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STUDY OF HYDROXYL TERMINATED ORGANOPHOSPHORUS CURING
AGENTS
T.LAKSHMIKANDHAN1, V.L.CHANDRA BOSS
2
1,2 Associate Professor,
Department of Chemistry,
BIST, BIHER, Bharath University,Chennai-73 lakshmikandhan.che@bharathuniv.ac.in, Chandraboss.che@bharathuniv.ac.in,
ABSTRACT
A novel hydroxyl-terminated hyperbranched polyphosphate (HHPP) was synthesized
by employing an A2 + B3 polycondensation with high functionality as a curing agent
and characterized by FTIR, 1H NMR and
31P NMR. The formation of the product was
monitored by thin layer chromatography, FT-IR and the evolution of HCl was
detected by using litmus paper. The distinctive absorption around 1300cm-1
corresponding to the stretching vibration of P=O in phosphorus oxychloride decreases
gradually until disappeared completely after 24 hours reaction. 1H NMR supports the
product formation. 31
P NMR Spectrum shows the incorporation of phosphorus in
hyperbranched (3-hydroxyphenyl) phosphate.
1. Introduction
Curing agents plays an important role in epoxy composites; it is also called as
“Hardener”. In chemistry[1-6], epoxy or polyepoxide is a thermosetting epoxide
polymer that cures (polymerizes and cross links) when mixed with a catalyzing agent
or hardener. The broad interest in epoxy resins originates from the extremely wide
variety of chemical reactions that can be used for the curing[7-12]. Increasing
requirements for thermally stable polymers have promoted research on the
modification of epoxies in particular certain organophosphorus compounds have
received considerable attention as possible candidates for making high-temperature
polymers. Various acid anhydrides are also used to crosslink the epoxy resins[13-21].
International Journal of Pure and Applied MathematicsVolume 119 No. 12 2018, 6173-6209ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu
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1.1 Applications of epoxy composites
Epoxy resins are a most important class of thermosetting resins and it has
many engineering applications because of their high strength and stiffness, good
dielectric behavior, resistance to chemicals, corrosion1. Epoxy composites have a very
good chemical and fatigue resistance[22-26], thus epoxy resins replace the less costly
unsaturated polyester resins in many applications. Reinforced epoxy resins are very
strong and they have good dimensional stability and service temperatures as high as
3150C. Preimpregnated reinforcing materials are used to produce products by hand
layup, vacumm-bag, or filament winding processes[27-32]. Epoxy-glass laminates
find many uses because they have high strength-to-mass ratio, superior adhesion to all
materials and compatibility make epoxy resins desirable. Filled epoxy resins are
commonly used for special castings. These strong compounds may be used for low-
cost tooling many different types of filler are used in caulking and patching. Epoxy
composites are outstanding in protecting electronic parts from moisture, heat, and
corrosive chemicals. They are molded into small electrical items and appliance parts
and have many modular uses. Epoxy coating have replaced glass enamel finishes for
tank car and other container linings that need to resist chemicals. The flexibility of
many coating makes them popular for post forming coated metal parts. For example
sheets of metal are coated while flat[33-36].
1.2 Disadvantages of epoxy composites
1. Poor oxidative stability
2. Thermal stability limited to 350-450 0F [178-232
0C]
3. Many grades are expensive [2].
1.3 Properties of curing agent
The term “curing” is used to describe the process by which one or more kinds of
reactants (i.e., an epoxide and a curing agent) are transformed from low-molecular-
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weight materials to a highly cross-linked network.. The network is composed of
segments involving only the epoxide or both the epoxide and the crosslinking. The
chemistry of epoxy-resin curing is that most of its reaction is ionic[37-41], that is a
bond is formed by the curing-agent species donating and the epoxide accepting the
necessary electron pair symbolized as follows
A: + B A: B
Where A: is the electron-donating species (in case of amine curing agent the
nucleophilic species ) and B is able to accept an electron pair (i.e., it is an
electrophilic species) It is used for epoxy, fusion bonded epoxy coating, paint, tanning
concrete, food preservation, building insulation materials[42-45].
