The Ethylene Propylene Diene Terpolymers Engineering Essay

INTRODUCTION AND OBJECTIVESEthylene-propylene-diene terpolymers ( EPDM ) have been astray utilize in industrial applications because of their first class foeman against heat, ozone and weathering, every bit good as their unusual availability of accepting risque burden of fillers 1-3 . Support in the overt presentments of mussitate bendable compounds, such as tensile strength, resiliency, wear opposition and flex opposition, behind be achieved by lading the compounds with particulate fillers. Different classs of C black atomic number 18 the well- cognise conventional fillers utilise in EPDM put on elastic bands compounds 4 . Increasingly, mineral fillers like te oxide and clay have attracted much attending as they personify less and give less wellness jeopardies 4 . But delinquent to the hapless silica- caoutchouc bonding, the support by atomic number 14 oxide has non been to the full exploited 4, 5 . The handiness of silanised atomic number 14 oxide, whi ch is normally obtained by pre-treating silicon oxide with Bi ( 3-triethoxysilylpropyl ) tetrasulphane ( TESPT ) , a sexual union agent, adheres silicon oxide to the put onwood elastic 6 . Furthermore, it is attractive that the sulphur-bearing bi operable organosilane can besides answer to bring forrader crosslinks mingled with maunder elastic ironss with the nominal head of gasoline pedals and activators at elevated temperatures, i.e. 140-240AC 5-12 . The presence of TESPT improves the animate procedure in silanised silica-filled EPDM apply elastics with other common vulcanizing systems. Though many another(prenominal) investigate workers have made attempts to look into different amends systems for EPDM put on elastics 3, 4, 13-17 , the inquiry on the power of doctor systems for commercial production remains unfastened. That gives the aim of this undertaking which is as followeUsing different remedy systems to crosslink silanised silica-filled EPDM gingiva el astic Assess efficiency of the remedy systems Choose the most efficient one for bring more or lessing the gluewood elastic.This literature reappraisal foremost introduces the basic background of EPDM gum elastic, including composing, chemical construction and identical belongingss and industrial applications in Section 2. and so a brief overview of the preparation of silanised silica-filled EPDM gum elastic compounds is given in Section 3, followed by the elabo step entering of recent plants on fillers and remedy systems for silanised silica-filled EPDM gum elastic in Sections 4, 5 and 6. Finally, the undertaking program will be discussed.BASIC BACKGROUND OF EPDM pr unconstipatedtiveTerpolymerisation of ethene, propene and a non-conjugated diene gives EPDM gum elastic with a concentrated ethyl radicalene-propylene anchor and unsaturation site in the side group, introduced by diene monomers 17 . Generally, ethene and propene monomers argon the major constituents in an EPDM , planning inherently first-class opposition against debasement by heat, visible radiation, O, and, in peculiar, ozone 18 . The pocket-sized nitty-gritty of non-conjugated diene monomers place the oxidizable unsaturation sites available for sulphur vulcanization or polymer alteration chemical science, as the dienes ar so structured that merely one of the dual bonds will polymerize 19 .Figure 1 EPDM ternonomersThe three co-monomers use in industry ar present in Figure 1. Each diene monomer incorporates with a different ability of triping long concatenation complication or polymer side ironss, hence affect the processing and vulcanization procedure 20 . The most normally employ termononer is ethylidene norborne ( ENB ) as it can integrate easier and has greater responsiveness with sulphur vulcanization 19 . The chemical construction of EPDM with ENB termonomer is illustrated as followsFigure 2 Chemical construction of EPDMA habitual sum-up of belongingss of EPDM gum e lastic is listed in bow 1 below. plank 1 Properties of EPDM gum elasticsPolymer PropertiesMooney Viscosity, ML ( 1+4, 125AC )5 to 200Ethylene Content ( wt. % )45 to 80Diene Content ( wt. % )0 