FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[see section 10 and rule13]
“A COMPOSITION COMPRISING XNBR AND EPDM ELASTOMER, METHODS AND APPLICATIONS THEREOF”
Name and Address of Applicant: Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai – 400 001, Maharashtra, INDIA.
Nationality: INDIAN
The following specification particularly describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present disclosure relates to a composition comprising Carboxylated Nitrile Butadiene Rubber (XNBR) and Ethylene Propylene Diene Monomer (EPDM) in a ratio of about 70:30, optionally along with industrially acceptable excipients and homogenizer and coupling agent. A method of obtaining a composition comprising Carboxylated Nitrile Butadiene Rubber (XNBR) and Ethylene Propylene Diene Monomer (EPDM) has been disclosed. Further, said composition can be exploited for fuel hose outer cover applications.
BACKGROUND AND PRIOR ART OF THE DISCLOSURE
The major function of the engine fuel return line hose is to carry the un-burnt fuel to the engine. For the system to work properly the fuel hose inner layer must have good resistance to fuel and the outer layer must have resistance to radiant heat generated by engine environment, engine oil and ozone. If the resistance quality of the fuel hose outer cover deteriorates, then there are chances of outer layer cracking and it will directly affect the performance of the inner layer. Poor performance of fuel hose will lead to poor performance of engine during the service.
Fuel hose return line (Diesel engine) is considered as a low pressure line and consists of two layers. The inner layer is used to carry the excess fuel, thereby hose material shall have resistance to fuel and its residues. The outer layer is used to protect inner layer from heat, ozone and oil spillage, thereby outer cover material shall have resistance against the heat, ozone and engine oil.
Currently NBR (Nitrile Butadiene Rubber), PVC (Poly Vinyl Chloride), NBR and FKM (Fluoroelastomers) materials have been used as inner layer materials in diesel engine fuel hose outer cover application, according to service temperature. Further, NBR material is used as carrier (Inner Tube) for diesel fuel due to its good resistance to fuel. Halogen contained CSM (Chlorosulfonated Polyethylene synthetic rubber) material has been used for outer cover application due to its good heat, oil and ozone resistance and the production of CSM material is withdrawn by one of the major manufacturer recently.
Current global challenge is to use environment friendly material in vehicle components to make hazardous free environment. To replace CSM material, which contains Halogen, the available options are CPE (Chlorinated polyethylene), CR (Polychloroprene), HNBR

(Hydrogenated NBR) and AEM (ethylene acrylic rubber) materials. CPE and CR contain Halogen but HNBR and AEM do not. HNBR and AEM can be used in high temperature application however they are more expensive than other materials. Also, it is well known that blends of elastomers containing polar groups are not compatible with hydrocarbon synthetic elastomers. Prior work of blending of polar and non polar material has resulted in inferior and inconsistent mechanical properties. Hence, the challenge lies in blending of these materials. Considering all these factors, there is a need in the art to develop a novel elastomer blend of polar and non-polar material having superior mechanical properties which can be effectively employed in fuel hose outer cover application.
STATEMENT OF DISCLOSURE
Accordingly, the present disclosure relates to a composition comprising Carboxylated Nitrile Butadiene Rubber (XNBR) and Ethylene Propylene Diene Monomer (EPDM) in ratio of about 70:30, optionally along with industrially acceptable excipient and homogenizer and coupling agent; a method of obtaining a composition comprising XNBR and EPDM in ratio of about 70:30,optionally along with industrially acceptable excipient and homogenizer and coupling agent, said method comprising acts of: a) mixing the XNBR, which is optionally present along with the industrially acceptable excipient, with EPDM, which is optionally present along with industrially acceptable excipient, to obtain the compound mixture, wherein the homogenizer cum coupling agent is added either during the mixing of the XNBR and the EPDM or into the obtained compound mixture of the XNBR and the EPDM, b)# optionally, adding the industrially acceptable excipient to the product of step (a), and obtaining the composition having the XNBR and the EPDM in the ratio of about 70:30; a method of obtaining a sheet made from composition as above, the method comprising act of passing the composition between rollers to obtain the sheet; and a fuel hose outer cover composed of the composition as above.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
The features of the present disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings. Understanding that the drawings depict only several embodiments in accordance with the disclosure and are therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings:

