Polyurethane Prepared from Neem Oil Polyesteramides for Self

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Polyurethane Prepared from Neem Oil Polyesteramides for Self-Healing Anticorrosive Coatings Ashok Bhadu Chaudhari, Pyus Dilipkumar Tatiya, Rahul Kishore Hedaoo, Ravindra Dattatrya Kulkarni, and Vikas Vitthal Gite Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/ie401237s • Publication Date (Web): 03 Jul 2013 Downloaded from http://pubs.acs.org on July 10, 2013

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Industrial & Engineering Chemistry Research

Polyurethane Prepared from Neem Oil Polyesteramides for Self-Healing Anticorrosive Coatings Ashok B. Chaudharia, Pyus D. Tatiyaa, Rahul K. Hedaooa, Ravindra D. Kulkarnib, Vikas V. Gitea*

a

Department of Polymer Chemistry, School of Chemical Sciences, b University Institute of Chemical Technology, North Maharashtra University, Jalgaon- 425 001, Maharashtra, India

Email: [email protected] Phone No: +91 257 2257431 Fax No: +91 257 2258403

1

ACS Paragon Plus Environment


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ABSTRACT Polymeric researchers desire strongly to reduce dependency on fossil or petroleum feed stock by utilizing renewable source based polymeric resins in coating.

The present research

representing the attempt made to develop neem oil (renewable source) two pack self-healing anticorrosive polyurethane coatings cured at room temperature. The oil based polyesteramide was prepared in two steps viz. in first step oil fatty amide was synthesized which directly converted to polyesteramide by condensing amide with phthalic anhydride. Spectral study of prepared resin was carried by FT-IR and NMR techniques. Polyesteramide further was utilized for preparation of self-healing PU coatings with incorporation of polyamidoamine based polyurea microcapsules containing natural self-healing agent. The obtained coatings were tested for thermal, physico-chemical and corrosion resistance tests. The coating properties like gloss, impact resistance, adhesion, flexibility were also studied and found to be superior for anticorrosive self-healing industrial coatings. Keywords: Neem oil, Renewable Source, Polyurethane Coatings, PAMAM, Self-healing Coatings.

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INTRODUCTION Now days, the use of vegetable oils in the preparation of polymeric resins is gaining more importance due to renewability of oils, lower cost and easy availability.1-8 Plant oils provide film forming properties through the number of unsaturation present in long and polar fatty acid chains with high potential to protect metallic surfaces from corrosion.9 Oils or fatty acids are also processed as reactive diluents to reduce the volatile organic content (VOC) emissions in coating formulations to substitute petroleum based feedstock.10-11 The literature of last few decades shown that, due to the liberal functional groups and special attributes present in vegetable seed oils such as linseed,12 neem,13 cotton,14 castor,15 jatropa,16 sunflower,17 nahar 18

and soybean19 oils were used to prepare the polymeric resins. Drying time and durability

related to films are important factors in paint and coatings industries. Azadirachta indica juss (neem oil) has attracted the attention of scientific society for its use as a bio-pesticide20 and in pharmaceuticals21 only. A neem tree extracts used as corrosion inhibitors have recently been investigated by Peter et al to the metallic substrate and showed inhibition efficiency increased with the trend of the plant extracts of seeds, roots and leaves.22 Fatty acid composition of neem seed oil contain total five fatty acids, which included palmitic (11.90 %, C16:0), stearic (29.96 %, C18:0) and arachidic acids (02.94 %, C20:0) as saturated fatty acids, while oleic (50.04 %, C18:1) and linoleic acids (05.15 %, C18:2) as unsaturated fatty acids. These long chain fatty acids with varying compositions depend on the season and growing conditions available for the plant.23 The neem oil is abundantly available in an India and Indian continent with production rate of 18000 per tones at arid land. However their application has not been listen carefully for preparation of polymeric resins or in development of coatings except our earlier report.13 Although in polymeric materials, polyurethane (PU) is a group of polymers with versatile and excellent physical, chemical and mechanical properties which increased the demand in the field of industrial coatings applications. The rapid research dealing to the development of renewable source based polymeric resins and performance enhancement for chemical resistance and anticorrosive nature in salt solution is in progress by adding metal nano particles like ZnO,

24

TiO2,

25

Al2O3,

26

silica,

27

montmorillonite28 in PU coatings

formulations. Microencapsulation of core has been utilised in various sectors viz. selfhealing coatings,29-30 control release of pesticides,

31

drug delivery

32-33

etc.

