自致密透明木材膜的制备及性能OA

To achieve self-densification while preserving the integrity of the wood structure,a combined sodium chlorite(NaClO2)and sodium hydroxide(NaOH)treatment was employed to remove lignin and hemicelluloses from balsa wood(Ochroma lagopus),followed by air drying to obtain self-densified transparent wood films(TWF).The effects of sodium chlorite concentration,heating time,and temperature during delignification on the film formation yield of the TWF were systematically investigated.The optimal delignification conditions were determined to be 2％of sodium chlorite solution mass fraction,a 2 h heating time,and a temperature of 90 ℃.Under these conditions,the resulting self-densified TWF exhibited a density of 0.79 g/cm³,which is 3.76 times higher than that of natural wood(NW)and 4.39 times higher than that of delignified wood(DW).The optical transmittance reached 60.37％,representing 10.74 times that of NW and 5.4 times that of DW.The tensile strength was 306.03 MPa,which is 19.80 times higher than that of NW and 8.84 times higher than that of DW.Cyclic folding endurance tests were performed using a folding endurance tester under a load of 4.91 N on specimens with a uniform thickness of 0.1 mm.The longitudinally oriented self-densified transparent wood film(TWF-L),prepared from wood slices with fibers aligned parallel to the length direction,endured 231 folding cycles—1.56 times that of A4 paper.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)analyses revealed that the delignification treatment preserved the porous structure of the wood cell walls while exposing additional hydroxyl groups,thereby facilitating self-densification during drying.The obtained self-densified transparent wood film exhibits excellent optical and mechanical properties as well as good biodegradability.This approach provides a novel strategy for the preparation of transparent wood and shows promising potential for applications in dyed paper,writing paper,and flexible electronics.