Chapter 2 Flashcards
protein behavior
act as individual units
stress/force denatures and decreases performance
other polymer behavior
act in concert (entanglement)
stronger b/c entangled
many conformations/varied lengths
stress/force leads to inc. order and inc. strength
PEO Recap
H2O cross-links to inc hydrodynamic volume
chains straighten entropy decreases
acts as solid when cut strands recoil randomly
viscoelastic properties solid+ liquid
Newtonian fluid
viscosity remains constant independent of force
non-Newtonian fluid
viscosity changes when shear force is applied
makes molecules slide past each other
shear-thinning
viscosity decreases as shear force increases
chains detangle under force
ex. razor strip (PEO) low MW
shear-thickening
viscosity increases as shear force increases
chains tangle under force
ex. body armor
info about shear-thickening
polymer solns are colloid-made of tiny particles in liquid
particles slightly repel each other so flow easily w/o clumping
energy of sudden impact on shear thickening
overwhelms repulsive forces of colloid
particles stick together and act as solid
when force is removed, particles repel again
