Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014.
Chapter 2
PU Coatings Based on Neem Oil Fatty Amide and IPDI Trimers
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 29
PU Coatings Based on Neem Oil Fatty Amide and IPDI Trimers
ABSTRACT
This chapter shows an entirely new application of Azadirachta indica juss
(neem oil) i. e. the preparation of polymeric resin from it. In the regards, we have
attempted to synthesize the neem seed oil based poly (urethane fatty amide) by reaction
of neem oil fatty amide (AIJFA) with trimer of isophorone diisocyanate (IPDI).
Initially fatty acid composition of neem seed oil was obtained by gas chromatographic
(GC) method and then we synthesized AIJFA. Spectral study of synthesized AIJFA
was done by FT-IR and 1H NMR techniques. Molecular weight of AIJFA was
determined by gel permeation chromatography (GPC). The prepared polyurethane was
applied as a coating on mild steel plates and evaluated for its coating performance,
chemical and corrosion resistances.
N
N
N
O
OO
OCN
NCOOCN
CH2
N
CH2
CH2
OH
CH2
OH
C
O
R
OCO CH2
CH2
N
CH2
CH2
C R
O
OCNH
O
NH OC
O
CH2
CH2
N
CH2
CH2
C R
NH
N
N
N
O
OONHCO
O
CH2
N
CH2
CH2
CH2
O
C
O
R
C
O
NH
O
OCNH
O
+
Trimer of IPDIAIJFA
Polyurethane
Published in Progress in Organic Coatings (2013) 76, 1779-1785
(Impact Factor - 2.43)
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 30
INTRODUCTION
Now day’s natural feed stock of fossil fuel is reducing continuously and due to
this, there is emergent interest in developing new feed stocks to prepare polymers. [1-3]
For preparation of polymers, renewable resources such as cellulose, carbohydrates,
polysaccharides, starch, fatty acids and vegetable oils have been focused in the
literature. [4-8] Amongst all of these, vegetable oil is having more importance in
polymer sectors by considering the sustainable energy resource and easy availability.
Vegetable oils such as linseed, tall, palm, nahar, cotton, jatropa, karanja, tung and
castor oils were used to prepare the polymeric resins according to their characteristic
properties. [9-13] Tons of vegetable oils are having their uses as renewable raw
materials for other industrially important chemicals such as soaps, surfactants, cosmetic
products, lubricants, inks, diluents, plasticizers, agrochemicals, food industry,
composite materials, etc. [14-16] In addition to this, vegetable oils have also been used
for decades in paint formulations and as binders for different types of coatings. The
most important parameters influencing on properties of oil based coatings are their
composition with respect to presence of fatty acids of different saturated and
unsaturated types, degree of unsaturations, the position and stereochemistry of the
double bonds and extent of oil content. [17] Types of binders used in coatings and
prepared from vegetable oils include alkyds, diethanolamides, polyesteramides,
polyetheramides and polyurethanes (PU). [18] In addition to above mentioned
applications of oil based polymers, PU are also having incredible significant
applications for adhesives, elastomers and foams. [19] For the preparation of PU,
vegetable oil need to convert into hydroxyl terminated polyols by chemical
modification or reaction on triglyceride molecules.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 31
Numbers of experimental reports are available in the literature for conversion of
vegetable oils into polyols by chemical modifications such as ozonolysis, [20]
epoxidation, [21, 22] hydroformylation, [23] esterification [24] and amidation. [25] PU
obtained from vegetable oils (e. g. castor oil) and copolymers of them with styrene,
methyl methacrylates and other monomers have noticed with much attention over the
last decades due to their remarkable properties. [26] Preparation of epoxidized plant
oils (canola, sunflower, soybean, linseed and corn) were also used to prepare polyols
[27, 28] Meshram et al developed the polyetheramide resin from cottonseed oil and
utilized it in moisture curing coatings after reacting it with TDI and shown cottonseed
oil is a good source of renewable material for preparing high performance coatings.
[29] Oils have also been reported for preparation of PU coatings by Gite et al from the
combination of monoglycerides (dehydrated castor, linseed, soybean and sesame oils)
with trimer of isophorone diisocyanate (IPDI). [30] The overall study shown that the
PU prepared from the four monoglycerides and IPDI trimer exibited significant
enhancement and have a strong potential to be used in the application as binder for
surface coatings.