Presently

technologist has focused on development of new shell material with better property over conventional shells for microencapsulation of self-healing agent. As per our earlier report, 3



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new shell material for microcapsules have successfully used in self-healing of polymeric coatings with better anti-corrosive properties.34 The performance of prepared 0.0 G polyamido-amine (PAMAM) based polyurea microcapsules for corrosion protection of petroleum based PU coatings by healing of cracks was examined by immersion study of PU coating panels. But the anticorrosive or self-healing properties of polyurea microcapsules with different percent loading in bio-based PU coatings, more specifically novel neem oil based polyesteramide (PEA) have not been studied before. This is the first time that any one is reporting synthesis of neem oil polyesteramide (PEA) and its advance version i.e. self-healing nature. The literature states the existence of repeating units of both ester (-COOR) and amide (-NCOR) in the polyesteramide improve the thermal stability, chemical resistance, mechanical properties, easiness of application and also contribute in rapid curing compared to normal polyesters resins.35 PEA further was used for preparation of PU coatings on mild steel panels with incorporation of 0 to 5 % percent loading of PAMAM based polyurea microcapsules. The coatings were tested by thermal, physico-chemical and corrosion resistance tests. The coating properties tested were included gloss, impact resistance, pencil hardness, adhesion, flexibility and found to be superior for anticorrosive industrial coatings. EXPERIMENTAL SECTION Materials and Chemicals Neem oil was purchased from local trader and characterized for their specific gravity, refractive index, saponification and iodine values, which matched with the standards. Therefore oil was utilized without any further amend. Methylene diphenyl diisocyanate (MDI) (Kishore Polyurethanes Pvt. Ltd., Nasik, India), toluene 2, 4 diisocyanate (TDI) and DBTDL (Merck, India), phthalic anhydride (Aldrich Chemicals, UK) were of laboratory grade.

Cylcohexanone, THF and diethanolamine (s. d. fine Chemicals, India) were of

analytical grade. The equipment used include assembly of reflux tools, rotary evaporator, vacuum oven, titration apparatus, glass beakers, separating funnel, heating mantle, magnetic stirrer, hot plate, sieve shaker, sand paper, desiccators, mild steel (MS) panels and instruments for measurement of coating properties.

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Synthesis of Azadirachta indica juss Fattyamide (AIJFA) AIJFA was obtained by the base catalyzed amidation of neem seed oil with diethanolamine according to our previously reported method.13 General reaction for synthesis of the AIJFA is given in Scheme 1.

Scheme 1. Synthesis of the Azadirachta indica juss Fattyamide (AIJFA) Synthesis of Polyesteramide (PEA) AIJFA (0.3 M) and phthalic anhydride (0.2 M) were dissolved in 50 mL xylene in presence of PbO as a catalyst in three necks round bottom ﬂask equipped with dean stark trap, nitrogen inlet tube, thermometer and mechanical stirring device. Under slow stirring, the reaction mixture was heated upto 115 ºC to dissolve anhydride. Then the reaction was continued at 180 ± 5 ºC. The reaction was monitored by taking acid value at regular intervals. As the acid value decreased below 10 and the amount of theoretically calculated water was collected in dean stark trap, reaction was allowed to stop. After completion of the reaction, solvent was evaporated in a rotary vacuum evaporator under reduced pressure to obtain the PEA. Presence of trace amount of solvent and moisture present in the PEA were removed by using vacuum oven. The general reaction for synthesis of the PEA is as given in Scheme 2.