Figure 1 illustrates comparative initial Tensile Strength (TS) properties of XNBR/EPDM and
CSM.
Figure 2 illustrates comparative Heat ageing properties of XNBR/EPDM and CSM.
Figure 3 illustrates comparative Oil Ageing properties of XNBR/EPDM and CSM.
Figure 4 illustrates comparative Compression Set properties (at High Temperature) of XNBR/EPDM and CSM.
Figure 5 illustrates comparative Compression Set properties (at Low Temperature) properties of XNBR/EPDM and CSM.
Figure 6 illustrates comparative Diesel Resistance properties of XNBR/EPDM and CSM.
Figure 7 illustrates comparative Grease Resistance properties of XNBR/EPDM and CSM.
Figure 8 illustrates comparative Distilled Water Resistance properties of XNBR/EPDM and CSM.
DETAILED DESCRIPTION OF DISCLOSURE:
The present disclosure relates to a composition comprising Carboxylated Nitrile Butadiene Rubber (XNBR) and Ethylene Propylene Diene Monomer (EPDM) in ratio of about 70:30, optionally along with industrially acceptable excipient and homogenizer and coupling agent.
In an embodiment of the present disclosure, the EPDM is a mixture of vulcanized EPDM and de-vulcanized EPDM.
In another embodiment of the present disclosure, the composition further comprises homogenizer cum coupling agent.
The present disclosure also relates to a method of obtaining a composition comprising XNBR and EPDM in ratio of about 70:30,optionally along with industrially acceptable excipient and homogenizer and coupling agent, said method comprising acts of: a) mixing the XNBR, which is optionally present along with the industrially acceptable excipient, with EPDM,

which is optionally present along with industrially acceptable excipient, to obtain the compound mixture, wherein the homogenizer cum coupling agent is added either during the mixing of the XNBR and the EPDM or into the obtained compound mixture of the XNBR and the EPDM, b) optionally, adding the industrially acceptable excipient to the product of step (a), and obtaining the composition having the XNBR and the EPDM in the ratio of about 70:30
In an embodiment of the present disclosure, the mixing of the XNBR and the EPDM is for time duration ranging from about 2 to about 4 minutes; and mixing homogenizer cum coupling agent with the compound mixture is for time duration ranging from about 1 to about 3 minutes.
In another embodiment of the present disclosure, the homogenizer cum coupling agent is an anhydride metallic salt.
In yet another embodiment of the present disclosure, the homogenizer cum coupling agent is in concentration ranging from about 1 to about 4 phr.
In still another embodiment of the present disclosure, the industrially acceptable excipient is selected from group comprising activator, anti-degradant, processing aid, filler, plasticizer, curing agent and accelerator or any combination thereof.
In still another embodiment of the present disclosure, the activator is selected from group comprising zinc salts & stearic acid, the antidegradent is selected from group comprising amine, quinoline and benzimidazole, the processing aid is selected from group comprising esters, petroleum resin and phenolic resin, the filler is selected from group comprising high abrasion furnace black, fast extruded furnace black, medium thermal black and calcium carbomate, the plasticizer is selected from group comprising paraffinic oil and factice, the curing agent is selected from group comprising sulphur, peroxide and cyanurates the accelerator is selected from group comprising thiazoles, dithiocarbamates, sulfenamides & thiuram sulfides, or any combination thereof.
In still another embodiment of the present disclosure, activator is in concentration ranging from about 1 phr to about 5 phr, antidegradent is in concentration ranging from about 1 phr to

about 3 phr, processing aid is in concentration ranging from about 1 phr to about 6 phr, filler is in concentration ranging from about 3 phr to about 180 phr, plasticizer is in concentration ranging from about 110 phr to about 130 phr, curing agent is in concentration ranging from about 0.6 phr to about 2.5 phr, accelerator is in concentration ranging from about 0.5 phr to about 2 phr or any combination thereof.
The present disclosure also relates to a method of obtaining a sheet made from composition as above, the method comprising act of passing the composition between rollers to obtain the sheet.
The present disclosure also relates to a fuel hose outer cover composed of the composition as above.
Blends of XNBR (Carboxylated Nitrile Butadiene Rubber) and EPDM (Ethylene Propylene Diene Monomer) mixture elastomers have been selected for carrying out experiments and the present work has led to successful blending of polar and non polar material thereby mechanical properties are achieved. EPDM elastomer is selected due to its inherent resistance to weather, heat and Ozone resistance properties. XNBR is selected for its excellent resistance to engine oil, ozone and good mechanical properties. The XNBR/EPDM elastomer combinations are studied for following properties against CSM:
(a) Physical properties.
(b) Volume swell in engine Oil.
(c) Resistance against heat and ozone.
(d) Resistance against diesel fuel.
(e) Low temperature brittleness and component level tests.
Other material level tests including compression set at elevated and low temperature, grease resistance, distilled water resistance, battery acid resistant and damping factor are tested as per the company internal standards for comparison.
METHODOLOGY
(A) Material level experiments on XNBR/EPDM mixture with different blending ratios.
XNBR/EPDM mixture with different blending ratios are tried. All these elastomers are compounded with sulfur curing system.