Azadirachta indica juss (neem oil) is present in plentiful amount with annual
production rate of 88, 400 tons in the India and the Indian continent. Neem seed
contains 33 - 38 % oil, which possesses total five fatty acids such as palmitic, stearic,
arachidic, oleic and linoleic acids. However their application in the preparation of
polymer is not studied and majority of the earlier applications of neem seed oil reported
are in agrochemical [31] and pharmaceutical [32] sectors. In other application of neem
tree, Peter et al investigated use of tree extracts as corrosion inhibitors and found high
inhibition efficiency to the surface of metal from corrosion comparing with root and
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 32
leaf extracts of it. [34] Chaudhari et al first time reported preparation of polymeric
resins from neem oil. [33]
This chapter represents development of the poly (urethane fatty amides) from
neem oil by reaction of its fatty amide with trimer of IPDI. Initially, we have prepared
neem oil fatty amides (AIJFA) by the reaction of neem oil with diethanol amine. The
prepared AIJFA was treated with laboratory synthesized and commercially obtained
IPDI trimers for the preparation of PU coatings. All the prepared PU coatings were
tested for their coating properties by standard experimental methods. Use of neem oil
in the development of PU coatings may definitely show environmental rewards like
declination in the requirement of fossil or petroleum resources and configuration of
very low greenhouse gas emission. The prepared PU coatings by this route may be
suitable for maintenance coatings for petrochemical refineries and tank linings in the
future.
EXPERIMENTAL
Materials and Methods
Neem (Azadirachta indica) seed oil was obtained from local supplier and
subjected for its characterization such as specific gravity, refractive index,
saponification and iodine values. These values of neem oil were matched with the
standard values and therefore it was used without any further chemical modification.
IPDI was purchased from Merk, Germany and used as such for the synthesis of its
trimer. Commercial IPDI trimer was purchased from Bayer Material Science, Mumbai
and characterized for its isocyanate content by ASTM D-2572-97 before use.
Laboratory grade dibutyltin dilaurate (DBTDL) was purchased from Aldrich
Chemicals, UK. Cylcohexanone, tetrahydrofuran (THF) and diethanolamine of
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 33
analytical grade were obtained from SDFCL, India. Remaining chemicals and solvents
used for synthesis or analysis were of either synthesis or of analytical grade as per their
need.
Synthesis of Azadirachta indica juss Fatty Amides (AIJFA)
AIJFA was synthesized by the base-catalyzed amidation of neem seed oil with
diethanolamine as shown in Figure 1. In the experimental process three-necked round
bottom flask of 500 mL capacity was used. Diethanolamine (0.3 mol, 31.8 g) and
sodium methoxide (0.05 %) based on an amount of oil were introduced in the flask and
heated with agitation by a over head motor stirrer at temperature of 80 0C for 20 min.
After maintaining inert atmosphere (purging of N2 gas for 20 min), the assembly was
immersed in an oil bath having arrangement of temperature controller. Neem seed oil
(0.1 mol, 90.4 g) was added drop-wise into the reaction mixture over a period of 60 min
with gradual increase in temperature to 120 0C and continued for next three hours under
constant agitation. The formation of product was tested by two ways viz. checking
solubility of the reaction mass in methanol and determining amine value. Completion
of reaction was confirmed by the complete solubility of reaction mass in methanol and
or the amine value near to zero. The obtained product was dissolved in a solvent
diethyl ether and washed with 15 % aqueous NaCl (salt) solution.
R
C
N
O
OHOHO
O
C R'
C R'''
O C R''
O
O
O
NaOCH3
120 0C
OH
OH
OHN
OHOH
H
+ +
Neem oil Diethanol amine GlycerolGlycerol
AIJFA
3 3
Where, R', R'' and R''' = Fatty acid chain R = R', R'' and R'''
Figure 1: Reaction for Synthesis of AIJFA
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 34
The upper organic ethereal layer containing product AIJFA was separated from
aqueous layer by separating funnel. The trace amount of solvent present in AIJFA was
evaporated in a rotary vacuum evaporator.
Synthesis of IPDI Trimer
General structure of trimer and the reaction for trimerization of IPDI is as
shown in Figure 2. For the trimerization of IPDI, the catalyst choline hydroxide was
synthesized in the laboratory according to the method reported in the literature. [35]
Trimerization reaction of IPDI was carried in a three-necked round bottom flask
equipped with thermometer, dropping funnel, mechanical stirrer, condenser, nitrogen
purging system and maintained at 75- 80 0C in an oil bath. Catalyst was added drop-
wise in to the round bottom flask containing IPDI. The reaction was continued for next
5-7 h until the isocyanate content of the reaction mixture reach to half of the initial
value. At last catalyst deactivation was carried out by adding appropriate quantity of p-
toluene sulphonic acid.
