What Are Cellulose Acetate Membranes?
Cellulose acetate refers to a thermoplastic resin obtained by acetic acid as a solvent, acetic anhydride as an acetylating agent, and esterification under the action of a catalyst. It is the earliest commercial production of cellulose derivatives and the continuous development of cellulose organic acid esters. [1] As a porous membrane material, cellulose acetate has the characteristics of high selectivity, large water permeability, and simple processing.
Cellulose acetate refers to a thermoplastic resin obtained by acetic acid as a solvent, acetic anhydride as an acetylating agent, and esterification under the action of a catalyst. It is the earliest commercial production of cellulose derivatives and the continuous development of cellulose organic acid esters. [1] As a porous membrane material, cellulose acetate has the characteristics of high selectivity, large water permeability, and simple processing.
- Chinese name
- Cellulose acetate
- English name
- CELLULOSE ACETATE
- nickname
- Cellulose acetate
- Chemical formula
- [C6H7O2 (OH) 3-m (OOCCH3) m], m = 0 ~ 3
- Molecular weight
- 0
- CAS Registry Number
- 9004-35-7
- EINECS registration number
- 618-380-7
- Melting point
- 230--300 ° C
- Boiling point
- no data
- Water soluble
- Insoluble
- Density
- 1.3g / mL
- Exterior
- White or transparent flakes or powder
- Flash point
- no data
- Security description
- No serious harm
- Danger symbol
- no
- Risk description
- No serious harm
- Related categories
- Cellulose, etc.
Cellulose acetate
Chinese name: | Cellulose acetate |
Chinese Synonym: | Cellulose acetate; cellulose diacetate; cellulose acetate, cellulose acetate; cellulose acetate; cellulose acetate; cellulose diacetate; acetyl cellulose; cellulose acetate (cellulose acetate) |
English name: | CELLULOSE ACETATE |
English synonyms: | a432-130b; acetatecotton; acetateesterofcellulose; aceticacid, celluloseester; acetose; acetyl35; allogel; ampacetc / a |
Related categories: | Cellulose; Materials Science; Natural Polymers; Polymer Science; Polymers |
[2]
cellulose acetate; CA
It is a chemically modified natural high polymer obtained by esterifying hydroxyl groups in cellulose molecules with acetate. Its performance depends on the degree of acetylation. [3]
Commercial products can be divided into general cellulose acetate (acetyl content 37% Different uses of cellulose acetate
40%). Plasticizers are often added for injection molded parts such as toothbrush handles, brushes, and the like. High acetyl content cellulose acetate (acetyl content 40% ~ 42%), white granular, powdery or cotton solid. Stable to light, not easy to burn, stable in dilute acid, gasoline, mineral oil and vegetable oil, swell in chloroform, soluble in acetone, methyl acetate, etc., can be eroded by dilute lye, with toughness, transparency and good gloss And other advantages, good melt fluidity, easy to shape and process. The dichloromethane homogeneous method uses refined cotton linters and acetic anhydride, using acetylsulfuric acid as a catalyst, and performing esterification in the presence of a solvent of dichloromethane. Partial hydrolysis can obtain acetic acid with a combined acetic acid content within the range of 60% ± 0.5%. Cellulose. The traditional method is to dry the purified cotton fluff, activate it with acetic acid, acetylate with a mixed solution of acetic acid and acetic anhydride in the presence of sulfuric acid catalyst, and then add dilute acetic acid to hydrolyze to the degree of substitution, neutralize the catalyst, precipitate, and deacid Wash, cook and dry to get the finished product. After partial hydrolysis, it is called cellulose diacetate, and the degree of esterification is 220-270. Those without hydrolysis, that is, the esterification degree value of 300 are called cellulose triacetate. Cellulose acetate plastic can be used for various tool handles, alphanumeric keys for computers and typewriters, telephone cases, automobile steering wheels, textile equipment parts, radio switches and insulation parts, pen holders, eyeglass frames and lenses, toys, daily necessities, etc. It can also be used as desalination membrane. Cellulose triacetate has a high melting point and can only be formulated into a solution for processing. It is used as a film base, X-ray base, insulating film electromagnetic, audio tape, transparent container, and separator in silver-zinc batteries.
Cellulose Acetate (hereinafter abbreviated as CA, or cellulose acetate, cellulose acetate), first prepared in 1865, is a cellulose acetate. CA is used as a base for photographic film and is one of the components of some adhesives; it is also used as a synthetic fiber.
