Synthesis, properties, and applications of urethane-modified acrylated poly(ester-amide)s

Article abstract of DOI:10.1007/s11164-012-0606-x

Epoxy resin-based unsaturated poly(ester-amide) resins (UPEAs) were treated with acryloyl chloride to afford acrylated UPEAs resins (AUPEAs). Urethane-based acrylated poly(ester-amide)s prepared by reaction with diisocyanate were characterized by elementa

Full text of DOI:10.1007/s11164-012-0606-x

Res Chem Intermed (2013) 39:941–949
DOI 10.1007/s11164-012-0606-x
Synthesis, properties, and applications
of urethane-modified acrylated poly(ester-amide)s
•
Pragnesh N. Dave Nikul N. Patel
Received: 10 April 2012 / Accepted: 16 May 2012 / Published online: 7 June 2012
Ó Springer Science+Business Media B.V. 2012
Abstract Epoxy resin-based unsaturated poly(ester-amide) resins (UPEAs) were
treated with acryloyl chloride to afford acrylated UPEAs resins (AUPEAs). Ure-
thane-based acrylated poly(ester-amide)s prepared by reaction with diisocyanate
were characterized by elemental analysis, by molecular weight determination (by
vapour pressure osmometry), by IR spectral study, and by thermogravimetry. The
curing of interacting blends was monitored by differential scanning calorimetry
(DSC). On the basis of DSC data in-situ glass-reinforced composites were prepared
from the resulting materials and their mechanical, electrical, and chemical properties
were characterized. Unreinforced blends were characterized by thermogravimetry.
Keywords Unsaturated bisamic acid ꢀ Epoxy resin ꢀ Urethane ꢀ Unsaturated
poly(ester-amide) resins (UPEAs) ꢀ Acrylation thermogravimetry ꢀ Glass-reinforced
composites
Introduction
Polyesters and polyamides have specific properties which result in applications
ranging from aerospace to microelectronics. They are also used as laminating resins,
moulding composites, fibres, films, surface-coating resins, and fibre cushions.
Polyamide materials are thermoplastics and are used, especially in the form of
fibres, in engineering applications. Glass fibre-reinforced nylon plastics are now of
substantial importance because of their rigidity and creep resistance. Because
polyamides are also used in other fibre applications, in the automotive industry, and
P. N. Dave (&)
Department of Chemistry, KSKV Kachchha University, Mundra Road, Bhuj 370001, Gujarat, India
e-mail: pragnesh7@yahoo.com; pragneshdave@gmail.com
N. N. Patel
Institute of Science, Nirma University, Ahmedabad, India
123

942
P. N. Dave, N. N. Patel
as valve covers and coatings, many researchers [1–8] have synthesized
co-poly(ester-amide)s from different raw materials to obtain specific properties of
different materials all in the same product.
Because of their special properties, polyurethanes are widely applied as
insulating materials in the electrical industry. Coating of magnet wire with
polyurethane varnish is one of the most important uses of polyurethane insulating
materials. The property which has led to the popularity of polyurethane-enamelled
magnet wire is solderability at 360–425 °C without the need for fluxing or stripping.
Another feature of polyurethane-insulated wire is its superior Q factor (reciprocal of
dissipation factor, DF).
Merging of all these unsaturated epoxy, ester, urethane, and amide groups in one
polymer chain has not received academic and technical attention. Specific properties
of thermoplastics may also be improved by blending. Addition to an unsaturated
resin is another possibility.
To improve the specific properties of such poly(ester-amide)s it was thought
interesting to study urethane modification. The work is summarised in Scheme 1.
Materials and methods
Materials
Commercially available epoxy resin, the diglycidyl ether of bisphenol-A, and vinyl
ester epoxy resin were obtained locally.
The specification of the diglycidyl ether of bisphenol-A (DGEBA) was:
1. epoxy equivalent weight, 190
2. viscosity 40–100 poise at 25 °C
3. density at 25 °C, 1.16–1.17 g/cm
The aromatic diamines used for preparation of unsaturated poly(ester-amide)
resin were:
1. 4,40-methylenedianiline
2. 4,40-oxydianiline
3. 4,40-sulfonyldianiline
Plain-weave fibres in the form of E-glass woven fabric (poly(ester-amide)-
compatible) 0.25 mm thick, of mass 270 g m-2 (Unnati Chemicals, India) were
used for fabrication of composites. All other chemicals used were of pure grade.
Synthesis of unsaturated bisamic acids
Unsaturated bisamic acids were prepared by simple addition of maleic anhydride to
diamines, at low temperature, in a beaker. The product was formed as a precipitate
and was isolated by filtration. This method has been reported in the literature [8, 9].
123