N
N
N
O
OO
OCN
NCOOCN
OCN NCO
Trimer of IPDI
3Cholin hydroxide
75 0C
IPDI
Figure 2: Synthesis of IPDI trimer
Preparation of PU Coatings
The general reaction for the preparation of PU is given in Figure 3. The
prepared neem oil based AIJFA was reacted with IPDI trimer by varying an NCO/OH
ratio (1:1, 1.1:1 and 1.2:1). Mixture of cyclohexanone and THF (80:20) was mixed
with AIJFA (1 mole) to obtain required solid content (50 %) solution of AIJFA.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 35
Initially DBTDL (0.05 %) as a catalyst was added to AIJFA part in order to control the
rate of urethane formation. Then appropriate amount of trimer was added to the 50 %
solid AIJFA solution. The reaction mixture was stirred for next 5 min at 27 0C
temperature to attain pourable viscosity. After attaining pourable viscosity, the mixture
was used to prepare coating samples using bar applicator (Raj Scientific Company,
Mumbai, India) with a wet film thickness of 120 µm on MS panels of 4 × 6 inch
dimensions. Different PU coated samples were prepared by changing the ratios of
NCO/OH as mentioned earlier. The prepared coating panels were allowed to cure at
room temperature under visual examination, until the coatings were dry to touch.
Before application of the coatings, steel panels were pretreated with sand paper,
washed with acetone and dried in an air-circulated oven.
N
N
N
O
OO
OCN
NCOOCN
CH2
N
CH2
CH2
OH
CH2
OH
C
O
R
OCO CH2
CH2
N
CH2
CH2
C R
O
OCNH
O
NH OC
O
CH2
CH2
N
CH2
CH2
C R
NH
N
N
N
O
OONHCO
O
CH2
N
CH2
CH2
CH2
O
C
O
R
C
O
NH
O
OCNH
O
+
Trimer of IPDIAIJFA
Polyurethane
Figure 3: Preparation of PU Coatings
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 36
CHARACTERIZATION
Characterization of Raw Materials
Oil was characterized by the standard experimental methods such as specific
gravity (ASTM D5355-95), refractive index (ASTM D1747-09), saponification value
(ASTM D464-05), acid value (ASTM D5768-02) and iodine value (ASTM D-5768-
02). The fatty acid composition of neem oil was determined by gas chromatography
(GC) using methyl esters of it. Neem oil fatty acid methyl esters (FAME) were
prepared by refluxing neem oil in a dry methanol in the presence of sodium methoxide
as a catalyst. Analysis of FAME was carried on gas chromatography (GC) (Shimadzu
GC-14B) having specially designed program for oven temperature starting from 180 to
250 0C, injection temperature 230
0C, column (Restek, Rtx-Wax) and FID detector.
Isocyanate content of the synthesized IPDI trimer was determined by the n-butyl amine
method as per ASTM D-2572-97 standards. The hydroxyl value of neem oil and
AIJFA was determined by acetylating reagent method as per experimental procedure
recommended by ISI: 354 (1987) and amine value was determined by IS 354 (Part-5),
1986.
Gel Permeation Chromatography (GPC)
Molecular weights of AIJFA were measured by a gel permeation
chromatography (GPC) with Agilent GPC-Addon Rev A02.02 series HPLC system.
The experimental conditions required an injection volume upto 20 μL and flow 1
mL/min using a column PL-Gel Agilent with RI detector and tetrahydrofuran as a
solvent.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 37
Fourier Transfer Infrared (FT-IR) Spectroscopy
The FT-IR spectra were scanned 50 times on a FT-IR spectrometer (Perkin-
Elemer 2000 FTIR spectrometer) in the range of 4000 to 500 cm-1
by making the
pellets of AIJFA using KBr.
1H NMR Analysis
The 1H NMR measurements were performed on a
1H NMR spectrometer
(Varian Mercury 300 MHz spectrometer). The reported chemical shifts were against
tetramethyl silane (TMS) and deuteriated chloroform (CDCl3) as a solvent.
Thermal Analysis of PU Coatings
Thermal analysis of the prepared PU coating samples was performed in a
Mettler Toledo TGA/SDTA- 85 instruments in the range of 40-700 0C. Samples (about
2 mg) were placed in a platinum pan and heated under N2 atmosphere (20 mL/min) at a
heating rate of 10 0C/min. During the heating, the weight loss versus temperature curve
was recorded and analysed further.
