POLYPYRROLE NANOCOMPOSITES FOR ENHANCING COOLING AND THERMAL INSULATING PROPERTIES OF ETHANOL

Abstract

TITLE OF THE INVENTION Polypyrrole Nanocomposites for Enhancing Cooling and Thermal Insulating Properties of Ethanol ABSTRACT Thermal diffusivity is a measure of how quickly heat spreads through a material. It is defined as the thermal conductivity divided by the product of density and specific heat capacity. The thermal diffusivity of ethanol at room temperature (25°C) is approximately 0.887x 10'7 m2/s Ethanol is sometimes used as a coolant due to its favourable thermophysical properties, such as a relatively high heat capacity and low freezing point (-114.1 °C). Its specific applications are 1) cryogenics and low-temperature systems: ethanol can be used in mixtures with other coolants to achieve very low temperatures without freezing, making it suitable for cryogenic applications, 2) automotive and aerospace: in some high-performance engines and aerospace applications, ethanol can serve as a heat transfer fluid and its low freezing point ensures functionality in extremely cold conditions, 3) electronics cooling: ethanol can be used in liquid cooling systems for electronics, providing efficient heat transfer while maintaining a safe operating environment due to its relatively low boiling point, 4) laboratory and industrial processes: ethanol is often used in laboratory settings for cooling baths and in industrial processes where precise temperature control is required. We have synthesised binary nanocomposites of polypyrrole silver and polypyrrole graphene and ternary composites of polypyrrole silver graphene with different concentrations of graphene. For synthesising both binary as well as ternary composites we used a simple one-pot chemical oxidative polymerisation method. Using a very sensitive and accurate thermal lens technique thermal diffusivity measurements were conducted taking ethanol as a base fluid. Both binary composites polypyrrole silver and polypyrrole graphene exhibited a thermal diffusivity values of 1.601 xlO’7 m2/s and 1.973 xlO'7 nr/s Thus, by adding this binary composite to ethanol we can enhance the heat transfer properties and this nanofluid can serve as a better coolant. But for the ternary composite with varying concentrations of graphene, as graphene concentration increases thermal diffusivity decreases. At 2wt.%, 2.5wt.% and 5wt.% graphene in the sample reduces the thermal diffusivity to 0.73 x 10'7 m2/s, 0.64 x 10'7 nr/s and 0.61 x IO’7 m2/s respectively which is lower than that of pure ethanol. These ternary composites containing nanofluid can be used as thermal insulators. But 0.2wt.% graphene-containing sample showed a thermal diffusivity value of 2.58 x 10'7 m2/s which is greater than that of the base fluid ethanol and this property can be utilised for making coolants. This study experimentally validates a laboratory-scale synthesis of the samples and determination of thermal diffusivity of nanofluid containing ethanol and different samples. Different techniques were used to comprehensively characterize the material's structural, optical, and compositional properties. Overall, this work presents a novel and cost-effective approach for synthesising polypyrrole silver and polypyrrole silver graphene nanocomposites for enhancing and reducing the thermal diffusivity of ethanol for coolant and thermal insulating applications.

Specification

PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL/COMPLETE SPECIFICATION
(See section 10 and rule 13)

1. TITLE OF THE INVENTION
Polypyrrole Nanocomposites for Enhancing Cooling and Thermal Insulating Properties of Ethanol

2. APPLICANT(S)
Name Nationality Address
a) VRINDA S PUNNAKKAL INDIAN Sree Sankara College, Union
Christian College, Ernakulam
Kerala, India
28-Oct-2024/130827/202441082215/Form 2(Title Page)
b) AN1LA E I INDIAN
Department of Physics &
Electronics
CHRIST (Deemed to be
University)
Hosur Road
Bangalore
Karnataka
India-560029
3. PREAMBLE TO THE DESCRIPT ON
^^-^PROVISIONAL
The follovvirTg-specification describes
the invention.
COMPLETE
The following specification particularly
describes the invention and the manner in
which it is to be performed.
4. DESCRIPTION (Description shall start from next page.)
ATTACHED

