Transcript Thursday Lecture – Fibers, Dyes and Tannins

Tuesday Lecture – Fibers and Dyes
Reading: Textbook, Chapter 15
Collect assignments – plant-derived chemicals added to food
products
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
Fig. 15.1, p. 556
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
10,000 yrs ago – linen (from Linum) in Turkey
Fig. 15.1, p. 556
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
10,000 yrs ago – linen (from Linum) in Turkey
8,000 yrs ago – fiber sandals in Missouri
Fig. 15.1, p. 556
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
10,000 yrs ago – linen (from Linum) in Turkey
8,000 yrs ago – fiber sandals in Missouri
7,000 yrs ago – sheep domesticated
Fig. 15.1, p. 556
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
10,000 yrs ago – linen (from Linum) in Turkey
8,000 yrs ago – fiber sandals in Missouri
7,000 yrs ago – sheep domesticated
5,400 yrs ago – cotton fibers used in Mexico
Fig. 15.1, p. 556
Fibers - History
Use of plant fibers seems to predate that of animal fibers
Note: relatively few plants or animals produce fibers that
can be woven or spun – use seems fairly recent
10,000 yrs ago – linen (from Linum) in Turkey
8,000 yrs ago – fiber sandals in Missouri
7,000 yrs ago – sheep domesticated
5,400 yrs ago – cotton fibers used in Mexico
5,000 yrs ago – silk in Asia
Fig. 15.1, p. 556
Plant vs. Animal Fibers
Plant fibers: composed – partly - of cellulose
-
Animal fibers: composed of protein molecules
Fig. 15.2, p. 557
Plant vs. Animal Fibers
Plant fibers: composed – partly - of cellulose
- can be heated
- hard to dye
- attacked by fungi, mold, termites
- less elastic but more absorbent of water
Animal fibers: composed of protein molecules
- denatured by heat  brittle
-
Fig. 15.2, p. 557
Plant vs. Animal Fibers
Plant fibers: composed – partly - of cellulose
- can be heated
- hard to dye
- attacked by fungi, mold, termites
- less elastic but more absorbent of water
Animal fibers: composed of protein molecules
- denatured by heat  brittle
- readily accept dyes
Fig. 15.2, p. 557
Plant vs. Animal Fibers
Plant fibers: composed – partly - of cellulose
- can be heated
- hard to dye
- attacked by fungi, mold, termites
- less elastic but more absorbent of water
Animal fibers: composed of protein molecules
- denatured by heat  brittle
- readily accept dyes
- attacked by moths, silverfish
Fig. 15.2, p. 557
Plant vs. Animal Fibers
Plant fibers: composed – partly - of cellulose
- can be heated
- hard to dye
- attacked by fungi, mold, termites
- less elastic but more absorbent of water
Animal fibers: composed of protein molecules
- denatured by heat  brittle
- readily accept dyes
- attacked by moths, silverfish
- more elastic, less absorbent of water
Fig. 15.2, p. 557
Classification of Fibers
Seed/Fruit Fibers – aid in seed dispersal
- cotton, coir, kapok
Bast Fibers – from phloem of stem
- hemp, jute, ramie, linen
Hard Fibers – from leaves of monocots
- sisal, henequen, Manila hemp
Material
% Cellulose
Cotton
98
Ramie
86
Hemp
65
Jute
58
Deciduous woods
41-42
Coniferous woods
41-44
Cornstalks
43
Wheat straw
42
Classification of Fibers
Seed/Fruit Fibers – aid in seed dispersal
- cotton, coir, kapok
Bast Fibers – from phloem of stem
- hemp, jute, ramie, linen
Hard Fibers – from leaves of monocots
- sisal, henequen, Manila hemp
Material
% Cellulose
Cotton
98
Ramie
86
Hemp
65
Jute
58
Deciduous woods
41-42
Coniferous woods
41-44
Cornstalks
43
Wheat straw
42
Classification of Fibers
Seed/Fruit Fibers – aid in seed dispersal
- cotton, coir, kapok
Bast Fibers – from phloem of stem
- hemp, jute, ramie, linen
Hard Fibers – from leaves of monocots
- sisal, henequen, Manila hemp
Material
% Cellulose
Cotton
98
Ramie
86
Hemp
65
Jute
58
Deciduous woods
41-42
Coniferous woods
41-44
Cornstalks
43
Wheat straw
42
Fiber Extraction
Seed Fibers (Cotton) – actually trichomes, not fibers