5



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Scheme 2. Synthesis of the Polyesteramide (PEA) Synthesis of PAMAM Based Polyurea Microcapsules PAMAM based polyurea microcapsules containing 55 % of core material (27 % linseed oil and 28 % solvent) as a self-healing agent were prepared by reacting 0.0 G PAMAM with commercial grade MDI according to our previously reported method.34 The synthesized polyurea microcapsules were subjected to sieve shaker to obtain fine uniform microcapsules within the range of 20-70 µm. Synthesis of PU Coatings The general reaction for the preparation of PU is as given in the Scheme 3. The prepared PEA of neem oil was reacted at room temperature with TDI by selecting NCO/OH ratio 1.2:1. In case NCO/OH ratio is greater than one, all available hydroxyl groups reacts with isocyanates groups that reduces risk of poor durability to coatings. Leftover NCO groups hydrolyze gradually by reacting with airborne moisture giving urea groups which increase the crosslink density, improve physical properties and chemical resistance of PU. 14, 36 The 50 % solid content solution of PEA was prepared in cyclohexanone and THF (80:20) mixture with catalyst DBTDL (0.05 %, to control the reaction rate).37 Microcapsules with varying percent from 0 - 5 % were added and dispersed into the PEA solution for 5 min. Then mixture of PEA containing catalyst and the polyurea microcapsules were allowed to react with appropriate amount of TDI. Then the reaction mixture was stirred for next 5 min for proper dispersion at 27 ºC. After attaining pourable viscosity, mixture was used for coating by bar applicator (Raj Scientific Company, Mumbai) with wet film thickness of 120 µm on MS steel panels of 4 x 6 inch dimensions. The prepared coating panels were allowed to cure at room temperature under visual examination, until the coatings were dry to touch.

Before 6


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application of the coatings, steel panels were pretreated by sand paper, washed with acetone and dried in an air circulated oven. The PU samples were coded as PU0, PU1, PU2, PU3, PU4 and PU5 in which suffix 0 to 5 indicated the percentage loading of polyurea microcapsules in PEA based PU coatings.

Scheme 3. Synthesis of the Polyurethane (PU) Coatings CHARACTERIZATION Characterization of Raw Materials Fatty acid’s composition of oil was determined by gas chromatography (Shimadzu GC-14B), column (Restek, Rtx-Wax) and FID detector using methyl esters route. Molecular weight of the prepared PEA was measured by gel permeation chromatography (GPC) with Agilent GPC-Addon Rev A02.02 series HPLC system using PL-Gel Agilent column and THF solvent. Solubility of the prepared PEA in various organic solvents was checked at room temperature. Physical properties such as hydroxyl value, iodine value, specific gravity and refractive index of the PEA were determined by standard experimental methods. Viscosity of prepared PEA was determined on the Brookfield Rheometer (RHEO 2000 version 2.5, Brookfield Engineering Laboratories Inc., USA) at 25 ºC temperature, 20 rpm and after rotating samples for 120 second. 7



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The FTIR spectra of AIJFA and PEA were scanned 50 times (Perkin-Elemer 2000 FTIR spectrometer) in the range of 4000 to 500 cm-1 by using KBr pellets. 1HNMR measurements were performed (Varian Mercury 300 MHz spectrometer using) using TMS as an internal standard in CDCl3. Morphological study of the polyurea microcapsules were observed under scanning electron microscopy (SEM) (JEOL JSM 6360 and JEOL JSM 5400, Japan) with voltage range from 0.5 to 30 kV. Before the morphological study, samples were placed at liquid nitrogen. PU Coatings Characterization Gloss The PU coating panels were tested for the gloss (Model BYK Additive & Instruments, Germany) measurement at an angle 60 º on the calibrated digital gloss meter. Flexibility by Conical Mandrel Elasticity of the prepared PU coated panels was measured by using a conical mandrel instrument (Raj Scientific Company, Mumbai) in the range of 45º to 180º angles. Pencil Hardness Pencil hardness of the coatings was measured by using a pencil hardness tester (Model BYK Additive & Instruments, Germany) according to ASTM D-3363 standard. In this test pencils having different grades were used to move over the surface of the coated panels at fixed 45o by using standard holder provided by company. This process was started with a softer level pencil and was repeated with progressively to hardest pencil until the pencil did not cut the film. The pencil, which did not cut the film, denoted its hardness. Cross Cut Adhesion To examine the adhesion of coatings with the substrate, cross cut adhesion test of prepared coating panels was carried out using the ASTM D-3359-02 standard. In this test a cross hatch adhesion tester (Elcometer 107, U.K.) consisting of a die with 11 number of closed set of parallel blades was passed and pressed on the coated panel into two directions at right angle to each others. Then surface of coating panel was brushed lightly to remove loose particles. A piece of adhesive tape (Scotch brand 810 Magic Tape or 3M adhesive tape) was placed over the lattice pattern and pressed with a fingertip. After 60 seconds adhesive tape was pulled off rapidly at an angle of 180º and the scribed area was inspected visually by 8


