SILK charvet marciliac morgand .pdf



Nom original: SILK charvet marciliac morgand.pdf

Ce document au format PDF 1.4 a été généré par Adobe InDesign CS4 (6.0) / Adobe PDF Library 9.0, et a été envoyé sur fichier-pdf.fr le 09/04/2011 à 14:47, depuis l'adresse IP 90.9.x.x. La présente page de téléchargement du fichier a été vue 1537 fois.
Taille du document: 1.4 Mo (24 pages).
Confidentialité: fichier public


Aperçu du document


NATURAL

AND SYNTHETIC
SILKS

THE SILK

ARTIFICIAL FIBERS

I. The thread

I. Definition

II. Synthesis by Bombyx
The silk gland
The fibroin
The sericin
The spinning

II. The differents cellulosic
fibers

III. Applications

III. Viscose
VI. Cellulose acetate and
triacetate

THE SILK
I. The thread
Silkworm: Bombyx Mori

Spiders

• 700 to 1200 m per cocoon

• Diameter: 25 to 70 µm

• Diameter: 24 to 30 µm

• Resistance: a thread of 0,5mm

• One fibril with bi-triangular fibroin
(schéma)

diameter can support 80 kg

• Resistance equal to steel

and sericin

• Intertwined fibrils constituded of fibroin

Sericin

Fibroin

Section of a silkworm thread

Section of a spider thread

II. Synthesis by Bombyx
The silk gland
POSTERIOR PART

MIDDLE PART

ANTERIOR PART

Production of
fibroin

Production of
sericin

Spinning

Heart of the fiber

Cement of the fiber

Similar with an
extrusion

Silk is a
gathering of
proteins

The fibroin
Proteins : amino acid polymers

--> Fibroin : Glycine 44% and
Alanine 29%

Synthesis of the fibroin
--> H-chain (high)
350 kDa 46%

--> L-chain (low)
26 kDa
46%

--> Glycoproteine P25 30 kDa
8%

alpha-helix
→Softness

High concentration of spherical masses of
fibroin fiber

beta-structure,
hydrogen bounds network
→ Resistance

The sericin
Synthesis of sericin

--> Made of amino acid residues

--> Mix of short and long side-chain
Serin 33%, aspartic acid 16,5% and glycin
13,9%
In water: only beta-structure
Dried: few alpha-helix, mostly beta-structure

--> Energetic stability

The spinning
In the lumen of middle part :

Orientation of the masses of fibroine fiber
At the exit of the worm’s spinneret:

Crystallisation ot the sericin along the fiber
axis


-->Complex and crucial step

Unexplainable process

Waterproof

Readilly soluble

3 layers around the fibroin

III. Applications
The thread of silk
• Debourrage
• Luxurious clothes
• Parachute
• Medical sutures
• Biodegradability

Fibroin and Sericin
• Fibroin and sericin close of
collagen

--> cosmetics

--> wound dressing and

drug delivrery
• Membranes with sericin copolymerized with others substance

--> osmosis

-->dialysis

--> desalinisation
• Biodegradable polymers

Impossibility of breeding spiders:
huge territorries and cannibalism

* New ways of using the raw *
* material sericin *

ARTIFICIAL FIBERS
I.

Definition
Artificial fibers can be product of
• plant origin

Cellulose

Corn fiber

• animal origin

Chitine

Milk fiber

II.

The differents cellulosic fibers

• Reactivated cellulose : initial polymer is re-established and his chemical
formula insn’t modified
→ VISCOSE, MODAL, LYOCELL
• Converted cellulose : initial polymer is modified and his chemical formula
changes
→ CELLULOSE ACETATE, CELLULOSE TRIACETATE

III.

Viscose

1) Historic
• Invented in 1884 by Comte Hilaire de Chardonnet
• first artificial filament which imitates silk.
• called fibranne or rayonne
• Patented in 1892
• Ingredients are mostly cellulose (wood cell): alpha-cellulose
percentage of 92 to 93%

III.

Viscose

2) Fabrication
Two process of fabrication exist :
• Soda process
1. Solubilization of cellulose

-

+ NaOH

-

Na+

+ H2O

Na+

-

Cellulose

Na+

Alkali-cellulose : soluble compound

• Soda process
2. Decure of cellulose

-

-

Na+

+ CS2

Na+

-

Na+

Alkali-cellulose

Cellulose xanthate

Cellulose xanthate + NaOH dilute

Collodion

Maturation of collodion

Spinning

• Soda process
3. Spinning

Final collodion + H2SO4

Cellulose regenerated + Na2SO4
= Viscose
Spinneret

CS2 is a toxic, flammable and polluting chemical and it cannot be recycling after the process

III.