to 15Specific Gravity ( gm/ml )0.855 to 0.88Vulcanisate PropertiesHardness ( Shore A Durometer )30 to 95Tensile Strength ( MPa )7 to 21Compaction Set B, ( % )20 to 60Elongation ( % )100 to 600Useful Temperature Range ( AC )-50 to +160Tear ResistanceFair to closeAbrasion ResistanceGood to ExcellentResilienceFair to GoodElectrical PropertiesExcellentEPDM is the fastest turning man-made gum elastic having to its excellent ozone and thermic opposition over other diene gum elastics and its burden of fillers and plasticizers to an highly high degree 18 . EPDM has found widespread applications in 18 automotive applications, such as seals, hosieries and profiles Construction applications, such as roof sheeting, profiles, and seals Electrical overseas telegrams and jacketing Moulded contraption parts besides isBlended with other gum elastics and thermoplastics.EPDM RUBBER FORMULATIONFillers for EPDM RubberDue to the non-crystallising nature of EPDM gum elastic, support is required for EPDM gum elastic, since the windup(prenominal) belongingss of the unfilled gum elastic atomic number 18 rather hapless. Carbon black is the most widely used filler for reenforcing EPDM gum elastics, but silicon oxide, clay, talc and some other mineral fillers are besides used 19 . Increasingly, more attending is being paid to silica 1, 2, 4, 15, 16, 21-25 . To accomplish full excogitatement of support by reenforcing fillers in EPDM gum elastics, C black and other fillers must be good dispersed. Good support can give EPDM gum elastics with high tensile strength, good tear opposition and improved deoxyephedrine opposition. Furthermore, a well- coalesce wad besides improves the processability for bulge, calendaring and modeling 19 . The reenforcing fillers and their cause on EPDM gu m elastics will be discussed in item in Sections 4 and 5.Remedy Systems for EPDM RubberAs mentioned before, the incorporation of unsaturation sites allows the atomic number 16 vulcanising of EPDM prophylactic. second remedy is the most widely used method, busying about 80 % of EPDM applications 17 . EPDM gum elastic can besides be vulcanize in a bleach remedy system. Rubber vulcanised by southward remedy system can suit more emphasis and exhibit higher(prenominal) extension phone at interruption, while the advantage of bleach remedy over sulphur remedy is the formation of thermo-stable carbon-carbon bonds alternatively of thermo-labile sulphur-sulphur bonds, as the dissociation temperature and energy of sulphur-sulphur bonds is place down than that of carbon-carbon bonds 17, 26 . Hence higher effectivity of heat opposition of EPDM gum elastic can be obtained by peroxide remedy systems. The treatment of remedy systems for EPDM gum elastics will be unwrapped in Section 6. Other AdditivesOther normally used additives in EPDM rubber compounds are plasticizers, softeners and treating AIDSs. Naphthenic oils have been the most widely used plasticizers as they have the mitigate compatibility with EPDM gum elastic and lowest cost. Paraffinic oils are normally used for elevated-temperature applications or in colored compounds due to the lower volatility and higher UV stableness. Stearic acid, Zn stearic and other internal lubricators are frequently used as processing AIDSs in EPDM rubber compounds. The presence of tackifier or non is dependent on if there is a demand for presenting tack as EPDM gum elastic compounds are inherently non tacky 19 .Different preparations of EPDM rubber compounds consequence in a assortment of applications. A typical formula for C black-filled EPDM gum elastic for sheeting application is shown in Table 2 below. Tiwari and colleagues 27 studied consequence of different interventions of silicon oxide on silica-filled EPDM gum elastic belongingss and the basic preparation for silanised silica-filled gum elastic is given in Table 3.Table 2 Typical formula for C black-filled EPDM sheeting 19 ComponentsAmount ( phr )EPDM A100N 347 black120Talc30PARAFFINIC oil type 103B95Zinc oxide5Stearic acid1MBTS2.2TMTD0.65TETD0.65Sulfur0.75Table 3 Basic preparation for silanised silica-filled individual EPDM gum elasticComponentsAmount ( phr )EPDM100Silica50ZnO5Stearic acid2.0Silane ( TESPT )4Sulfur1.04N-cyclohexylbenzothiazole-2- sulphonamide ( CBS )1.5Tetramethylthiuram disulphide ( TMTD )0.8Zinc dibenzyldithiocarbamate ( ZBEC )1.5Fillers USED IN EPDM RUBBERCarbon Black A Conventional FillerCarbon inkinesss are the most widely used reenforcing fillers in gum elastic industry since the find of their effectivity of intermiting the physical and robotic belongingss of natural elastomers in 1904 12 . Different classs of C black have been used in EPDM gum elastics for industrial applications, such as roof sheeting and automotive profiles and many research workers have studied about the mechanical behavior of C black reinforced EPDM gum elastics.Ghosh and Chakrabarti 28 reported effects of different sums of C inkinesss on the physical and mechanical belongingss, ageing behavior and conduction of EPDM rubber compounds and the rheological behavior of EPDM gum elastic in bulge processing. Osanaiye 29 used sinusoidal shear flows to analyze the effects of C black, temperature and shear frequence on dynamic mechanical belongingss of EPDM rubber compounds. The effects of different sums of carry oning C black filler on thaw rheology and relaxation behavior of healing leave office EPDM gum elastic by cone home base viscometer was reported by Ghosh and Chakrabarti 30 . Abd-El Salam and colleagues 31 used inactive and dynamic analysis to analyze consequence of different vulcanizing systems on the mechanical belongingss of butyl rubber/ EPDM general furnace black. Cavdar, S. et al 3 reported a co mparative survey on mechanical, thermic, viscoelastic and rheological belongingss of cured C black filled EPDM gum elastic.thither are many more illustrations of research on other facets of C black reinforced EPDM gum elastics. For illustration, conductive gum elastics have been made by adding conductive C inkinesss into EPDM and its blends by Das, N. C. et Al 32 . The electrical and mechanical belongingss have been studied.Silica A Novel FillerRecently, man-made silicon oxide is going more pop as reenforcing filler in EPDM gum elastics because they have proved to be every bit effectual as C inkinesss 12 . Furthermore, silica offers some(prenominal) advantages over C black in tyre paces, a higher wear opposition and better derisory-grip with a lower turn overing opposition can be obtained by utilizing silicon oxide instead than carbon black 1 . Besides, silica-filled compounds are really suited for light coloring material applications.Problem and TreatmentsThe support of si licon oxide in EPDM gum elastic has non reached the coveted degree because of the hapless silica-EPDM bonding. The surfaces of silicon oxides have siloxane and silanol groups, which make the filler acidic and polar 7 while EPDM gum elastic is non-polar. When the polar silicon oxide is assorted with non-polar and olefinic hydrocarbon gum elastics, e.g. EPDM, hydrogen-bond interactions among polar siloxane or silanol groups in agglomerates are more likely to happen than the interactions between silicon oxide and rubber 1 , ensuing in hapless compatibility of hydrocarbon gum elastics with silicon oxide. Furthermore, the acidic silanol groups interact with the basic gas pedals, spread outing the remedy clock to an unacceptable degree and take downing the crosslinking engrossment 5 . The polar surface of silicon oxide will besides be given to absorb wet and this influences remedy and belongingss of the cured gum elastic 5 . Additionally, the viscousness increases with increasi ng sum of silicon oxide filler and if the viscousness is excessively high, the processability will be cut back and inordinate wear and tear of the processing machine will take topographic point 5 .However, the handiness of specific matching agents makes the usage of silicon oxide in EPDM rubber compounds possible. Bifunctional organosilanes are normally used to better the compatibility between silicon oxide and hydrocarbon gum elastics by falsifying the surfaces of silicon oxide 1 .Silanes and Silanised SilicaBifunctional silanes can be used to chemically associate an organic stuff to an inorganic substrate. The