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using an illuminated magnifier to determine the percentage of cubes remained on the coating panels. Impact Resistance During determination of impact resistance of the dried PU coatings, panel was deformed rapidly by application of weighted indenter (1.818 lb), which is dropped from the certain height starting from 5 - 40 inch of tubular impact tester until the film cracked. After falling a weighted indenter peeling, cracking and film detachment from the substrate was examined. Water and Chemical Resistance Chemical resistance tests of the PU coated panels were performed in water, solvent (xylene), acid (5 % HCl) and alkali (5 % NaOH) solutions. Periodic visual inspection was evaluated until the coatings showed evidence of softening, deterioration or development of cracks (if any). Self Healing Study After 3 days curing of prepared PU coatings, coated panels were cracked manually with a razor blade to coatings and ruptured the polyurea microcapsules present in the path of cracks. Then linseed oil oozed from microcapsules present inside the coated sample was allowed to fill the gap for next 10 minutes. The coatings were examined by FE-SEM (Model No. S4800, HITAHCI High Technologies Corporation, Japan) to record self healing process of released linseed oil from ruptured microcapsules. Corrosive Resistance by Immersion Test Anticorrosion self-healing properties of the prepared PU coatings with different loading (0-5 %) of polyurea microcapsules were evaluated through immersion study in an aqueous solution of NaCl (3.5 wt. %). The sample panels were tested in NaCl solution initially for 24 hours and further extended for a total exposure time of 120 hours (5 days). Panel specimens were continuously examined for corrosion inside and at the crossed area of substrate time to time by visual inspections and recorded using a digital camera (Sony, 16 mega pixels). Thermal Analysis of PU Coatings Thermal analysis of prepared PU coatings was performed by thermo gravimetric analysis (TGA 4000, Perkin Elmer, USA) in the range of 40 to 700 ºC temperature at heating rate of 20 ºC/min in N2 atmosphere. 9



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RESULTS AND DISCUSSION Characteristic Properties of Neem oil, AIJFA and PEA Specific gravity, refractive index, viscosity, saponification, acid, hydroxy and iodine values of oil, fatty amides and PEA are given in the following Table 1. From GPC technique, it was found that polydispersity index of prepared PEA was 1.17 while weight and number average molecular weights were 661 and 563 respectively. Table 1. Characteristic properties of neem oil, AIJFA and PEA Specific

Refractive

Viscosity

Sap

Acid

OH

Iodine

gravity

index

(cPs)

value

value

value

value

Neem oil

0.920

1.503

2068

186

1.0

0.0

65

AIJFA

0.929

1.542

3846

-

00

205

60

PEA

1.026

1.479

5123

096

2.0

137

47

Properties

Increment in specific gravity and viscosity for neem oil to AIJFA and PEA were observed. Hydroxyl, sap and iodine values were decreased, which may be due to increase in molar masses of prepared resins compared to parent neem oil. Scanning Electron Microscopy (SEM) The surface morphology of the synthesized microcapsules was observed using SEM micrographs and the results are presented in Figure 1. SEM images noticed that the sphereshaped with non porous microcapsules were obtained with average diameter from 20 to 70 µm. Presence of non-porous shell wall may be responsible for impermeability of prepared capsules towards leakages and diffusion of liquid healing agent.

Figure 1. SEM micrographs of PAMAM based polyurea microcapsules 10


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Spectroscopic Analysis The formation of AIJFA was confirmed by FT-IR and 1H-NMR spectral analysis according to our earlier report.13 FTIR of PEA FT-IR spectrum of the neem oil based PEA (Figure 2) shown characteristic absorption broad band at 3381 cm -1 due to a terminal hydroxyl group. The bands at 2825 – 2932 cm -1 were of methyl and methylene groups. The ester and amide carbonyl bands were found at 1712 and 1616 cm -1 respectively. The band at 1456 cm bending was found at 1373 cm absorption band at 717 cm

-1

-1

-1

was due to C–N stretching vibrations. OH

while C-O stretching attributed to 1149 cm

-1

. The

recognized for the presence of C–H vibrations in the phthalic

anhydride ring. Hydroxyl and ester carbonyl peaks in FTIR of PEA were highly distinct which support the formation of PEA.

