Research on Influence of Post-treatment for Quantitative Analysis of Cross-linked Lyocell Fibre and Viscose Fibre

YUAN Yuanyuan， WANG Jianzhao， SUN Huiyu ，ZHANG Xiangli，SUN Lixia
(1. Technology Center of Shijiazhuang Customs District，Shijiazhuang Hebei，050051;
2.PetroChina Hebei Marketing Company, Shijiazhuang Hebei，050051)

Abstract: When conducting quantitative analysis on mixed samples of cross-linked lyocell fibers
and viscose fibers,although the difference in dissolution properties between the two fibers in
formic acid/zinc chloride can be considered to achieve the dissolution of one type of fiber while
leaving another type of fiber, the post-processing method has a great impact on the calculation
results of fiber content, and improper post-processing methods can make the data unable to be
used for fiber content calculation. In this paper we use several commonly used filtration and
washing methods in chemical experiments to post-treat the dissolved residue and compare the
d-value and stability of cross-linked Lyocell fibers, to study the impact of post-treatment methods
on the quantitative analysis of cross-linked Lyocell fibers and viscose fibers. At last the optimal
post-treatment method is ultimately determined.The quality correction coefficient of cross-linked
racer fiber is 0.98.

Key words:Cross-linked Lyocell fiber;Viscosefiber;Quantitativeanalysis;Post-processing
methods; Quality correction coefficient

Title:
The Influence of Post-treatment on the Quantitative Analysis of Cross-linked Lyocell Fiber and Viscose Fiber

Authors:
Yuan Yuanyuan, Wang Jianzhao, Sun Huiyu, Zhang Xiangli, Sun Lixia

Received Date:
April 23, 2024

Online First Date:
July 29, 2024

Citation:
Yuan Yuanyuan, Wang Jianzhao, Sun Huiyu, Zhang Xiangli, Sun Lixia. The Influence of Post-treatment on the Quantitative Analysis of Cross-linked Lyocell Fiber and Viscose Fiber [J/OL]. Cotton Textile Technology. https://link.cnki.net/urlid/61.1132.TS.20240729.1019.002

Abstract:
This paper explores the post-treatment methods suitable for the quantitative analysis of blended products of cross-linked Lyocell fiber and viscose fiber. Formic acid/zinc chloride is used to dissolve the viscose fiber in the blend, and six common filtration and washing methods in chemical experiments are used for post-treatment of the residual material after dissolution. The size and stability of the mass correction coefficient d-value of the cross-linked Lyocell fiber are compared. The results show that the post-treatment method using a stainless steel sieve for filtration, manual oscillation washing with dodecyl benzene sulfonate solution for the residual, and soaking in dilute acetic acid after cleaning, has good stability in the d-value, and the d-value for cross-linked Lyocell fiber is determined to be 0.98.

Keywords:
Cross-linked Lyocell fiber; Viscose fiber; Quantitative analysis; Post-treatment method; Mass correction coefficient

Introduction:
Due to the similar structure and properties of regenerated cellulose fibers, the quantitative analysis of their blended products using the dissolution method has always been a challenge. Continuous research has found that there is a significant difference in the dissolution properties of cross-linked Lyocell fiber and viscose fiber in formic acid/zinc chloride, thus enabling quantitative analysis of the two fibers. According to the dissolution conditions in GB/T 39621—2020 “Textiles – Quantitative Chemical Analysis of Mixtures of Cross-linked Lyocell Fiber and Viscose Fiber, Cuprammonium Fiber, Modal Fiber (Formic Acid/Zinc Chloride Method)”, the viscose fiber is dissolved, and the remaining cross-linked Lyocell fiber appears as a transparent viscous gel, not the conventional fiber shape. At the same time, the solution is viscous after the dissolution of the viscose fiber, which can easily lead to incomplete cleaning, resulting in inaccurate fiber content calculation results.

Methods:

1. Sample Preparation

• Cross-linked Lyocell fiber (Lenzing Group); Viscose fiber (Shanghai Textile Industry Technology Supervision Institute, standard material). Self-made samples with cross-linked Lyocell content of 5%, 10%, 60%, and 90%.

1. Reagents

• Formic acid/zinc chloride solution: 20 g of anhydrous zinc chloride (mass fraction greater than 98%) and 68 g of anhydrous formic acid are added to water to make 100 g.

1. Equipment

• Analytical balance, sensitivity 0.0001 g; drying oven, (105±3)℃; constant temperature water bath oscillator, temperature control accuracy ±1℃, oscillation frequency 80 times/min to 120 times/min; stainless steel sieve, 60-65 mesh; glass sand core crucible, capacity 30-40 mL, micropore diameter 90-150 μm; ultrasonic cleaner, temperature control accuracy ±3℃; filtration setup; magnetic stirrer.

1. Experimental Steps

• (1) Sample preparation. According to the ratio of cross-linked Lyocell fiber and viscose fiber in the sample, weigh the two fibers, dry and weigh them separately, then mix the two fibers to obtain the sample. The total mass of the two fibers after mixing is about 1 g.
• (2) Dissolution. In a 250 mL stoppered conical flask, add 100 mL of formic acid/zinc chloride solution, cover with a stopper, and preheat it in a 44℃ constant temperature water bath oscillator. Place the sample in the conical flask and oscillate at 44℃ for 90 minutes.
• (3) Post-treatment. Remove the conical flask from the constant temperature water bath oscillator and perform post-treatment according to different methods, then rinse, dry, weigh, and calculate the d-value of the cross-linked Lyocell fiber.

Results and Discussion:
The d-values under the six post-treatment methods are shown in Table 1.

Below is the English translation of the provided table, presented in a text format that resembles a table:

Table 1: The Influence of Different Post-treatment Methods on the d-value of Cross-linked Lyocell Fiber

Conclusion:
The similarity in properties between cross-linked Lyocell fiber and viscose fiber determines that there is a certain degree of difficulty in their quantitative analysis. After dissolution in formic acid/zinc chloride solution for 90 minutes, although the viscose fiber is completely dissolved, the solution is slightly viscous, and the remaining cross-linked Lyocell fiber is in a transparent gel state, making it difficult to clean. The choice of post-treatment method greatly affects the accuracy and stability of the fiber content calculation results. If the post-treatment method is not properly selected, accurate and stable fiber content calculation results cannot be obtained.

Through comparison of the above several post-treatment methods, it was found that using a stainless steel sieve for filtration, manual oscillation washing with formic acid/zinc chloride and dodecyl benzene sulfonate respectively, and soaking in dilute acetic acid after cleaning, the dissolved cross-linked Lyocell fiber is easy to collect, does not require other equipment, is simple to operate, and the obtained d-value of the cross-linked Lyocell fiber is stable and essentially independent of the content. The traditional d-value method can be used to calculate the fiber content. Therefore, this post-treatment method is the optimal post-treatment method.

References:
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