P. A. WASEKAR ET AL.
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tained without any purification or chemical modification
or surface treatment. Finalux G3 (wetting agent) was
obtained fr o m Fine Organics Ltd., M umbai, India.
2.2. Preparation of Composite
Concentration of cenosphere was varied upto 10 phr into
the nylon matrix. Firstly, dry blending of cenosphere and
nylon 6 was done in tumbler mixer for 15 - 20 min, using
finalux G3 as the wetting agent. Then the mix was melt
blended in a twin screw co-rotating extruder (Lab Tech
Engineering Co. Ltd., Germany) having L/D ratio of 32:1
and temperature profile from the hopper to the die as
170˚C, 190˚C, 200˚C, 210˚C, 220˚C, 230˚C, 240˚C and
250˚C. Extruded strands were water cooled at 30˚C and
pelettized. Pellets obtained were used for injection mold-
ing after pre-drying at 80˚C for 8 - 10 hrs. Injection
molding (Boolani machineries India ltd, Mumbai, India)
was done maintaining temperature profile as 210˚C,
230˚C and 250˚C from the hopper to the ejection nozzle.
Standard ASTM based samples for tensile, flexural and
impact testing were obtained from injection molding.
Samples for impact testing were notch cut before testing.
2.3. Characterization and Testing
2.3.1. Mechanica l Pro p e rties
Tensile properties; tensile strength and elongation at
break and flexural properties; flexural strength and flex-
ural modulus, were measured at ambient condition using
a universal testing machine (LR-50K, Lloyds Instrument,
UK), according to ASTM procedures D638 and D790; at
a crosshead speed of 50 mm/min and 2.8 mm/min re-
spectively. The notch for impact test was made using a
motorized notch-cutting machine (Polytest model 1, Ray
Ran, UK). Notched Izod impact strength was determined
at ambient condition according to ASTM D256 standard,
using impact tester (Avery Denison, UK) having striking
velocity of 3.46 m/s employing a 2.7 J striker.
2.3.2. Thermal Properties
Differential scanning calorimetry (Q 100 DSC, TA in-
struments Ltd., India) characterization was done to in-
vestigate the crystallization and melting behaviour of the
composite. Two consecutive heating scans were found to
minimize the influence of possible residual stresses in the
material due to any specific thermal history. Scanning
rate of 10˚C/min was maintained for both heating and
cooling cycle; whereas nitrogen gas purge rate main-
tained at 50 ml/min. Melting temperature was determined
from the second heating scan while the crystallization
temperature (Tc) from cooling scan.
2.3.3. Rheological Properties
The melt viscosity was measured using rotational rheometer
(MCR101, Anton Paar, India) with parallel plate assem-
bly having diameter of 35 mm. Samples were predried
before analysis. Viscosity was determined for sh ear rates
from 0.01 s–1 to 100 s–1 at the constant temperature of
250˚C.
2.3.4. M orp hologica l Properties
Scanning electron microscope (SEM) analysis was per-
formed with JEOL 6380 LA (Japan). Samples were frac-
tured under liquid nitrogen to avoid any disturbance to
the molecular structure and then coated with gold before
imaging.
2.3.5. X-Ray Diffr ac tion
The XRD analysis was carried out to determine the per-
centage crystallinity of the prepared co mposite. A normal
focus copper X-ray tube was operated at 30 kV and 15
mA. Sample scanning was done from 2.00˚ to 80.00˚ at
the rate of 3.00˚/min. The data processing was done us-
ing Jade 6.0 software.
2.4. Formulation
The formulations prepared are as shown in the Table 2.
Concentration of cenosphere was varied from 0 to 10 phr
of nylon 6, while concentration of wetting agent was
maintained constan t at 5 phr of nylon 6.
Table 1. Chemical composition of cenosphere obtained from Nasik thermal power plant.
Components Al2O3 SiO2 P
2O5 SO3 K
2O CaO TiO2 V
2O5 Fe2O3
wt% 24.559 50.300 0.409 0.060 6.765 1.109 5.129 0.102 11.566
Table 2. Formulation of cenosphere/nylon 6 composites.
Sr. No. Sample Name Nylon 6 (gm) Cenosphere (phr, gm) Wetting Agent (phr, gm)
1 VNY 500 0.0, 0.0 5, 25
2 NC 2.5 500 2.5, 12.5 5, 25
3 NC 5 500 5.0, 25.0 5, 25
4 NC 7.5 500 7.5, 37.5 5, 25
5 NC 10 500 10.0, 50.0 5, 25
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