In order to evaluate material performance, these elastomer combinations are molded in standard sheet form as per ASTM D 3182 -07 and the same is used for material characterization.
The below mentioned recipe’s are tried –
Table 1: Recipe combinations tried for material level experiments
Table 1(a)

Ingredients EPDM XNBR

Phr Phr
XNBR Krynac 750 - 100
EPDM KEP 270 100 -
DE VULCANIZED EPDM 10.5 -
ACTIVATORS
ZNO 4.2 -
Stearic Acid 1.1 -
ANTI-DEGRADEN TS
TDQ 1 2
Pilflex 13 - -
MBI - -
PROCESSING AIDS
Phenolic Resin 3.2 -
Petroleum Resin - -
Fatty acid ester - 4
Mayolux TPO 440 1.6 -
FILLERS
Black 550 170 -
Black 325 10.5 -
Black 330 - 55
Caco3 3.2 -
PLASTICIZER

Paraffinic oil 120 -
Nitrex Factice - -
CURING AGENTS
Sulfur 0.8 -
PEROXIDE 98 1.6 1.8
TAC 50 - 1.5
ACCELARATORS
MBTS 1.6 -
ZDBC 0.7 -
CBS 1.1 -
Table 1(b)

Ingredients EPDM XNBR

Phr Phr
XNBR Krynac 750 - 100
EPDM KEP 270 100 -
DE VULCANIZED EPDM 10.5 -
ACTIVATORS
ZNO 3 -
Stearic Acid 2 -
ANTI-DEGRADEN TS
TDQ - 2
Pilflex 13 - -
MBI - -
PROCESSING AIDS
Phenolic Resin 5 -
Petroleum Resin - -
Fatty acid ester - 6
Mayolux TPO 440 - -
FILLERS

Black 550 180 -
Black 325 - -
Black 330 - 60
Caco3 5 -
PLASTICIZER
Paraffinic oil 130 -
Nitrex Factice - -
CURING AGENTS
Sulfur 1 -
PEROXIDE 98 - 1
TAC 50 - 2
ACCELARATORS
MBTS 1.2 -
ZDBC 0.7 -
CBS 1 -
Table 1(c)

Ingredients EPDM XNBR

Phr Phr
XNBR Krynac 750 - 100
EPDM KEP 270 100 -
DE VULCANIZED EPDM 10.5 -
ACTIVATORS
ZNO 5 -
Stearic Acid 1 -
ANTI-DEGRADENTS
TDQ - 1.5
Pilflex 13 - -
MBI - -
PROCESSING AIDS

Phenolic Resin 2 -
Petroleum Resin - -
Fatty acid ester - 5
Mayolux TPO 440 3 -
FILLERS
Black 550 160 65
Black 325 20 -
Black 330 - -
Caco3 - -
PLASTICIZER
Paraffinic oil 125 -
Nitrex Factice - -
CURING AGENTS
Sulfur 1.2 -
PEROXIDE 98 - 2
TAC 50 - 1
ACCELARATORS
MBTS 1.2 -
ZDBC 0.5 -
CBS 0.8 -
Table 2: Specific combination of XNBR and EPDM compounds employed for material level
experiments

FINAL
COMPOUND
DETAILS TRIAL 1 TRIAL 2 TRIAL 3 TRIAL 4 TRIAL 5 TRIAL 6 TRIAL 7
XNBR COMPOUND % 70 60 50 40 30 20 10
EPDM COMPOUND % - 40 50 60 70 80 90
AUROSIN 6860 (PHR) 3 3 3 3 3 3 3