rule purpose of utilizing silanes to respond with silica involves cut downing ablating hydrophilicity of silicon oxide and presenting a new organo functional groups onto the silicon oxide surfaces 1 . In the instance of sulphur-cured compounds, sulphur-functional silanes perform best and for peroxide-cured compounds, unsaturated silanes such as vinylsilanes are reco mmended.In footings of sulphur-cure systems, the usage of Bi ( 3-triethoxysilylpropyl- ) tetrasulphane ( TESPT ) ( Figure 3 ) as a yoke agent is good established, since foremost introduced in 1991 in a practical application in green tyres by Rauline 33 ..Figure 3 Chemical construction of TESPTTESPT possesses ethoxy groups and tetrasulphane groups. The ethoxy groups oppose with silanol groups on the silicon oxide surfaces via hydrolysis tool 33 , taking to the strong covalent silica-filler bonding. The tetrasulphane groups are no-good reactive and therefore stable rubber-silica bonding can be achieved via due south crosslinking. Bis ( 3-triethoxysilylpropyl ) -disulphane ( TESPD ) was subsequently introduced chiefly to get the better of the pro-scorching job of TESPT, as the sulphur-sulphur dissociation energy of TESPD was lower than that of TESPT 33 .The silanisation of silicon oxides are normally obtained by two attacks. Silica and silanes are assorted preliminarily at an o ptimal temperature and reaction clip, or, instead, they can be mixed in situ during the commixture procedure 5 . The latter is the more normally used method 34 . A good silanisation is required as it yields best support and reduces compound indurating during storage. A certain sum of H2O can speed up the silanisation. The optimum wet subject is suggested to be around 3-6 % 34 . The chief influences on the in situ silanisation of silica-silane filled compounds are summarised in Figure 4.Furthermore, if silicon oxide is used in a blend with, e.g. , C black, relatively more silane is required as silane is less likely to make the silica surface quantitatively in a given commixture clip 34 . In these instances, silanised silicon oxide obtained by the pre-treatment is advisable.Optimum silanisationAndShort commixture timesRelease of ethyl alcoholT aand T aRelease of ethyl alcoholTaand taGood silicon oxide scatterIaas TaComplete matching reaction Ta and T aAvoid pre-crosslinkingT a and T aFast transit proceduresIaas T a high school mobility of the silane little sizeBest rotor and blending chamber geometryFigure 4 chief influences on the silanisation reaction 34 Apart from sulphur vulcanization, the addition of vinylsilanes is normally applied to better the mechanical belongingss of peroxide-cured compounds. The general construction of vinylsilanes is shown in Figure 5.Figure 5 generalized construction of vinylsilanesIn contrast to the reasonably high dose of sulphur-functional silanes in merchandises necessitating high mechanical belongingss, a strong support can be achieved by the incorporation of merely 2 parts by weight Si 225 ( VTEO ) per silicon oxide 34 . Adding more extremist instigator or activators can ensue in higher crosslink densenesss 34 .However, the applications of silanised silicon oxide are elephantinely focused in natural gum elastic ( NR ) , styrene butadiene gum elastic ( SBR ) , and polybutadiene gum elastic ( BR ) . Very few re search works has been published on the effects of silane on EPDM gum elastics, but there are still some. Kim 33 reported consequence of TESPD on the processability and mechanical belongingss of EPDM rubber. Taikum and Luginsland 16 studied the function of silane-rubber yoke in sulfur, peroxide and metal oxide bring arounding systems for EPDM gum elastic. Das et al 4 showed that the presence of TEPST change magnitude the marrow of bound gum elastic in silica-filled EPDM compounds, which was critical to the mechanical belongingss of the gum elastic.Other TreatmentsOther matching agentsBesides silane, several other matching agents have been employed to modify the silica-EPDM bonding. Das et al 4 usage Bi diisopropyl thiophosphoryl disuli?de ( DIPDIS ) , to modify EPDM rubber alternatively of silicon oxide by two-stage