor and comprehensive experiments it is know that after loading drug,the mildew resistance of wood or bamboo treated by CTS/PVA IPN is not improved.(3)Chitosan quaternary ammonium salt/Polyvinyl alcohol(HACC/PVA)alloy with IPN structure was prepared by one-step polymerization.The dimensional stability tests of wood or bamboo via three wet-dry cycles showed that the treated wood or bamboo had lower shrinkage and expansion.Through indoor and comprehensive experiments it is known that,after loading drug,the Trichoderma viride resistance of wood or bamboo treated by HACC/PVA IPN is not obvious while the Penicillium citrinum and Aspergillus niger resistances are greatly improved.(4)Polyacrylamide/Polyvinyl alcohol(PAm/PVA)alloy with IPN structure was prepared by two-steps polymerization.The SEM shows that the drug can enter the cell wall of wood.The dimensional stability tests of wood or bamboo via three wet-dry cycles showed that the treated wood or bamboo had lower shrinkage and expansion.Through indoor and comprehensive experiments it is known that whether loading drug or not,the mildew resistance of wood or bamboo treated by PAm/PVA IPN is well,so the effect of loading drug on mildew can not be determined.