FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
Nano composites with improved thermal conductivity and electrical
insulation.
APPLICANT
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
Bhattacharya Subhendu, Swain Sarojini, Sharma Ram Avatar and Chaudhari Lokesh; all of Crompton Greaves Ltd., Advanced Material and Processing Technology Centre, Global R&bD Centre, Bhaskara Building, Kanjur Marg (East), Mumbai 400 042, Maharashtra, India; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF INVENTION
This invention relates to the field of electrically insulating and thermally conducting
thermoset composites.
Particularly, this invention relates to nano composites comprising modified carbon
nanotubes for improvement in thermal conductivity and electrical insulation.
More particularly, this invention relates to the nano composites comprising allyl
modified carbon nano tube (ie CNT) for improvement in thermal conductivity and
electrical insulation.
This invention also relates to a simple, efficient and economical method for preparation of allyl modified CNTs.
BACKGROUND OF THE INVENTION
Conductive polymers have long been in demand and offer a number of benefits for a variety of applications due to their combined insulating and conductive properties. The conductive element of the conductive polymer includes additives like metallic powder or carbon black.
Thermoplastics being malleable and flexible have proven to be more commercially practical and viable option for conductive polymers. Thermoplastics are easy to mix with conductive additives to form a conductive thermoplastic polymer. Thermoplastics can also be softened upon heating so as to reshape the thermoplastic as necessary. However, thermoplastics lack the strength of thermosets, which crosslink to form stronger polymers. To overcome the said disadvantage associated with thermoplastic, recent technological developments permit the addition of cross linking agents to thermoplastics to endow the thermoplastic with greater strength.

However, such process has its own disadvantages such as extra cost, effort, experimentation, etc.
On the other hand, thermosets, which are more rigid and inflexible in nature, are difficult to mix with conductive additives to form a conductive thermoset polymer. Unlike thermoplastics, thermoset polymers are typically formed through a chemical reaction with at least two separate components. Once cured, however, a thermoset polymer is stronger than thermoplastic and is also better suited for high temperature applications since it cannot be easily softened, re-melted, or re-molded on heating like thermoplastics. Thus, conductive thermoset polymers offer the industry a much desired combination of strength and conductivity.
A sonication, stirring or milling are the preferred methods to disperse conductive additives in thermosets.
There are a number of known conductive additives in the art, including carbon black, carbon fibers, carbon fibrils, metallic powder, etc. Carbon fibrils have grown in popularity due to its extremely high conductivity and strength compared to other conductive additives. Carbon fibrils are commonly referred to as CNTs. They exist in a variety of forms. CNTs differ physically and chemically from continuous carbon fibers which are commercially available as reinforcement materials, and from other forms of carbon such as standard graphite and carbon black.
Epoxy, Unsaturated polyester resins (UPR) and polyurethanes are a commonly used thermoset polymer system used for a number of electrical/ high voltage applications. Also, nanocomposites have been used extensively over the past several years in the electrical / high voltage applications. Efforts have been made to modify the matrix properties by mixing in various nanoparticle materials.

The study of carbon nano-tubes (CNT) has become important due to the possibility of formulating high strength polymer composites from the same. In order to increase the performance of CNT based composites their dispersion and compatibility with the polymer matrix plays a large role.
Also, chemical modification of CNT has been reported in literature starting from the oxidation of CNT to result in carboxyl and hydroxyl modified CNTs to secondary modification with acid chlorides and amines. Recent literature has reported the use of carboxyl and hydroxyl functionalized CNT similar to organic molecules for the purpose of secondary reaction.
US 2008292531 disclose a method of chemically functionalizing multi walled CNT with carboxyl and allyl moieties by passing an electric current through a nanotube film. This generates defects on the nanotubes and exposes the nanotubes to a reactive film such that at least one chemical functional group is formed on the nanotube.
Also, CN 101440192 relates to a conductive / heat insulating composite material consisting of thermosetting phenolic resins, carbon nanotubes, hollow fibres and surfactant, which is obtained after dispersion of the nanotubes, preparation of a glue solution, preimpregation of the fibres and curing forming.
However, there is still need to developing nano composites comprising thermosets like unsaturated polyester resin (UPR), Epoxy and polyurethanes and the like and modified CNT having an improved electrically insulation and thermally conductivity. The object of the invention is not only to bring about increased interaction of the resins with the nanoparticles but also to bring about enhancement in mechanical properties like tensile and flexural strength as compared to the base resin. Additionally the electrically conducting nanoparticles are converted to electrically insulating nanoparticles by using proper encapsulation