vulcanization technique. The effects of TAC ( Triallyl Cyanorate ) as a yoke agent on hardening and mechanical belongingss of silica-filled EPDM gum elastic wer e studied by Abtahi and associates 1 .Others methodsTiwari et al 23 treated the surfaces of silicon oxide by plasma-polymerisation with acetylene monomer and one twelvemonth subsequently, the comparative survey of plasma-thiophene and -acetylene coated silicon oxide in EPDM support was reported 27 . Tan and Isayev 22 treated silicon oxide utilizing a coaxal supersonic extruder and investigated the effects on belongingss of ultrasound-treated silicon oxide on filled EPDM gum elastic.Other fillersIn most instances, C black and silicon oxide are used to reinforce EPDM gum elastics. Some other sorts of fillers have been added to EPDM rubber matrix and their effects been investigated, affecting montmorillonite ( OMMT ) nanofiller 35 , nano-zinc oxide 36 , Sm2O3 26 , short cyanuramide fibers 37 , modify/halloysite 38 and so on.Effects OF FILLERS ON PROPERTIES OF EPDM RUBBEREffectss of Carbon BlackAs mentioned before, research workers have studied a batch about the effe cts of adding C black on the mechanical belongingss of EPDM rubber, demoing that the belongingss were improved significantly 3, 28-32 . Cavdar and associates 3 reported that the Young s modulus, Shore A hardness, and compaction force over distortion ranage increased with increasing content of C black, while the lengthiness at interruption reduced ( Figure 6 ) .Figure 6 Effectss of C black content on ( a ) mechanical belongingss and ( B ) rheological belongingss of EPDM rubber 3 .The Young s modulus was most filler content medium as the value increased aggressively with sum of C black. In footings of rheological belongingss, increasing C black content resulted in higher upper limit torsion and the difference between upper limit and minimal torsion, which corresponded to relative crosslinking denseness. The optimal remedy clip decreased with increasing the filler content.Considerable research has been done to understand the mechanism of support. Two chief features of active i nkinesss are their surface country and sum construction, which determine the inactive and dynamic in-rubber belongingss and therefore do it possible to orient the public presentation of gum elastic merchandises.Effectss of SilicaEffectss of silicon oxide on the mechanical belongingss of EPDM gum elasticWithout silanesThe effectivity of silicon oxide as reenforcing filler in EPDM gum elastic was confirm by Ichzo and colleagues 2 who showed that tensile strength had improved by 500 % , tear strength by 400 % and elongation at interruption at 140 % by adding 20 phr of precipitated silicon oxide. They used silicon oxide with different size and demonstrated that an increasing inclination of tensile strength can be achieved when the size of silica atom decreased. The hardness of EPDM gum elastic increased with the filler burden but it was non particle size dependant. They besides found that silicon oxide sums size distribution affected the mechanical belongingss and it deserved more att ending.With silanesDas 4 indicated that the Young s modulus, tensile strength and crosslinking value of silica-filled EPDM gum elastics increased well when 1-2 phr of TESPT was added, while the elongation at interruption decreased, as illustrated in Figure 7 below.( B )( a )( vitamin D )( degree Celsius )( degree Fahrenheit(postnominal) )( vitamin E ) Figure 7 Consequence of TESPT on the mechanical belongingss of EPDM rubber compounds ( a ) modulus at 100 % elongation ( B ) modulus at 300 % elongation ( degree Celsius ) tensile strength ( vitamin D ) hardness ( vitamin E ) elongation at interruption ( degree Fahrenheit ) crosslinking value 4 .Consequence of silicon oxide on treating belongings of EPDM gum elasticAs mentioned earlier, adding silicon oxide to EPDM gum elastic will do the processing more hard as the viscousness increases significantly when a large sum of silicon oxide is involved 5 .However, the handiness of silanes such as TESPT or TESPD weaken the interact ion between silica atoms as the ethoxy groups in