5. CLAIMS (not applicable for provisional specification. Claims should start with
the preamble- "1/ We claim" on separate page)
ATTACHED
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
Date: 24th October 2024
(1) VRINDA S PUNNAKKAL(2) AN1LA E I
28-Oct-2024/130827/202441082215/Form 2(Title hage)
7. ABSTRACT OF THE INVENTION (to be given along with complete
specification on separate page)
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TITLE OF THE INVENTION
Polypyrrole Nanocomposites for Enhancing Cooling and Thermal Insulating Properties of Ethanol

DESCRIPTION
FIELD OF THE INVENTION
[0001] This work presents a cost-effective approach for synthesising polypyrrole silver, polypyrole graphene and polypyrrole silver graphene nanocomposites for enhancing and reducing the thermal diffusivity of ethanol for coolant and thermal insulating applications.

BACKGROUND OF THE INVESTIGATION
[0002] Polymer composites have garnered significant attention due to their broad range of applications. Understanding the characteristics of these composites is crucial for their effective use in specific applications. One key property is thermal conductivity, which plays a vital role in determining a material's thermal behavior; however, measuring thermal conductivity can be challenging. Thermal diffusivity, defined as a material's ability to transfer thermal energy relative to its storage capacity, is the ratio of thermal conductivity to the product of density and specific heat capacity at constant pressure. Many industries rely on the thermal diffusivity of materials to select those that facilitate efficient heal transfer. Materials with low thermal diffusivity are particularly valuable in applications requiring thermal insulation. Several methods exist for determining thermal diffusivity, with the thermal lens technique being one of the most sensitive. This technique directly measures the optical energy absorbed and requires only a small sample volume.

[0003] The thermal diffusivity of ethanol at room temperature (25°C) is approximately O.887x 10'7 m2/s. Ethanol is sometimes used as a coolant due to its favourable thermophysical properties, such as a relatively high heat capacity and low freezing point (-114.1 °C). Its specific applications are 1) cryogenics and low-temperature systems: ethanol can be used in mixtures with other coolants to. achieve very low temperatures without freezing, making it suitable for cryogenic applications, 2) automotive and aerospace: in some high-performance engines and aerospace applications, ethanol can serve as a heat transfer fluid and its low freezing point ensures functionality in extremely cold conditions, 3) electronics cooling: ethanol can be used in liquid cooling systems for electronics, providing efficient heat transfer while maintaining a safe operating environment due to its relatively low boiling point, 4) laboratory and industrial processes: ethanol is often used in laboratory settings for cooling baths and in industrial processes where precise temperature control is required.

[0004] If the thermal insulating properties of ethanol were improved, it might be possible to use it in some specific applications. However, there are major challenges involved in making ethanol a viable thermal insulator. There are certain challenges to overcome to enhance ethanol's insulating properties and the feasibility of using it in applications. Ethanol's thermal conductivity would need to be signi ficantly reduced. This could be done by altering its structure at the molecular level, adding insulating additives, or using ethanol in combination with other materials to slow heat transfer. If the challenges were overcome, ethanol could find niche use in chemical and biological insulation. In specific environments where ethanol's chemical properties are advantageous such as in laboratory settings, ethanol-based insulators might have a role, particularly if mixed with other insulating agents.

[0005| Polypyrrole composites have been made to tune.their properties to make them suitable for various applications such as biosensors, gas sensors, supercapacitors, photocataiysis, thermoelectric power generators, and many more We do not find any literature that conducted a thermal diffusivity study of this potential ternary and binary composites Ppy/Ag/Gr, Ppy/Ag and Ppy/Gr. In this work for the first time, we report the thermal diffusivities of the simple one-pot synthesised polypyrole composites by a highly sensitive mode-matched thermal lens method. The base fluid used for this study is ethanol. We can enhance as well as reduce the thermal diffusivity of ethanol by adding the synthesised samples and thus can find applications in heat transfer devices and thermal insulators.