Thus the present invention, which addresses the needs of the prior art provides a method of preparing a thermally conductive thermoset precursors containing CNTs.
OBJECTS OF THE PRESENT INVENTION
An object of the invention is to provide nano composites comprising allyl modified CNTs having improved electrical insulation and thermal conductivity.
Another object of the invention is to provide the nano composites comprising allyl modified CNTs, which will increases the interaction of allyl modified CNTs with base resin thereby improving mechanical properties like tensile, flexural strength, impact strength, glass transition temperature, etc as compared to that of the base resin.
Yet another object of the invention is to provide a simple and economical method for preparation of nano composites comprising allyl modified CNTs having improved electrical insulation and thermal conductivity.
Still another object of the invention is to provide a simple and economical method for preparation of nano composites comprising allyl modified CNTs having improved electrical insulation and thermal conductivity, which will increases the interaction of allyl modified CNTs with base resin.
An additional object of the invention is to provide a simple and economical method for preparation of nano composites comprising allyl modified CNTs having improved electrical insulation and thermal conductivity which leads to increase in mechanical properties like tensile and flexural strength as compared to that of the base resin.
Yet another additional object of the invention is to provide a simple, efficient and economical method for preparation of ally modified CNTs.

Still another additional object of the invention is to eliminate problems associated with the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates Fourier Transform Infra Red (FTIR) spectra of carboxy functional CNT and allyl modified CNT (ACNT).
Figure 2 illustrates variation in thermal diffusivity by using different concentration of ACNTs and CNTs against blank unsaturated polyester resin.
Figure 3 illustrates variation in surface resistivity by using different concentration of ACNT against blank unsaturated polyester resin.
Figure 4 illustrates variation in tensile strength of nano-composites by using different concentration of ACNTs and CNTs against blank unsaturated polyester resin.
Figure 5 illustrates variation in elongation at break by using different concentration of ACNTs and CNTs against blank unsaturated polyester resin.
Figure 6 illustrates variation in flexural strength by using different concentration of ACNTs and CNTs against blank unsaturated polyester resin.
Figure 7 illustrates variation in impact strength by using different concentration of ACNTs and CNTs against blank unsaturated polyester resin.
Figure 8 illustrates variation in Glass transition temperatures of nano composites by using different concentration of carboxyl functional ACNTs and CNTs against blank unsaturated polyester resin.

DETAILED DESCRIPTION OF THE INVENTION
Before the present invention is described, it is to be understood that this invention is not limited to particular methodologies and materials described, as these may vary as per the person skilled in the art. It is also to be understood that the terminology used in the description is for the purpose of describing the particular embodiments only, and is not intended to limit the scope of the present invention.
Before the present invention is described, it is to be understood that unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it is to be understood that the present invention is not limited to the methodologies and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described, as these may vary within the specification indicated. Unless stated to the contrary, any use of the words such as "including," "containing," "comprising," "having" and the like, means "including without limitation" and shall not be construed to limit any general statement that it follows to the specific or similar items or matters immediately following it. Embodiments of the invention are not mutually exclusive, but may be implemented in various combinations. The described embodiments of the invention and the disclosed examples are given for the purpose of illustration rather than limitation of the invention as set forth the appended claims. Further the terms disclosed embodiments are merely exemplary methods of the invention, which may be embodied in various forms.
It is also understood that the terms "a", "an", "the" and like are words for the sake of convenience and are not to be construed as limiting terms. Moreover, it will be understood that the illustrations are for the purpose of describing a particular exemplary embodiment of the invention and are not limited to the invention thereto.

The term "CNTs" or "CNT" as used herein intends to cover all kind of carbon nanotubes.
The term "ACNTs" or "ACNT" as used herein intends to cover all kind of allyl modified carbon nanotubes.
The term "UPR" as used herein intends to cover unsaturated polyester resin.
According to the invention, there is provided a method for preparation of nanocomposites with improved electrical insulation and thermal conductivity; the method comprises:
a) Preparing ACNTs by simple, efficient and economical process;
b) Preparing a dispersion by dispersing the ACNTs into a resin matrix or polymer matrix and subjecting it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion;
c) curing dispersed mixture to form nanocomposites by adding initiator to the degassed dispersion with stirring; and
d) Stabilizing the nano composites.
The dispersed mixture of step (b) is poured into desired moulds after adding initiator and used for curing. Alternatively the films are casted from the dispersed mixture of step (b) after adding initiator and used for curing.
Optionally, the films or moulds are post cured at temperature of 45°C-90°C. preferably, the films or moulds are post cured at temperature of 80°C
ACNTs dispersed in the resin matrix is in the range of 0.1 to 1.0% by weight.
The step (b) of dispersion is carried out at a controlled temperature of 25°C to 45°C.