PU Coatings Characterizations
Gloss
Gloss measurement is important for finding the capacity of a surface or coating
to reflect light. Precautions taken during the measurement in such a way that the
coated samples should not contaminated by any chemical or oil. A digital gloss meter
(Model BYK Additive & Instruments, Germany) was kept on the coated samples with
on auto calibration mode at an angle of 60 0 after calibration of it as per the procedure
given by the manufacture.
Flexibility
Flexibility of film or coating is measured to check the ability of the coatings for
elongation under bent condition or it is test that gives tolerance of the coatings against
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 38
cracking when elongated. The flexibility of the coated samples was performed on a
conical mandrel instrument (Raj Scientific Company, Mumbai). While performing the
test, mandrel was freed to rotate on its axis and then coated sample was kept in between
the rotating axis. The handle of conical mandrel was lowered in a vertical direction to
obtain specific angles.
Pencil Hardness
To determine the hardness of polymeric coating films, pencil hardness
measurements is essential. The pencil hardness of the coating was measured by using
a pencil hardness tester (Model BYK Additive & Instruments, Germany). In this test
pencils having different grades were used to move over the surface of the coated panels
from the distance of 6 mm at fixed 45 0 by using a standard holder. The force were
applied on the pencil and moved over the surface of the test sample at a fixed angle.
The coated panels were checked for the removal of the film. The same procedure was
repeated with pencil of higher grades of hardness until the film is scratched or
penetrated. The pencil which does not remove the coating denoted the pencil hardness
of the particular coating.
Cross Cut Adhesion
In this test a cross cut adhesion tester consisting of a die with 11 number of
closed set of parallel blades was passed and pressed on the coated panel in two
directions at right angle to each other so that the lattice of 100 squares of 1 mm2 area
each were formed. The adhesion tape was placed at the centre over of lattice pattern
made on the panel. After 5 min, self adhesive tape was removed by pulling it steadily
in 2 seconds at an angle close to 60 0. Then the sample was examined carefully with
the help of magnifier to determine the percentage of cubes remained on the coating
panel.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 39
Scratch Resistance
Scratch hardness of the coated panel studied by a ‘Automatic Scratch Tester’,
(Rajdhani Pvt. Ltd., India).
Impact Resistance
The impact resistance test of the prepared coatings was carried out for
evaluating the load carrying capacity of them. During this test the dried PU coating
panels were placed on hock properly and movable weighted indenter (1.818 lb) was
lifted from the certain height starting from 0 - 40 inch until the film cracked. After
falling the weighted indenter peeling, cracking and film detachment from the coated
substrate was examined. If there are any cracks on coatings test is considered as failed
otherwise it is passed.
Mar Resistance
The mar resistance of the prepared PU coating was evaluated in the laboratory
using a mar resistance tester of BYK Instruments, Mumbai. Mar resistance is express
in gram, the term of load that fails to spoil the coating film.
Chemical Resistance and Anticorrosive Properties
The chemical resistance of sample was measured by dipping the coated panel in
alkali solutions (10 % NaOH and 10 % NH4OH), acid solutions (25 % H2SO4 and 25%
CH3COOH) and xylene as a solvent for 7 days. Periodic visual inspection was taken
for 7 days to find any evidence of softening, deterioration or development of cracks.
Anticorrosion properties of the prepared PU coatings were also evaluated
through immersion studies and compared coated (crossed and uncrossed) and uncoated
steel panels with each other. The crossed panels were obtained by crossing panels with
sharp razor blade. Immersion study of these coatings was carried out in an aqueous
solution of NaCl (3.5 wt. %). The sample panels were tested for a total exposure time
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 40
of 144 h and further extend to 192 h. The panels were continuously monitored time to
time by visual inspections and recorded using a digital camera (Sony, 16 mega pixels).
RESULTS AND DISCUSSION
Characterization of Raw Materials
The chemical analysis of neem oil and AIJFA is furnished in Table 1. The
isocyanate content of the synthesized trimer of IPDI was found to be 15.60 %.
Molecular weight of the AIJFA was measured by GPC and it was found to be 520
( , weight average) and 431 ( , Number average) with polydispersity index (PDI)
of 1.20. The amine value of AIJFA was found to be 0.37 indicated almost all
secondary amines present in diethanol amine have been converted into amide groups
during formation of the AIJFA.
