Mechanical and Thermal Properties of Acrylic Hydrazide
Cured Epoxy; In- Situ Polymerization
R. P. Yadav, P. C. Gope and P. L. Sah
Department of Mechanical Engineering, College of Technology,
G. B. Pant University of Agriculture & Technology, Pantnagar-263145, Uttranchal, India
E mail: [email protected] , Ph 91 9411159916
ABSTRACT
In the present investigation a series of acrylic hydrazide (AH) cured epoxy were synthesized at varying
concentration of acrylic hydrazide ranging from 11.5:1 to 6.14:1 (ER: CA, v/v %) through benzoyl peroxide
initiated in-situ polymerization method. In present investigation it has been observed that density of AH cured
epoxy composite is higher compared to hardener HY951 cured epoxy composite at same concentration of
curing agent. It is observed that acrylic hydrazide cured epoxy 9:1 & 7.33:1 (epoxy: acrylic hydrazide, v/v %)
have lower wear rate compared to hardener HY951 cured epoxy. Mechanical and thermal property of the
developed composite is found to be superior compared to composite made from commercially available
hardener HY951 cured epoxy CY230. It is found that composite developed with acrylic hydrazide cured epoxy
CY230 of ratio 9:1 & 7.33:1 have higher mechanical strength compared to HY951 cured epoxy composite. For
spectral characterization UV-VIS spectra and FTIR tests were conducted to study the stabilization of the
developed composites. DTA-DTG-TG tests were conducted to study the thermal properties of the composites.
Results are compared with HY951 cured epoxy composite. Properties are found to be superior than the
composite made from HY951 cured CY230.
INTRODUCTION
Recent advances in space and other technologies have continuous and growing need for composite materials
that could withstand under prolong wear without loss in their transparency. Since this need has emerged in
both civilian and military applications, therefore a number of industries and defense institutes have initiated and
sponsored research in this area [1-10]. Jordon [1] discussed the possibility of using composite material in a
mass production industry where material cost is a big factor i.e. automobile industry. Steijn [2] has given an
exhaustive account of polymer science, polymer friction and wear. To substantiate his arguments on various
aspects, he has reported to a number of studies/experimental work carried out by various eminent researchers
in this field. Lancaster [3] carried out various wear tests on a polymeric material and reported that in early
stages of sliding the volumetric rate of wear is strongly dependent on properties of the counterface. Holmberg
et al. [4] carried out friction and wear study of a several commercially available polymers material groups, such
as polymides (Nylons), PTFE, Polyethylene etc.
Wears are generally classified based either on the phenomena observed or on the causative agents believed to
be responsible i.e. cohesive wear and adhesive wear. Cohesive wear processes include those mechanisms
which involve the dissipation of frictional work and its resultant damage in relatively large volumes adjacent to
interface. Abrasion and fatigue wear fall within this category. One form of wear that is present only in polymeric
materials is interfacial thermal decomposition due to their poor thermal conduction characteristics. The addition
of fillers to basic polymers improves their thermal conductivity and in turn reduces this type of wear. Epoxy
resins are pre-polymers that react with curing agent to yield high performance thermosetting system. These
composite display wide usage as engineering materials largely due to their inexpensive nature, ease of casting,
high mechanical strength and toughness along with large recoverable deformability, chemical analysis,
flexibility addition with others materials, electrical insulation and low shrinkage upon care . By
phenomenological wear we mean the type of wear which is actually observed and measured. The behavior
encountered ranges from the crude qualitative observations of ordinary experience to the highly sensitive
measurement of the rigorously controlled laboratory experiments. Phenomenological wear is based on four
types of motion that can be identified in the mechanical interaction of contacting surface: pure sliding;
sliding/rolling; pure rolling and impinging motion. In pure sliding the contact region remains fixed on the
stationary body and travels along the rubbing patch on the moving body. A familiar example of this kind of
contact is found in a stationary pin running on a rotating disc or a ring and it is used in the present experimental
analysis.
1
MATERIAL & METHOD
Composite materials are cast with hardener Acrylic Hydrazide (AH) cured with epoxy (CY230) at varying
concentrations of AH ranging 8 –14%, volume to volume. The hardener Acrylic Hydrazide (AH) was prepared
in a round bottom flask (500ml) equipped with condenser, water source and calcium chloride drying tube, by
ethyl acrylate (1.08 mole), hydrazine hydrate (99%, 1.45 mole) and hydroquinone( 1.0 g). The contents were
thoroughly mixed with dry ethanol (50 ml) and were refluxed for 6- 8 hours. AH as light brown syrup was
isolated through distillation of the contents at 20 mm Hg/100oC.