MOTIVATION AND CONTRIBUTION
[0006] Pursuing advanced thermal management materials is crucial across a wide range of industrial and technological applications. Specifically, optimizing the thermal properties of ' fluids used in heat transfer systems, such as coolants, and materials for thermal insulation plays a pivotal role in enhancing energy efficiency and performance. Ethanol, widely recognized for its desirable thermophysical properties such as low freezing point, high volatility, and ease of availability, is often considered a viable candidate for coolants and thermal insulators. However, ethanol's inherent thermal diffusivity may not always be suitable for every application. Tailoring its thermal diffusivity could significantly broaden its practical use in these areas.

Polypyrrole (PPy) composites, known for their excellent thermal and electrical conductivity, chemical stability, and tunable properties, provide a promising approach for modifying the thermal diffusivity of ethanol. The ability to enhance or reduce ethanol's thermal diffusivity through the incorporation of PPy composites offers potential breakthroughs in two distinct application domains such as coolants and thermal insulators. This study is motivated by the need to tailor ethanol's thermal diffusivity for these applications. Investigating the effect of adding polypyrrole composites provides an innovative approach to enhancing or reducing ethanol's thermal properties, which could lead to more efficient coolants and advanced thermal insulators.

BRIEF SUMMARY OF INVENTION
[0007] The present study is focused on developing polypyrrole composite materials synthesized by a simple one-pot method for tuning the thermal diffusivity of ethanol for two different applications. For the synthesis of Ppy/Ag, 20 ml of distilled pyrrole was mixed with 1.5 g of
silver nitrate (7.5wt.%) and this mixture was heated to 100°C for 4h by placing the test tube containing the mixture in a water bath. The precipitate formed was filtered and washed with chloroform ethanol and distilled water. This filtered precipitate was then dried for 6h in a 60°C oven. The 99% pure research-grade graphene was purchased from Adnano Technologies: For synthesising the Ppy/Gr composite, 0.1 g of graphene was mixed with 0.2 M of distilled pyrrole and to this an aqueous solution of 0.6M of ferric chloride was added and stirred continuously at 0°C using a magnetic stirrer for lh. The filtered precipitate was washed several times and dried forbh in an oven at 60°C. A mixture of 20 ml of distilled pyrrole, 0.04 g of graphene (0.2wt.%), and 1.5g of silver nitrate was heated to 1UU°U m a water bath for 4h. The filtered precipitate was washed with chloroform and ethanol and dried at 60°C by placing it in an oven for 6h. The sample obtained was named Ppy/Ag/Gr (0.2wt.%). Samples with different weight percentages of graphene were synthesised and named Ppy/Ag/Gr (0.5wt.%), Ppy/Ag/Gr (lwt.%), Ppy/Ag/Gr (1.5wt.%), Ppy/Ag/Gr (2wt.%), Ppy/Ag/Gr (2.5wt.%) and Ppy/Ag/Gr (5wt.%).

[0008] In this investigation/ the thermal diffusivity of nanofluid of ethanol and polypyrrole composites was found using a highly accurate and sensitive mode-matched thermal lens technique. In this technique a pump source of continuous wave laser of wavelength 488 nm and power of 50 mW and a probe source of solid-state laser of wavelength 632 nm and maximum power of 30 mW was used. The power of these sources was reduced using neutral density filters to avoid lens abeiration. A mechanical shutter was used to generate changes in the intensity of the pump beam. For mode-matched thermal lens formation, a convex lens of 20 cm focal length was used to focus two beams into the sample cell to get the same areas of the beams in the sample cell. The pump and the probe were suitably placed, and a beam splitter was used to get the same path for the beams from the two sources. 1 mg of each sample was added to 1 ml of ethanol and to disperse the sample in the base fluid the mixture was ultrasonicated for 30 min. This nanofluid was taken in a cuvette in which the path length was 1cm. The thermal lens effect of the pump beam was analysed using the probe beam intensity. The signal after passing through the sample cell was collected and the pump beam was filtered out. The filtered probe signal was then connected to a phototransistor by optical fiber and to a digital storage oscillator. Math lab
software was used to determine the time constant tc by the theoretical fitting of the
experimental probe signal intensity values using the equation,
/(o = /»[ i - 0(1+£ r1 +102(x + «r2i_1
Thermal diffusivity (D) of the base fluid ethanol was calculated using the equation,
. D values of different samples were estimated using the equation
Dsample ~ Dcthanol ethanol
t-c sample

