Study On The Improvement Of Wood And Bamboo Properties By Chitosan-based Drug-loaded Polymer Network

In order to solve the dimensional stability and mildew problem of wood and bamboo at the same time,the paper describes the cross-linked polymers of chitosan/polyvinyl alcohol?CS/PVA?and chitosan/poly?acrylate??CS/PEMA?and in situ construction in wood and bamboo.By optimizing the ratio of monomer,initiator,type and dosage of crosslinking agent,a polymer system with low water absorption and swelling capacity and suitable for wood and bamboo wood modification was obtained.The CS/PVA and CS/PEMA systems were constructed in wood and bamboo by in-situ reaction.The dimensional stability,antiseptic and mildew resistance of wood and bamboo in the three cycles of drying-immersion and drying-humidification were studied.Fourier transform infrared spectroscopy,scanning electron microscopy and thermal analysis were used to test the structure and morphology of polymers and treated materials,and to analyze their anti-bacterial and anti-cracking mechanisms.The main results are as follows:?1?Taking the swelling degree of polymer as response value and the dosage of CS,PVA and compound crosslinking agent?GA?as independent variables,response surface experiments were designed to study the swelling stability of CS/PVA polymer.The results show that the amount of PVA has the greatest influence on the swelling degree of polymer,CS takes the second place,and GA has the least influence on the swelling degree,the optimal treatment scheme is:CS accounts for 0.51%,PVA3.30%and GA 0.13%.The infrared analysis and DTG results of the CS/PVA polymer showed that the polymer formed a crosslinked structure and the thermal stability was improved.?2?CS/PVA polymer was constructed in situ from wood and bamboo to study the dimensional stability and anti-mildew and anti-corrosion properties of treated wood.The CS/PVA treated bamboo has a highest anti-expansion rate of 47.82%in the three water absorption-drying cycles,and the modified wood has a swelling resistance of up to 40.53%;In the three cycles of moisture absorption and drying,the highest anti-swelling rate of modified bamboo was 63.07%,and the highest anti-swelling rate of modified bamboo was 59.77%.It can be seen that CS/PVA constructed in situ in wood and bamboo can significantly improve its dimensional stability.The results of indoor anti-mildew experiment showed that CS/PVA polymer containing IPBC and Cu²⁺in bamboo was constructed in situ,and no mildew occurred in one month's indoor anti-mildew test.?3?CS/PVA polymer containing propiconazole and Cu²⁺was constructed by in situ reaction in bamboo.The mass loss rate caused by white rot fungi was 4.99%and 5.01%respectively in three months'anti-corrosion test,which was similar to that of bamboo treated by propiconazole and Cu²⁺alone,much lower than that of untreated bamboo;The mass loss rate caused by brown rot was 12.84%and 14.05%,slightly lower than the mass loss rate of bamboo treated with PPA and Cu²⁺alone.In-situ reaction in wood to construct a polymer carrying PPA and Cu²⁺,the mass loss rate caused by white rot fungus was 2.82%and 2.26%;The mass loss rate caused by brown rot was 8.21%and 7.88%.The in-situ construction of CS/PVA drug-loaded polymer in wood and bamboo can significantly improve its decay resistance.?4?Experimental results of response surface methodology show that the dosage of EMA/CS has the greatest influence on the swelling degree of polymer.The dosage of GA,APS and BIS decreases in turn.It is concluded that the minimum swelling degree is 0.50%for CS,53.50%for EMA,0.05%for APS,0.09%for BIS and 0.16%for GA.?5?The CS/PEMA polymer was constructed in situ in wood and bamboo to study the dimensional stability and anti-mold and decay properties of the treated material.The anti-swelling rate of bamboo treated by CS/PEMA reached 59.04%in the three water absorption-drying cycles,and 53.32%in the modified wood.In the three water absorption-drying cycles,the anti-swelling rate of modified bamboo was 68.87%and that of modified wood was 70.65%.It can be seen that the in-situ construction of CS/PEMA in wood and bamboo can significantly improve the dimensional stability.The results of indoor anti-mildew experiment showed that CS/PEMA modified bamboo had better inhibition on the growth of mildew,and there was no m ildew phenomenon in bamboo.The in-situ construction of CS/PEMA polymer containing IPBC and Cu²⁺in bamboo did not appear mildew phenomenon in one month's indoor anti-mildew test.?6?CS/PEMA polymer containing propiconazole and Cu²⁺was constructed by in-situ reaction in bamboo.The mass loss rate caused by white rot fungi was 3.71%and 5.99%respectively in three months'anti-corrosion test.The mass loss rate caused by brown rot was 3.71%and 6.72%.In-situ construction of CS/PEMA drug-loaded polymer in wood and bamboo can significantly improve the decay resistance of wood and bamboo.The above results indicate that the chitosan-based cross-linked polymer is used to modify the wood bamboo material,which improves the dimensional stability of the wood bamboo material,and uses the polymer-loaded drug to treat the wood bamboo material,which has good mold and decay resistance.