Table 1: Chemical Analysis of Neem Oil and AIJFA
Properties
Specific
gravity
@ 30 0C
Refractive
index @
40 0C
Acid
value
(mg of
KOH/g)
OH value
(mg of
KOH/g)
Iodine
value (g of
I2/ 100g)
Amine
value (mg
of KOH/g)
Neem oil 0.920 1.503 0.5 0.0 64.55 0.0
AIJFA 0.927 1.542 0.6 205 59.82 0.37
Fatty Acid Composition of Neem Oil
Table 2 is representing the composition of fatty acids for the utilized neem oil
which was determined by GC. Total five fatty acids were found in the gas
chromatogram of neem oil FAME. These fatty acids included palmitic, stearic and
arachidic acids as saturated fatty acids, while oleic and linoleic acids as unsaturated
fatty acids. The obtained qualitative and quantitative fatty acid composition of the
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 41
neem oil (utilized in preparation of PU coatings) is in agreement with the values
available in the literature. [36]
Table 2: Composition of Fatty Acids in Neem Oil
Name of fatty
acids Structure
Composition % by
weight
Oleic acid
50.04
Stearic acid
29.96
Palmitic acid
11.90
Linoleic acid
05.15
Arachidic acid
02.94
FT-IR Spectroscopy
400600800120016002000280036001/cm
10
20
30
40
50
60
70
80
90
100
110%T
34
87
.42
29
41
.54
28
37
.38
23
26
.23
16
45
.33
15
43
.10
14
60
.16
14
19
.66
13
61
.79
13
00
.07
10
64
.74
93
5.5
1
86
6.0
7
Viscous
Figure 4: FT-IR Spectrum of AIJFA of Neem Oil
The results of FT-IR analysis of AIJFA is represented in Figure 4. FT-IR
spectra of AIJFA showed the absorption broad band at 3487 cm-1
for presence of OH
stretching. Absorption bands at 2837 and 2941 cm-1
were attributed to symmetrical and
asymmetrical stretching’s of –CH2 and –CH3 groups respectively. The characteristic
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 42
band at 1645 cm-1
indicated the presence of C=O stretching of amide carbonyl groups.
Presence of absorption bands at 1361 and 1460 cm-1
in the FT-IR spectra revealed the
CH2– bending vibrations and band at 1300 cm-1
was a result of C–O stretching. The
medium absorption band at 1250 cm-1
was assigned to presence of C–N stretching in
AIJFA. Overall result showed absence of –COOH group and appearance of >N–C=O
group which confirmed the formation of AIJFA.
1H NMR Analysis
Figure 5: 1H
NMR of AIJFA of Neem Oil
1H
NMR spectrum of AIJFA (Figure 5) showed the peak at 0.88 - 0.9 ppm of
terminal CH3 group of fatty acid chain, 2.04 -2.06 ppm for –CH2–C= and 2.37 - 2.41
ppm for –CH2–C=O protons. It also showed peak at 1.27 ppm for presence of protons
of –CH2– in fatty acid chain. The protons of –CH2 attached to amide nitrogen appeared
at 2.86 - 2.97 ppm, while –CH2– attached to –OH occurred at 3.71-3.88 ppm and
alcoholic –OH at 5.24 ppm. For C=C–H proton of fatty acid chain was observed at
5.43 ppm. The results of 1H
NMR spectra confirmed the proposed structure of neem oil
fatty amide.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 43
Thermal Analysis (TGA)
Figure 6: TGA Curve of AIJFA Based PU Coatings
Initially the TGA curve (Figure 6) of polyurethane coating sample showed
about 4 % of weight loss at 200 0C that may be due to entrapped moisture and solvent
moiety. Then it went through three steps degradation. The first step occurred with 17
% of weight loss at 300 0C, the second with 37 % of weight loss at 420
0C and the last
with 30 % of weight loss at 600 0C. Normally it is observed that decomposition of
urethane bond starts between 150 and 200 0C depending on the type of substituent like
isocyanate and polyol as reported in the literature. [37] In our case urethane bond
decomposition started at higher temperature range than mentioned in the literature
revealed higher thermal stability of urethane linkage. Second and last decomposition
step corresponded to decomposition of amide and hydrocarbon chains. Thermal
stability of neem oil based fatty amide and trimers of IPDI based PU system is higher
in comparison to urethane fatty amide of linseed oil. [10] (27.7 wt % at 260 0C, 21.11
wt% at 360 0C and 40.62 wt% at 505
0C), alkyd and uralkyd (10 wt % at 95.4
0C, 20 wt
% at 147.6 0C and 50 wt % at 367.12
0C). Cross-linked structure of polyurethanes
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 44
synthesized from trimers of IPDI and presence of isocyanurate heterocyclic ring may
also be responsible for higher thermal stability.