NOTE : XNBR – Carboxylated Nitrile Butadiene Rubber EPDM- Ethylene Propylene Diene Monomer Phr- Parts per hundred rubber
Mixing Procedure:
a) EPDM with conventional ingredients including curing chemicals is compounded separately by two stage mixing to obtain EPDM compound.
b) XNBR with conventional ingredients including curing chemicals is compounded separately by two stage mixing to obtain XNBR compound.
c) Homogenizer cum coupling agent (AUROSIN 6860- Anhydride metallic salt) is added and mixed for 2 minutes. Whole rubber compound is passed through nip cap of 0.8 to1.2 mm for 2 times in two roll mixing mill and then 6-10 mm thick sheet are taken out.
d) In an alternate procedure, final compounds of XNBR and EPDM obtained in steps a) and b) are mixed together for 3 minutes to obtain a compound mixture. After this, homogenizer cum coupling agent is added to the compound mixture and mixed for 2 minutes. Whole rubber compound are passed through nip cap of 0.8 to1.2 mm for 2 times in two roll mixing mill and then 6-10 mm thick sheet are taken out.
The above procedure is carried out for all the XNBR/EPDM combinations.
The functions of the various categories of ingredients employed during the compounding process are as follows -
a) Activator: Increases the effect of accelerators.
b) Filler: It is used to reinforce or increase mechanical properties of rubber including tensile strength , modulus ,elongation , abrasion and etc.
c) Plasticizer: It is used to soften the compound and to facilitate the mixing and processing.
d) Curing chemical: Chemical used to cure (cross linking) the compound under heat & pressure.
e) Accelerators: They are used to speed up the cross linking process of curing chemical.
f) Antidegradents: It deters the aging of rubber products.
The below mentioned compound combinations are tested for resistance against ozone and engine oil-

Table 3: Elastomer combination tried for material level experiments

Sr. No.
1 2 Elastomer Blending Ratio Curing Sulphur
Sulphur Tests

XNBR:EPDM 70:30
Ozone &
Oil resistance

60:40

50:50

40:60

30:70

20:80

10:90

CSM NA
Ozone &
Oil resistance
NA: Not Applicable
From these combinations, material XNBR: EPDM mixture 70:30 is further tested for detailed material level tests and component level tests.
PHYSICAL & MECHANICAL PROPERTIES OF RUBBER MATERIALS
XNBR / EPDM with different blending ratios are tested for following basic material level properties-
(i)Tensile strength test
Stress – Strain curve of vulcanized rubber compound, is linear in lower strain range values and the same is non-linear at higher strain. Stress – Strain properties of the rubber compound in tension mode are carried out as per the ASTM D- 412.
(ii) Hardness test
Hardness is one of the most often quoted properties of the rubber compound. Hardness increases while oxidation, accordingly strength/ flexibility decreases. Also hardness changes in presence of oil /fuel /grease; thereby hardness change behaviour is important to know for any new application. Hardness is tested as per the ASTM D-2240.

(iii) Heat and Oil ageing test
Heat and Oil ageing properties of the rubber compound are important to study the oxidation effect / resistance quality of rubber compound against various media. After ageing of rubber compound, the strength drops due to oxidation / absorption of test media. Heat and oil ageing test is carried out as per the ASTM D 573 and ASTM D 471 respectively.
(iv) Diesel fuel ageing test
Diesel fuel ageing properties of the rubber compound are important to study the oxidation effect/resistance quality of rubber compound. After fuel ageing of rubber compound, volume swell increases and accordingly the strength drops. Diesel fuel ageing test is carried out as per ASTM D 471standard for 24 hours at room temperature.
(v) Grease ageing test
Since the hose is fitted with engine, there may be chances of grease contact during service. Hence the grease ageing test is conducted for comparison. Grease ageing test is carried out as per ASTM D 471 standard for 72 hrs at 90°C.
(vi) Distilled water ageing test
Since the hose is fitted with engine, there may be chances of distilled water contact during service. Hence the distilled water ageing test is conducted for comparison as per company’s internal standard for 72 hrs at boiling temperature with 1% of emulsifying anti corrosion oil.
(vii) Battery acid resistance test
Since the hose is fitted with engine, there may be chances of battery acid contact during service. Hence the battery acid resistance test is conducted for comparison as per company’s internal standard. The test samples are immersed in test medium (Battery acid with 37.4 % of Sulfuric acid) for 5minuts at room temperature and then stored for 5 minutes in air at 60°C.
(viii) % Compression set at elevated temperature and at low temperature
Compression set measurement is carried out as per the ASTM D- 395 Method B, for high temperature and as per ASTM D 1229 for low temperature. In both the tests, constant strain is applied for specified duration under specified temperature. Compression set property is directly related to cross link density of the rubber compound. Compression set at low temperature is useful to determine the low temperature flexibility.

