Yu Flashcards
What are alginate fibers made from?
Sodium alginate, a natural polymer extracted from brown seaweeds such as Laminaria, Ascophyllum nodosum, and Macrocystis pyrifera
Alginate fibers are utilized in various pharmaceutical applications.
Who discovered alginate and in what year?
Stanford in 1881
This discovery marked the beginning of the understanding of alginate’s properties.
What are the physical properties of alginate fibers?
Fairly lustrous and pale cream colored
These properties contribute to their aesthetic and functional uses.
List some pharmaceutical uses of alginate fibers.
- Non-absorbable surgical sutures
- Specialist silk underclothing for eczema
- Disposable cups and drug delivery systems
What is the primary component of silk fibers?
Protein fibroin, coated externally by sericin
Sericin acts as a glue that cements the fibers together.
How does silk differ from wool in terms of chemical properties?
Silk contains little or no sulfur; it rapidly dissolves in concentrated hydrochloric acid
This distinction is crucial for identifying silk.
What is the biological source of silk?
Bombyx mori L.
This species is the domestic silkworm primarily used in sericulture.
What is the texture and strength characteristic of silk?
Smooth, soft texture and one of the strongest natural fibers
Silk loses up to 20% of its strength when wet.
What distinguishes wild silk from mulberry silk in microscopy?
Wild silk shows well-marked striations
The structure of mulberry silk is more uniform without striations.
What is the process of preparing silk from cocoons?
- Collect cocoons
- Bake or steam to kill pupae
- Soften in hot water
- Catch and twist filaments to form raw silk
What are the key physical properties of wool?
- Hydrophilic
- Creamy white color
- Higher ignition temperatures than cotton
- Resistant to static electricity
What is the chemical nature of wool fibers?
Composed of protein keratin
This gives wool its elasticity compared to cellulose and silk fibers.
What is the approximate composition of raw wool?
- Wool fiber: 31%
- Wool sweat (suint): 32%
- Earthly matter: 26%
- Wool grease
What is cellulose wadding primarily composed of?
Pure cellulose
Its properties make it similar to absorbent cotton wool.
How is nylon synthesized?
By polymerization from long-chain adipic acid and hexamethylenediamine
This process leads to the creation of synthetic fibers.
What are the uses of nylon in the pharmaceutical field?
- Surgical dressings
- Artificial ligaments
- Absorbent pads
What distinguishes nylon from natural fibers upon ignition?
Nylon behaves like cotton, unlike wool and silk
This is important for identifying the type of fiber.
What happens to nylon when it is wetted?
It loses about 60% of its tensile strength
This characteristic is significant in applications where strength is critical.
What is the appearance of nylon fibers under a microscope?
Solid and transparent with slight twists and grooves along their length
These features aid in the identification of nylon fibers.
What is the chemical composition of alginate?
Composed of 1,4-linked β-D-mannuronic acid and α-L-guluronic acid residues
This structure contributes to its properties and uses.
What are the general tests for alginate fibers?
- Soluble in ammoniacal copper nitrate
- Burns in flame and goes out when removed
- Produces a brownish-red color with iodine and sulfuric acid
Describe the preparation process of alginate fibers.
- Aqueous sodium alginate solution is pumped through a spinneret into acidic calcium chloride bath
- Calcium cations substitute sodium cations, precipitating insoluble calcium alginate
What is required to make cellulose water repellent?
Chemical treatment
What is the primary chemical component of rayon?
Cellulose
