Factors Influencing the Measurement of Absorption Speed of Sanitary Napkins (Part Two)
Posted: 11/30/2020 11:44:07 Hits: 59
3. Discussion
The index for evaluating the absorption performance of sanitary napkins was revised from permeation time to permeation amount, and the latest standard was revised to absorption rates. The standard synthetic test solution was used to replace pig blood for testing by GB 8939-1999. The introduction of the sanitary napkin absorption speed tester including the curved sample holder, automatic liquid filling device and automatic timer makes the sanitary napkin's absorption speed measurement method close to the actual state of use and better reflects the practical requirements of the sanitary napkin. During the test, the stability and accuracy of the standard synthetic test solution are the key factors to ensure the absorption speed. The standard synthetic test solution is not only similar to pig blood in terms of viscosity, oiliness and salt content, but also the surface tension of the synthetic test solution is close to that of pig blood by adding the standard coal agent, so that the test results could be more reasonable and accurate.
The storage period of the solution is inconsistent due to conditions such as laboratory environment, solvent, cleanliness of vessels, degrees of sealing and frequency of use, and it is not specified in detail in the GB/T 8939-2018. The shelf life of the test solution is estimated by obtaining the absorption rates of the same batch of sanitary napkins by testing standard synthetic test solutions with different storage time.
The effect of the storage time of the standard synthetic test solution on the absorption rate shows that the absorption rate of the test solution at 0 months is not significantly different from that at the first one to the second months, and the standard deviation is slightly great. This may caused by the unstable solvent solute in the test solution that has just been prepared. The standard deviation increased significantly at the third to the fourth months, and the precision of the test results decreased. Maybe the test solution starts to become unstable. By the fifth month, the absorption rate showed a significant difference, and the surface tension also fell below the standard, the test solution being deteriorated. It is believed that the standard synthetic test solution can remain stable for no more than 3 months, and the best test time is the first two months. The results showed that the standard synthetic test solution can be stable for more than two months under conditions which are cool and away from sunlight, and try to use it within three month. By the fifth months, the surface tension of the test solution is too low to meet the experimental requirements, and it can be judged to be deteriorated.
It is believed that the moisture content of paper has a great influence on the physical properties of paper, and the amount of moisture depends on the humidity of the surrounding atmosphere. Because the moisture content of paper changes with the relative humidity of the atmosphere and the increase of the moisture content of the paper will reduce the bonding strength between the fibers in the paper, result in changes in many physical properties, especially tensile strength, burst resistance, tear resistance and folding resistance being more obvious.
Sanitary napkins are paper products. The absorption rate of samples processed for different time under standard atmosphere is tested to explore whether moisture will affect this index. The effect of the treatment time on the absorption rate of the sample under standard atmospheric conditions shows that the longer the treatment time is, the more stable the absorption rate value becomes. Only after 2 hours of treatment, the absorption rate has a significant difference. The deviation tends to be stable at 4 hours. Four hours or longer is considered the best processed time under the standard atmospheric conditions. The moisture content does not affect the absorption rate of the sanitary napkin base on the difference in absorption rates from 0 hour and 5 hours. This research provides a theoretical basis for the actual experience of using sanitary napkins in a short period of time after opening the package.