Cellulose acetate physical properties
Melting point | 230-300 |
density | 1.3 g / mL at 25 ° C (lit.) |
Refractive index | n 20 / D 1.475 (lit.) |
Merck | 13,1978 |
stability | Stable. Combustible. Incompatible with strong oxidizing agents. |
[2]
CA is a very readily available man-made fiber with low cost and good weaving properties. Its properties make it a beautiful fiber. CA is used in satin, brocade, and taffeta to improve its luster, body, drage, and beauty.
1. Feel: soft, slippery, dry, soothing and elastic;
2. Comfort: good air permeability, core material, fast drying, no static adsorption;
3, non-toxic, harmless, long-term contact with the skin is not allergic.
4. Fibrous and plastic;
5. Selective adsorption and removal of certain low levels of organic matter;
6. It is easy to glue them together with plasticizer, heat or pressure;
7. Soluble in many common solvents (especially acetone and other organic solvents). After modification, it can be dissolved in other types of solvents, such as water;
8. Hydrophilicity: CA is easy to wet, has good liquid permeability and excellent adsorption; in the fabric, it is comfortable and absorbs sweat, but when CA is wet, the strength decreases;
9. Large specific surface area;
10. Can be prepared from new raw materials: wood pulp;
11. Can be used as mixed fertilizer or burned away;
12. Can be colored, but because CA is not suitable for cotton and rayon, special dyes and pigments are required;
13. Anti-mildew;
14. Deterioration in alkaline solutions and strong oxidants;
15. Can be dry cleaned or washed, and usually does not shrink.
Cellulose acetate chemical properties
It is generally not harmful to water. Do not discharge materials into the surrounding environment without government permission. [4]
Preparation of cellulose acetate
1. After the purified short cotton wool is dried, it is activated by acetic acid, and then esterified with a mixed solution of acetic acid and acetic anhydride in the presence of an acetic acid catalyst to make it acetic, and then hydrolyzed by dilute acetic acid. Neutralize the catalyst to make the product deeply precipitate out. It can be obtained by acid removal, washing, refining and drying.
2. After drying the purified lint, it is activated by acetic acid, and in the presence of a sulfuric acid catalyst, it undergoes an esterification reaction with a mixture of acetic acid and acetic anhydride 7 times as much as that of the purified lint. Hydrolysis to the required degree of hydrolysis (1.72 to 1.95). The catalyst is neutralized to precipitate the product. After deacidification, washing, refining and drying, cellulose acetate is obtained. During the acetylation reaction, the amount of the mixed solution of acetic acid and acetic anhydride added can be changed to obtain cellulose diacetate and cellulose triacetate. The amount of the mixed solution of acetic acid and acetic anhydride is 8.5 times that of the purified short cotton wool. After the reaction, the diluted acetic acid is hydrolyzed to achieve a degree of substitution of 2.28 to 2.49 to obtain cellulose diacetate. The amount of the mixed solution of acetic acid and acetic anhydride was 10 times that of the purified short cotton wool. After the reaction, the diluted acetic acid was hydrolyzed to achieve a degree of substitution of 2.8 to 2.9, and cellulose triacetate was obtained. [4]
Use of cellulose acetate
It is used for the production of enteric coatings for pharmaceuticals, acetate filter membranes, etc., and for the manufacture of cellulose acetate plastics, cellulose acetate filter membranes, etc.
Cellulose acetate can be divided into diacetate spinning grade cellulose acetate, diacetate plastic grade cellulose acetate, and triacetate cellulose according to different products.
1. Diacetate spinning grade cellulose acetate: Spinning grade products are non-toxic and harmless products that have been recognized internationally and no alternative materials have been found so far. Its most important and main purpose is to be used as filtering equipment, especially Cigarette filters are used in very large quantities. In addition, they are used as medical filtering equipment, such as blood filtering equipment. At the same time, it can also be used for spinning, with the luster of silk, and is used as a name for high-end suits.
2. Diacetate plastic grade cellulose acetate: It is mainly used for making plates and sheets. The main products are spectacle frames and advanced tool handles.
3. Cellulose triacetate: mainly used as electronic films, such as polarizers for liquid crystal displays, film films, and camera films.
Cellulose acetate miscible substance
Both cellulose acetate (Acetate fiber (AF) and triacetate fiber (TAF) are often mistaken for the same fiber. In fact, although they are similar, they have different chemical compositions. TAF is described as a general molecular structure and is also the most basic acetate, which does not contain hydroxyl groups. AF is considered to be a modified or secondary acetate that contains hydroxyl groups in the molecular chain. Although TAF is rarely produced today, it has a higher degree of esterification than AF.