(ix) Low temperature brittleness test
Low temperature brittleness test is carried out as per the ASTM D 2137, Method B. The brittleness temperature is highly dependent on the Tg of elastomers and importance of this test is to determine the low temperature flexibility.
Tg (Glass transition temperature): At this temperature an amorphous polymeric material like almost all the rubbers become as brittle as glass.
(x) Ozone resistance test
Ozone resistance test is important, because Ozone can attack the outer layer easily and can create surface cracks during the service. Hence it is mandatory to evaluate the material against Ozone. Ozone resistance test is conducted as per ASTM D1149, at test temperature 25±2°C, Ozone concentration 50±10pphm, relative humidity 55± 5 % for 70 hrs.
(xi) Damping coefficient test
Damping co-efficient test is conducted at 15 Hz with amplitude of ±0.11 mm as per company’s internal standard. Specimen is made as per JIS K6394 N2 type. Higher damping co-efficient is good for vibration dampening (Low frequency vibrations).
COMPONENT LEVEL TESTS (i) Hose burst pressure test
The fuel hose return line is a low pressure line thereby the hose should withstand the working pressure. Engine fuel hose return line hose is placed in a hot chamber at 100°C for 30 minutes. After that, burst test is conducted as per SAE J 30 R9.
(ii) Vacuum collapse test
Collapse test is to ensure the component withstanding pressure in suction. Vacuum collapse test is conducted as per 6.4 of SAE J 30 and results are noted. Also the hose is checked for visual defects including crack, break and layer separation after the test.
(iii) Cold flexibility test
Low temperature behaviour is importance when it is under cold conditions. Flexibility changes under cold condition according to the base elastomer. Cold flexibility test is

conducted as per company’s internal standard at -40°C for 5 hrs and hose is checked for visual defects including crack , break and layer separation.
(iv) Ozone resistance test
In addition to material level ozone resistant test, component should meet ozone resistance test since the outer layer thickness is lesser than the material slab thickness. Ozone resistance test is conducted as per ASTM D1149, at test temperature 25±2°C, Ozone concentration 50±10pphm, relative humidity 55± 5 % for 70 hrs.
RESULTS & DISCUSSION
Test results of different combinations are given below in table 2 & 3. ASTM 2 oil resistance test is carried out at 100°C for 72 hrs and Ozone resistance at 50 pphm, 40° C for 72 hrs. Results are compared to select the appropriate combinations.
Table 4: Ozone resistance of XNBR/EPDM and CSM with different blending ratios

Sr. No. Elastomer Blending Ratio Ozone Resistance Specification
XNBR:EPDM 70:30 No cracks found

60:40 Found surface roughness

50:50 Found surface roughness.

1
40:60 Found surface roughness.

30:70 Found surface roughness.

20:80 No cracks found

10:90 No cracks found

2 CSM NA No cracks found

Table 5: Oil resistance of XNBR/ EPDM and CSM with different blending ratios

Sr. No. Elastomer Blending Ratio Oil Resistance (Volume Swell) Specification
1 XNBR:EPDM 70:30 +5.6 %

60:40 Found surface roughness.

50:50 Found surface roughness.

40:60 Found surface roughness.

30:70 Found surface roughness.

20:80 +56.71%

10:90 + 68.9%

2 CSM NA +11.2 %
From the tables 4 & 5, combination of XNBR and EPDM with ratio of 70:30 shows better results in oil and ozone resistance test than that of other combinations. Consequently, the XNBR/EPDM (70:30) combination is taken further, for other material level tests.
The present disclosure is further elaborated with the help of following examples and associated figures wherein the combination of XNBR/EPDM are in the ratio of 70:30. However, these examples should not be construed to limit the scope of the present disclosure.
EXAMPLES -
Results Of Detailed material level properties of XNBR/EPDM against CSM elastomer -
EXAMPLE – 1
Initial physical properties of compound is tested and results are given below:
Table 6: Initial Physical Properties

Properties XNBR (100) EPDM (100) XNBR: EPDM (70: 30) CSM (100) SPEC. (In line with
CSM material)
Hardness 72 68 70 67 64 ~ 70
Shore A
Tensile 140 80 123 123 80 Min
Strength
Kg/cm2
Elongation 350 400 440 420 350 Min
%
Remarks:
Tensile strength and elongation of XNBR/EPDM combination is observed at par / superior in
comparison with CSM.
It can be noted that there is a good indication in test results to use XNBR/EPDM material for this application.
EXAMPLE - 2
Heat ageing at 120°C for 72 Hrs.
It is important to know the performance of the material under heat, which is being experienced by the material during the service. Heat ageing test is conducted on materials and results are given below:
Table 7: Heat ageing at 120°C for 72 Hrs

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
Change in hardness (Points) +11 +5 + 8 + 5 +10Max
Change in +10 +7 + 1.8 + 1.5 -30 Max