1.4 Types of curing agents
Epoxy resin are the classical matrix resins for composite .these can be cured
by different curing agent types namely by
1. Amine curing agent
u2. Anhydrides curing agents
3. Carboxylic acids curing agent
4. Phenolic curing agents
5. Organophosphorus curing agents
6. Lewis acid catalyst curing agent
1. Amine curing agent
These cross-link the resins either catalytically or establishing links across the
resin molecules. In general, the primary and the secondary amines act as reactive
hardeners while the tertiary amines act as catalytic hardeners. Depending upon the
type of hardener or curing agent, the resin would have different quantities added to it
and consequently, it would have different pot life. For instance, diethylenetriamine is
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more reactive than the triethylene tertramine and hence, while the former is added to
the extent of 9-10 phr (parts per hundred parts of resin), the latter is added to the
extent of 12-13 phr. The resulting resin has a pot life of less than one hour at room
temperature for the former case and a little above one hour for the latter. Aromatic
amines give higher thermal resistance but require a higher cure temperature. Aliphatic
amines lead to fast cure and are suitable to room temperature curing epoxy resins.
2. Anhydrides curing agent’s (acid hardeners)
Acid hardening systems have been in use since the mid-fifties. Acid hardeners
have a lower level of skin irritation and give lower exotherm on cure. But the amine –
cured resins show greater alkali resistance than the acid-hardened ones. While using
the acid hardeners, the anhydrides are preferred over the acid hardeners because they
release less water on cure. Greater release of water may lead to foaming of the
products. Also, anhydrides are more soluble in the resin than the acids. When an
anhydride is used, first it goes through a ring-opening reaction by the hydroxyl group
in the resin [4].
3. Organophosphorus Curing Agents:
Organophosphorus compounds have exhibited high flame retardant efficiency
for epoxy resins and also been found to generate less toxic gas and smoke than
halogen-containing compounds therefore; less destruction to the earth’s environment
is the networthy benefit of replacing halogen with phosphorus in flame retardant
epoxy resins and the flame retardancy on epoxy resins via phosphorylation.
Incorporating covalently boned phosphorus into epoxy resins could be achieved via
using phosphorus-containing oxirane compounds or curing agents [5]. The oxirane
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compound with phosphorus in the back bone of epoxy resins exhibits much better
than flame retardancy and over comes. Several drawbacks associated with the
physical blend of the epoxy resins and the flame retardants [6]. A free epoxy is used
as the control resin for comparison of curing properties with the phosphorus-
containing epoxy resins. Flame resistance microscale combustibility and fire behavior
were used to assess flammability of phosphorus containing epoxy and diamine
formulation. Phosphorus was introduced as either part of the diamine curing agent or
part of an epoxy compound in a typical aerospace epoxy. Flame combustion
efficiency was used as a global measure of gas phase activity [7].
A phosphorous-containing reactive bis (3-hydroxyphenyl) phosphate
(BHPP) was incorporated into epoxy resin and is expected to impart the required
flame retardancy, less fume and higher thermal stability than the conventional
bromine containing fire retardant system. Phosphorus containing flame retardants
influence the reaction taking place in the condensed phase. Their effectivity depends
on the chemical structure of the polymer, they are particularly effective in materials
with high oxygen content, like polyesters, polyurethanes, epoxies or cellulose. The
phosphorus flame retardant is converted by thermal decomposition to phosphoric
acid. Further thermal decomposition leads to the formation of poly-phosphoric acid.
The polyphosphoric acid esterifies and dehydrates the pyrolysing polymer [8].
The phosphorus moiety decomposes at low temperature relative to the
polymer matrix. Phosphorus-containing compounds for flame retardants are used
either by blending with polymers or by reacting onto polymers. It is believed that
phosphorus containing compounds can quench flammable particles like H*
and OH*
reduce the energy of the flame in the gas phase. Moreover in the solid phase, the
phosphorus-containing functional groups are converted by thermal decomposition to
phosphoric acid [9].
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Several investigations in this regard have been recently reported such as
phosphorylated diamines, hydroxyphenyl phosphate, and phosphorus-containing
bismaleimide. Furthermore, excellent flame retardancy is also achieved through the
introduction of phosphoruscontaining functional groups into the backbones of epoxy
compounds such as triphenyl phosphate and its analogues have received much
attention due to absence of toxic gases and smokes during combustion compared with
halogen type flame retardants. The action of phosphorus containing flame retardant
can occur predominantly through a condensed-phase mechanism, i.e. a mechanism in
which combustion of the outer layers of the polymeric article containing the flame-
retardant mixture leads to the production of an intumescent carbonaceous char which
protect the underlying polymeric material as a thermal barrier from further attack of
flame or heating [10] .
