Saurastra University 2006 M.Sc Computer Science Physical Chemistry : – VIII (Physical Chemistry of Polymers-II) - Question Paper

M. Sc. (Part–II) exam
April / May – 2006
Physical Chemistry : Paper – VIII
(Physical Chemistry of Polymers-II)
Time : three Hours] [Total Marks : 100
Instructions : (1) All ques. carry equal marks.
(2) Attempt 5 ques. in all.
(3) ques. one is compulsory.
1 ans the subsequent : (any four)
(a) describe :
(i) Dielectric constant
(ii) Glass transition temperature
(iii) Transparency
(iv) Chain expansion factor
(v) Poly dispersity.
(b) Classify methods of investigating physical structure of
materials.
(c) elaborate fibrillar crystals ? How are they made ?
(d) discuss the effect of tacticity and plasticizer on temperature
dependence of tan d .
(e) State the subsequent statements as actual or false. accurate it if
it is false :
(i) Osmotic pressure measurement is a colligative property.
(ii) Viscosity is a transport property
(iii) Degree of super cooling is not important during
crystallization.
(iv) Glass is a crystalline substance
(v) The chain expansion factor a is unity in q-state.
ST-2758] two [Contd...
(f) State different tests for determining softening temperature of
a provided polymer.
(g) What info can we find from IR and NMR spectra
of a substance ?
(h) elaborate virgin polymers ? provide brief account on compounding.
2 Write notes : (any three)
(a) Injection moulding
(b) Die casting
(c) Electron microscopy
(d) Partial dissolution technique
3 (a) State the Brag’s legal regulations and provide the significance of the terms
involved. discuss the determination of crystallinity. A
polyethylene sample crystallized from the melt at equllibrium
conditions after anealing gave the density value of 0.9420
g/cm3 at 20oC. The densities of corresponding pure crystalline
and amorphous specimen are 1.000 g/cc and 0.855 g/cc at
20oC respectively. compute the degree of crystallinity.
(b) explain the determination of h . Huggins and Kramer’s
constants Mv , Mark-Houwink constants K and a and chain
expansion factor a.
(c) provide brief account of endgroup analysis.
4 discuss :
(a) Strain-time diagrams of Maxwell and Kelvin-Voigt models.
(b) Frequency dependence of dielectric constant and loss
(c) Elastomer and fibers
(d) Principles of DSC and TGA with hypothetical thermograms
ST-2758] three [Contd...
5 (a) define the determination of S0 and D0 in sedimentation.
The sedimentation and diffusion coefficients of aqueous
solutions of insulin and hemoglobin at 20oC are found by
sedimentation technique. The data are.
For insulin : S = three five ´ 10- S 13 . , D = eight two ´ 10-7 . cm / s two ,
V = 0.75 cm / g three .
For Hemoglobin : S = four 4 ´10- S 13 . , D = six three ´ 10-7 . cm / s two ,
V = 0.75 cm / g three .
compute Mw of both the proteins.
(b) define number avg. molecular weight determination by
VPO.
(c) explain the determination of Mw by zimmand dissym. methods.
6 (a) explain the fractionation and determination of different kinds
of molecular weights by GPC.
(b) The subsequent GPC data of PMMA-THF system are found
at 25oC :
Retention quantity Recorder chart,
VR ml dN NiMi b g
130 0.50
135 6.00
140 25.70
145 44.5
150 42.0
155 25.6
160 8.9
165 2.2
Under identical condition, narrow distribution polystyrene
sample chromatrogrammed to find linear calibration curve
with M = 98000 eluting at 130 ml. and M = 1800 eluting at
165 ml. The calibration formula is VR = 230.64 - 20.16 log M.
compute Mn , Mw and
M
M
w
n
.
ST-2758] four [ 100 ]
7 (a) Derive Freeman Carroll relation for the determination of
kinetic parameters from a single heating rate TG thermogram.
(b) subsequent data are found for a compound from TGA by
single heating rate :
 l dw dt n / b g 0.0630, 0.0219, –0.0157, –0.0518, –0.0878,
–0.1239, –0.1588
 l w n 0.2334, 0.1936, 0.1601, 0.1316, 0.1072,
0.0858, 0.0670
By Freeman canol method, determine the value of order of
reaction (n) and Energy of activation graphically.
R = eight 314 JK-1 . e j.
(c) State various methods of determining molecular weights of
the polymers. Which method is more convinient and which
one is more labourious ?
There are 100 polymer molecules of molecular weight
103, 200 molecules of molecular weight 104 and 200 molecules
of molecular weight 105. compute Mw and Mn .

Earning:   Approval pending.