Polymers 4

Question 1

what is a cationic polyelectrolyte

Answer 1

a polymer with positive charged groups (polybases)

Question 2

what is anionic polyelectrolyte

Answer 2

polymer with negative charged functional groups

Question 3

what is amphoteric polyelectrolyte

Answer 3

polymer with mixture of charged functional groups

Question 4

what is an example of polyampholytes

Answer 4

gelatin

proteins (BSA)

Question 5

what is the isoelectric point

Answer 5

IEP is the pH at which the effective net charge on a macromolecule is 0

Question 6

at what point do proteins precipitate at

Answer 6

proteins as typical polamphoyltes often precipitate at the isoelectric point thus we can see at what point the IEP is on a protein if we plot its pH and its turbidity

Question 7

if a polyampholyte is below its IEP

Answer 7

it is positively charged

Question 8

if a polyampholyte is above the IEP

Answer 8

it is negatively charged

Question 9

what is viscosity

Answer 9

measure of a materials resistance to flow

it is a result of the internal friction of the materials molecules

Question 10

what are the 4 conformation of macromolecules in solution

Answer 10

globule

statistical coil

rigid rod

helix

Question 11

what does the conformation depend on

Answer 11

chain flexibility and polymer solvent interactions

Question 12

in what form can viscosity not be measured

Answer 12

if a polymer precipitates from solution its viscosity cannot be measured

Question 13

what is rheology

Answer 13

rheology is the study of the flow and deformation of properties of matter

Question 14

what is shear rate

Answer 14

shear rate is the rate at which a progressive shearing deformation is applied to some material.

Question 15

what is shear rate proportional to

Answer 15

shear stress

Question 16

what is shear rate = to

Answer 16

applied stress divided by dynamic viscosity

Question 17

what are 3 non newtonian fluids

Answer 17

dilatant flow (tapers off at the end)

simple pseudoplastic flow (slow to start then goes straight)

Simple plastic flow (slow to start and finishes shorter than simple psuedoplastic flow)

Question 18

what is plastic flow associated with

Answer 18

presence of flocculated particles in concentrated suspension

Question 19

what is a flocculated particle

Answer 19

Flocculation is a two-step particle aggregation process in which a large number of small particles form a small number large flocs.

Question 20

when is psuedoplastic flow exhibited in polymers

Answer 20

typically exhibited by polymers in relatively concentrated solution

Question 21

when is dilitant flow exhibited

Answer 21

certain suspension with a high percentage of dispersed solids.

Question 22

what are some factors that effect viscosity of poylmer solutions

Answer 22

concentration of polymer in solution 
molecular weight of a polymer 
polymer solvent interactions 
temperature
charge of macromolecules
solution pH for weak polyelectrolytes
presence of small molecules in solution

Question 23

how does pH affect polyanion viscosity

Answer 23

reduced viscosity as PH increase

Question 24

how pH affect polycation viscosity

Answer 24

as pH increases more viscous

Question 25

how ph affect polyampholyte viscosity

Answer 25

viscous at IEP

Question 26

what are some properties of alginates

Answer 26

sodium and potassium alginates are soluble in water

spotaneously form physical gels upon contact with divalent metal ions

egg box structure between four g residues

Question 27

how does gaviscon work

Answer 27

works by forming a gel raft (thick layer) on top of the stomach contents soon after it has made contact with the stomach acid

raft acts as a strong physical barrier and helps keep all the components of the stpmach contents in the stomach where they work

not letting them seep back up into the oesophagus where they hurt

Question 28

what active ingredients does gaviscon advance contain

Answer 28

sodium alginate

sodium bicabonate

calcium carbonate