However, the use of additives as flame retardant has several disadvantages
including high loading required to achieve a sufficient level of flame retardation,
detrimental changes to the polymer’s physical and mechanical properties and leaching
of the additive during service. In order to overcome these problems phosphorus
containing monomers or oligomers can be chemically incorporated into the polymer
backbone linking airborne carbon fibers to any unusual health hazard [11]. The use of
phosphorus (P) as a flame retardant, particularly in epoxy resins, has been widely
improved fire resistance, reduced smoke and toxicity .This effort concentrated on the
use of bis (3-aminophenyl) - methylphosphine oxide as a curing agent for epoxies.
Phosphorus when incorporated in polymers as an additive or reactive comonomer is
known to impart fire retardation by condensed phase and gas phase mechanisms. In
the condensed phase P catalyzes char formation which protects the underlying
material from heat and acts a barrier to the release of fuel gases from the surface.
When acting in the condensed phase as a char catalyst, P retards the spread of fire
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with minimal release of toxic gases. In the gas phase P acts as a flame poison with PO
species participating in a kinetic mechanism that is analogous to that of halogens in
flames. Gas phase activity is indicated by low heats of flaming combustion, the
production of visible smoke and mineral acids (halogens), and high yields of carbon
monoxide as consequence of the incomplete combustion of the fuel gases in the
flame. Phosphorus has been incorporated into polymeric materials both as an additive
and as part of the polymeric chain. Additives are normally more economical but tend
to leach out, and have a negative impact on processability and mechanical properties.
Cured epoxy resins have a high concentration of hydroxyl (OH) groups and therefore,
P-containing flame retardant compounds are particularly effective because P tends to
react with OH groups [7]
Curing characteristics of epoxy resin-hardener systems
Useful guides to the handling properties of an epoxy resin-hardener system are
the pot life and exothermic .the pot life is the time during which the epoxy resin-
hardener mixture remains usable and is generally regarded as the time required for a
system to become gelled. Tests intended to classify the curing behavior are commonly
carried out under orbitrary conditions. Pot life can simply be determined by trial
stirring. However gel timers are commercially available. Available also is apparatus’
that allows simultaneous measurement of viscosity and temperature.
The exotherm generally understood as the maximum temperature evolved by a
system, depends strongly on the mass of the casting and its shape. It can be
determined by temperature measurement with a thermocouple, the tests conducted
under a given set of experimental circumstances .in order to obtain complete
information a curve of temperature versus time should be plotted.
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The cure time required at a fixed cure temperature to bring about thorough
cross linking for each application by development of the optimum value of some
important property.dannenbery and harp dived cure into two components
“conversion” related to the extent of chemical reaction, and “cross linking”, which
considers the three-dimensional aspect of the cure process. The degree of cross
linking, which depends on chemical conversion and on the functionality of the
compounds entering the cure reaction
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2. Aim & Objectives
A review of recent literature reveals that there is no much report on hydroxyl
terminated phosphorus containing curing agents. Hence the aim of the present
investigation is to synthesize Hydroxyl-terminated hyperbranched polyphosphate
(HHPP).It was synthesized by employing an A2 + B3 polycondensation of various
dihydroxy compounds as an A2 monomer and phosphorus oxychloride as a B3
monomer.
A2 – Dihydroxy benzene, substituted dihydroxy benzene and Bisphenol
A.
B3 – Phosphorus Oxychloride
1. Synthesis of Hydroxyl Terminated Organophosphorus Curing Agents
2. The products were characterized by FT-IR, 1H NMR and
31P NMR.
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3. Experimental
3.1 Materials
Resorcinol, Hydroquinone, bisphenol-A were kindly purchased from Sisco
Research Laboratories. Phosphorus Oxychloride, ter-Butyl catechol, Catechol,
Acetone, Pet. ether, Ethyl acetate, DMSO, Triethylamine, Ethanol supplied by sdfine
chem. Ltd. Solvents were purified by using standard procedures prior to use.
3.2 Measurements
The Fourier transform infrared (FTIR) spectra were recorded with a Thermo
Nuclear330 instrument. The 1H NMR spectrum was recorded with AMX-400
spectrometer using tetramethylsilane as an internal reference and CD3COCD3 as a
solvent. The 31
P NMR spectrum was recorded with a JEOL GSX-400 NB multi
nuclei FT NMR spectrometer using tetramethylsilane as an internal reference and
CD3COCD3 as a solvent.
