Chapter 2

Question 1

protein behavior

Answer 1

act as individual units

stress/force denatures and decreases performance

Question 2

other polymer behavior

Answer 2

act in concert (entanglement)

stronger b/c entangled

many conformations/varied lengths

stress/force leads to inc. order and inc. strength

Question 3

PEO Recap

Answer 3

H2O cross-links to inc hydrodynamic volume

chains straighten entropy decreases

acts as solid when cut strands recoil randomly

viscoelastic properties solid+ liquid

Question 4

Newtonian fluid

Answer 4

viscosity remains constant independent of force

Question 5

non-Newtonian fluid

Answer 5

viscosity changes when shear force is applied

makes molecules slide past each other

Question 6

shear-thinning

Answer 6

viscosity decreases as shear force increases

chains detangle under force

ex. razor strip (PEO) low MW

Question 7

shear-thickening

Answer 7

viscosity increases as shear force increases

chains tangle under force

ex. body armor

Question 8

info about shear-thickening

Answer 8

polymer solns are colloid-made of tiny particles in liquid

particles slightly repel each other so flow easily w/o clumping

Question 9

energy of sudden impact on shear thickening

Answer 9

overwhelms repulsive forces of colloid

particles stick together and act as solid

when force is removed, particles repel again