Viscose

2) Fabrication
• Cuprammonium process

Reducer chemical for avoid
the oxidation of the solution

Cellulose
Cu, NH4OH

Cuoxame

Viscous liquid

Viscose

Cuoxame + H2SO4
Spinneret

III.

Viscose

2) Fabrication
• After the process
-Stretching of the cellulose:
macromolecules are organised in a parallel
direction and the liquid heart filament is eliminated

-Cellulose DP=10000

Viscose DP=300

III.

Viscose

3) Properties

Viscose filament

Viscose material

III.

Viscose

3) Properties
• Shiny like silk
• Properties chemical and tinctorial similar to cotton
• Density = 1,2
• Heatproof until 125°C → turns yellow and burns
without melt
• Tenacity of 15 to 20 cN/tex for rayonne with a lost
of 50% when it’s wet, breaking-off lengthening correct (10% to 30%)

→ VISCOSE HIGH TENACITY
• At last 95% of alpha-cellulose
tenacity in cN/tex
Material

dry

wet

viscose

15 to 20

6 to 10

viscose high-tenacity

25 to 50

20 to 40

III.

Viscose

4) Applications
• Use for clothing and fine lingerie
• Medical use : dressing, cotton wool

→ VISCOSE HIGH TENACITY
• Use as reinforcement on which rubber are extrude (pneumatic)
• Thread for sewing

VI.

Cellulose acetate and triacetate

1) Fabrication
1.

Cellulose acetate

→ Cellulose treatment

Cellulose

Cellulose triacetate

Cellulose acetate

VI.

Cellulose acetate and triacetate

1) Fabrication
1.

Cellulose acetate

→ Cellulose acetate dissolution

is dissolved in a solution
of acetone →

Cellulose acetate

VI.

Cellulose acetate and triacetate

1) Fabrication
1.

Cellulose acetate

→ Spinning of Cellulose acetate

• Cellulose acetate is
sent pressurized in
the spinneret
• Solvent is evaporated thanks to hot
air
• After the spinning,
solvent is saved
Dry spinning

VI.

Cellulose acetate and triacetate

1) Fabrication
2.

Cellulose triacetate

→ Same process than cellulose acetate EXCEPT for the solvent
• Solvent is dichloromethane because acetone doesn’t dissolve
cellulose acetate
• Estherification is more advanced than cellulose acetate

Cellulose triacetate

VI.

Cellulose acetate and triacetate

2) Properties
1.

Cellulose acetate

• Fiber soften at 200°C and melt at 230°C
• Resists to diluted acids
• Destroied by concentrated acids especially by acetic and formic acid
• Resists to oxidizes (except if very concentrated)
• Soluble in acetone-water blend → be careful with clothings
• Good dimensional structure
• Bad conductor of heat → good thermal insulator

VI.

Cellulose acetate and triacetate

2) Properties
2.

Cellulose triacetate

• Close to synthetic material
• Melt at 300°C
• Resistance like acetate
• Absorbent power limited like cellulose acetate
• Good resiliency
• Resistance to chemicals as cellulose acetate
• Soluble in several organics solvents (perchlorethylene, mineral essence)
but caution with trichlorethylene

VI.

Cellulose acetate and triacetate

3) Utilisations
Both are used in
• Clothings
• Tissue imitating silk
• Imitation fur
• Rubannerie
• Cigarette filter
• Cotton wool
• sunglasses, buttons
• Diapers
• playing cards
• Nail varnish

SUMMARY

SILK

Advantages

• Resistance, Elasticity

VISCOSE

CELLULOSE
ACETATE
AND TRIACETATE

• Heatproof, Burns without melt
• Quick drying

• Good moisure-absor• Cheapness
• Cheapness
bing
• Possibility of procu• Thermal insulator
ding high tenacity

Bad points

• Bad resistance
• Very bad resistance
• Weakness with javel
(especially when wet)
• Weakness with cheand light
micals such as ace• Turns yellow with
• Price
tone
heat

Chemistry

• Absorbtion of mineral
substances

• Tinctorials propreties • Attacked by bases
like cotton
and
concentrated
acids


SILK charvet marciliac morgand.pdf - page 1/24
 
SILK charvet marciliac morgand.pdf - page 2/24
SILK charvet marciliac morgand.pdf - page 3/24
SILK charvet marciliac morgand.pdf - page 4/24
SILK charvet marciliac morgand.pdf - page 5/24
SILK charvet marciliac morgand.pdf - page 6/24
 




Télécharger le fichier (PDF)


SILK charvet marciliac morgand.pdf (PDF, 1.4 Mo)

Télécharger
Formats alternatifs: ZIP



Documents similaires


silk charvet marciliac morgand
memoire exemple bibliographie
lecture notes mdc2014
2017 tp comp guillouroux huret 2
natural fibres used
dw200 dewal