Indian Journal of ChemistryVol. 22A, March 1983, pp 229-230
Molar Volumes & Fluidities of SeedOils & Their Fatty
Acids
N ISLAM* & IMRAN AHMAD
Department of Chemistry, Aligarh Muslim University,Aligarh 202
001
Received 19 July 1982; revised and accepted 2 September 1982
The densities and viscosities of the seed oils of
Vernonia-anthelmintica (A), Leucas caphalotes (B), and those of
theircomponent fatty acids. viz. palmitic, oleic, stearic and
myristic.acids are measured over the temperature range 298-433
K.These data are least-squares-fitted to equations of relevance.The
Hildebrand equation seems to be better than that ofDoolittle in
explaining the data. The temperature dependenceof the energies of
activation is described by a parabolic-equation.
A number of attempts=+ have been made to explainthe flow
behaviour of a variety of organic liquids,which could be
categorised as simple or non-associatedand associated, either by
the two or three-parameterequation. In addition, the Hildebrand
equation- andthat based on the environmental relaxation model"were
also employed for the purpose. In view of thelimitations of
Hildebrand equation the suitability ofits modified" form,
... (1)
was demonstrated in the cases of highly viscous-organic liquids
and melts.
In this note the flow behaviour of highly viscousseed oils from
Vernonia anthelmintica (A) and Leucascephalotes (B) was examined.
The composition of thefatty acid components of the seed oils was
workedout earlier by Gunstone? and Osman and coworkers",
The seed oils (A) and (B) respectively fromV. anthelmintica and
L. cephalotes extracted by Osmanand coworkers" were used as liquids
while myristic(Koch Light), palmitic (Koch Light), stearic
(BOH).and oleic (Riedel) acids were used in the moltenform.
The densities and viscosities of the oils (A) and(B) and of
their fatty acid components were measuredat different. temperatures
with the help of a calibratedpyknometer (±O.02 %) and
Cannon-Ubbelohde visco-meter (viscometer constant, ~=O.023 cSt/see;
accuracy±O.l %), respectively, in a thermostated (accuracy±O.! %)
glycerol bath and the values are given inTable 1_ An examination of
Table ! reveals thatthough the densities of acids are in the
expectedrange, those of the two oils (A) and (B) are surpri-singly
large. These large values for oils (A) and (B)may be due to the
crowding of esters of the consti-tuent acids resulting in somewhat
compact arrange-ment. The temperature dependence of densities
is
Table I-Densities and Viscosities of Seed Oils (A) and (B)and of
Stearic Acid (C), Palmitic Acid (D), Oleic Acid (E) and
Myristic Acid (F) over 298.15-433.15 K
TK (A) (B) (C) (D) (E) (F)
Density (p, g m1-1)
298.15 4.7867 4.7718 0.8953303.15 4.7695 4.7540 0.8918313.15
4.7351 4.7185 0.8847323.15 4.7007 4.6830 0.8776333.15 4.6663 4.6475
0.8705 0.8619338.15 0.8557343.15 4.6319 4.6121 0.8521 0.8635
0.8548348.15 0.8491353.15 4.5975 4.5766 0.8455 0.8449 0.8564
0.8476363.15 4.5631 4.5411 0.8381 0.8377 0.8493 0.8404373.15 4.5287
4.5056 0.8308 0.8305 0.8422 0.8332383.15 4.4942 4.4701 08235 0.8233
0.8351 0.8261393.15 4.4598 4.4346 0.8162 0.8161 0.8281 0.8189403.15
4.4254 4.3991 0.8089 0.8089 0.8209 0.8118413.15 4.3910 4.3636
0.8016 0.8018 0.8139 0.8046423.15 4.3566 4.3281 0.7943 0.7945
0.8068 0.7975433.15 4.3222 0.7870 0.7874 0.7903
Viscosities ('I), poise)
298.15 1017.1 269.68 23.000303.15 507.09 230.60 19.116313.15
326.24 160.76 13.501323.15 216.64 110.55 10.208333.15 153.76 81.624
7.989 6.909338.15 8.197343.15 113.20 61.992 7.816 6.166 5.420348.15
8.314353.15 83.155 49.273 7.265 5.703 4.932 4.357363.15 70.275
39.250 5.745 4.599 4.069 3.566373.15 60.6212 31.980 4.636 3.733
3.386 2.963383.15 48,810 26.988 3.762 3.077 2.827 2.461393.15
40.538 22.806 3.144 2.577 2.455 2.089403.15 34.078 19.639 2.683
2.207 2.117 1.792413.15 32.570 .16.981 2,262 1.886 1.861
1.539423.15 29.109 15.211 1.964 1.634 1.642 1.329433.15 26.960
1.765 1.429 1.174
described by the empirical equation (Eq. 2).
p=a-bT(K) ... (2)
The values of parameters of Eq. (2) are given inTable 2. The
fluidities of the above samples showingnon-Arrhenius behaviour are
least-squares fitted tothe three-parameter Vogel-Tammann-Fulcher
equa-tion (Eq. 3)
rp=A+T-lj2 exp [-k+/(T- To)] ... (3)
and the best fit parameters are listed in Table 2.These
parameters have been employed to obtain theenergy of
activation,
E+=dlncP/d(I/T) ... (4)
The plots of E+ versus temperature being parabolic innature were
described by an empirical equation,
E~=p+qt+rt2 (Table 3) ... (5)
229
INDIAN J. CHEM., VOt: 22A, MARCH 1983
Table 2-Computed Parameters of Eq. 0), Eq. (6) and Eq. (3)over
the Temperature Range 298.15 to 433.15 K
System" Eq. No.
Parameters of the abovethree equations-------------- S.D.
(1): a bx 103(6): A'~ B~ Vo
(3): A", k", To4.8727 3.4406 0.96x 10-34.8605 3.5496 1.52 x
10-30.9039 0.7306 0.44 x 10-35.03 109.4 240.0 0.028.20 605.9 206.1
0.020.9025 0.7193 0,36 x 10-36.49 132.0 267.0 0.Q3
11.98 690.0 191.3 0.040.91303 0.7080 0.36x 10-37.43 167.2 283.4
0.Q39.5 690.0 173.9 0.060.9049 0.7161 0.35 x 10-3
11.52 190.6 286.7 0.0413.51 690.0 185.08 0.05
(A)(B)(C)
11163163163163
"Systems referred to in Table 1.
(D)
(E)
(F)
The molar volumes obtained from the density datawere employed in
least squares fitting the fluidity datato Doolittle equation.
Finally, the fluidity data wereleast squares fitted to the modified
Hildebrandequation" (Eq. 1) and the best fit Y~ values (Table
4)turned out to be very close to those obtained fromthe molar
volume versus temperature plots. Sucha fit also demonstrates that
the Hildebrand equationis equally suitable for the present systems
as n is veryclose to unity when the two equations approach
eachother. The deviations obtained in the logarithms of theobserved
fluidity and those calculated from the Hilde-brand and similarly
with those from the Doolittleequation (Eq. 6)