Figure 2. FT-IR spectrum of the PEA 1

H NMR Spectra of PEA

The H1 NMR spectrum of PEA (Figure 3) given the peak of terminal –CH3 at 0.85 ppm. A chemical shift of –CH2 of long chain fatty amides seen at 1.25 ppm. Appearance of peaks at 11



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3.45 - 3.83 ppm corresponded to –CH2– linked with –OCO– groups. Methylene adjacent to olefin =CH–CH2– found at 1.6 ppm and –CH2– attached to amide nitrogen appeared at 3.1 ppm. Protons of phthalic anhydride ring (aromatic ring) observed at 7.20 – 7.95 ppm. The peak at 4.21 ppm was attributed to proton of hydroxyl group and the protons near to olefinic unsaturation given the peak at 5.38 ppm. The above observations confirmed the formation and broad structural features of the PEA.

Figure 3. 1H NMR Spectrum of the Synthesized PEA Coating or Film Properties of PU All the prepared PU coating panels were cured at room temperature. Time taken for dry to touch for the coded samples PU0, PU1 PU2, PU3, PU4 and PU5 was found to be 6, 8, 9, 11, 12 and 13 hours respectively, which indicated that on increase in loading of the microcapsules curing time of the coatings was also increased. This may be due to increase in amount of the microcapsules increased the distance between reactive functional groups. Adhesion was found to increase in the PU0, PU1 and PU2 samples, while decreased slightly from PU3 to PU5 and for all the PU samples it fall in the range of 94-98 %. Gloss was observed in the range of 86 to 112 for all prepared coating samples. In the case of pensile 12


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hardness test, all soft to hard level of pencils were unable to cut the film, it indicated that all the prepared PU coating samples were with superior pencil hardness. Impact resistance of the coatings was increased upto 2 % loading of capsules and then it decreased. Increase of concentration of microcapsules in the PU coatings beyond 2 % loading contributed to decrease in impact resistance. It may be due to the diffusion of number of microcapsules after falling the indenter on film that resulted some signs of crack and film detachment. All the PU samples passed the flexibility test and no any kind of failure was observed. The prepared coatings (containing 1, 2 and 3 % loaded microcapsules) showed no severe effect on the film when immersed in water, solvent, acid and alkali for specified time of period. While in the case of 4 and 5 % microcapsules loaded PU coatings, partially detachment of film from the substrate shown in solvent and alkali. It indicated that the good chemical resistance of the prepared coatings was found upto 3 % loading of the polyurea microcapsules. The results of prepared PU coatings are shown in Table 2. Table 2. Coating Properties of the PU Coatings Sample code

Dry to touch (hr)

Cross cut adhesion (%)

Gloss 60 º

Impact resistance (lb.inch)

Chemical resistance Water 168 hr

Xylene 120 hr

Acid (5% HCl) 120 hr

Alkali (5 % NaOH) 48 hr

PU0

6

94

112

36.36

a

b

e

c

PU1

8

96

97

45.45

e

c

e

b

PU2

9

98

92

50.90

e

c

a

b

PU3

11

96

90

47.27

b

c

b

b

PU4

12

94

89

43.63

b

d

c

d

PU5

13

94

86

38.18

c

d

c

d

Where, a-loss in gloss, b-film swell, c-slightly cracks, d-film partially removed and eunaffected Thermo Gravimetric Analysis (TGA) Thermograms (Figure 4) showing the effect of percentage variation of the polyurea microcapsules on the PU coatings. TGA curve of all the PU coating samples shown three steps degradation. First step degradation was in the temperature range of 181 – 221 ºC and degradation resulted into 6 % weight loss which may be attributed to loss of solvent and moisture moieties present in the coating samples. Second step degradation occurred in between 221 – 294 ºC temperature and degradation was found upto 26 % weight losses. At 13



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this time degradation would have been taken place due to the decomposition of urethane group of PU coatings. The last, third step degradation was seen in the temperature range of 300 – 530 ºC with decomposition of 66 weight percent. Third step degradation may be a result of decomposition of hydrocarbon chains of neem oil based PEA. Highest thermal stability was observed to the 3 % loading of polyurea microcapsules in PU samples at the second and last steps, while least thermal stability was observed to pristine PU (PU0) amongst all PEA based PU coatings. In the series thermal stability increased as PU0, PU5, PU4, PU1, PU2 and PU3. All the polyurea microcapsules loaded PU coatings showed better thermal stability than pristine PU0 sample. From the thermograms of prepared PU coatings, we can conclude that the optimize 3 % loading of polyurea microcapsules in PEA based PU coating shown the better thermal stability.

