# Transmission Reduction for UV and IR Radiation with Dyed Lyocell Knitted Textiles
## 3 Results
### Usability of the Dyed Knitted Fabrics
#### 3.3.2 Abrasion Resistance  
The abrasion resistance describes the resistance of fabric against mechanical friction and is used to determine changes in the functional and optical properties of use. The dyed samples made of 100% Lyocell and Lyocell with TiO\({}_{2}\) were tested against abrasion, both in unwashed and washed conditions.  
After the abrasion procedure, all investigated knitted samples did not exhibit any holes or broken meshes appeared. However, there are clear differences between the two types of knitted fabrics. Figure 7 shows the microscopic images of the samples after the abrasion procedure.  
The knitted fabrics made of 100% Lyocell tended to form fiber knots and preliminary stages of these knots formed on all variants with varying degrees of severity. In the Solophenyl Bordeaux 3 BLE dyed fabrics, this development manifested itself in the form of a greyish veil. Here, the overall fabric appearance was better, and damage to the knitted structure was much less compared to the samples dyed with Drimaren Yellow HF. In addition to the formation of pilling knots, these samples showed strong fiber abrasion in some areas, which caused the knitted fabric to lose a lot of density.  
All Lyocell knitted fabrics with TiO\({}_{2}\) were more resistant, although hairiness and accumulations of individual fibers on the surface were also noticeable here, although less pronounced. The loss of mass due to the abrasion load was analyzed and is shown in Figure 8.  
Figure 7: Microscopic images of the samples after the abrasion test (10,000 rubbing cycles in the Martindale device).  
Furthermore, the influence of abrasion on the transmission was investigated. Figure 9 shows the transmission spectra for the unwashed samples in order to analyze the sole influence of rubbing without the additional influence of washing.  
After the abrasion test for all samples, a significant loss of mass (Figure 8) and an increase in optical transmission (Figure 9) is determined. The mass reduction most likely results from fiber abrasion. In consequence, the fabrics become thinner and more permeable. The loss of mass is stronger for the knitted fabrics made of 100% Lyocell and in the range between 12 to 17%. The strongest abrasion occurred in the sample dyed with Drimaren Yellow. The increase in transmission of the 100% Lyocell knitted fabrics is comparable for Drimaren Yellow and Solophenyl Bordeaux. The knitted fabrics with TiO\({}_{2}\) showed a significantly lower weight loss, which is in good agreement with the optical assessment (Figure 7). For this, the developed fabrics dyed with Drimaren Yellow exhibited a slight advantage. The transmission values did not confirm the advantage of the Drimaren Yellow dyeing. The scouring here led to a stronger increase in transmission than with the Solophenyl  
Figure 8: Mass loss after abrasion procedure (10,000 rubbing cycles in the Martindale device).  
Figure 9: Transmission spectra of unwashed knits dyed with Drimaren Yellow (**left**) or Solophenyl Bordeaux (**right**) from 100% Lyocell and Lyocell with TiO\({}_{2}\). Comparison of non-rubbed and rubbed samples (10,000 rubbing cycles).