Synthesis, properties and applications of urethane
943
O
R
H2N
NH2
O
+
O
Aromatic Diamines
(1.0 Mole) (a-c)
Maleic Anhydride
(2.0 Mole)
0-5 0
NH
Unsaturated Bisamic Acids (1a-c)
C
HOOC
CH
COOH
CH
CO HN
R
OC
CH
CH
Diglycidylether of Bisphenol-F
OH
CH CH2
OH
CH2
CH2
O
R1
O
CH
NH
CH2 CH
R
CH CO
HN
OC
CH
CH
COO
OOC
n
Unsaturated Poly(Ester-Amide) Resin (UPEAs 2a-c) [X]
Acrylol Chloride
CH
CH2
CH2
CH
CH2
CO
O
CO
O
CH2
CH2
O
O
R1
CH
NH
CH2 CH
R
CH
CH CO HN
OC
CH
CH
OOC
COO
n
Acrylated Unsaturated Poly(Ester-Amide) Resin (AUPEAs 3a-c)[Y]
[X] + Diisocyanates + [Y]
stoichiometrically
Unsaturated Poly(Urethane-ester-amide) resin
Benzoyl Peroxide
Coating
Glass Fiber Reinforced Composites (5a-c)
H2
Where,
O2
S
(c)
H2N
C
NH2(b)
H2N
O
NH2
(a)
H2N
NH2
R=
4,4'-methylenedianiline
4,4'-oxydianiline
4,4'-sulfonyldianiline
H
C
H
O
O
R1=
Scheme 1 Synthesis steps
Synthesis of unsaturated poly(ester-amide) resins and acrylated poly(ester-
amide) resins
Unsaturated poly(ester-amide) resins (UPEAs) were prepared by the method
reported for the reaction of epoxy resin with a carboxyl group. The diglycidylether
123

944
P. N. Dave, N. N. Patel
Impact Rockwell Electrical strength
Table 1 Chemical, mechanical, and electrical properties of the composites
Composite % Change on exposure to Compressive
25 % (w/v) NaOH
strength (MPa) strength hardness (R) (in air) (kV/mm)
(MPa)
Thickness
Weight
5a
5b
5c
0.78
0.81
0.79
1.07
1.10
1.02
460
467
478
424
456
447
111
104
106
22.65
19.45
23.35
of bisphenol-F (DGEBF) (1.0 mol) and unsaturated bisamic acid (1.0 mol) were
placed in a three-necked flask equipped with a mechanical stirrer, and triethylamine
(TEA), 8.0 % of the total weight, was added as basic catalyst. The reaction mixture
was slowly heated to 85 °C with continuous stirring until the acid value fell below
60 mg KOH/g. The resulting resins were denoted unsaturated poly(ester-amide)
resins (UPEAs); their properties are listed in Table 1. These unsaturated poly(ester-
amide) resins (UPEAs) were reacted further with acryloyl chloride (i.e., acrylation).
The resulting products were denoted acrylated poly(esteramide)s (APEAs) [1].
Synthesis of urethane-containing acrylated poly(ester-amide)s
Urethane-modified acrylated poly(ester-amide)s were prepared in accordance with
Scheme 1. A stoichiometric mixture of X, Y, and the diisocyanate was placed,
under an inert atmosphere, in a three-necked flask equipped with a mechanical
stirrer. The flask was immersed in an oil bath and mechanical stirring was continued
until the appropriate viscosity was obtained.
Analysis and thermal study
Elemental analysis
The C, H, N content of the unsaturated poly(ester-amide)s (UPEAs) and the
acrylated poly(ester-amide)s (APEAs) was estimated by means of a Thermofinnigan
(Italy) 1101 flash elemental analyser. The IR spectra were recorded in Kerr pellets
on a Nicolet 760 D spectrometer. The number average weight of the unsaturated
poly(ester-amide)s (UPEAs) and the acrylated poly(ester-amide)s (APEAs) was
estimated by non-aqueous conductometric titration by use of a method reported in
the literature [10]. Pyridine was used as a solvent and tetra-n-butylammonium
hydroxide was used as titrant.
Thermal study
Curing of all the samples, with benzoyl peroxide as catalyst, was performed on a Du
Pont 900 differential scanning calorimeter (DSC). The instrument was calibrated
123