3.3 Synthesis of hyper branched (3-hydroxy phenyl) phosphate (HHPP)
6.988g (0.0636mol) of Dihydroxy benzene (DHB) was taken in a 500ml three
necked RB flask equipped with a reflux condenser and an over head mechanical
stirrer, and heated to 120oC under a dry nitrogen atmosphere. Then 3.889g
(0.0254mol) phosphorus oxychloride was added dropwise into the flask after DHB
was melted. The evolution of HCl was detected immediately by litmus paper. The
reaction mixture was further heated to 135oC and the temperature maintained for 24
hour with continuous stirring. Finally ethyl alcohol was added into resultant and then
the freshly distilled triethylamine was added dropwise to neutralize the residual HCl
until no white smoke was observed. The formed triethylamine hydrochloride salt was
removed by simple filtration, then the solvent was distilled off and the obtained
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product was washed with water until the peaks around 2700 cm-1
in the FT-IR
spectrum disappeared.
The above same procedure was followed to prepare various hyperbranched
poly phosphate esters by various dihydroxy compounds, substituted dihydroxy
compound and Bisphenol A used as A2 monomer with phosphorus oxychloride. Name
of the reactants and product codes were given in Table 1
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General Reaction scheme:
OHHO
Resorcinol
P
O
Cl
Cl
Cl135oC
N2
O P
O
O
O
O
O
P
P
O
O
O
O
OO
HO
O
HO
O P
O
O
O
HO
O P
O
O
O
HO
O
O
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Table 1 Product codes
S.No Dihydroxy compounds Product Code
1 Resorcinol (HHPP) RES
2 Catechol (HHPP) CAT
3 Bisphenol A (HHPP) BPL
4 4-ter Butyl Catechol (HHPP) TBC
5 Hydroquinone (HHPP) HRQ
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4. Results and Discussion
Synthesis of Hyperbranched (3-hydroxyl phenyl) phosphate (HHPP)
4.1 FT-IR Studies
In this study, the synthesis of HHPP was performed by starting from DHB as
A2 monomer and phosphorus oxychloride as B3 monomer. The reaction process was
monitored by FT-IR as the reaction between phosphoryl oxychloride and DHB
proceeded, the distinctive absorption around 1300cm-1
corresponding to the stretching
vibration of P=O in phosphoryl oxychloride decreases gradually until disappeared
completely after 24h reaction. The formation of the product was confirmed by FT-IR
spectrum by the formation of P-O-Ph bond, P=O shifted from 1300 cm-1
to around
1270 cm-1
which is a characteristic of phosphate compounds.
Figures 1-5 and Table 2 shows the FT-IR spectrum of HHPP, characteristic
peaks at around 1080 and 910-988 cm-1
are attributed to the stretching frequency of P-
O-Ph stretching frequency. The peak at around 1260 cm-1
indicates that the P=O of
the compound. The peaks at around 3450 cm-1 show the Ph-OH groups of the
compound. Around 2960cm-1
indicates the presence of methyl C-H stretching
frequency.
