MANUFACTURED CELLULOSIC FIBERS/ PROTEIN FIBERS Chapter 5

Identification of Regenerated Fibers Manufactured regenerated fibers: From naturally occurring polymers; regenerated fibers – cannot be used in their natural state, but are chemically processed into a solution that is then extruded through a spinneret  Cellulosic: Rayon, lyocell  Protein: Azlon – soy silk, silk latte Derivative cellulosic Fibers: chemically changed derivative of cellulose known as esters  Acetate, triacetate

Rayon Production: Wet spun rayon (viscose); high wet modulus (HWM) rayon. Physical structure:  Naturally bright  Can be solution dyed  Regular rayon: Serrated cross section.  HWM rayon: Rounder cross section and better performance.

Chemical Composition and Molecular Arrangement of Rayon Manufactured fiber of regenerated cellulose in which substitutes have replaced not more than 15 percent of the hydrogens of the hydroxyl groups.

Rayon Properties Physical: Fluid drape, soft hand; control luster, length, diameter. Mechanical:  Regular: Weak, especially wet.  HWM: Stronger; adequate breaking elongation. Chemical: Absorbent, dyes well, high regain, smooth, soft, good heat & static conductor.

Rayon Appearance retention: Moderate  Regular: poor resiliency, progressive shrinkage  HWM: less wrinkling, accepts durable press & dimensional stability finishes, can be merceriz ed Care:  Regular: limited washability (wrinkling, loss of sizing, excessive shrinkage) dry clean  HWM: greater washability, less wrinkling, shrinkage may be controlled

Rayon Environmental effects: Similar to other cellulosics. Environmental impact: Tree harvesting, processing of wood pulp, chemicals (acid rain), recycling, water & chemicals in finishing, dry cleaning. Identification: Burns readily, striations, may be crimped.

Rayon Common modifications: Staple, solution dyed, acid dyeable, cross sections & sizes, high tenacity, HWM, optically brightened, flame retardant, high absorbency. Uses: Apparel, furnishings, industrial (medical, nonwovens, disposables).

Lyocell Production: Wet spun with the solvent recycled. Physical structure: Staple and filament; rounded cross section, but can be modified. Chemical structure: Manufactured fiber composed of solvent spun cellulose.

Lyocell Properties Physical: Size, luster, denier related to use. Mechanical: Strong ( g/d), 18% weaker when wet; adequate breaking elongation; poor resistance to abrasion (fibrillates). Chemical: Good regain (11.5%), no static, soft hand.

Lyocell Appearance retention: Moderate, dimensional stability moderate. Care: Dry cleaned; unacceptable changes in hand and color if washed in regular cycle.

Acetate/Triacetate Production: Dry spun; Triacetate no longer produced in the U.S. Physical structure: Staple and filament; lobular cross-section, can be modified.

Chemical Composition and Molecular Arrangement of Acetate/Triacetate Manufactured fiber in which the fiber forming substance is cellulose acetate. Where, not less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description of the fiber; modified cellulose.

Acetate Properties Physical: Control cross section, luster, denier for end use. Mechanical: Weak, especially when wet; adequate breaking elongation; poor resistance to abrasion. Chemical: Lower regain (acetate 6%, triacetate 3.2%), static, resistant to weak acids, alkalis, and bleach.

Acetate/Triacetate Appearance retention: Poor resiliency for acetate, better for triacetate. Dimensional stability moderate for both; elasticity low for both. Care: Both can be dry cleaned and are thermoplastic and heat sensitive. Identification: Slight striations. Environmental effects: Resistant to moths, mildew, & bacteria; less than other cellulosics unless sunlight resistant type (SLR).

Acetate/Triacetate Environmental impact: Tree harvest; processing of wood pulp; solvent reclaimed & reused, dry cleaning. Common fiber modifications: Solution dyed, cross section & fiber sizes, textured, sunlight & weather resistant, flame retardant. Uses: Apparel, furnishings, industrial.

Other Regenerated Fibers Alginate fiber: Polysaccharides processed from brown seaweed; used for wound dressings. Regenerated protein fibers  Soysilk®: from soybean waste; durable, good drape, good comfort; apparel  Silk Latte®: from milk protein; soft hand, dyeable; apparel Bamboo: Soft, silky hand; similar to high quality ramie.

Soy Silk and Bamboo

Properties (Other Fibers) Identification: Round cross-section, resistant to most organic solvents. Environmental effects: Resistant to moths, similar sunlight resistance to rayon & cotton. Environmental impact: Some made from waste from other industries; small amounts produced. Common fiber modifications: Few at present. Uses: Apparel, furnishings, industrial.