[0009] The thermal diffusivity of base fluid ethanol, binary composites Ppy/Ag, Ppy/Gr and
28-Oct-2024/130827/202441082215/Form 2(Title Page)
the ternary composites Ppy/Ag/Gr with varying concentrations of graphene are listed in the
table 1. The D value of ethanol is found to agree with those reported in the literature.. Thermal
diffusivity values of binary composites Ppy/Gr and Ppy/Ag are greater than that of the base
fluid. Among the different samples, the greatest thermal diffusivity of 2.58 xl0'7 nr/s is
obtained for the ternary composite Ppy/Ag/Gr (0.2wt.%). The synergistic effect of Ppy, Ag,
and.Gr in the phonon transport may be the reason for this enhancement of D value. The FESEM
image of this sample also supports this result as the chain-like structure provides an easy path
for the lattice phonons.

But as the concentration of graphene increases the D value decreases noticeably. It is evident
from the FESEM images that the graphene layers got agglomerated as the concentration of
graphene in the sample increased. The increase in the number of graphene layers restricts the
dominance of out-of-plane acoustic modes of phonon vibration which carries the absorbed heat
in graphene sheets. This may be the reason for the reduction in the thermal diffusivity in the
samples Ppy/Ag/Gr (0.5wt.% to 5 wt.%). When the graphene concentration increases from 1.5
wt.% to 5 wt.% the thermal diffusivity of the samples decreases below the thermal diffusivity
of the base fluid used. This property can be made use of in making them as thermal insulators.

Table 1. Values of probe beam shift (0), characteristic time constant (tc) and thermal diffusivity (D) of different samples
Sample
9
k (ms)
D (m2/s) x IO'7
Ethanol
-0.1000
678.08
0.763
Ppy/Ag
-0.0430
323.08
1.601
Ppy/Gr
-0.0495
262.09
1.973 ■
Ppy/Ag/Gr(0.2wt.%)
-0.0447 ■
200.43
2.580
Ppy/Ag/Gr(0.5wt.%)
-0.0515
570.29
0.900
Ppy/Ag/Gr(lwt.%)
-0.0914
582.01
0.880
Ppy/Ag/Gr(1.5wt.%)
-0.0877
675.31
0.756
Ppy/Ag/Gr(2wt.%)
-0.0810
703.84
0.730
Ppy/Ag/Gr(2.5wt.%)
-0.0839
812.79
0.636
Ppy/Ag/Gr(5wt.%)
-0.1506
820.01
0.610

CLAIMS
[0010] We claim,
1. Binary composites polypyrrole silver (Ppy/Ag) polypyrrole graphene (Ppy/Gr) and - ternary composites of polypyrrole, silver and graphene (Ppy/Ag/Gr) with different concentrations of graphene can be synthesised by simple cost-effective method for photothermal applications.

2. A highly sensitive and accurate thermal lens technique is used for the first time to find the thermal diffusivity of nanofluid containing the base fluid ethanol and the synthesised samples.

3. The binary composites Ppy/Ag, Ppy/Gr and the ternary composite Ppy/Ag/Gr with 0.2wt.% graphene exhibits thermal diffusivity values of 1.6 xlO'7, 1.97 xlO'7, 2.58 xlO* 7m2/s respectively for a small volume fraction of Img of the sample in ImL of ethanol.

4. The thermal diffusivity of ethanol at room temperature is 0.887 x 10"7 m2/s. Thus, adding these samples can enhance the thermal diffusivity of ethanol.