A series of composition of epoxy resin and AH ranging 8-14% volume to volume were separately mixed with
BZ2O2 (0.5 g) and heated at 85o C for one hour. At this stage, a highly viscous solution formed was poured into
moulds of specified dimensions, where a composite was solidified. In present investigation, developed
composites are designated as C1, C2, C3 and C4 for 8%, 10%, 12% and 14% concentration of AH cured in
epoxy volume to volume respectively.
The commercial composite is developed by heating of epoxy at 85oC for one hour. Thereafter it was cooled to
o
45 C and a commercially available hardener HY951 (10% v/v) was added to epoxy resin where a highly
viscous solution was produced. It was immediately poured into the moulds of specified dimensions. Developed
composite is designated composite C0. Composites developed so are then used for testing for wear,
mechanical, thermal etc properties.
RESULTS AND DISCUSSION
Wear test were conducted at different hydraulic end load and disc speed in dry environment at room
temperature. The variation of wear volume with time elapsed at hydraulic end loading 53.09 N and disc speed
230 rpm for different composites i.e. C0, C1, C2, C3 and C4 are shown in Fig.1. The results indicate that C1 and
C4 have higher wear volume compared to C0 while C2 and C3 have less wear volume at a given time. C2 has
least wear volume compared to other composites. This indicates that C2 has higher wear resistant than others.
The material C0 is cured with 10% HY951 epoxy resin CY230 and C2 is cured with 10% of newly developed
hardener AH with epoxy CY230. The base material for C0 and C2 are same. It is found that the deformation
time of this newly developed composite is also higher than commercial available composites.
10
W ear vo lu m e (m m 3 )
9
C0
C1
C2
C3
C4
Poly. (C4)
Poly. (C0 )
Poly. (C3)
Poly. (C2)
8
7
6
5
4
3
2
1
0
0
30
60
90
120
150
180
210
240
270
300
Wear time(sec.)
Fig. 4.1
volume
(mm3for
) Vs
Wear time
(sec.) for
HY 951
and
Cured
FigWear
1 Wear
properties
different
composites
(Load
53.09
N, AH
speed
232Epoxy
RPM) composites
Hydraulic end load =1.0 bar (53.09N)
Disc speed= 232 r.p.m.
2
SPECTRAL CHARACTERIZATION
UV-vis Spectra
Acrylic hydrazide shows maximum absorption at 285 nm and epoxy at 291 nm. Composite formed by curing of
epoxy with acrylic hydrazide shows common absorption at 285 nm for the composite (C2 & C3). Composite C4
shows absorption at higher wave length 288 nm. Commercially available hardener HY 951 shows at 294 nm
whereas epoxy at 291 nm, absorption at 291 nm of Bisphenol-A. That was shifted to 285 nm for composite C0.
(Fig. 2).
2.5
C0
C2
AH
Ep
2
HY
BA
Absorbance
C3
C4
1.5
1
0.5
0
240
250
260
270
280
290
300
310
320
330
340
350
Wave Length (nm)
Fig. 4.6 UV-vis spectrum of HY951, AH, Epoxy, Bisphenal -A and Related
Fig. 2. UV – vis spectrum of HY951, AH, Epoxy, Bisphenal-A and related composites
composites
FTIR
Acrylic hydrazide shows characteristics FTIR absorptions corresponding C-N stitching (1047.4, 1084.8 cm-1);
-1
-1
-1
N-H bending (1530.1 cm ); C-H bending (1420.1, 1379.5 cm ); C=C stitching (1622.2 cm ); C=O
(1665.5 cm-1) and a noise wide band corresponding to NH-NH2 in the range to (3429.1, 3211.1 cm-1). These
UV-vis and FTIR absorptions confirmed the formation of acrylic hydrazide. Commercial epoxy (CY230) shows
characteristic absorptions corresponding to C-O stitching (1118.3, 1319.9 cm-1). C-H bending (1475.5 cm1
); C-H stitching for aromatic ring (1655.3 cm-1) and due to epoxy group at (3402.4 cm-1) (Fig. 4). Composite C0
has shifted C-O stitching in epoxy from (1118.3 cm-1 to 1029.1 cm-1); C-H bending (1319.9 to 1351.5 cm-1)
-1
-1
aromatic C-H stitching (1655.3 to 1594.5 cm ) and O-H absorption at (3434.7 cm ). The acrylic hydrazide
cured epoxy FTIR absorptions have shown substantial shifting. Composite C2 shows absorptions
-1
-1
corresponding to C-O stitching at (1024.7 cm ) C-H bending (1381.8, 1351.3 cm ) aromatic C-H stitching
-1
-1
(1593.5 cm ) and O-H stitching (3430.5 cm ) (Fig. 5).
