To Know the Features of Filter Paper Well, Understand the Cotton Fiber First
Filter paper is one of the most frequently used tools in many experiments. Filter paper manufacturers are divided into qualitative and quantitative filter papers. If you would like to know the filter paper better, you should know the raw material first-cotton fiber.
Composition properties
The main component of cotton fiber is cellulose. Cellulose is a natural polymer compound. The chemical structural formula of cellulose consists of repeatingαglucose as the basic structural unit. Its elemental composition is carbon 44.44%, hydrogen 6.17%, and oxygen 49.39%. The degree of polymerization of cotton fiber is between 6000 and 11000. In addition, cotton fiber also has about 5% of other substances, called companion organisms, which have an impact on spinning technology, bleaching, printing, and dyeing.
The surface of cotton fiber contains fat wax, commonly known as cotton wax. Cotton wax has a protective effect on cotton fiber, which is one of the reasons for the good spinning performance of the cotton fiber. Therefore, the cotton cloth is easy to wind around the roller and the rubber roller. After degreasing treatment, the moisture absorption of raw cotton increases, and the water absorption capacity can reach 23~24 times its own weight.
The linear density of cotton fiber refers to the thickness of the fiber, which is one of the important quality indicators of cotton fiber, and it is closely related to the maturity and strength of the cotton fiber. The linear density of cotton fiber is also one of the main factors that determine the spinning characteristics and yarn quality.
Folding strength and elasticity
If the fiber strength is high, the yarn strength is also high. The strength of the cotton fiber is often expressed by breaking strength and breaking length. Because of the large difference in the strength of individual cotton fibers, the strength of cotton bundle fibers is generally measured and then converted into a single fiber strength index.
Folding moisture absorption
Cotton fiber is a porous substance, and there are many hydrophilic groups (-OH) on its cellulose macromolecule, so its moisture absorption is good. Under normal atmospheric conditions, the moisture regains rate of cotton fiber can reach about 8.5%.
Acid and alkali resistance
Cotton fiber has weak resistance to inorganic acids. Cotton fiber has greater resistance to alkali, but it will cause lateral expansion. Dilute alkali solution can be used to “mererify” cotton cloth. In addition, there are impurities and defects in the cotton fiber. The impurities include sand, leaves, bell shells, etc., and the defects include neps and ropes. They affect not only the amount of cotton used in textiles but also the processing and yarn quality, so inspections and strict control must be carried out.
Chemical stability
Since the main component of cotton fiber is cellulose, it is more alkali-resistant but not acid-resistant. Caustic soda can cause the cotton fiber to swell violently, increase the diameter and shorten the length, which causes the strong shrinkage of cotton products. At this time, if tension is applied to restrict its shrinkage, the surface of the cotton product will become smooth and bright and greatly improve the dyeing performance.
This processing is called mercerizing; if it is allowed to shrink without tension, it is called alkali shrinkage. Knitted fabrics will become compact and elastic after alkali shrinkage, and have good shape retention. Acid can make the strength of cotton fiber worse, and especially strong acid and concentrated acid should be avoided. It can be dissolved in more than 70% concentrated sulfuric acid. Concentrated hydrochloric acid and concentrated nitric acid also have a serious impact on their strength.