5. Ethanol can be used as a heat transfer agent in many applications for which enhancement in thermal diffusivity is desirable. Thus Ppy/Ag, Ppy/Gr and Ppy/Ag/Gr (0.2wt.%) can be utilised for making better coolants.

6. The ternary composites Ppy/Ag/Gr with 1.5 wt.%, 2 wt.%, 2.5 wt.% and 5 wt.% graphene the thermal diffusivity values obtained are 0.77 xl0'7, 0.73 xlO'7, 0.64 xlO'7, 0.61 xlO"7 m2/s respectively.

7. These values are less than the thermal diffusivity of the base fluid ethanol. Thus, adding the samples with greater concentrations of graphene thermal diffusivity values of ethanol can be reduced.

8. The thermal insulators should have low thermal diffusivity values. The ternary composites (Ppy/Ag/Gr) containing 1.5wt.%, 2wt.%, 2.5wt.% and 5wt.% graphene reduces the thermal diffusivity values below the value of pure ethanol and therefore can be used for making thermal insulators.

9. The laboratory scale measurement of the thermal diffusivity of the synthesised samples is reported here for the first time.

10. Economically viable synthesis of these samples and their uses in making coolants and insulators is also reported for the first time.

BRIEF DESCRIPTION OF DRAWINGS
[0011] This study utilizes figures to clarify and interpret the findings. These visual aids play a key role in supporting the claims made throughout the report, enabling a thorough analysis of the experimental results.
Figure 1: Photoluminescence spectra of Ppy/Ag, Ppy/Grand Ppy/Ag/Gr composites.
Figure 2: Raman spectrum of graphene, Ppy/Ag, Ppy/Gr, and Ppy/Ag/Gr.
Figure 3: Field Emission Scanning Electron microscope images of graphene, Ppy/Gr, Ppy/Ag, Ppy/Ag/Gr(0.2wt%), Ppy/Ag/Gr(2.5wt.%) and Ppy/Ag/Gr(5wt.%)
Figure 4: Thermal lens response curves of the output probe signal of base fluid ethanol, Ppy/Ag, Ppy/Grand Ppy/Ag/Grcomposites.

DETAILED DESCRIPTION
[0012] The PL spectrum of the samples was taken with an excitation wavelength of 488 nm.
One emission peak at 547 nm and a small peak at 734 nm were observed in the spectrum. The
547 nm peak is due to the intrachain excitons, also known as polaron-excitons. Polarons are
electron-hole pairs weakly bound together and coupled to local deformations of the conjugated backbone of polypyrrole. These singlet excitons, in turn, are responsible for efficient radiative recombination. A quenching of the intensity of the peak at 547 nm was observed in Figure 1 for the Ppy/Gr binary composite as well as for the ternary composite Ppy/Ag/Gr as the graphene concentration increased. Graphene accepts electrons at the composite's interface, which may be the reason for the quenching effect. The presence of graphene in the composite plays an important role in quenching PL intensity considerably. In the molecular structure of a pure graphene cluster, all the carbons are sp2 hybridized. The overlap of the p-orbitals from these sp2 carbons forms a te bonding orbital and a it* antibonding orbital, analogous to the valence and conduction bands. In graphene oxide, a finite number of carbons are oxidized to sp3 hybridization. These sp3 carbons distort the graphene structure and introduce disorder-induced defect states. These states have lower energy than the n-ir* gap and exhibit a broad energy distribution, which is responsible for the pho to luminescence peak centered at 734 nm. As the graphene concentration in the composite increases the intensity of this peak also increases