PU Coating Properties
The coating properties tested for the prepared PU coated samples include dry to
touch, gloss, scratch resistance, mar resistance, pencil hardness, impact resistance,
flexibility and cross cut adhesion. These coating properties are furnished in Table 3a
and 3b.
Table 3a: Coatings Properties of PU from AIJFA and Synthesized IPDI Trimer
Sr. No. Samples/ Property
PU coatings with
ratio of NCO/OH
1:1 1.1:1 1.2:1
1) Cross cut adhesion (%) 99 100 100
2) Gloss 94.3 98.1 93.9
3) Mar resistance (g) 100 130 110
4) Impact resistance (lb.inch) 33 44 40
5) Pencil hardness 1H 1H 1H
6) Flexibility at 180 0 Pass Pass Pass
7) Scratch resistance (Kg) 3.5 4 4
8) Dry to touch (h) 40 32 38
Table 3b: Coatings Properties of PU from AIJFA and Commercial IPDI Trimer
Sr. No. Samples/ Property
PU Coatings with
ratio of NCO/OH
1:1 1.1:1 1.2:1
1) Cross cut Adhesion (%) 99 100 100
2) Gloss 96.3 99.6 98.9
3) Mar resistance (g) 110 140 120
4) Impact resistance (lb.inch) 33 43 40
5) Pencil hardness 1H 1H 1H
6) Flexibility at 180 0 Pass Pass Pass
7) Scratch resistance (Kg) 3.5 4 4
8) Dry to touch (h) 40 26 38
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 45
Gloss of the PU samples of ratio 1.1:1 (NCO/OH) was found better for both
types of PU coatings. The flexibility of all prepared samples of PU coatings were
excellent with adhesion (measured by pencil hardness tester) of 1H. Mar, scratch and
impact resistances of the synthesized IPDI trimer based PU coating prepared from same
ratio were found to be higher compared with samples prepared from other ratios.
Similarly properties of the coatings prepared from commercial IPDI trimer based PU
coatings were also higher than the samples prepared from other ratios. It concludes that
the PU coatings were almost similar for synthesized as well as commercial IPDI trimer
and 1.1:1 NCO/OH ratio was the best amongst all three.
Corrosion Resistance of PU Coatings
It has been noticed that no significant change in the physical appearance of the
PU coating samples was found after exposing them to acids, alkalis and solvent. In
H2SO4, specimens upto some extent became deteriorated and showed slightly loss in
gloss when dried. Corrosion properties of the PU coated, uncoated and cross-cut
coated panels were done by immersion of the panels in an aqueous solution of NaCl
(3.5 wt. %) for 144 h (6 days). The results of study are shown in Figure 7. The panel
without PU coating quickly corroded within 144 h, while slight corrosion was observed
to the cross-cut coated panel even though the metal surface exposed to a salt solution.
It has been found that coated panels were free from corrosion and blister even after 144
h. After achieving excellent results from the immersion study of AIJFA based PU
coatings after 144 h, we extended the test upto 192 h and we found no cracking or any
physical damage to coated panels and only little deterioration was observed to cross-cut
film. Good corrosion resistance to the PU coatings may be due to the presence of
excellent adhesion of coatings with the substrate (as reported by cross cut adhesion in
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 46
earlier part of the report). This study conclusively revealed the presence of extensive
corrosion resistance to the AIJFA based PU coatings in salt solution.
Figure 7: Anticorrosive Test of the Prepared PU Coatings
CONCLUSIONS
The Azadirachta indica juss (neem oil) based fatty amide has been prepared and
characterized by physical properties as well as by spectroscopic techniques. Further,
AIJFA was used as a polyol in the preparation of the PU coatings. The impact
resistance, flexibility and adhesion test showed excellent results for the prepared PU
coatings. The results also showed that the polyurethanes prepared from AIJFA and
trimers of IPDI were of similar coating properties and chemical resistance in
comparision with commercial IPDI trimer based PU coatings. Thermal stability of
AIJFA based PU coatings was also better over normal urethane and alkyd coatings.
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Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 47
From this study it can be concluded that the neem seed oil is one of the important
renewable material for the synthesis of PU to be used for the application in coatings.
REFERENCES
1. Meier M. A. R., Metzger J. O., Schubert U. S., Plant Oil Renewable Resources as
Green Alternatives in Polymer Science, Chem. Soc. Rev. 2007, 36, 1788–1802.