Figure 4. TGA Thermographs of the Prepared PU Coatings Self Healing Performance The Figure 5 showing the images obtained from FE-SEM analysis of PU coatings loaded with microcapsules. It was found that the released linseed oil (core material) from broken microcapsules filled the cracks and grasped the film forming ability through atmospheric oxidative polymerization on exposure to oxygen in air. As discussed in report, 38 mechanism 14


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of oxidative polymerization of drying oils is complicated and has not been totally clarified. The typical mechanism involves the formation of radical on activated carbon adjacent to conjugation (in our case fatty acids of linseed oil) by separation of hydrogen radical due to the effect of light and heat.

This radical transforms into a more stabilized structure

containing conjugated double bonds where the radical reacts with oxygen forming peroxide radical. The peroxide radical after reacting with double bond (present with neighboring fatty acid chain of linseed oil or PEA component present in PU) forms the cross linked structure. Peroxide radical also stabilizes itself forming hydroperoxide by detaching hydrogen from another molecule. Due to the unstability of hydroperoxide compounds, they may undergo fission by the action of heat, light or cations of metals and form alkoxyl or hydroxyl radicals. Again the alkoxyl radical cross-links with a neighboring double bond of another chain of oil. Unsaturations present in PEA component of PU which is in vicinity of linseed oil may show their participation in oxidative polymerization during self-healing process of linseed oil. Participation of PEA component might have revealed the healthier adhesion between newly formed film and PU that may be accountable for better anticorrosive properties to self-healed coatings.

Figure 5. FE-SEM Images of Healing Process of Linseed Oil from Ruptured Microcapsules Immersion Study for Anticorrosive Performance The corrosion and its rate of metal mostly depend upon the type of metal, temperature, presence of electrolytes (hard water, salt water, battery fluids, etc.), availability of oxygen, occurrence of biological organisms and time of exposure in corrosive environment. The PU 15



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coatings containing microcapsules when subjected to scratch or cut, the exposed surface of metal will be covered by the released linseed oil from ruptured microcapsules that will form a cohesive film by oxidative polymerization of unsaturations present in oil as well as PEA matrix. Hence the polymerized linseed oil has prevented the metal surface from a direct contact with aggressive electrolytes (salt solution) and deterioration in the properties which may occurred due to the further corrosion. The results of the images in Figure 6 are of immersion test of the prepared PU coatings in salt solution. It was noticed that the scratched or crossed area of panel with 4 % microcapsules loading showed nearly least corrosion and no effect on adhesion of film to the substrate after 120 hours of immersion in salt solution. Harsh corrosion was observed in the region of crack of the coating panels without loading of the microcapsules, while at 5 % loading of microcapsule shown some damage to adhesion of film with the substrate. The performance of corrosion resistance of these coatings may be due to healing of cracks by newly formed film through oxidative polymerization of linseed oil released from the diffused microcapsules.

The healing of crack was responsible for

protection of the substrate from corrosion process even after 120 hours. The results clearly revealed the corrosion was decreased with increased in percent incorporation of the polyurea microcapsules containing linseed oil (healing agent). Therefore from immersion test, it can be concluded that the polyurea microcapsule offered better anticorrosion property

in

aggressive electrolytes (salt solution) at optimize level i.e. 4 % capsules loading to the PU coating applied on MS steel panels.

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Figure 6. Images Obtained from Immersion Test of the Prepared PU Coatings CONCLUSIONS The novel Azadirachta indica juss (neem oil) based polyesteramide resin has been prepared and characterized by physical properties and spectroscopic techniques. Further the PEA used as a polyol part in the preparation of PU coatings.

The incorporation of PAMAM based

polyurea microcapsules given significant improvement in self-healing anticorrosive properties of the prepared PU coatings.

The PU coating with 4 % microcapsule was

optimized for best anticorrosive properties. Highest thermal stability was found to the PU 17



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coating with 3 % loading of microcapsules. Other coating properties like dry to touch, gloss, pensile hardness, adhesion, impact resistance and chemical resistance shown good results. From the above experimental results we can conclude that the neem oil based resins have excellent eventual for using in the formulation of surface coating binders or can be converted into industrial self-healing anticorrosive coatings. ACKNOWLEDGEMENT Authors are thankful to University Grants Commission (UGC), Govt. of India, New Delhi for providing the financial support.

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