[0013] Figure 2 depicts the Raman spectrum of Ppy/Ag, Ppy/Gr, and the ternary composite Ppy/Ag/Gr. All the characteristic peaks of Ppy are observed in Ppy/Gr and Ppy/Ag/Gr samples. The peak observed at 1578 cm'1 corresponds to C=C stretching, and it is also ascribed to the G band of graphene. The G band of graphene is shifted from 1585 cm'1 to 1578 cm''in the spectrum of the composites. This red shift of the G band indicates good coordination of Ppy, Ag and Gr in the composite. Three small peaks, at 976 cm'1, 1048 cm'1, and 1418 cm'1 were not seen in the Ppy/Ag sample. The high-energy laser source used in Raman spectroscopy may pierce into the polymer matrix and silver particles in the composite may reflect this light. This may be the reason for the absence of some of the peaks of polypyrrole in Ppy/Ag sample. Compared to Ppy/Ag/Gr sample, silver concentration is higher in Ppy/Ag and this is the reason for the absence of these peaks only in Ppy/Ag.

[0014] Morphological studies of the samples were done by taking field emission scanning electron microscopic (FESEM) images as shown in Figure 3. The images of the graphene that we used for the synthesis of Ppy/Gr and Ppy/Ag/Gr exhibit a sheet-like structure. In the FESEM image of Ppy/Gr spherical polypyrrole particles can be seen on the graphene sheets. Ppy/Ag sample's morphology exposed a tubular or rod-like structure for polypyrrole since the polymerisation technique used was different from that for Ppy/Gr sample. The nodule-shaped structure may be that of silver nanoparticles. The ternary composite Ppy/Ag/Gr(0.2wt.%) displays a tubular chain-like structure of polypyrrole with bright spots of silver particles on the graphene sheet. With higher concentrations of graphene (2.5 wt.% and 5 wt.%) structure of polypyrrole and -silver was not seen. These structures may be embedded in the agglomerated sheets of graphene

[0015] Figure 4 represents the thermal response curves for the base fluid ethanol and for all the synthesised polypyrrole composites containing nanofluids. In this figure the thermal lens probe signal intensity is plotted with time. The experimental values are fitted with the theoretical values and from this fitted data we can calculate characteristic time constant tc using math lab software.

PRODUCT EVALUATION
[0016] Enhancing the coolant and thermal insulating properties of ethanol is significant for several industrial applications due to its wide use in processes where temperature regulation is critical. In applications such as heat exchangers, refrigeration, and chemical processing, ethanol serves as a coolant due to its relatively low freezing point and good heat transfer properties. Enhancing these properties allows for more efficient heat transfer, leading to faster cooling and heating rates. Improved coolant efficiency reduces the energy required to maintain optimal temperatures, cutting down energy consumption and operational costs.By improving ethanol's ability to retain or reject heat, it can be used over a broader temperature range. This is crucial in industries such as pharmaceuticals, cryogenics, or distillation, where precise temperature control is critical for product quality and.process stability. Ethanol's thermal properties can influence the materials selected in industrial systems, if ethanol's cooling properties are enhanced, it can reduce the need for highly specialized, expensive materials that resist heat-induced corrosion, lowering costs and extending equipment lifespan. Enhanced thermal insulation properties of ethanol are useful in cryogenics and low-temperature storage. With better insulation, ethanol can effectively slow down heat transfer, preserving the temperature stability of sensitive products like biological samples, vaccines, or chemicals. Ethanol is less harmful than many conventional coolants like ethylene glycol, which are toxic. Enhancing its coolant and thermal properties

could lead to greener solutions in industries like HVAC, where environmental sustainability is a
growing concern. Enhanced thermal properties ensure more stable operation, reducing risks
associated with overheating or freezing in processes. This stability is essential for industrial
safety, especially in processes where volatile chemicals are involved. In industries such as
petrochemical refining and distillation, enhancing the coolant properties of ethanol allows for
more efficient separation and purification processes. Better thermal regulation directly leads to higher throughput and productivity. Overall, improving the coolant and thermal insulating properties of ethanol can result in significant economic, safety, and environmental benefits in various industrial processes, making it a critical focus for innovation.