2. Gandini A., Polymers from Renewable Resources: A Challenge for the Future of
Macromolecular Materials, Macromolecules 2008, 41, 9491–9504.
3. Guner S. F., YagcI Y., Erciyes T. A., Polymers from Triglyceride Oils, Prog.
Polym. Sci. 2006, 31, 633–670.
4. Montero E. L., Meier M. A. R., Plant Oils: The Perfect Renewable Resource for
Polymer Science, Eur. Polym. J. 2011, 47, 837–852.
5. Galia M., de Espinosa L. M., Ronda J. C., Lligadas G., Cadiz V., Vegetable Oil-
Based Thermosetting Polymers, Eur. J. Lipid Sci. Technol. 2010, 112, 87–96.
6. Lligadas G., Ronda J. C., Galia M., Cadiz V., Plant Oils as Platform Chemicals for
Polyurethane Synthesis: Current State-of-the-Art, Biomacromolecules 2010, 11,
2825–2835.
7. Gonzalez-Paz R. J., Lluch C., Lligadas G., Ronda J. C., Galia M., Cadiz V., A
Green Approach Toward Oleic and Undecylenic Acid-Derived Polyurethanes, J.
Polym. Sci., Part A: Polym. Chem. 2011, 49, 2407–2416.
8. Anand A., Kulkarni R. D., Gite V. V., Preparation and Properties of Eco-friendly
Two Pack PU Coatings Based on Renewable Source (Sorbitol) and Its Property
Improvement by Nano ZnO, Prog. Org. Coat. 2012, 74, 764–767.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 48
9. Shende P. G., Dabhade S. B., Phalke Y. D., Preparation and Characterization of
Linseed Oil Modified Polyesteramide Resins for Surface Coatings, Pigm. Resin.
Technol. 2004, 33, 85–90.
10. Yadav S., Zafar F., Hasnat A., Ahmad S., Poly (urethane fatty amide) Resin from
Linseed Oil-A Renewable Resource, Prog. Org. Coat. 2009, 64, 27–32.
11. Dutta N., Karak N., Dolui S. K., Synthesis and Characterization of Polyester Resin
Based on Nahar Seed Oil, Prog. Org. Coat. 2004, 49, 146–152.
12. Meshram P. D., Puri R. G., Patil A. L., Gite V. V., Synthesis and Characterization
of Modified Cottonseed Oil Based Polyesteramide for Coating Applications, Prog.
Org. Coat. 2013, 76, 1144–1150.
13. Mutlu H., Meier M. A. R., Castor Oil as a Renewable Resource for the Chemical
Industry, Eur. J. Lipid Sci. Technol. 2010, 112, 10–17.
14. Khot S. N., Lascala J. J., Can E., Morye S. S., Williams G. I., Palmese G. R.,
Kusefoglu S. H., Wool R. P., Development and Application of Triglyceride-Based
Polymers and Composites, J. Appl. Polym. Sci. 2001, 82, 703–723.
15. Pelletier H., Gandini A., Preparation of Acrylated and Urethanated
Triacylglycerols, Eur. J. Lipid Sci. 2006, 108, 411-420.
16. Derksen J. T. P., Cuperus F. P. Kolster P., Renewable Resources in Coatings
Technology: A Review, Prog. Org. Coat. 1996, 27, 45–53.
17. Sperling L. H., Manson J. A., Interpenetrating Polymer Networks from Triglyceride
Oils Containing Special Functional Groups: A Brief Review, J. Am. Oil. Chem.
Soc. 1983, 60, 1887–1892.
18. Chaudhari A. B., Tatita P. D., Hedaoo R. K., Kulkarni R. D., Gite V. V.,
Polyurethane Prepared from Neem Oil Polyesteramides for Self-Healing
Anticorrosive Coatings, Ind. Eng. Chem. Res. 2013, 52, 10189–10197.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 49
19. Tatiya P. D., Hedaoo R. K., Mahulikar P. P., Gite V. V., Novel Polyurea
Microcapsules Using Dendritic Functional Monomer: Synthesis, Characterization
and Its Use in Self-Healing and Anticorrosive Polyurethane Coatings, Ind. Eng.
Chem. Res. 2013, 52, 1562–1570.
20. Petrovic Z. S., Zhang W., Javni I., Structure and Properties Of Polyurethanes
Prepared From Triglyceride Polyols by Ozonolysis, Biomarcomolecules 2005, 6,
713–719.