Tensile %
Change in
Elongation
% -33 -28 -42.8 - 13 -45 Max**
Remarks:
The heat ageing properties of XNBR/EPDM combination is found to be acceptable as against
the specification.
EXAMPLE - 3
Oil ageing at 100°C for72 Hrs. in 15 W 40 oil
Since the hose is fitted with engine, there may be chances of oil contact due to engine oil spillage (15W40). Hence it is important to know oil ageing performance of the material. Oil ageing test results are given below:
Table 8: Oil ageing at 100°C for 72 Hrs in 15 W 40 oil

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) +2 -34 - 3 + 1 -10 to +5
Change in Tensile % -20 -37 - 24.3 - 13.8 -45Max
Change in Elongation % -35 -30 - 44.7 - 4.5 -45Max **
Change in Volume % -4 +65 + 11.1 - 1.2 -10 to +30
Remarks:

The oil ageing properties of XNBR/EPDM combination is found to be acceptable as against the specification.
From the oil ageing results it can be noted that the material XNBR/EPDM can be used for this application.
EXAMPLE - 4
Oil ageing at 100°C for72 Hrs. in ASTM 1 oil
Oil ageing with ASTM 1 oil is conducted for comparison and results are given below:
Table 9: Oil ageing at 100°C for 72 Hrs in ASTM 1 oil

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) +4 -18 + 6 + 8 DFC
Change in Tensile % +25 -34 - 2.6 + 27 DFC
Change in Elongation % -30 -39 - 36.1 - 15.8 DFC
Change in Volume % -4.6 +48 - 3.89 12.2 DFC
Remarks:
% Change in volume of XNBR/EPDM combination is found superior in comparison with
CSM material.
The test results shown above are for comparison only, there is no specification for this test.
EXAMPLE - 5

Oil ageing at 100°C for72 Hrs. in ASTM 2 oil
Oil ageing with ASTM 2 oil is conducted for comparison and results are given below:
Table 10: Oil ageing at 100°C for 72 Hrs in ASTM 2 oil

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) -2 -20 -1 + 4 ±5
Change in Tensile % +21 -30 -7.2 + 17 DFC
Change in Elongation % -26 -19 -35.2 - 15.8 DFC
Change in Volume % +3 +66 +5.6 + 10 +40
Remarks:
% Change in volume of XNBR/EPDM combination is found superior in comparison with
CSM material.
It can be noted that there is a good indication in test results to use XNBR/EPDM material for this application.
EXAMPLE - 6
Oil ageing at 100°C for72 Hrs. in ASTM 3 oil
Oil ageing with ASTM 3 oil is conducted for comparison and results are given below:
Table 11: Oil ageing at 100°C for 72 Hrs in ASTM 3 oil

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) -6 -32 - 11 - 2 DFC
Change in Tensile % +6 -61 - 41 - 4.7 DFC
Change in Elongation % -35 -46 - 46.4 - 20.8 DFC
Change in Volume % +10 +98 + 28.7 + 22.7 DFC
Remarks:
% Change in volume of XNBR/EPDM combination is found to be acceptable.
The test results shown above are for comparison only, there is no specification for this test.
EXAMPLE - 7
Compression set at 100°C for 72 Hrs.
Compression set test is done at high temperature to address the permanent set.
Compression set test results are given below:
Table 12: Compression set at 100°C for 72 Hrs.

Properties XNBR EPDM XNBR: EPDM CSM SPEC.
%
Compression
Set 15 20 19.2 40 DFC
Remarks:

Compression set property of XNBR/EPDM combination is found much superior in comparison with CSM material. The test results shown above are for comparison only, there is no specification.
EXAMPLE - 8
Compression set at -40°C for 24 Hrs.
Compression set test is done at low temperature to address the permanent set. Compression
set test results are given below:
Table 13: Compression set at -40°C for 24 Hrs.

Properties XNBR: EPDM CSM SPEC.
%
Compression
Set 23 45 DFC
Remarks:
Low temperature compression set property of XNBR/EPDM combination is found superior
in comparison with CSM material.
The test results shown above are for comparison only, there is no specification for this test.
EXAMPLE – 9
Ozone resistance test at 50PPHM, 40°C, 20% elongation.
Ozone resistance is equally important in addition to oil & heat ageing. The effect of ozone are
tested and results are given below:
Table 14: Ozone resistance test at 50PPHM, 40°C, 20% elongation

Properties XNBR: EPDM CSM SPEC.
Presence of ozone Cracks No Cracks No Cracks No Cracks
Remarks:

There are no cracks observed in all three combinations.
EXAMPLE – 10
Low temperature brittleness at -40°C for 24 Hrs.
Considering low temperature application the effect of low temperature are compared. The
results are given below:
Table 15: Low temperature brittleness at -40°C for 24 Hrs.

