1. A Study on Curing Behaviour of Benzoxazines on
the Properties of Epoxy Resin
DEEPAK KUMAR
(Reg. No. 11013881)
UNDER THE SUPERVISION OF
Dr. Gagan Deep,
Asst. Professor,
DEPARTMENT OF CHEMISTRY
LOVELY PROFESSINAL UNIVERSITY

2. INTRODUCTION
EPOXY RESIN
Epoxy resin is defined as a molecule containing
more than one epoxide groups. The epoxide group
also termed as, oxirane or ethoxyline group.
There are two main categories of epoxy resins,
namely the glycidyl epoxy, and non-glycidyl
epoxy resins. The glycidyl epoxies are further
classified as glycidyl-ether, glycidyl-ester and
glycidyl-amine.

3. Glycidyl-ether epoxies such as, diglycidyl ether of
bisphenol-A (DGEBA) and novolac epoxy resins are most
commonly used epoxies.
These resins are thermosetting polymers and are used as
adhesives, high performance coatings ,potting and
encapsulating materials. These resins have excellent
electrical properties, low shrinkage, good adhesion to
many metals and resistance to moisture, thermal and
mechanical shock.

4.  In order to extend the application of epoxy
resin as electronic material and in the aerospace
industry it is crucial to improve its flame and
thermal resistance. Several approaches has been
reported in the literature for thermal and flame
resistance of the resin. Epoxy-benzoxazine
polymer has received increasing attention during
recent year in attempts to enhance their thermal
properties.

5. OBJECTIVE AND SIGNIFICANE :-
 To study the curing behaviour of benzoxazines
on the properties of epoxy resin.
To synthesize novel product with flame
retardant, good thermal properties and excellent
mechanical properties .

6. METHODOLOGY :-
Following steps will be used during research work:
 Literature survey was done to know the
advancement, technology, significance, application
and progress in the field till today.
 Synthesis of Benzoxazine monomers.
. Systematic Curing of DGEBA with Benzoxazine
monomers.

7. EXPERIMENTAL
The development of benzoxazine based family of
phenolic resins prepared by reacting phenols
(Bisphenol-A), primary amines, and formaldehyde
has attracted significant attention as show in
general reaction sechme : R
N
X OH + 4CH2O + 2NH2R X O
Benzoxazine
Where X = OH
R=
CH3
or or or
Cl
Br Cl

8.  Benzoxazine monomer of varying structure(as
shown below)
O O O
O
H 3C N N CH3 N N
B O TF BPC F
Cl
Cl
O O
O O
N N
N N
Cl Cl
BM C F
BPB F Br
Br

9. For recording DSC traces at a heating rate of 10oC/
min, TA 2100 thermal analyzer having 910 DSC
module was used. About 5 mg of sample was used in
each experiment.
The samples were prepared by mixing directly
DGEBA with each benzoxazine monomers in the
molar ratio of 1:1, 1:3 and 3:1.
These have been designated as DBOTF-01, DBOTF-
11, DBOTF-13 and DBOTF-31. The first numeral digit
represents the amount of DGEBA and second digit
represents the amount of Benzoxazine monomer.

10. RESULTS AND DISCUSSION:-
 The benzoxazine monomers were viscous liquids of
yellow colour and became transparent solid on heating.
The color of benzoxazine monomers and DGEBA
mixture after heating was orange.
 Characterization of benzoxazine monomers :-
(a) FT-IR
The characteristic absorption band due to
benzoxazine ring present at 1500 5 cm-1 in the
spectra of all the benzoxaine monomer .

11. The bands observed approx. at 1236 cm-1,
1031 cm-1 and 1158 cm-1 are due to
asymmetrical C-O-C stretching, symmetrical
C-O-C and symmetrical C-N-C respectively.
The bands observed around 1599-1680 cm-1
were correspond to the C = C stretching of
benzene ring. The figure: 1 shows the FTIR
Spectrum of benzoxazine monomer (BPBF).

