Cellulose Acetate

Question 1

steps

Answer 1

1) cellulose + H2SO4 + acetic anhydride
2) proton exchange, kicks off carbox. acid
3) HSO4- deprotonates resulting structure

Question 2

if excess acetic anhydride…

Answer 2

you get triacetate cellulose

Question 3

triacetate cellulose

Answer 3

hydrophobic polymer with no h-bonding

soluble in organic solvent

processed into film/fibers

Question 4

control properties of triacetate cellulose

Answer 4

by removing acetate groups

backhydrolyze with NaOH to get “free” OH

h-bonding reinstated, more hydrophilic

Question 5

properties that can be altered in triacetate cellulose

Answer 5

flame resistant

high MP

toughness

Question 6

degree of substitution for triacetate cellulose

Answer 6

<1 adhesives

1-2 plastics

2.2-2.7 lacquers, protective metal/glass/pipe coatings

3 fabrics (rayon acetate that is chem modified)

Question 7

end of use for triacetate cellulose

Answer 7

hydrolyze back to cellulose

biodegradable

Question 8

permanent press fabric

Answer 8

processed cellulose that is wrinkle-resistant

triacetate cellulose chains held together by Van der Waals

chains have a high degree of order, pack well, crystalline

Question 9

permanent press process

Answer 9

manufacturer adds high T to lock in a desired shape

when washed, less interaction w/ H2O, holds shape

Question 10

chemistry of wrinkles

Answer 10

cotton fabric absorbs H2O

competes w/ h-bonding between cellulose molecules

when dry, h-bonding in cellulose changes

new h-bonds form in a different arrangement

Question 11

chemistry of ironing

Answer 11

heat up fabric, molecules move around

set in desired shape (crease)

works better if fabric is damp b/c H2O acts as a plasticizer (more flexible)

when heat is removed, molecules stiffen and stop moving