silane react with the surfaces of silicon oxide by the silanol groups, taking to a alteration in interfaces between the polymer-polymer, polymer-silica and silica-silica 33 . Hence, it reduces the viscousness and improves the processability of the gum elastic compounds 5 . Kim 33 reported that the add-on of TESPD to silica-filled EPDM gum elastic yielded lower Mooney viscousness, heat coevals and bulge force per unit area build-up through an extruder, which made treating easier.Effectss of silicon oxide on thermic belongings of EPDM gum elasticMadani 39 studied the thermic belongings of gamma radiation cured silica-filled EPDM via thermohydrometric analysis ( TGA ) and demonstrated that the presence of silicon oxide reduced the rate of debasement and the weight loss of vulcanisates. This was due to the improved adhesion between silicon oxide and EPDM rubber matrix. He besides stated that thermic belongings of silica-filled EPD M gum elastic was firm by the burden of filler, filler size and construction, filler-matrix interactions and processing technique.Consequence of silicon oxide on the ageing belongings of EPDM gum elasticAirplanes et al 15, 40 used gamma radiation to age unfilled and filled EPDM gum elastics at room temperature and at 80AC to analyze the influence of silicon oxide on the gum elastic debasement. They evidenced that adding untreated silicon oxide accelerated the polymer stage debasement due to the formation of auxiliary groups triggered by silica irradiation. If silane-treated silicon oxide was presented, the debasement acceleration was delayed.Effectss of silicon oxide on the electrical belongings of EPDM gum elasticRaw EPDM gum elastic is an dielectric with a conduction of about 10-14 S-1 39 . It was proved that the add-on of inorganic fillers such as silicon oxide increased the conduction of polymer 39 . Madani 39 investigated the fluctuation of dielectric changeless ( ) o f some healed EPDM and silica-filled EPDM gum elastics as a map of frequence and found that was filler content dependant it increased up to 10 phr, and so decreased with increasing burden. He pointed that the addition was due to the polar groups present on silicon oxide surfaces, and that the lessening was due to the increasing system denseness and the extent of orientation of dipoles.Effectss of scattering of silicon oxide on the belongingss of EPDM gum elasticFiller scattering has a distinguishable consequence on the belongingss of gum elastic compounds. Poor scattering has a negative consequence on gum elastic belongingss by making structural defects 5 . Polmanteer and Lentz 41 demonstrated that some belongingss such as tensile strength and tear strength improved as the filler scattering quality increased after they examined consequence of scattering of silicon oxide on the belongingss of some sulphur-cured gum elastics. To obtain a better scattering of fillers in gum elastic compounds, increasing commixture clip is an efficient method, nevertheless, at the cost of take downing the molecular weight of polymer, which leads to the decrease in mechanical belongingss 5 . The arrange of scattering of filler can be examined by microscopy methods, such as negatron microscopy and atomic force microscopy.CURE SYSTEMS FOR EPDM RUBBERSulphur Cure systemsEvery gum elastic merchandise is vulcanised with its ain specific remedy system, ensuing in assorted belongingss. As already mentioned, the incorporation of pendent unsaturation sites enables that EPDM rubber to be vulcanised by sulphur plus gas pedals. Sulphur remedy is the most widely used vulcanising method for bring arounding EPDM gum elastics, representing about 80 % of the EPDM applications 17 . Compared with peroxide-cured EPDM gum elastics, sulphur-cured gum elastic compounds are able to suit more emphasis and exhibit higher elongation at interruption.Basically, three types of sulfur crosslinks are use d in elastomers, viz. , monosuphfidic ( C-S-C ) , disulphidic ( C-S2-C ) and polysuphidic ( C-Sn-C ) . The crosslink denseness and the value of Ns are chiefly determined by vulcanizing system and procedure conditions such as remedy temperature and