PLMSE 406Practice Test 21. A polymer chain in the melt or in the rubbery state has an average end-to-enddistance that is proportional toa. Nb. N0.75c. N0.6d. N0.5e. N0.33where N is the number of units in the chain.2. Which of the following polymers would you expect to have the best barrierproperties (i.e., provide the best barrier to diffusion of a gas and hence prove mosteffective as a beverage container)?a. Atactic polystyreneb. A random ethylene/propylene copolymer (50/50) composition.c. Low density polyethylened. High density polyethylene3. Consider the following polymer crystal form:This is a schematic picture ofa. A spherulite.b. A fringed micelle.c. A single crystal lamellae.4. The material marked 3 isa. Folded chain crystals.b. Crystalline chains.c. Amorphous material.5. The thing labeled 2 isa. A fold.b. A randomly coiled chain.c. A tie molecule.6. Atactic polystyrene (Tg - 100°C) quenched (i.e., cooled very quickly) from 120°Cto room temperaturea. Is a rubbery material.b. Crystallizes.c. Is a glassy material.7. High density polyethylene cooled slowly from 160°C to room temperaturea. Is still amorphous.b. Crystallizes.c. Is a glass.d. Is a mixture where some regions are rubbery and some regions are glassy.8. When a single polymer chain is stretched the origin of the restoring force is relatedtoa. The entropy of chain conformations.b. The enthalpy of chain conformations.c. The degree of cross-linking.d. The elastic forces in each of the individual bonds in the chain.9. A polymer drawn from the melt usually formsa. Fringed micellesb. Single crystal lamellae.c. Spherulites.d. Extended chain fibers.10. Polyethylene and polypropylene (in the melt) willa. Form hydrogen bonds with one another.b. Interact strongly due to polar forces.c. Only interact weakly through dispersion forces.11. Which of the following polymers would you expect to be most suitable for theproduction of a rubber car bumper guard?a. Atactic polystyrene (Tg ~ 100°C)b. A random ethylene/propylene copolymer (50/50 composition) Tg ~ 40°C).c. Low density polyethylene.d. High density polyethylene.12. Which of the polymers in question 19 would be most suitable for use as a flexible filmwrap?13. What is the root mean square end-to-end distance of a chain of 100 freely hingedand jointed monomer units, each of which has a length of 4 Å?a. 200 Åb. 400 Åc. 20 Åd. 40 Åe. 100 2 Å14. If rotations around a bond in a polymer chain can take on any one of fourconformations (i.e. arrangements of the groups it is linking relative to one another),then for a polymer chain consisting of 1000 bonds there are the following numberof possible conformations;a. 41000b. 4 x 1000c. 10004d. 1000 x 4100015. Consider the two transitions from the “solid” to the liquid or rubbery state shownbelow on a plot of specific volume vs temperaturea. The transition X is a Tg while transition Y is a crystalline melting point.b. Y is the Tg while X is the Tm.c. Both X and Y are melting points, but X is the Tm of a semi-crystallinematerial and Y is the Tm of an almost perfect crystal. yxVsT16. A fringed micelle isa. An exotic form of nightware that can be purchased at Victoria’s Secret.b. A model for polymer crystals where polymer chains have parts ofthemselves in crystal domains and parts in amorphous regions.c. A sphere shaped crystal form obtained by cooling from the melt.d. A flat lozenge shape crystal obtained from dilute solutions17. Polymer crystalline in a folded chain form becausea. This is the shape that minimizes the free energy, because folds are created.b. Extended chain crystals have a lower free energy, but the probability offorming the first nuclei with fully stretched out chains is vanishingly small.Therefore folded chain nuclei are formed first and become kineticallytrapped.c. Extended chain crystals have a higher free energy because there are lessfolds and therefore stronger interactions between the segments in thecrystals. Again the folded chain form becomes kinetically trapped.18. Consider the following polymersWhich of these will have the highest Tg?19. Which will have the lowest? (A-D of previous question) A.B.C.D.CHCH2ClCH2CH2CHCH2CH3CH2CH2O20.A) Weaker intermolecular attractionsB) Free Volume effectsC) the stiffness of the side chain Poly n-butyl acrylatebecause ofhas a lower Tg than