H
H
C
H
H
C
H
H
i
H
H
C C
H
H
H C C H
H H H H H H H H
H C C C C C C C C H
= H3C CH2 CH2 CH2 CH2 CH2 CH2 CH3

H H H H H H H H
H3C ( CH2 ) CH3
6
CH3
H3C CH CH2 CH CH3
CH2
CH3
Differentiate between polymorphism and isomerism.
f
)
Polymorphism is when two or more crystal structures are possible for a material of
given composition. Isomerism is when two or more polymer molecules or repeat units
have the same composition, but different atomic arrangements.
R
+
H H
H H
C C
R C C
free radical
H H
monomer
(ethylene)
H H
H H
H H H H
C C
R C C C C
H H
H H H H
R C C
H H
+
initiation
H H
propagation
dimer
H
C O O C
H
H
H
H
2
C O
H
=2R
-
탸
鵡硏
이중화iN
✓
.co.cr
•
✓
v
3중활다
쪄N
✓
o
total wt of polymer
Mn =
total # of molecules
M n = Sx i M i
M w = Sw i M i
weight
range
number of
students
mean
weight
Ni
Wi
mass (lb)
2
2
3
2
0
0
0
1
110
142
184
223
380
SNi
10
SNiWi
1881
mass (lb)
81-120
121-160
161-200
201-240
241-280
281-320
321-360
361-400
number
fraction
xi
0.2
0.2
0.3
0.2
0
0
0
0.1
weight
fraction
wi
NiWi
Ni
wi =
xi =
Ni
å NiWi
å0.117
0.150
0.294
0.237
2
0.000
x81-120 =
= 0.2
0.000
10
0.0002 x 110
w 81- 120
=
= 0.117
0.202
1881
mean
weight
mass (lb)
Wi
mass (lb)
81-120
121-160
161-200
201-240
241-280
281-320
321-360
361-400
110
142
184
223
380
number
fraction
xi
weight
fraction
wi
0.2
0.2
0.3
0.2
0
0
0
0.1
0.117
0.150
0.294
0.237
0.000
0.000
0.000
0.202
å x M = (0.2 x 110 + 0.2 x 142 + 0.3 x 184 + 0.2 x 223 + 0.1 x 380) = 188 lb
= å w M = (0.117 x 110 + 0.150 x 142 + 0.294 x 184
Mn =
Mw
weight
range
Mw =
i
i
i
i
å wM
i
i
= 218 lb
+ 0.237 x 223 + 0.202 x 380) = 218 lb
H H H H H H H H H H H H
H C C (C C ) C C C C C C C C H
H H H H H H H H H H H H
H
H H
H
C C
H
C C
R
H R
’
H R
or
C C
H H
H H H H H H H H
H H H R H H H R
C C C C C C C C
C C C C C C C C
H R H R H R H R
H R H H H R H H
뒤
냠
H H H H H R H H
C C C C C C C C
H R H R H H H R
CH3
CH2
H
C C
CH2
CH3
CH2
C C
CH2
H
,