clip. oer the old ages three particular types of remedy systems have been established based on the degree of sulfur and the ratio of accelerator-to-sulphur applied. They areEfficient vulcanization ( EV ) systems,Semi-efficient vulcanization ( SEV ) systems andConventional vulcanization ( CONV ) systems.EV systems are characterised by a high ratio of accelerator-to-sulphur or even sulphurless, but incorporating sulphur-donor alternatively. They are normally used in vulcanisates which require an highly high heat and reversion opposition 42 . CONV systems are vulcanisation systems with a low ratio of gas pedals to sulfur and they can supply better flex and dynamic belongingss but worse thermal and reversion opposition. A semi-efficient reme dy system has an accelerator-to-sulphur ratio in between those of the CONV and EV vulcanization systems. For SEV systems, optimal degrees of mechanical and dynamic belongingss of vulcanisates with intermediate heat, reversion and flex belongingss can be obtained 42 . The composings of CONV, SEV and EV systems are shown in Table 4.Table 4 the degrees of gas pedals and sulfur in CONV, SEV and EV systems 42 TypeSulphur ( phr )Accelerator ( phr )A/S ratioCONV2.0-3.51.2-0.40.1-0.6SEV1.0-1.72.5-1.20.7-2.5Electron fivesome0.4-0.85.0-2.02.5-12Increasing accelerator-to-sulphur ratio consequences in increased sum of shorter mono- and disulphidic crosslinks. As the dissociation energy of C-C bonds are larger than that of S-S bonds. Vulcanisates obtained by EV and SEV systems possess a better heat and reversion opposition than those cured by CONV systems. The general influences of the type of vulcanization systems on the construction and belongingss of the vulcanisates are summarised in Tab le 5.Table 5 vulcanisate construction and belongingss for different remedy systemsFeaturesRemedy systemsCONVSEVElectron voltPoly-and disulphidic crosslinks ( % )955020Monosulphidic crosslinks ( % )55080Cyclic sulfide ( conc. ) naughty sensitive humbleNon-sulphidic ( conc. )HighMediumLowReversion oppositionLowMediumHighHeat ageing oppositionLowMediumHighFatigue oppositionHighMediumLowHeat construct upHighMediumLowTear oppositionHighMediumLowCompaction set ( % )HighMediumLowFurthermore, nitrosamine free or safe hardening bundles were developed for the replacing of remedy systems which develop nitrosamines during vulcanization. N-nitrosamines formed during vulcanization as condensation merchandises from certain gas pedals and azotic gasses and are carcinogenic 43 . They are generated from some thiuram and dithiocarbamates gas pedals, which are known as ultra-accelerators and normally used in EPDM gum elastic intensifying 43 . Traditional ultra-accelerators can be replaced by nitros amine-free systems, but at outlay of high costs.About all imaginable combination of bring arounding ingredients for EPDM rubber compounds have been evaluated over the old ages 42 . Five typical remedy systems are listed in Table 6. The alternate nitrosamine free or safe remedy systems are suggested in Table 7.Table 6 Five remedy systems for EPDM rubber 42 Systems ( phr )AdvantagesDisadvantagesSystem 1Low costBloomingS 1.5TMTD 1.52-mercaptobenzothiazole ( MBT ) 0.5System 2Excellent physical belongingss and fast remedyScorchy and expensiveS 2.0MBT 1.5Tellurium diethyl dithiocarbamate ( TDEC ) 0.8Dipentamethyl thiuram tetrasulphide ( DPTT ) 0.8TMTD 0.8System 3Excellent compaction set and good heat ageing oppositionBloom and really high costS 0.5Zinc dibutyldithiocarbamate ( ZDBC ) 3.0Zinc dimethyldithiocarbamate ( ZDMC ) 3.04,4dithiodimorpholine ( DTDM ) 2.0TMTD 3.0System 4Non-bloomingCure comparatively slow and worse compaction setS 2.02,2-dithiobenzothiaole ( MBTS )ZDBC 2.5TMTD 0 .8System 5Zinc O, O-dibutylphosphorodithioate ( ZBPD ) 2.0TMTD 1.0N-butylbenzothiazole-2-sulfenamide ( TBBS ) 2.0S 1.0Fast remedy and good physical belongingssBloomingTable 7 Some NA free options for the remedy systems above 42 SystemsNA free optionsSystem 1S 1.5S 1.3MBT 0.5MBT 0.75TMTD 1.5CBS 3.8System 2S 2.0S 1.5MBT 1.5ZMBT 2.0TDEC 0.8ZBEC 0.5DPTT 0.8ZBPD 2.0System 5ZBPD 2.0ZBPD 2.5TMTD 1.00TBBS 2.0TBBS 2.0S 1.0S 1.2Besides, an