21. Santacesaria E., Renken A., Russo V., Turco R., Tesser R., Serio M. D., Biphasic
Model Describing Soybean Oil Epoxidation With H2O2 In Continuous Reactors,
Ind. Eng. Chem. Res. 2012, 51, 8760–8767.
22. Tan S. G., Chow W. S., Biobased Epoxidized Vegetable Oils and Its Greener
Epoxy Blends: A Review, Polym. Plast. Technol. Eng. 2010, 49, 1581–1590.
23. Guo A., Demydov D., Zhang W., Petrovic Z. S., Polyols and Polyurethanes from
Hydroformylation of Soybean Oil, J. Polym. Environ. 2002, 10, 49–52.
24. Satheesh M. N. K., Maimunah S., Yaakob Z., Siddaramaiah A. S., Synthesis of
Alkyd Resin from Non-Edible Jatropha Seed Oil, J. Polym. Environ. 2010, 18,
539–544.
25. Lee C., Ooi T., Chuah C., Ahmad S., Synthesis of Palm Oil-Based
Diethanolamides, J. Am. Oil Chem. Soc. 2007, 84, 945–952.
26. Zlatanic A., Lava C., Zhang W., Petrovic Z. S., Effect of Structure on Properties of
Polyols and Polyurethanes Based on Different Vegetable Oils, J. Polym. Sci., Part
B: Polym. Phys. 2003, 42, 809–819.
27. Oprea S., Properties of Polymer Networks Prepared by Blending Polyester
Urethane Acrylate with Acrylated Epoxidized Soybean Oil, J. Mater. Sci. 2010, 45,
1315–1320.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 50
28. Sharmin E., Ashraf S. M., Ahmad S., Synthesis, Characterization, Antibacterial,
and Corrosion Protective Properties of Epoxies, Epoxy-polyols and Epoxy-
polyurethane Coatings from Linseed and Pongamia glabra Seed Oils, Int. J. Biol.
Macromol. 2007, 40, 407–422.
29. Meshram P. D., Puri R. G., Patil A. L., Gite V. V., High Performance Moisture
Cured Poly(ether-urethane) Amide Coatings Based on Renewable Resource
(Cottonseed Oil), J. Coat. Technol. Res. 2013, 10, 331–338.
30. Gite V. V., Kulkarni R. D., Hundiwale D. G., Kapadi U. R., Synthesis and
Characterization of Polyurethane Coatings Based on Trimer of Isophorone
Diisocyanate (IPDI) and Monoglycerides of Oils, Surf. Coat. Int., Part B. 2006, 89,
99–192.
31. Bagle A. V., Jadhav R. S., Gite V. V., Hundiwale D. G., Mahulikar P. P.,
Controlled Release Study of Phenol Formaldehyde Microcapsules Containing
Neem Oil as An Insecticide, Int. J. Polymer. Mater. Polymer. Biomater. 2013, 62,
421–425.
32. Biswas K., Chattopadhyay I., Banerjee R. K., Bandyopadhyay U., Biological
Activities and Medicinal Properties of Neem (Azadirachta indica), Curr. Sci. 2002,
82, 1336–1345.
33. Chaudhari A. B., Anand A., Rajput S. D., Kulkarni R. D., Gite V. V., Synthesis,
Characterization and Application of Azadirachta indica juss (Neem Oil) Fatty
Amides (AIJFA) Based Polyurethanes Coatings: A Renewable Novel Approach,
Prog. Org. Coat. 2013, 76, 1779-1785.
34. Peter O. C., Ebenso E. E., Udofot J. E., Azadirachta indica Extract as Corrosion
Inhibitor for Mild Steel in Acid Medium, Int. J. Electrochem. Sci. 2010, 5, 978–
993.
CHAPTER 2
Ph. D. Thesis, Mr. A. B. Chaudhari, School of Chemical Sciences, N. M. U., Jalgaon, 2014. 51
35. Gite V. V., Mahulikar P. P., Hundiwale D. G., Kapadi U. R., Polyurethane Coatings
Using Trimer of Isophorone Diisocyanate, J. Sci. Ind. Res. 2003, 63, 348–354.
36. Hilditch T. P., Murti K. S., The Fatty Acids Glycerides of Neem Seed Oil, J. Soc.
chem. Ind. Lond. 1939, 58, 310–312.
37. Javni A., Petrovic Z. S., Guo A., Fuller R., Thermal Stability of Polyurethanes
Based on Vegetable Oils, J Appl. Polym. Sci. 2000, 77, 1723–1734.