Ginning – separates fibers from seeds
Mostly Bast Fibers:
Retting – rots away non-fiber parts
Scutching – beat and scraping retted plant material to
remove broken pieces of woody matter
Hackling – drawing a mass of fibers across pins to separate
and align fibers
Leaf Fibers
Decorticating – crushing plant material and scraping away
the nonfibrous material
Fiber Extraction
Seed Fibers (Cotton) – actually trichomes, not fibers
Ginning – separates fibers from seeds
Mostly Bast Fibers:
Retting – rots away non-fiber parts
Scutching – beat and scraping retted plant material to
remove broken pieces of woody matter
Hackling – drawing a mass of fibers across pins to separate
and align fibers
Leaf Fibers
Decorticating – crushing plant material and scraping away
the nonfibrous material
Fiber Extraction
Seed Fibers (Cotton) – actually trichomes, not fibers
Ginning – separates fibers from seeds
Mostly Bast Fibers:
Retting – rots away non-fiber parts
Scutching – beat and scraping retted plant material to
remove broken pieces of woody matter
Hackling – drawing a mass of fibers across pins to separate
and align fibers
Leaf Fibers
Decorticating – crushing plant material and scraping away
the nonfibrous material
Seed Fibers - Cotton
Fig. 15.7, p. 562
Cotton – Ancient History
4 independent domestications of cotton
Fig. 15.9, p. 564
Problem: New World domesticates – have one genome present
in wild only in Old World
Possible resolution: AA genome predates continental separation
G. arboreum
G. hirsutum
Tetraploids
AADD
G. barbadense
G. herbaceum
Diploids
AA
Cotton – Ancient History
4 independent domestications of cotton
Fig. 15.9, p. 564
Problem: New World domesticates – have one genome present
in wild only in Old World
Possible resolution: AA genome predates continental separation
G. arboreum
G. hirsutum
Tetraploids
AADD
G. barbadense
G. herbaceum
Diploids
AA
Cotton – Ancient History
4 independent domestications of cotton
Fig. 15.9, p. 564
Problem: New World domesticates – have one genome present
in wild only in Old World
Possible resolution: AA genome predates continental separation
G. arboreum
G. hirsutum
Tetraploids
AADD
G. barbadense
G. herbaceum
Diploids
AA
Cotton – More Recent History
Hand Labor – Associated
with Slavery in U.S.
Cotton Gin – Enhanced Value
Fig. 15.11, p. 565
Cotton - Spinning
Cotton - Today
Cotton – Issues:
Chemical Use
Irrigation
Cotton Cloth - Details
Cleaning – boiling in caustic soda, then treat with hydrogen peroxide
 removes pectins, waxes; lightens color of fibers
Mercerizing (invented by J. Mercer) – soak thread or textile under
pressure in caustic soda  fibers swell, change shape
Sizing – add starch or gel to thread, fills in irregularities, strengthens
Sanforization – ammonia process, swells fibers and prevents
shrinking
Permanent press – use chemicals to cross-link cellulose polymers 
garment retains shape even after washing
Dye Plants
Paradox: We associate plants with beautiful colors, yet most plant
pigments do not make good dyes
Dye Plants
Paradox: We associate plants with beautiful colors, yet most plant
pigments do not make good dyes
Resolution: Most plant pigments are chemically instable – when
removed from the environment of the plant cell they are quickly
degraded or washed away
Dye Plants
Paradox: We associate plants with beautiful colors, yet most plant
pigments do not make good dyes
Resolution: Most plant pigments are chemically instable – when
removed from the environment of the plant cell they are quickly
degraded or washed away
Plant Dyes:
- must be chemically stable (many oxidize when exposed to air)
- must bind to object being dyed (=fastness)
Mordant: chemical that increases adherence of dye to fabric
- may also change color of dye
Reminder
This Thursday, April 21 – class will meet at UT Institute of
Agriculture Gardens, next to the Vet School. Dress appropriately
to be outside and take a garden tour.