DTA-DTG-TG
Composite C0 shows a week endothermic with heat of thermo oxidation at 1169 mJ/mg at 534oC .
Replacement of CY951 with acrylic hydrazide result the composite with two stage DTA endothermic. In this
o
case first endothermic appeared at 411 C with heat of thermo-oxidation 178 mJ/mg (Fig. 6). Composite C4
o
shows monotonous DTA endothermic at 534 C with highest heat of oxidation at 1574 mJ/mg.
3
Composite C0 shows quartrat DTG in the temperature range 399 oC to 421oC with corresponding rate of
o
decomposition 1.852 to 0.68 mg/min . Composite C2 shows a sharp DTG at 411 C with rate of composition 8.3
mg/min. Pair of DTG profile was observed for composite C4 relatively at higher temperature with lower rate of
o
decomposition then the composite C2. In this case first DTG profile was appeared at 426 C with rate of
o
decomposition 1.5 mg/min. (sharp) and 531 C with rate of decomposition 0.2 mg/min.
TG profile indicates all three composites show three stage decomposition. Composite C0 shows initial
o
decomposition at 109 C with 97.67 residues. This composite was gradually decomposed at first stage up to
399 oC with 45.49% residue. At the second stage decomposition was started with multiple steps and narrow
o
time intervals. This was continued up to 421 C with 11.9% residue. Beyond this stage composite was
decomposed with slow rate of third stage of decomposition. TG of composite C2 shows initial decomposition at
o
107 C with 97.98% residue. This was relatively at lower temperature due to hygroscopic nature of hydrazide
linkages. second stage decomposition of same epoxy was recorded at 409 oC with 40.1% residue (Fig. 6). This
was relatively higher temperature than composite C0. Second stage decomposition of epoxy comparatively
faster than the composite C0. Composite C4 was highly hygroscopic with week decomposition stages. In this
o
case first stage decomposition started at 101 C with 98.13% residue. Second stage decomposition of this
composite highest among all and appeared 425 oC with 38.75% residue. These observations clearly indicate
that highest heat of thermo-oxidation was recorded in the composite C4 followed by composite C0 and C2.
Highest DTG profile was recorded composite C4. TG data indicates the among all the three most stable
composite was C4.
Fig. 3 FTIR Spectrum of Acrylic Hydrazide
4
Fig. 4. FTIR Spectrum of Epoxy (CY230)
Fig. 5 FTIR Spectrum of Composite C2
5
Fig. 6 DTA-DTG-TG Spectrum of Composite C2
CONCLUSIONS
On the basis of the present investigation following conclusions are drawn.
1.
Composite materials developed by AH cured epoxy synthesized at varying concentration of acrylic
hydrazide ranging 11.5:1 to 6.14:1 (ER:CA, v/v%) through benzoyl peroxide initiated in-situ
polymerization method shows better mechanical and thermal properties compared to the composite
developed with HY951 cured with epoxy.
2.
AH shows maximum absorption at 285 nm, epoxy 291 nm, cured epoxy with HY951 at 285 nm, and
AH cured composites C2 & C3 at 285 nm.
3.
Acrylic hydrazide as new curing agent for epoxy resin was synthesized and characterized through UVvis, FTIR.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
Jordan, A. 1987. Mass Production Composites, 6th international conference on composite materials,
ICCM and ECCM, Vol.1.pp.1.1-1.4.
Steijn, R.P. 1967. Metals Eng. Quart, Vol. 7, pp.9, pp.371-383
Lancaster, J.K. 1972. Tribology, Vol.5, pp.249-255.
Holmberg, K. and Wickstrom, G. 1987. Wear, Vol.115, pp.95-105.
Saran, Sanjeev. 1991. Experimental investigation of filled PTEE under different conditions. M. Tech
Thesis G.B.P.U.A& T., Pantnagar. pp.12-25.
Chatteauminois,B.; Chabert, J.P. and Vencent, L. 1995 Journal of Polymer Composites Vol 16(IV)
pp.288-296.
Friedrich, K.1992. Friction and wear of polymer composites, Elsevier Sci. Publications, Vol 1, pp.1466.
Gould, R.F.(ed.) 1970. Epoxy resins (Advances in chemistry series No.92). American Chemical
Society, Washington.
6
9.
May, C.A. and Tanaka, Y.(eds.) 1973). Epoxy Resin: Chemistry and Technology, Marcel Dekker,
New York.
10. Zaidi, Mohd. G.H. 1998. Oriental J.Chem., Vol.14 (1), 177-178. Chem. Abstr.Vol.129 (14), pp. 737.
7