Preferably, step (b) of dispersion is carried out at a controlled temperature of 25°C for 6 hours.
The step (c) of curing is carried out at 25°C to 40°C and under 25 to 60% Relative Humidity (R.H.).
Preferably, step (c) of curing is carried out at 25°C and 60% Relative Humidity (R.H.) for 12 hours.
The step (d) of stabilizing the composites is carried out at 25°C to 35°C and under 50 to 70 % Relative Humidity (R.H.).
Preferably, step (d) of stabilizing the composites is carried out at 25°C and 50% Relative Humidity (R.H.) for 7 days before carrying out any kind of testing.
The resin matrix or polymer matrix used is selected from but not limited to epoxy resin, unsaturated polyester resin, polyurethane resins, etc.
According to the invention, there is provided nanocomposites with improved electrical insulation and thermal conductivity; Said composites having
I. improvement in thermal diffusivity ranges from 25 - 45 %;
II. about 76% increase in the tensile strength in ACNTs based composites as compared to 30% increase in the case of CNTs based composites;
III. about 30 % of decrease in the elongation at break in ACNTs based composites
as compared to that of 15 % of decrease in the elongation at break in the nano
composites comprising CNTs; IV. about 84 % increased in the flexural strength in ACNTs based composites of
the invention as compared to a 33 % increased in the flexural strength in
CNTs based composites;

V. about 146 % increased in the impact strength in ACNTs based composites as compared to 66 % increased in the impact strength in CNTs based composites; and VI. about 11 °C increased of about glass transition temperature at concentration of 0.075% of CNTs and ACNTs.
According to another embodiment of the present invention, ACNTs used for preparing nano composites with improved electrical insulation and thermal conductivity.
The scope of the invention includes modification of CNT. In general such methods includes introduction of a chemical functional group (chemical moiety) onto the CNT.
The Scheme 1 illustrates schematic representation of preparation of modified ACNTs.
According to the present invention, there is provided a simple, economic and efficient
process for the production of ACNTs of step (a);
said process comprises:
i preparing a dispersion by dispersing the carboxyl functional CNTs of formula
(I) into a solvent; ii preparing a acid chloride CNTs of formula (III) by treating the dispersion
obtained in step (i) with thionyl chloride of formula (II) followed by distilling
off the unreacted thionyl chloride; iii preparing ACNTs of formula (V) by esterifying the acid chloride CNTs of the
formula (III) obtained in step (ii) with allyl alcohol of formula (IV); and iv isolating the ACNTs of formula (V) by distilling off allyl chloride from the
reaction mixture obtained in step (iii) followed by washing it with solvent and
drying it.


Scheme I
The step (i) of preparing the dispersion of the carboxyl functional CNTs of formula (I) is carried out by dispersing the carboxyl functional CNTs of formula (I) into a solvent and subjecting the dispersion to ultrasonication coupled with mechanical agitation at 1500rpm/5min.
The step (i) is carried out at a controlled temperature 25°C to 35°C for 2 hours.
Preferably, step (i) is carried out at a controlled temperature 25°C for 2 hours.
The solvent used in step (i) is selected from ethylene chloride, propylene chloride, etc.
According to the invention, the general step of dispersing the functionalized CNTs in a solvent may require selection of a solvent suitable for dispersing functionalized CNTs with a particular group. Such dispersion may further require mixing or mechanical agitation and/or ultrasonic assistance.