Properties XNBR: EPDM CSM SPEC.
Absence of cracks Pass Pass Pass
Remarks:
There are no cracks or visual defects observed in all three combinations. The test results
shown above are for comparison only, there is no specification for this test.
EXAMPLE – 11
Resistance to grease at 90°C for72 Hrs.
Table 16: Resistance to grease at 90°C for72 Hrs.

Properties XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) + 6.0 +2 DFC
Change in Tensile % - 18.50 - 31.6 DFC
Change in Elongation % - 51.0 - 26.8 DFC
Change in - 3.40 - 3.9 DFC

Volume %
Remarks:
% Change in volume of XNBR/EPDM combination in grease is found superior in
comparison with CSM material.
The test results shown above are for comparison only, there is no specification for this test.
EXAMPLE – 12
Resistance to Diesel fuel at room temperature for 48 Hrs.
Table 17: Resistance to Diesel fuel at room temperature for 48 Hrs.

Properties XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) - 7 - 2 +5 to -10
Change in Volume % + 22.3 + 8.2 -5 to +25
Remarks:
% Change in volume of XNBR/EPDM combination in diesel is found to be acceptable as
against the specification.
From the fuel ageing results it can be noted that the material XNBR/EPDM can be used for
this application.
EXAMPLE – 13
Resistance against battery acid (37.4% Sulfuric Acid).

Table 18: Resistance against battery acid (37.4% Sulfuric Acid).

Properties XNBR: EPDM CSM SPEC.
Absence of
visible
Attack Pass Pass DFC
Remarks:
There are no cracks and visible attacks found in all three combinations. The test results
shown above are for comparison only, there is no specification for this test.
EXAMPLE – 14
Resistance to distilled water with 1% emulsifying anti corrosion oil at boiling temperature for72 Hrs.
Table 19: Resistance to distilled water with 1% emulsifying anti corrosion oil at boiling
temperature for72 Hrs.

Properties XNBR: EPDM CSM SPEC.
Change in
hardness
(Points) - 1.0 - 20 DFC
Change in Tensile % - 18.2 - 65.2 DFC
Change in Elongation % - 25.0 - 46.3 DFC
Change in Volume % + 17.8 + 64.1 DFC

Remarks:
Change in volume % of XNBR/EPDM combination is found superior in comparison with
CSM. The test results shown above are for comparison only, there is no specification for this
test.
EXAMPLE – 15
Damping Coefficient at 15 Hz, 50Hz with amplitude of ± 0.11 mm
Table 20: Damping Coefficient at 15 Hz, 50Hz with amplitude of ± 0.11 mm

Properties XNBR: EPDM CSM SPEC.
Damping factor at 15 Hz (Ns/mm) 3.16 0.55 DFC
Damping factor at 50 Hz (Ns/mm) 1.18 0.22 DFC
Remarks:
Damping coefficient is found superior in comparison with CSM material. The test results
shown above are for comparison only, there is no specification for this test.
Note:
SPEC. – Specification
** Specification modified / created.
DFC – Data for Comparison.
EXAMPLE – 16 Component Level Test Results:
Component level properties are very important in addition to material level properties to ensure the performance during the service.
Extrusion is done for all three combinations and hoses are cured with same curing conditions in the autoclave.

Component level tests are carried out on the cured hoses and the results are reported as follows-Table 21: Component Level Test Results

PROPERTIES XNBR/EPDM CSM SPEC.
Hose burst pressure (Mpa) 17 16 4
Hose vaccum
Collapse test
(mm/Hg) No collapse till 600 No collapse till 600 200
Hose cold flexibility test Pass Pass Pass
Ozone resistance test Pass Pass Pass
From overall test results, it can be noted that the XNBR/EPDM (70:30) blend material is meeting the material level and component level test criteria.
In one aspect of the present disclosure, a method of manufacturing outer cover of a fuel hose is disclosed. A XNBR and EPDM are co-extruded onto a surface (inner layer) of the fuel hose to form a multi layered outer cover for the fuel hose. In the co-extrusion process(T head Extruder), each compound (XNBR and EPDM) is fed to an extrusion die from separate extruders onto the surface of the inner layer to form an extrudate. The extrudate is then solidified by passing through a cooling bath. After solidification, the extrudate is passed through a conveyer having a cutting mechanism to cut the extrudate into desired length for curing. After cutting the extrudate to desired lengths, a mandrel is inserted into the inner surface of the extrudate to prevent shrinking of the extrudate during curing process. The mandrel containing the fuel hose outer cover is subjected to curing in autoclave. The autoclave is an instrument used to cure the equipment; the autoclave is pressurized with air or Nitrogen gas and heated via internally mounted electric or other type of heating coils. Under external equal pressure and heat, materials will cure in the autoclave. During curing process, the shrinkage of the compounds is prevented by the mandrel.