[0017] The more sensitive thermal lens technique is successfully employed to determine the
thermal diffusivities (D) of the samples Ppy/Ag, Ppy/Gr and the ternary composites Ppy/Ag/Gr
with varying concentrations of graphene in a laboratory scale. It is observed that Ppy/Ag, Ppy/Gr Ppy/Ag/Gr(0.2wt.%) has the D values of 1.601 xlO'7 m2/s, 1.973 xl0'7 m2/s and 2.58 xlO'7 m2/s respectively with a small volume fraction of the nanofluid and they can be used as coolants. As
the graphene concentration increases there is a reduction in D value. At 2wt.%, 2.5 wt.%, and
5wt.% concentrations the D values decrease below the D value of the base fluid ethanol. Thus,
these concentrations can be used for thermal insulation which has potential applications in
industries. The absence of prior works related to the synthesized composite's application in
enhancing the coolant and thermal insulating properties of ethanol highlights the novelty of the proposed invention.

TITLE OF THE INVENTION
Polypyrrole Nanocomposites for Enhancing Cooling and Thermal Insulating Properties of Ethanol

Figure 1: Photoluminescence spectra of Ppy/Ag, Ppy/Gr and Ppy/Ag/Gr composites.

Figure 2: Raman spectrum of (a) graphene and (b)Ppy/Ag, Ppy/Gr and Ppy/Ag/Gr.

Figure 3: FESEM (a) graphene (b) Ppy/Gr (c) Ppy/Ag (d) Ppy/Ag/Gr(0.2wt%) (e) Ppy/Ag/Gr(2.5wt.%) (f) Ppy/Ag/Gr(5wt.%)

Figure 4: Thermal response curves of ethanol, Ppy/Gr, Ppy/Ag, Ppy/Ag/Gr(0.2wt.%), Ppy/Ag/Gr(0.5wt.%) and Ppy/Ag/gr(lwt.%).

TITLE OF THE INVENTION
Polypyrrole Nanocomposites for Enhancing Cooling and Thermal Insulating Properties of Ethanol
CLAIMS
[0010] We claim,
1. Binary composites polypyrrole silver (Ppy/Ag) polypyrrole graphene (Ppy/Gr) and ternary composites of polypyrrole, silver and graphene (Ppy/Ag/Gr) with different concentrations of graphene can be synthesised by simple cost-effective method for photothermal applications.

2. A highly sensitive and accurate thermal lens technique is used for the first time to find the thermal diffusivity of nanofluid containing the base fluid ethanol and the synthesised samples.

3. The binary composites Ppy/Ag, Ppy/Gr and the ternary composite Ppy/Ag/Gr with 0.2wt.% graphene exhibits thermal diffusivity values of 1.6 xlO'7, 1.97 xlO'7, 2.58 xl0'7m2/s respectively for a small volume fraction of Img of the sample in ImL of ethanol.

4. The thermal diffusivity of ethanol at room temperature is 0.887 xlO'7 nr/s. Thus, adding these samples can enhance the thermal diffusivity of ethanol.

5. Ethanol can be used as a heat transfer agent in many applications for which enhancement in thermal diffusivity is desirable. Thus Ppy/Ag, Ppy/Gr and Ppy/Ag/Gr (0.2wt.%) can be utilised for making better coolants.

6. The ternary composites Ppy/Ag/Gr with 1.5 wt.%, 2 wt.%, 2.5 wt.% and 5 wt.% graphene the thermal diffusivity values obtained are 0.77 xlO'7, 0.73 xlO'7, 0.64 xlO"7, 0,61 xlO-7 nr/s respectively.

7. These values are less than the thermal diffusivity of the base fluid ethanol. Thus, adding the samples with greater concentrations of graphene thermal diffusivity values of ethanol can be reduced.

8. The thermal insulators should have low thermal diffusivity values. The ternary composites (Ppy/Ag/Gr) containing 1.5wt.%, 2wt.%, 2.5wt.% and 5wt.% graphene reduces the thermal diffusivity values below the value of pure ethanol and therefore can be used for making thermal insulators.

Dated: 24/10/24
(1) VRINDA S PUNNAKKAL (2) ANILA E I

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