Table 2 Characteristic stretching frequency of HHPP
Characteristic
Stretching
frequency
RES
cm-1
BPL
cm-1
CAT
cm-1
TBC
cm-1
HRQ
cm-1
Ph-OH 3413 3434 3479 3429 3451
P-O-Ph 1081, 915 1091, 906 1091, 988 1066, 964 1088, 992
P=O 1242 1233 1254 1283 1279
CH3 - 2962 - 2954 -
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Figure 1 FT-IR of HHPP (CAT)
CA T -B
40
8.1
4
55
9.9
7
68
4.7
8
77
4.3
5
98
8.1
210
91
.12
11
28
.72
12
54
.02
13
84
.26
14
78
.00
15
97
.72
34
79
.52
37
41
.20
37
93
.66
38
50
.40
2 5
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
%T
ran
sm
itta
nce
5 00 1000 1500 2000 2500 3000 3500
W avenum bers (c m-1 )
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Figure 2 FT-IR of HHPP (TBC)
18
T B C
43
3.9
1
54
8.4
8
64
4.9
8
81
5.2
68
56
.53
96
4.4
4
10
66
.11
12
83
.30
13
84
.38
14
55
.47
15
05
.76
15
99
.93
17
31
.78
29
54
.62
34
29
.33
38
86
.54
2 5
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
%T
ran
sm
itta
nce
5 00 1000 1500 2000 2500 3000 3500
W avenum bers (c m-1 )
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16
Figure 3 FT-IR of HHPP (RES)
RE ST
40
7.1
7
53
4.0
4
68
4.6
577
6.3
38
13
.84
86
2.6
0
91
5.4
6
98
8.3
71
01
1.6
2
10
81
.58
11
27
.31
11
62
.60
12
42
.34
13
84
.10
14
79
.63
15
05
.79
15
39
.03
15
58
.23
15
99
.26
16
52
.18
16
83
.66
16
99
.31
34
13
.29
7 6
78
80
82
84
86
88
90
92
94
96
98
100
%T
ran
smit
tan
ce
5 00 1000 1500 2000 2500 3000 3500
W avenum bers (c m-1 )
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17
Figure 4 FT-IR of HHPP (HRQ)
HRQ
69
5.5
2
82
8.9
4
99
2.5
9
12
79
.61
13
72
.43
14
55
.47
15
05
.46
16
00
.75
16
44
.65
16
98
.671
87
3.1
1
20
94
.81
34
51
.88
37
53
.30
38
02
.91
38
22
.60
38
45
.57
39
06
.09
2 5
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
%T
ran
sm
itta
nce
5 00 1000 1500 2000 2500 3000 3500
W avenum bers (c m-1 )
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19
Figure 5 FT-IR of HHPP (BPL)
BP L-B
40
3.6
8
58
3.1
86
37
.86
69
3.7
975
7.6
1
83
6.6
3
90
6.5
9
98
3.1
01
01
5.6
7
10
87
.89
11
65
.70
12
33
.00
13
83
.99
14
46
.39
14
78
.91
15
08
.78
15
47
.08
16
04
.29
16
38
.02
17
09
.51
29
62
.64
34
34
.42
8 8
89
90
91
92
93
94
95
96
97
98
99
100
%T
ran
sm
itta
nce
5 00 1000 1500 2000 2500 3000 3500
W avenum bers (c m-1 )
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4.2 NMR Studies
The 1H NMR spectra of HHPP are given in figures 6-10 and data given in
Table 3. It shows that all the distinct peaks can be assigned to the hydrogen in HHPP
and further confirms the reaction of phosphoryl chloride with dihydroxy compounds.
Aromatic protons comes around 6.5 – 8 ppm, hydroxyl protons at 3 – 3.6 ppm and
methyl protons shows the peaks at around 1.3 -1.6ppm.
Table 3 Proton NMR chemical shifts
Chemical shift BPL (ppm) CAT (ppm) TBC (ppm) HRQ (ppm) RES (ppm)
Aromatic
protons
7-8 6.8-7 6.6-7 6.6-7.4 6.5-7.5
-OH proton 3.5 3.2 3.0 3.0 3.6
Methyl protons 1.6 - 1.3 - -
The outcomes obtained from 31
P NMR spectra demonstrated the reaction
mechanism. Figures 11-15 and in Table 4 displays the 31
P NMR spectrums of a
typical HHPP prepared via A2 + B3 route with 3:1 molar ratio of dihydroxy compound
to POCl3. Three Signals at obtained for HHPP (RES), -6.5, -12.5 and -17.7 ppm are
assigned to terminal, linear and dendritic units, respectively. Signals at -12.3 and -
17.4ppm are assigned to linear and dendritic units, respectively for HHPP (BPL).
Table 4 Phosphorus NMR chemical shifts
Chemical
shift RES(ppm) BPL(ppm) CAT(ppm) HRQ(ppm) TBC(ppm)
Terminal -6.5 -- 0.2 - 0.8
Linear -12.5 -12.3 -2.1 -11.8 -1.5
Dendritic -17.7 -17.4 -11 -16.3 -3.2
Three Signals at obtained for HHPP (CAT), 0.2, 2.1 and -11 ppm are assigned
to terminal, linear and dendritic units, respectively. Signals at -11.8 and -16.3 ppm are
International Journal of Pure and Applied Mathematics Special Issue
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assigned to linear and dendritic units, respectively for HHPP (HRQ). Three Signals at
obtained for HHPP (TBC), 0.8, -1.5 and -3.2 ppm are assigned to terminal, linear and
dendritic units, respectively.