CONCLUSIONS
(a) XNBR/EPDM (70:30) blend material is found to meet all material level properties including tensile strength, Elongation, heat /oil ageing and ozone resistance. Also, hose made with XNBR/EPDM (70:30) blend material is found to meet the component level test requirements.
(b) XNBR/EPDM (70:30) blend material demonstrated superior results in grease resistance, distilled water resistance & compression set test than that of CSM material. Also this material is found to have better damping characteristics than that CSM material which will help in enhanced vibration damping during service.
(c) Hose made with XNBR/EPDM (70:30) blend found equivalent /superior than that of CSM elastomer material. Thereby, XNBR/EPDM (70:30) blend can be used for fuel hose outer cover application.
Based on the above conclusion and material cost, XNBR/EPDM (70:30) blend with 70:30 ratio is selected for fuel hose (return line) outer cover application.

We Claim :
1. A composition comprising Carboxylated Nitrile Butadiene Rubber (XNBR) and Ethylene Propylene Diene Monomer (EPDM) in ratio of about 70:30, optionally along with industrially acceptable excipient and homogenizer and coupling agent.
2. The composition as claimed in claim 1, wherein the EPDM is a mixture of vulcanized EPDM and de-vulcanized EPDM.
3. A method of obtaining a composition comprising XNBR and EPDM in ratio of about 70:30, optionally along with industrially acceptable excipient and homogenizer and coupling agent, said method comprising acts of:
a. mixing the XNBR, which is optionally present along with the industrially
acceptable excipient, with EPDM, which is optionally present along with
industrially acceptable excipient, to obtain the compound mixture, wherein
the homogenizer cum coupling agent is added either during the mixing of the
XNBR and the EPDM or into the obtained compound mixture of the XNBR
and the EPDM;
b. optionally, adding the industrially acceptable excipient to the product of step
(a); and obtaining the composition having the XNBR and the EPDM in the
ratio of about 70:30.
4. The method as claimed in claim 3(a), wherein the mixing of the XNBR and the EPDM is for time duration ranging from about 2 to about 4 minutes; and mixing homogenizer cum coupling agent with the compound mixture is for time duration ranging from about 1 to about 3 minutes.
5. The composition as claimed in claim 1 and the method as claimed in claim 3, wherein the homogenizer cum coupling agent is an anhydride metallic salt.
6. The composition and the method as claimed in claim 5, wherein the homogenizer cum coupling agent is in concentration ranging from about 1 phr to about 4 phr.
7. The composition as claimed in claim 1 and the method as claimed in claim 3, wherein the industrially acceptable excipient is selected from group comprising activator, anti-

degradant, processing aid, filler, plasticizer, curing agent and accelerator or any combination thereof.
8. The composition and the method as claimed in claim 7, wherein the activator is selected from group comprising zinc salts & stearic acid, the antidegradent is selected from group comprising amine, quinoline and benzimidazole, the processing aid is selected from group comprising esters, petroleum resin and phenolic resin, the filler is selected from group comprising high abrasion furnace black, fast extruded furnace black , medium thermal black and calcium carbomate, the plasticizer is selected from group comprising paraffinic oil and factice, the curing agent is selected from group comprising sulphur , peroxide and cyanurates the accelerator is selected from group comprising thiazoles, dithiocarbamates , sulfenamides & thiuram sulfides, or any combination thereof.
9. The composition and the method as claimed in claim 7, wherein activator is in concentration ranging from about 1 phr to about 5 phr, antidegradent is in concentration ranging from about 1 phr to about 3 phr, processing aid is in concentration ranging from about 1 phr to about 6 phr, filler is in concentration ranging from about 3 phr to about 180 phr, plasticizer is in concentration ranging from about 110 phr to about 130 phr, curing agent is in concentration ranging from about 0.6 phr to about 2.5 phr, accelerator is in concentration ranging from about 0.5 phr to about 2 phr or any combination thereof.
10. A method of obtaining a sheet made from composition as claimed in claim 1, the method comprising act of passing the composition between rollers to obtain the sheet.
11. A fuel hose outer cover composed of the composition as claimed in claim 1.