Particularly, the step (ii) of preparing the acid chloride CNTs of formula (III) by treating the dispersion obtained in step (i) with thionyl chloride of formula (II) with simultaneously stirring the reaction mixture using a magnetic stirrer followed by refluxing the reaction mixture for 24 hours and distilling off the unreacted thionyl chloride from it to obtain the acid chloride CNTs.
Particularly, the step (iii) of preparing the ACNTs of the formula (V) by esterifying the acid chloride CNTs of the formula (III) obtained in step (ii) with allyl alcohol of formula (IV) at 40°C to 65°C with simultaneous stirring the reaction mixture.
More preferably the step (iii) is carried out at 50°C for 24 hours.
Particularly, the step (iv) of isolating the ACNTs of the formula (V) by distilling
off allyl chloride from the reaction mixture obtained in step (iii) at temperature of
50°C to 80°C followed by washing it with solvent, centrifuging the washings to obtain
the residue, washing the residue with solvent, combining the residue with isolated
ACNTs and drying it at 50°C.
Particularly, the solvent used for washing the ACNTs is selected from acetone,
xylene, iso-propyl alcohol, ethyl alcohol, etc.
According to the present invention, the CNT may include but are not limited to, single-wall carbon nanotubes, multi-wall carbon nanotubes, double wall carbon nanotubes, buckytubes, fullerene tubes, tubular fullerenes, graphite fibrils or vapor grown carbon fibres, and combinations thereof.
According to the invention, the general step of removing the solvent from the reaction mixture to form a largely solvent-free mixture generally involves a distillation step.

According to the present invention, Figure 1 illustrates Fourier Transform Infra Red (FTIR) spectra of carboxyl functional CNT and ACNT. A broad peak as appearing in the range of 3000 to 3400 cm-1 indicates the presence of hydroxyl group of the carboxyl functional group in the carboxyl functional CNT. However, in the case of ACNT this peak was not present indicating the complete esterification of the carboxyl group by the allyl alcohol. In both cases, i.e. carboxy functional CNT and ACNT, a peak between 1740 and 1760 cm-1 was observed which corresponded to the C=0 stretching vibrations of the carboxyl and ester groups in carboxyl functional CNT and ACNT respectively. The FTIR spectra show that the esterification of the CNT was complete. The introduction of an allyl group in the ACNT results in two peaks at 2800-2900 cm-1 which is due to the C-H stretching vibrations. Further from the spectra, it can be seen that the modification of the CNTs did not result in destruction of the nano-particles.
According to the present invention, the incorporation of allyl modified CNT into resin matrix or polymer matrix leads to increase in interaction in the nano composites thereby increasing the mechanical properties like tensile strength and flexural strength. It is also contributed to improvement in thermal diffusivity. The nano composites comprising ACNTs of the invention is tested for its thermal diffusivity, Electrical Conductivity and Surface Resistivity, mechanical properties like tensile strength, elongation at break, flexural strength, impact strength, etc, glass transition temperature.
Thermal diffusivity:
Thermal Diffusivity of the nano composites such as standard base resin without CNTs (ie Control sample), nano composites comprising CNTs and nano composites comprising ACNTs are tested. It is found that nano composites of the invention increases 40 % of the thermal conductivity without changing the electrical insulation

property as compared to that of 20 % to that of nano composites comprising only CNTs. The improvement in thermal diffusivity is studied based on the standard base resin.
Electrical Conductivity and Surface Resistivity:
Electrical Conductivity and Surface Resistivity of the nano composites comprising ACNTs of the invention is tested. It has been observed that there is no substantial variation in the electrical conductivity of the nano composite with ACNTs as compared to pure UPR as in all the concentrations the resistivity varies in the range of 1014 ohm/Sq. Therefore, there is no variation in the electrical conductivity and the surface resistivity remains in the insulating region with incorporation of ACNTs.
MECHANICAL PROPERTIES
A. Tensile Strength
Tensile strength of the nano composites of the invention, standard base resin and nano composites comprising CNTs is tested. The addition of CNT resulted_in an increase in the tensile strength of the composites; however, ACNT based composites showed a higher increase in tensile strength as compared to CNT based composites. In both cases it was observed that agglomeration of the particles occurred at 0.075%, after which the strength of the composites were seen to decrease. The optimum concentration of ACNT was seen to be 0.075%. About 76% increased in the tensile strength was observed in ACNTs based composites of the invention as compared to a 30% increased in the tensile strength in CNTs based composites. The improvement in tensile strength is studied based on the standard base resin. This increased performance of ACNT based composites was due to the increase interaction between the polymer matrix and the ACNTs.

