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Unformatted text preview: November 2, 2007 MSE 182 — Quiz 3 Name: Ke 18 pts 1. T rue/False 315's eme Lyotropic liquid crystals contain two components, usually water and surfactant False
Thermotropic liquid crystals undergo phase transitions as the composition is changed True
The melting point of a polymer is determined by the number of crosslinks per unit volume True
The degree of polymerization of polyethylene is higher than the degree of polymerization of nylon True DNA is an example of a biopolymer False
In “Polymer”, “Poly” means plastic, and “mer” means chemical True 24 pts 2. Polymer structures
a) Draw amorphous polymers with I) no, 11) some and 111) many cross-links. 3 P13 eack
II) 111) b) Draw a branched polymer 5st; 1%; c) Draw a diblock copolymer. Use capital letters to denote various monomers as we did in class. 5193 _, . AAAAA asses »~ d) Draw a random copolymer. Use capital letters to denote various monomers as we did in class. S'pt: BABAM MA a BM -~~ 24 pts 3. Draw schematic diagrams of the following: Hexagonal phase of a lyotropic liguid cgstal Lamellar base of a1 otro ic 1i uid c stal Nematic phase of a thermotropic liguid cgstal Smectic base of a thermotro ic 1i uid c stal
, \ \/ \ \ l \I \
I] /\ |\\\\/\
\ I // \“
/ 20 pts 4. Polymer structures
Here is the chemical structure of polyvinyl chloride (PVC): HCl ||
H H Given the following molecular weights: H=1
C1=35 a) If the molecular weight of the polymer is 50,000 g/mole, what is n (the degree of
polymerization) rounded to the nearest whole number? lowmw Hui @005” «gland macaw w 3’» aim n __ (30 M01 353 WM
. W (oi howl 16ch* 9““ b L \ =8oel b) If a C-C bond is 0.154 nm, how lon will the chain be if it is stretched to its maximum length?
Do not worry about bond angles.
4 r i 4 ' cn—IXCQ
a ,4 +010 +<H~N +n<¢fl D.» '
j c (H' A? ) > (Le’rgLA-‘bunk band) mac?“
re pct um g
.6 +0.: + $Oé-K0. :5‘1 T $03705“ ‘ Pp nﬂl “Hygng Let): (9.15nm
(,"N (M’i‘nm "e"
0--\_\ ~59. | nm
N “M 19] (um 14pts 5. What is the primary difference between thermoset and thermoplastic polymers? Thermoplastics are uncrosslinked polymers that ﬂow and melt with increasing temperature.
Thermosets are highly cross-linked polymers that maintain their shape with heating and will not
ﬂow or melt. ...
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- Fall '07