International Journal of Pure and Applied Mathematics Special Issue
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22
Figure 6 1H NMR of HHPP (CAT)
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6194
25
Figure 7 1H NMR of HHPP (TBC)
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23
Figure 8 1H NMR of HHPP (RES)
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24
Figure 9 1H NMR of HHPP (HRQ)
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26
Figure 10 1H NMR of HHPP (BPL)
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2
7
Figure 11 31
P NMR of HHPP (CAT)
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Figure 12 31
P NMR of HHPP (TBC)
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Figure 13 31
P NMR of HHPP (RES)
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30 Figure 14 31
P NMR of HHPP (HRQ)
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32
Figure 15 31
P NMR of HHPP (BPL)
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6203
CONCLUSIONS
A novel hydroxyl-terminated hyperbranched polyphosphate (HHPP) was
synthesized by employing an A2 + B3 polycondensation with high functionality as a
curing agent and the products were characterized by FT-IR, 1H NMR and
31P NMR..
1H NMR supports the product formation.
31P NMR Spectrum shows the incorporation
of phosphorus in hyperbranched (3-hydroxyphenyl) phosphate.
International Journal of Pure and Applied Mathematics Special Issue
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13. Manikandan, J., Hussain, J.H., Design on blind shoe using ATMEGA328
micro controller, International Journal of Mechanical Engineering and
Technology, V-8, I-8, PP-1575-1579, 2017
14. Manikandan, J., Hussain, J.H., Design and fabrication of blind shoe using
ATMEGA328 micro controller and vibration motor, International Journal of
Pure and Applied Mathematics, V-116, I-17 Special Issue, PP-287-289, 2017
International Journal of Pure and Applied Mathematics Special Issue
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15. Manikandan, J., Hussain, J.H., Design and fabrication of blind shoe using
ATMEGA328 micro controller and vibration motor, International Journal of
Mechanical Engineering and Technology, V-8, I-8, PP-1588-1593, 2017
16. Manikandan, J., Sabarish, R., Waste heat recovery power generation system
using thermoelectric generators, International Journal of Pure and Applied
Mathematics, V-116, I-17 Special Issue, PP-85-88, 2017
17. Meenakshi, D., Udayakumar, R., Protocol with hybridized bluetooth scatternet
formation for wireless network, International Journal of Applied Engineering
Research, V-9, I-22, PP-7299-7307, 2014
18. Meikandaan, T.P., Hemapriya, M., Use of glass FRP sheets as external
flexural reinforcement in RCC Beam, International Journal of Civil
Engineering and Technology, V-8, I-8, PP-1485-1501, 2017
19. Meikandaan, T.P., Hemapriya, M., Use of glass FRP sheets as external
flexural reinforcement in RCC beam, International Journal of Pure and
Applied Mathematics, V-116, I-13 Special Issue, PP-481-485, 2017
20. Meikandaan, T.P., Hemapriya, M., Study on properties of concrete with partial
replacement of cement by rice husk ash, International Journal of Pure and
Applied Mathematics, V-116, I-13 Special Issue, PP-503-507, 2017
21. Meikandaan, T.P., Hemapriya, M., Experimental behaviour of retrofitting of
prestressed concrete beam with FRP laminates, International Journal of Pure
and Applied Mathematics, V-116, I-13 Special Issue, PP-509-513, 2017
22. Meikandaan, T.P., Hemapriya, M., Study of damaged RC beams repaired by
bonding of CFRP laminates, International Journal of Pure and Applied
Mathematics, V-116, I-13 Special Issue, PP-495-501, 2017
23. Meikandaan, T.P., Hemapriya, M., Experimental study on strengthening of
shear deficient RC beam with externally bonded GFRP sheets, International
Journal of Pure and Applied Mathematics, V-116, I-13 Special Issue, PP-487-
493, 2017
24. Michael, G., Arunachalam, A.R., Srigowthem, S., Ecommerce transaction
security challenges and prevention methods-new approach, International
Journal of Pure and Applied Mathematics, V-116, I-13 Special Issue, PP-285-
289, 2017
25. Michael, G., Karthikeyan, R., Studies on malicious software, International
Journal of Pure and Applied Mathematics, V-116, I-8 Special Issue, PP-315-
319, 2017