12. Figure 1 : FTIR Spectra of BPBF

13. (b) 1H-NMR
The peaks due to methylene group of (O-CH2-N) and
(Ar-CH2-N) of oxazine ring were observed at δ 5.2
and δ 4.2 respectively in the 1H-NMR spectra of all
the monomers. The aromatic protons were observed
at ~ δ 6.3-7.9. The observation of signal at δ 2.4 in
case of monomer BOTF, was due to the methyl group
joined to the benzene ring. The proton integrations
were consistent with the molecular formula of the
monomers. The following figure shows the 1H-NMR
spectra of benzoxazine monomers BMCF.

14. H-NMR spectra of BMCF :-

15. Curing Studies:-
In the DSC scans of all samples of monomers, a
broad exothermic transition was observed. These
transitions were dependent upon the structure of
benzoxazine monomers.
 the DSC scans of samples of BOTF and BMCF
at a heating rate of 10oC/minute.

16.  DSC scans of BOTF at a heating rate of
10oC/min

17.  The curing temperatures were higher in case of
BPCF as compared to BOTF but Δ H value showed an
opposite trend when curing behaviour of BOTF was
compared with BPCF
Table1.1 :- Results of DSC scans of benzoxazine monomers at a heating
rate of 10oC/minute
Resin
Ti Tonset Tp Tf ∆H
Designatio
(oC) (oC) (oC) (oC) (J/g)
n
BOTF 160.4 176.7 226.1 259.6 64.5
BPCF 185.4 191.8 231.9 298.5 126.5
BMCF 185.4 191.5 228.9 254.4 41.3
BPBF 148.8 152.4 221.4 270.9 150.9

18. (b) Curing Studies of Benzoxazines and DGEBA
 The Results of DSC scans of benzoxazines in
presence of varying amounts of DGEBA are
summarized
 The blending of benzoxazine monomers with
DGEBA in different molar ratio could affect the
curing of the cross-linked network.
 So different benzoxazines like
BPCF, BOTF, BMCF and BPBF were used to
investigate curing behaviour of DGEBA and
results are shown in following tables:

19. Table 1.2: Results of DSC scans of DGEBA in the presence of
BOTF
Resin Ti Tonset Tp Tf ∆H
Designation (oC) (oC) (oC) (oC) (J/g)
DBOTF-31 147.8 160.6 202.4 241.9 67.8
DBOTF-11 138.4 157.4 198.6 253.6 70.5
DBOTF-13 115.5 127.4 177.3 205.4 27.9
Table 1.3: Results of DSC scans of DGEBA in the presence of BPCF
Resin Ti Tonset Tp Tf ∆H
Designation (oC) (oC) (oC) (oC) (J/g)
DBPCF-31 121.9 175.6 220.5 280.7 125.6
DBPCF-11 147.6 165.7 218.4 265.4 122.5
DBPCF-13 128.9 159.4 202.7 288.4 168.6

20. Table 1.4: Results of DSC scans of DGEBA in the presence of BMCF
Resin Ti Tonset Tp Tf ∆H
Designation (oC) (oC) (oC) (oC) (J/g)
DBMCF-31 167.6 172.4 213.4 266.9 44.4
DBMCF-11 146.5 166.8 211.4 251.4 83.5
DBMCF-13 151.4 159.4 207.9 277.4 67.3
Table 1.5: Results of DSC scans of DGEBA in the presence of BPBF
Resin Ti Tonset Tp Tf ∆H
Designation (oC) (oC) (oC) (oC) (J/g)
167.6 172.6 212.5 261.5 28.5
DBPBF-31
DBPBF-11 95.7 99.1 173.5 254.8 54.9
DBPBF-13 74.5 99.5 154.3 254.8 141.2

21.  The results summarized in tables 1.2-1.5 clearly showed
that cross linking reactions were dependent on the structure
of benzoxazine monomers and the DGEBA and benzoxazine
monomer blend composition. However no definite trend
was observed for ΔH values as a function of molar ratios for
DGEBA and benzoxazine monomers.
 No exothermic transition was seen in the DSC scans of
cured polymer, thereby indicating the completion of cross
linking reaction. The following trend was observed in the
DSC scans of benzoxazine monomers alone:
BPCF ~ BMCF > BOTF > BPBF

22. CONCLUSION
Curing behaviour of DGEBA in the presence of different
benzoxazine monomers was found to be dependent on the
molar ratio of DGEBA and benzoxazine monomers in the
DGEBA-benzoxazine polymers. Cure temperature decreased
upon the addition of DGEBA to the benzoxazine