B. Elongation at Break
Elongation at break of the composites comprising ACNTs of the invention, standard base resin and nano composites comprising CNTs is tested. The addition of nano-particles of CNTs to resin resulted in 15 % of decrease in the elongation at break as compared to that of 30 % of decrease in the elongation at break in the nano composites comprising ACNTs. This is due to the increased interaction between the polymer and the nano-particles of ACNTs as compared to that of CNTs. As in the case of the tensile strength, there was an inflection in the trend of the elongation at break at 0.075% due to the agglomeration of particles at higher concentrations.
C. Flexural Strength
Similarly flexural strength of the composites comprising CNTs, standard resin and nano composites comprising ACNTs of the invention is tested. The addition of CNT resulted in an increase in the flexural strength of the composites; however, ACNT based composites showed a higher increase in flexural strength as compared to that of CNT based composites. In both cases, it was observed that agglomeration of the particles occurred at 0.075%, after which the flexural strength of the composites were seen to decrease. The optimum concentration of ACNT was seen to be 0.075%. About 84% increased in the flexural strength was observed in ACNTs based composites of the invention as compared to a 33% increased in the flexural strength in CNTs based composites. The improvement in flexural strength is studied based on the standard base resin. This increased performance of ACNT based composites was due to the increase interaction between the polymer matrix and the ACNTs.
D. Impact Strength
The impact strength of the composites comprising CNTs, standard resin and nano

composites comprising ACNTs of the invention were also evaluated. From the test results, it is clear that the addition of CNT or ACNTs to the polymer matrix resulted in an increase in the impact resistance of the resultant composites. As in the case of tensile and flexural properties, the ACNT based composites showed higher impact strength as compared to that of composites based on CNT. The modification of CNTs allows for increased stress transfer from the polymer matrix to the filler which also allows for dissipation of this force and thus resulting in the increase in impact strength. In this case also the optimum concentration of ACNT was seen to be 0.075%. About 146% increased in the impact strength was observed in ACNTs based composites of the invention as compared to a 66% increased in the impact strength in CNTs based composites. The improvement in impact strength is studied based on the standard base resin.
E. Glass Transition Temperature
The glass transition temperatures (Tg) of the composites comprising CNTs, standard resin and nano composites comprising ACNTs of the invention is also tested. The variation of Tg is observed with variation in concentration of CNTs and ACNTs. It was observed that the Tg of the composites increased on addition of CNTs, due to the restriction in polymer chain mobility on interaction with the filler. In the case of ACNT, it was observed that the Tg of the composites was higher than that of equivalent CNT concentrations based composites. This was due to the increased interaction between the ACNT and the polymer matrix resulting in greater chain immobilization. At concentrations above 0.075%, it was observed that the Tg decreased due to the formation of agglomerates which are not as effective in restriction of chain mobility. At lower concentrations, the difference between the Tg in the case of composites base CNTs and ACNTs was not very large i.e. 3°C for 0.01%, however at 0.075% concentration of CNTs and ACNTs, there was a

difference of 11°C, which indicates the effectiveness of the chemical modification in increasing interaction and dispersion of the ACNT in the polymer matrix.
The following experimental examples are illustrative of the invention but not limitative of the scope thereof.
Example 1:
Preparation of Allyl Modified Carbon Nanotubes
5 gm of CNT [obtained from Cheaptubes.com and were carboxyl functionalized, had a purity of 95% and outer diameter of 30-50nm and a length of 3 microns] were placed in a 250ml flat bottom flask with 50ml of ethylene Chloride was subjected to ultrasonication coupled with mechanical agitation, using an rpm of 1500 ± 50, in a temperature controlled bath maintained at 25°C for 2 hours to disperse the CNTs m the solvent. 10 ml of thionyl chloride was added to the reaction mixture and it was stirred with a magnetic stirrer. The reaction mixture was refluxed for 24 hours. After the chlorination of the CNTs was completed, the unreacted thionyl chloride and ethylene chloride were distilled off to obtain acid chloride CNTs. 50ml of allyl alcohol was added to the acid chloride CNTs and it was stirred at 50°C for 24 hours. After the completion of the esterification of the CNTs with allyl chloride, excess allyl chloride was distilled off. The ACNTs synthesized were washed with acetone, centrifuged and the residue washed with acetone again. The ACNT was washed thrice to remove unreacted chemicals. The ACNT was dried in a vacuum oven at 40°C for 8 hours.
We have characterized ACNT by FTIR and compared with FTIR of carboxyl functional CNT. Figure 1 illustrates FTIR spectra of carboxyl functional CNT and ACNT. A broad peak as appearing in the range of 3000 to 3400 cm-1 indicates the

