class notes 4 纺织材料学

Types
Other:
naturally colored:
Mostly
brown or
green Eventually all brown Inconsistency Poor properties
Application
~55%
of apparel fibers are cotton ~70% of men’s apparels made of cotton ~40% of women’s apparels made of cotton 65% of all cotton fibers were used for apparels in 1990 Additional 27% of cotton for sheets and towels or other non-apparel household applications ~7% for industrial use
Cuticle:
Structure
Submicrostructure
5
distinctive regions:
wall: composed of fibrils: a sheath of spiraling fibrils 20 - 30 degree to the fiber axis
Life of a Silkworm
Silkworm
Cocoon
Chrysalis
Butterfly
Tussah: “wild” silk
Spider
Structure
Macrostructure:
Length:
915-1190 m (1000-1300 yds )/cocoon Max 2750 m (3000yds)/cocoon, 1 fiber/cocoon. Thickness: 9-11 mm or 1.2-1.5 denier. Varies: thickest in the middle thinnest inside.
High
heat of wetting: lots of polar groups available High water absorption: up to 1/3 of its weight Smooth and soft High luster: high crystallinity and triangular cross-sectional shape. Scroop: rustling sound due to an acid treatment that hardens fiber surface.
Duppioni:
2 silk worm spin their cocoons together: having special appearance (irregular thickness) similar to wild silk but better color
Regular cocoon
Asakura et al
Properties
For
silk producers, i.e. silk worm, spider etc., silk fibers are for protection, transport and food capture Mechanical properties
Medium

tenacity but higher than wool
from molecular structure:
resulted
zigzag b-sheet of silk vs a-helix of wool extruded instead of grown as a cell higher crystallinity than wool
Structure

Macrostructure Length to breadth ratio: 6000:1 to 350:1 Relatively uniform along its length Color: never truly white but creamy white to gray
Chapter 11 Silk Fibers
Yiping Qiu
Introduction
The
larva of certain insects for use in their building webs, climbing ropes and cocoons Commercial silk industry: use larva of silkworm Spiders Application: mostly apparel, also used for parachutes.
Spinning of silk by silkworm
Asakura
et al ： birefringence increases as silk fiber is spun out
Spinning of silk
Silkworm
and spider spin the fibers started with liquid crystals, resulting in good molecular orientation and high crystallinity
Structure
Fibroin
A
protein polymer
chain of amino acids forming a protein called fibroin composed of 15-18 different amino acids. Glycine, alanine and serine occupy 86% of the polymer The side groups of the above 3 amino acids are small compared with those in wool: glycine: R = H alanine: R = -CH3 Serine: R = -CH2OH Crystallize readily: 70-75%
Raw
silk: silk with gum
Production
Silk

yarn spinning:
Duppioni cocoon
Filament yarn, 7 – 8 ends (cocoons) per yarn, total linear density 20 – 22 denier Staple yarns
Properties
Other
properties
Ignites
and burns but sometimes selfextinguishing Dry-cleaning preferred due to:
lower
tenacity and initial modulus when wet degraded by alkaline solutions may be hand-washed using mild detergents
Structure
Cotton
fiber: single plant cell Macrostructure Staple length: 1/8 - 2.5 inch (0.32 - 6.35 cm) Cotton fibers used in textile yarns: 7/8 1.25 inch (2 – 3 cm) Diameters: 16 - 20 mm but varies from fiber to fiber: longer fibers are finer
Cotton
Ginning mill
Types:
Commodity:
Long
Upland
staple:
Pima
cotton: extra-long staple (ELS) cotton grown in the U.S., Australia, Peru etc. Sea island Egyptian
Amino Acids in wool
Structure
Fibroin
Pack
protein polymer
well: lots of H-bonds, small number of ionic bonds No cystine: no S-S bonds Configuration: pleated b-sheet Degree of polymerization of silk DPsilk > DPwool
Medium
modulus Medium abrasion resistance Medium resilience: (cotton < silk < wool) pleated sheets can slide over one-another.
Properties
Comfort
Cotton fiber
Structure
Submicrostructure
5
distinctive regions:
out layer of wax, a few molecules thick to protect seeds but can be removed by wet processing and laundering.
Chapter 12 Cotton Fibers
Introduction
Cotton:
seed hair obtained from the boll of the cotton plant