26. Michael, G., Srigowthem, S., Vehicular cloud computing security issues and
solutions, International Journal of Pure and Applied Mathematics, V-116, I-8
Special Issue, PP-17-21, 2017
27. Micheal, G., Arunachalam, A.R., EAACK: Enhanced adaptive
acknowledgment for MANET, Middle - East Journal of Scientific Research,
V-19, I-9, PP-1205-1208, 2014
28. Murugesh, Kaliyamurthie, Thooyamani, K.P., ICI self-cancellation schee for
OFDM systems, Middle - East Journal of Scientific Research, V-18, I-12, PP-
1775-1779, 2013
29. Murugesh, Kaliyamurthie, Thooyamani, K.P., Preprocessing and
postprocessing decision tree, Middle - East Journal of Scientific Research, V-
13, I-12, PP-1599-1603, 2013
International Journal of Pure and Applied Mathematics Special Issue
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30. Nakkeeran, S., Hussain, J.H., Innovative technique for running a petrol engine
with diesel as a fuel, International Journal of Pure and Applied Mathematics,
V-116, I-18 Special Issue, PP-41-44, 2017
31. Nakkeeran, S., Nimal, R.J.G.R., Anticipation possessions for seismic use
carbon black on rubbers, International Journal of Pure and Applied
Mathematics, V-116, I-17 Special Issue, PP-63-67, 2017
32. Nakkeeran, S., Sabarish, R., New method of running a petrol engine with
diesel diesel as fuel, International Journal of Pure and Applied Mathematics,
V-116, I-18 Special Issue, PP-35-38, 2017
33. Nakkeeran, S., Vino, J.A.V., Prevention effects for earthquakes using carbon
black on rubbers, International Journal of Pure and Applied Mathematics, V-
116, I-17 Special Issue, PP-301-305, 2017
34. Nakkeeran, S., Vino, J.A.V., Performance development by using mesh plates
in parallel and counter flows of heat exchangers, International Journal of Pure
and Applied Mathematics, V-116, I-17 Special Issue, PP-291-295, 2017
35. Nalini, C., Arunachalam, A.R., A study on privacy preserving techniques in
big data analytics, International Journal of Pure and Applied Mathematics, V-
116, I-10 Special Issue, PP-281-285, 2017
36. Nalini, C., Ayyappan, G., Academic social network dataset applying various
metrics for measuring author's contribution, International Journal of Pure and
Applied Mathematics, V-116, I-8 Special Issue, PP-341-345, 2017
37. Nalini, C., Brintha Rajakumari, S., Iron toxicity of polluted river water based
on data mining prediction analysis, International Journal of Pure and Applied
Mathematics, V-116, I-8 Special Issue, PP-353-356, 2017
38. Nandhini, P., Arunachalam, A.R., Fault-tolerant quality using distributed
cluster based in mobile ADHOC networks, International Journal of Pure and
Applied Mathematics, V-116, I-8 Special Issue, PP-365-368, 2017
39. Nandhini, P., Arunachalam, A.R., Security for computer organize database
assaults from threats and hackers, International Journal of Pure and Applied
Mathematics, V-116, I-8 Special Issue, PP-359-363, 2017
40. Nandhini, P., Arunachalam, A.R., Mobile ADHOC networks: Security and
quality of services, International Journal of Pure and Applied Mathematics, V-
116, I-8 Special Issue, PP-371-374, 2017
41. Naveenchandran, P., Vijayaragavan, S.P., A high performance inverter fed
energy efficient cum compact microcontroller based power conditioned
distributed photo voltaic system, International Journal of Pure and Applied
Mathematics, V-116, I-13 Special Issue, PP-165-169, 2017
42. Naveenchandran, P., Vijayaragavan, S.P., Combination of wind energy-solar
energy power generation, International Journal of Pure and Applied
Mathematics, V-116, I-13 Special Issue, PP-117-121, 2017
43. Naveenchandran, P., Vijayaragavan, S.P., A sensor less control of SPM using
fuzzy and ANFIS technique, International Journal of Pure and Applied
Mathematics, V-116, I-13 Special Issue, PP-43-50, 2017
44. Nima, R.J.G.R., Hussain, J.H., Design and fabrication of an indexing fixture in
a shaper machine, International Journal of Pure and Applied Mathematics, V-
116, I-18 Special Issue, PP-441-445, 2017
International Journal of Pure and Applied Mathematics Special Issue
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45. Nimal, R.J.G.R., Hussain, J.H., Deflection and stress analysis of spur gear
tooth using steel, International Journal of Pure and Applied Mathematics, V-
116, I-17 Special Issue, PP-119-124, 2017
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