presence of hydroxyl group of the carboxyl functional group in the carboxyl functional CNT. However, in the case of ACNT this peak was not present indicating the complete esterification of the carboxyl group by the allyl alcohol. In both cases, i.e. carboxy functional CNT and ACNT, a peak between 1740 and 1760 cm-1 was observed which corresponded to the C=O stretching vibrations of the carboxyl and ester groups in carboxyl functional CNT and ACNT respectively. The FTIR spectra show that the esterification of the CNT was complete. The introduction of an allyl group in the ACNT results in two peaks at 2800-2900 cm-1 which is due to the C-H stretching vibrations. Further from the spectra, it can be seen that the modification of the CNTs did not result in destruction of the nano-particles.
Example 2:
Preparation of Nanocomposites comprising 0.01% CNTs (COMPOSITION A)
1 gm CNTs was dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. Then 1 wt percent of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.

Example 3:
Preparation of Nanocomposites comprising 0.025% CNTs (COMPOSITION B)
2.5 g of CNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposite was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 4:
Preparation of Nanocomposites comprising 0.05% CNTs (COMPOSITION C)
5 gm of CNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into

Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 5:
Preparation of Nanocomposites comprising 0.075% CNTs (COMPOSITION D)
7.5 gms of CNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 6:
Preparation of Nanocomposites comprising 0.1% CNTs (COMPOSITION E)
10 gm of CNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg

KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 7:
Preparation of Nanocomposites comprising 0.01% ACNTs (COMPOSITION F)
1 gm of ACNTs was dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion. with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.

Example 8:
Preparation of Nanocomposites comprising 0.025% ACNTs (COMPOSITION
G)
2.5 gms of ACNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 9:
Preparation of Nanocomposites comprising 0.05% ACNTs (COMPOSITION H)
5 gms of ACNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was

added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 10:
Preparation of Nanocomposites comprising 0.075% ACNTs (COMPOSITION I)
7.5 gms of ACNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55% and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
Example 11:
Preparation of Nanocomposites comprising 0.1% ACNTs (COMPOSITION J)
10 gms of ACNTs were dispersed into the unsaturated polyester resins [obtained from M/s Naphtha Resins, Bangalore, India and was used as such.] The resin was pre-accelerated with 0.2% cobalt naphthanate (6% Co content), had a solid content of 55%

and used styrene as the reactive diluent. The acid value of the composition was 12 mg KOH/g resin and had a viscosity of 330 mPas (@ 25°C and 50 rpm)]. The composition was subjected it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion. The 1 gm of initiator, methyl ethyl ketone peroxide (MEKP) [obtained from M/s Naptha Resins and used as such] was added to the degassed dispersion with stirring. The composition was poured into Teflon moulds. The composition was cured at room temperature i.e. 25 ± 1°C for 12 hours. It was further post - cured at 80 ± 1°C for fours. The nanocomposites was stabilized at 25 ± 1°C and 50% Relative Humidity (R.H.) for 7 days before any testing.
The compositions A to J is evaluated for its thermal diffusivity, electrical conductivity and specific resistivity, tensile strength, elongation at break, flexural strength, impact strength and glass transition temperature by standard method and shown in graphs as illustrated in Figures 2 to 8.
Thermal Diffusivity
As illustrated in figure 2, the thermal diffusivity of the compositions F to J was measured against the standard unsaturated polyester resin. From the graph it is observed that the diffusivity of the standard unsaturated polyester resin was 0.13 mm /s where it increases to 0.18 mm /s with 0.05 % of ACNTs ie composition H. The results shows around 40% increase in the thermal conductivity.
Electrical Conductivity and Surface Resistivity
Figure 3 illustrates Electrical conductivity of the compositions F to J measured against the standard Unsaturated Polyester Resin (UPR) resin. From the graph it has been observed that there was no substantial variation in the electrical conductivity of

