Week 13 Cellulose and its Derivatives

Question 1

CEllulose- material properties and bonding

Answer 1

• long chain polymers with a lot of _OH groups, which attract water through hydrogen bonding
  the chains also bond to eachother through h bonding
  this makes a rigid 70% crystalline structure, these features make it a useful polymer in nature

Question 2

Cellulose nitrate; process and history of production

Answer 2

Question 3

what happens when cellulose is nitrated, and what properties occur from this

Answer 3

the hydrogen is replaced with an NO2 group
How? this uses nitric acid, h2so4, giving hydrogen and oxygen to the hydrogen, producing water and no2 which joins onto the cellulose chain

the water produced needs to be removed with acid , maintaining the reaction process

Question 4

what is hydrolysis, and its reverse reaction

Answer 4

Question 5

why is the degree of substitution, or nitration, important in the production

Answer 5

• there is a maximum possible nitration, which would produce an explosive, trinitrate, or gun cotton
• a lower substitution level produces plastics, a slightly higher one, produces a stiffer polymer, and transparent lacquer used in nail polish
• higher again substitution produces films

Question 6

brittleness is a problem, how do we solve this in the production of plastics, and how does it work

Answer 6

source of decay in future, due to migration
migration leaves gaps for oxygen and moisture to get in
in the presence of acidity, better dissolution to form acid solution, or a higher level of oxidation because of increased oxygen (this is initiated by heat and light).

Question 7

past and current uses of cellulose nitrate. what technical properties make it an excellent adhesive

Answer 7

• waterproof aircraft wings- very stiff
• painted on textiles used for early biplane wings
  -imitation tortoise shell
• st cuthberts coffin

Question 8

examples of coatings containing cellulose nitrate

Answer 8

• lacquer for metal and paint
• produces very think high gloss finish

Question 9

stability of cellulose

Answer 9

• manufacturing; built in acidity, bad washing
• cellulose nitrate hydrolyses or becomes acid
• brittle and micro-cracking (paving effect)

Question 10

how does cellulose nitrate decay

Answer 10

heavily plasticiser, migration causes shrinkage and cracking

Question 11

thinking about a cinematic collection at a museum; what are the major concerns fro cellulose nitrate decay

Answer 11

• originally used for film, very unstable
• ferrous and ferric ions produces an acidic environment through hydrolysis
• produces a catalytic effect, speeding up decay of cellulose nitrate
• storage in or with metal is a big no no
• film copied/ moved to cellulose acetate

Question 12

how is cellulose acetate produced and what are its uses

Answer 12

both nitrate and acetate use sulphuric acid as a dehydrating agent (problematic if the manufacturing is bad)
acetic acid is very volatile, but less aggresive then nitric acid, an organic acid

Question 13

uses and decay of cellulose acetate

Answer 13

takes dyes differently, different finish
produces a thin film

Question 14

what is important to consider in the environment and display of cellulose nitrate

Answer 14

Question 15

what is regenerated cellulose

Answer 15

breaks down in burial after 2 months

Question 16

What are cellulose ethers, traditional uses

Answer 16

Family of polymers, can be modified to be water soluble.
Traditionally used in paper conservation or as sizes/ adhesives, or to bulk out paper.

Question 17

CEllulose ethers: structure

Answer 17

cellulose, wood derived, beta glucose units joined together between condensation reactions between two alcohols, three OH groups in ring structure. Compatible with water, absorbs moisture.

Is modified by producing these groups. Adding an aliphatic group C,H, produces ethyl cellulose, adding a carbon produces methyl cellulose. modifying the side group by adding alcohol produces hydroxyethyl cellulose

The length of the side chain can be variable.

Question 18

What do the modifications to cellulose to produce these new molecules cause, in terms of changes to properties

Answer 18

Ethyl cellulose: more hydrophobic, side chain not compatible with water. the longer you make it, the more hydrophobic

hyroxyethylcellulose: maintaining compatibility with water, added branching of chains, increasing viscosity and changing flow

Question 19

process of modifying cellulose into hydroxy cellulose ether

Answer 19

Question 20

with the structure of hydroxy cellulose ethers, what do you get by keeping the -OH groups

Answer 20

compatibility with water

Question 21

Good properties of cellulose ether

Answer 21

Question 22

what does using a combination of added side groups produce in terms of cellulose ether properties

Answer 22

match cellulose ethers to their solubility in water, using groups that ensure solubility and that decrease it.

Question 23

what is sodium carboxy methylcellulose (NaCMC)

Answer 23

Used before Cellulose ethers were introduced as consolidants, 30 yrs ago.

a carboxylic acid and sodium substitution,

can get disassociation of sodium in water, but its polarity makes it have good adhesive properties

Question 24

what does this nomenclature mean (cellulose ethers)

DS, MS, high DS, high MS

Answer 24

These influence properties like solubility and viscosity

Question 25

Uses of cellulose ether in conservation

Answer 25

paper adhesive; because paper is mostly cellulose

Question 26

Decay of cellulose ethers eg. Klucel

Answer 26

Question 27

(Feller and Wilt) evaluating cellulose ethers, ranked from most to least stable

Answer 27

small side chain- big side chain impacts stability