# Ultraviolet-Assisted Modified Delignified Wood with High Transparency
## 3 Results and Discussion
### Analysis of Transmittance and Haze  
The mean values of transmittance and haze for the four \"transparent wood\" groups TW-A-U, TW-B-U, TW-C-U and TW-D-U were 55% and 96%, 71% and 90%, 78% and 83%, and 82% and 75%, respectively. At the same time, the transmittance and haze of the four  
Figure 3: XRD images of natural wood (NW), four groups of delignified wood DW-B, DW-B-U, DW-D, DW-D-U and “transparent wood” TW-D-U.  
\"transparent wood\" groups TW-A, TW-B, TW-C and TW-D were measured to be 34% and 99%, 59% and 94%, 72% and 87%, and 78% and 78%, respectively. As shown in Figure 4a,b, the transmittance of the \"transparent wood\" increased, and the haze decreased as the lignin modification time increased, both with and without UV assistance. The TW-D-U group achieved the highest value of 82% for transmittance and the lowest value of 75% for haze, having the best optical measurements. In addition, the shorter the delignification time, the more significant the difference in transmittance between \"transparent wood\" made under UV-assisted and dark conditions; with the \"transparent wood\" TW-A-U obtained by UV-assisted lignin modification for two hours being 20% more transparent than TW-A, and TW-B-U 12% more transparent than TW-B. It is clear from Figure 4c that DW-B is light yellow, and TW-B is more turbid. Part of the incident light propagation direction changes significantly after passing through TW-B, and the light-absorbing substance absorbs the light, and the 'TW-B' characters become blurred. DW-B-U is whiter than DW-B, while TW-B-U is more transparent and clearer than TW-B. This is due to the accelerated removal of chromophores from the wood lignin by UV irradiation. The increased removal of lignin and the reduction in colour-forming clusters reduces the absorption of light by the wood. As a result, UV-assisted delignified wood can appear white in a shorter period of time, resulting in clearer wood.  
Figure 4: Transmittance (**a**) and haze (**b**) of eight groups of “transparent wood” was obtained by soaking the wood in a lignin-modifying solution under UV-assisted or dark conditions for 2 h, 4 h, 6 h and 8 h, followed by a 3 h impregnation treatment, respectively. (**c**) Photographs of TW-B-U, TW-U, DW-B-U and DW-B under daylight source. (**d**) The transmittance and haze of TW-B-U1, TW-B-U2 and TW-B-U were obtained by changing the impregnation time.  
In addition, the impregnation time of the \"transparent wood\" in the TW-D-U group was changed to 1 h and 2 h to obtain the TW-D-U1 and TW-D-U2 groups, respectively. The transmittance and haze were measured to be 55% and 95% for the TW-D-U1 group and 74% and 87% for TW-D-U2. As shown in Figure 4d, the transparency increases with the time of impregnation, and the haze gradually decreases, resulting in a clearer picture through the transparent wood sheet and better optical properties. As the impregnation time increases, the more epoxy resin immerses into the cell and binds closely to the cell wall, the fewer pores become. The degree of refractive index matching inside the transparent material increases; thus, light produces less refraction inside, leading to a decrease in haze and an increase in transmittance [11].