the composites with ACNTs F to J as compared to that of standard UPR as in all the concentrations the resistivity varies in the range of 1014 ohm/Sq. Thus, there was no variation in the electrically conductivity and the surface resistivity remains in the insulating region with incorporation of ACNTs.
MECHANICAL PROPERTIES
A. Tensile Strength
Figure 4 illustrates evaluation of mechanical properties of compositions based CNTs ie Compositions A to E and ACNTs i.e. Compositions F to J with respect to standard unsaturated polyester resin. The addition of CNTs resulted in an increase in the tensile strength of the composites A to E; however, ACNTs based composites F to J showed a higher increase in tensile strength as compared to CNTs. In both cases it was observed that agglomeration of the particles occurred at 0.075%, after which the strength of the composites were seen to decrease. The optimum concentration of ACNTs was seen to be 0.075%. The compositions comprising ACNTs F to I were showed 76%> increase in the tensile strength as compared to 30% increase in the case of CNTs based composites A to D. This increased performance of ACNT based composites F to I was due to the increase interaction between the polymer matrix and the ACNTs.
B. Elongation at Break
Figure 5 illustrates variation of elongation at break of the composites comprising CNTs ie compositions A to E and ACNTs ie compositions F to J with respect to standard unsaturated polyester resin matix. The compositions comprising nano-particles of CNTs ie A to E resulted in 15 % of decrease in the elongation at break as compared to that of 30 % of decrease in the elongation at break in the nano

composites comprising ACNTs ie F to J. This was due to the increased interaction between the polymer and the nano-particles of ACNTs. As in the case of the tensile strength there was an inflection in the trend of the elongation at break at 0.075% due to the agglomeration of particles at higher concentrations.
C. Flexural Strength
Figure 6 illustrates graphic comparative representation of flexural strength of nano composites comprising CNTs ie compositions A to E and ACNTs ie compositions F to J to the standard unsaturated polyester resin. The flexural strength was found to be increased due to increase in the interaction between sthe polymer and the filler. The flexural strength of ACNT based composites F to I was higher than that of CNT based composites A to D. The optimum concentration of ACNT was seen to be at 0.075%. About 84% increased in the flexural strength was observed in ACNTs based composites of the invention ie F to I as compared to a 33% increased in the flexural strength in CNTs based composites A to D. The improvement in flexural strength was studied based on the standard base resin. This increased performance of ACNT based composites was due to the increase interaction between the polymer matrix and the ACNTs. The mechanical properties of the ACNT based composites F to I showed superior performance as compared to the CNT based composites A to D which was higher than that of the standard unsaturated polyester resin matrix.
D. Impact Strength
The impact properties of the composites comprising CNTs, standard resin and nano composites comprising ACNTs of the invention were evaluated and shown as graphic representation in figure 7. From the graph, it is clear that the addition of CNT or ACNTs to the polymer matrix results in increase in the impact resistance of the resultant composites. As in the case of tensile and flexural properties, the ACNT

based composites F to I showed higher impact strength as compared to that of CNT based composites A to D. The modification of CNTs resulted in increase in stress transfer from the polymer matrix to the filler which also resulted for dissipation of this force and thus resulted in increase in impact strength. In this case also, the optimum concentration of ACNT was seen to be 0.075%. About 146% increased in the impact strength was observed in ACNTs based composites of the invention F to I as compared to 66% increased in the impact strength in CNTs based composites A to
D. The improvement in impact strength was studied based on the standard base
resin.
E. Glass Transition Temperature
The glass transition temperatures (Tg) of the composites comprising CNTs A to E, standard resin and nano composites comprising ACNTs of the invention F to I was also tested. The variation of Tg was observed with variation in concentration of CNTs and ACNTs. It was observed that the Tg of the composites increased on addition of CNTs, due to the restriction in polymer chain mobility on interaction with the filler. In the case of ACNT, it was observed that the Tg of the composites was higher than that of equivalent CNT concentrations based composites. This was due to the increased interaction between the ACNT and the polymer matrix resulting in greater chain immobilization. At concentrations above 0.075% , it was observed that the Tg decreased due to the formation of agglomerates which are not as effective in restriction of chain mobility. At lower concentrations, the difference between the Tg in the case of composite base CNTs ie A and ACNTs is F was not very large i.e. 3°C for 0.01%, however at 0.075% concentration of CNTs ie D and ACNTs ie I, there was a difference of 11°C, which indicates the effectiveness of the chemical modification in increasing interaction and dispersion of the ACNT in the polymer matrix.

We Claim,
1. A method for preparation of nanocomposites with improved electrical insulation
and thermal conductivity;
the method comprises:
a) Preparing allyl modified carbon nanotubes;
b) Preparing a dispersion by dispersing the allyl modified carbon nanotubes into a resin matrix and subjecting it to ultrasonication coupled with mechanical agitation at 1500 ± 50 rpm and degassing the dispersion;
c) curing the dispersed mixture to form nanocomposites by adding initiator to the degassed dispersion with stirring;
d) stabilizing the nano composites.