Synthesis, properties and applications of urethane
945
with standard indium metal with known heat of fusion (DH = 28.45 J/g). Curing
was performed from 30 to 300 °C at 10 ° min-1 heating rate. The sample weight
used for this investigation was in the range 4–5 mg; an empty reference cell was
used.
Unreinforced cured samples were subjected to thermogravimetric analysis (TGA)
on Du Pont 950 thermogravimetric analyser in air at a heating rate of 10 ° min-1
.
The sample weight used for this investigation was in the range 4–5 mg. The TGA
and DSC data are shown in Figs. 1 and 2, respectively.
IR spectral characteristics of UPEAs
The IR spectra of all the UPEAs contained an intense band at approximately
1,730 cm-1; this band is characteristic of the [C=O stretching of A,B-unsaturated
esters (Fig. 3).
1. The spectra of all the resins contained the characteristic[C=O stretching band
of the amide group at approximately 1,690 cm-1 and the characteristic –NH
band of the amide group between 1,550 and 1,510 cm-1
.
2. The spectra of all the resins contained the characteristic O–H stretching band of
the secondary hydroxyl group between 3,600 and 3,200 cm-1
3. The spectra of all the resins contained the characteristic band of the ether group
.
at approximately 1,260 cm-1
.
4. The spectra of all the resins contained a band at approximately 1,655 cm-1
which may arise from a cis C=C stretching vibration.
Thus IR spectral analysis of the resins confirmed formation of the unsaturated
poly(ester-amide)s.
Composite fabrication
The composites were prepared by use of E-type glass fibre. Composite fabrication
was performed by our reported method [1].
Composite characterization
Chemical resistance test
The resistance of the composites to chemicals was measured in accordance with
ASTM D 543.
Mechanical and electrical testing
Flexural strength, compressive strength, impact strength, Rockwell hardness,
electrical strength, and tensile elongation were tested in accordance with the ASTM.
123

946
P. N. Dave, N. N. Patel
Fig. 1 TGA curves. a TGA of
4a, b TGA of 4b, c TGA of 4c
123

Synthesis, properties and applications of urethane
947
Fig. 2 DSC curves. a DSC
curve of 4a, b DSC curve of 4b,
c DSC curve of 4c
123

948
P. N. Dave, N. N. Patel
Fig. 3 a IR spectrum of 2a, b IR spectrum of 2b, c IR spectrum of 2c
123

Synthesis, properties and applications of urethane
949
Results and discussion
The C, H, and N content of all the unsaturated poly(ester-amide)s (PEAs) and
acrylated poly(ester-amide)s (APEAs), estimated by means of a Thermofinnigan
(Italy) 1101 flash elemental analyser, were consistent with their predicted structures.
The number-average molecular weights of the unsaturated poly(ester-amide)s
(PEAs) and acrylated poly(ester-amide)s (APEAs), estimated by non-aqueous
conductometric titration [10], indicated that the degree of polymerization of both
materials was approximately 6. The IR spectra were consistent with those expected
from the structures of the PEAs (3a–c) and APEAs (4a–c).
Numbers of hydroxyl groups present per repeat unit in unsaturated poly(ester-
amide)s (PEAs) was also analysed by use of the acetylating method [11]. The
acrylated poly(ester-amide)s (APEAs) were also characterized for the presence of
double bonds per repeat unit, by use of the mercury-catalysed bromate–bromide
method [12]. Satisfactory results were obtained.
Acknowledgments The authors gratefully thank the Head, Department of Chemistry, KSKV Kachchha
University, for research laboratory facilities.
References
1. P.N. Dave, N. Patel, J. Chem. Phar. Res 1, 3 (2011)
2. V. Shukla, Pigment & Resin Technol 35, 353 (2006)
3. B.C. Samanta, T. Maity, S. Dalai, A.K. Banthia, Pigment & Resin Technol 37, 3 (2008)
4. S. Khambete, U.S. Patent 7,290,300 (2007)
5. M. Malik, V. Choudhary, I.K. Varma, J. Macromol. Sci. Rev. Macromol. Chem. Phys. C40, 139
(2000)
6. A.J. Pekarik, U.S. Patent 4,840,980 (1989)
7. S. Ahmad, S.M. Ashraf, A. Hasant, S. Yadav, A. Jamal, J. Appl. Polym. Sci 82, 1855 (2001)
8. H.S. Patel, K.K. Panchal, Int. J. Polym. Mater. 54, 1 (2005)
9. H.S. Patel, K.K. Panchal, Int. J. Polym. Mater. 54, 795 (2005)
10. R.N. Patel, S.R. Patel, Angew. Makromol. Chem 96, 85 (1981)
11. A.I. Vogel, Quantitative organic analysis, vol. 3(2) (CBS Publishers, New Delhi, 1998), pp. 677–679
12. A.I. Vogel, Quantitative organic analysis, vol. 3(2) (CBS Publishers, New Delhi, 1998), pp. 765–766
123