2. The method as claimed in claim 1, wherein the ACNTs dispersed in the resin matrix is in the range of 0.1 to 1.0% by weight.
3. The method as claimed in claim 1, wherein the step (b) of dispersion is carried out at a controlled temperature of 25°C to45°C.
4. The method as claimed in claim 1, wherein the step (c) of curing is carried out at 25°C to 40°C and 25 to 60 Relative Humidity (R.H.).
5. The method as claimed in claim 1, wherein the step (d) of stabilizing the composites is carried out at 25°C to 35°C and under 50 to 70 % Relative Humidity (R.H.).
6. The method as claimed in claim 1 wherein the process for the production of allyl modified carbon nanotubes of step (a) comprises the steps of:
i preparing a dispersion by dispersing the carboxyl functional carbon nanotubes of formula (I) into a solvent;

ii preparing a acid chloride carbon nanotubes of formula (III) by treating the
dispersion obtained in step (i) with thionyl chloride of formula (II) followed
by distilling off the unreacted thionyl chloride; iii preparing allyl modified carbon nanotubes of formula (V) by esterifying the
acid chloride carbon nanotubes of the formula (III) obtained in step (ii) with
allyl alcohol of formula (IV); and iv isolating the allyl modified carbon nanotubes of formula (V) by distilling off
allyl chloride from the reaction mixture obtained in step (iii) followed by
washing it with solvent and drying it.

Scheme I
7. The method as claimed in claim 6, wherein the step (i) of preparing the dispersion is carried out by dispersing the carboxyl functional CNTs of formula (I) into a solvent and subjecting the dispersion to ultrasonication coupled with mechanical agitation at 1500rpm/5min.
8. The method as claimed in claim 6, wherein the step (i) is carried out at a controlled temperature 25 to 35°C for 2hours.

9. The method as claimed in claim 6, wherein the solvent used in the step (i) is selected from ethylene chloride or propylene chloride.
10. The method as claimed in claim 6, wherein the step (ii) of preparing the acid chloride carbon nanotubes by treating the dispersion obtained in step (i) with thionyl chloride of formula (II) with simultaneously stirring the reaction mixture using a magnetic stirrer followed by refluxing the reaction mixture for 24 hours and distilling off the unreacted thionyl chloride from it to obtain the acid chloride carbon nanotubes.
11. The method as claimed in claim 6, wherein the step (iii) of preparing the allyl modified carbon nanotubes of formula (V) by esterifying the acid chloride carbon nanotubes of the formula (III) obtained in step (ii) with allyl alcohol of formula (IV) at 40°C to 65°C with stirring.
12. The method as claimed in claim 6, wherein the step (iv) of isolating the the allyl modified carbon nanotubes of formula (V) by distilling off allyl chloride from the reaction mixture obtained in step (iii) at temperature of 50°C to 80°C followed by washing it with solvent, .centrifuging the washings to obtained the residue, washing the residue with solvent, combining the residue with isolated the allyl modified carbon nanotubes of formula (V) and drying it at 50 °C.
13. The method as claimed in claim 6, wherein the solvent used for washing the the allyl modified carbon nanotubes of formula (V) is selected from acetone, xylene, toluene , isopropyl alcohol or ethyl alcohol.
14. The method as claimed in any of the preceding claims, wherein the CNT used may include but are not limited to, single-wall carbon nanotubes, multi-wall carbon nanotubes, double wall carbon nanotubes, buckytubes, fullerene tubes,

tubular fullerenes, graphite fibrils or vapor grown carbon fibres, and combinations thereof.
15. The method as claimed in any of the preceding claims, wherein the resin used may include but not limited to unsaturated polyester resin, polyurethane or epoxy resin.
16. The nanocomposites prepared according to any of the preceding claims, wherein

I. improvement in thermal diffusivity ranges from 25 - 45 %;
II. about 76% increase in the tensile strength in ACNTs based composites as compared to 30% increase in the case of CNTs based composites;
III. about 30 % of decrease in the elongation at break in ACNTs based composites as compared to that of 15 % of decrease in the elongation at break in the nano composites comprising CNTs;
IV. about 84 % increased in the flexural strength in ACNTs based composites of the invention as compared to a 33 % increased in the flexural strength in CNTs based composites;
V. about 146 % increased in the impact strength in ACNTs based composites as compared to 66 % increased in the impact strength in CNTs based composites; and VI. about 11°C increased of about glass transition temperature at concentration of 0.075% of CNTs and ACNTs.