activator, such as Zn oxide, is normally needed in EPDM remedy systems to maximize the efficiency of gas pedals and chemical adhesion between the filler and gum elastic.Silanised Silica a Crosslinking Filler An of import issue must be considered sing the sulphur remedy systems for silanised silica-filled EPDM gum elastic is the fact that the usage of sulphur-functional silanes such as TESPT combine silicon oxide with sulfur into one individual merchandise known as a crosslinking filler 6 , such as silanised silicon oxide. It can non merely better the mechanical belongingss of gum elastic, but besides can bring forth crosslinks between the gum elastic ironss at elevated temperatures in the presence of gas pedals due to the sulphur-containing groups. Therefore, the vulcanization procedure can be achieved without elemental sulfur being present 6 . Research has shown that the mechanical belongingss of some vulcanisates improved significantly in malice of the decrease in the usage of the hardening chemicals 6 .It was demonstrated that during the vulcanization procedure the formation of both rubber matrix crosslinking web and silica-rubber yoke web occurred at the same time and did non separate. In the presence of elemental sulfur, the two different crosslinking reactions compete for the added sulfur as the sulphur-functional silanes like TESPT are sulphur acceptor 34 . Therefore the crosslinking construction and the support are determined by the sums of silane and sulfur. The influence of adding different sums of sulfur and sil ane on the matrix and silica-rubber yoke webs is shown in Figure 8.Figure 8 consequence of the sum of ( a ) added sulfur and ( B ) silane ( TSEPT ) on the crosslinking densenesss of matrix and silica-rubber yoke 34 It is apparent that increased sum of sulfur enhances the efficiency of the silica-rubber yoke until all the silane is activated. Initially, a little grade of addition in the matrix crosslink denseness is observed, due to the ingestion of free sulfur by the activation of silane. After the full activation of silane, the matrix crosslink denseness additions much faster. With regard to the increasing sum of silane at a changeless sum of sulfur, the entire figure of silica-rubber bonds additions while the degree of the matrix crosslink denseness reduces, owing to the incorporation of sulfur by the silane 34 . Furthermore, in the instance of TESPD, a disulphide silane, the consequence is more important. Therefore it can be concluded that altering the sum of elemental sulfur and silane consequences in different ratios of the matrix and silica-rubber webs 34 . Furthermore, mechanical belongingss of silanised silica-filled gum elastic can be predicted because silica-rubber yoke dominates the modulus and hydrophobation lowers hardness values. Some exercise effects of silane on the mechanical public presentation of silica-filled EPDM gum elastic have been presented in Section 5.2.1.Peroxide Cure systemsOverviewCrosslinking with peroxides was foremost introduced in 1915, but did nt pull excessively much attending until the development of to the full saturated ethylene-propylene copolymers ( EPM ) 42 . Many sorts of elastomers can be vulcanised by peroxide remedy systems expeditiously, including NR, SBR, EPDM, BR, nitrile gum elastic, Silicones and fluorocarbon elastomers 42 . The unsaturation can better the efficiency of peroxide vulcanization 17 , due to the higher concentration of allylic Hs 42 . The comparative efficiency of peroxide crosslink ing for different elastomers isBR & gt NR and SBR & gt NBR & gt CR & gt EPDMThe advantages and disadvantages of peroxide remedy compared to sulfur vulcanization are listed in Table 8 42 Table 8 Advantages and disadvantage of peroxide remedy compared with sulphur remedyAdvantagesDisadvantagesThermo-stable C-C bonds alternatively of thermo-labile S-S bonds,Scorch free storage of compounds,Simple compound preparation,Low compaction set even at high remedy temperature,It is possible to bring around at high temperatures without reversion,Good electrical belongingss of healed gum elastic,No stain of compounds.Low intensifying flexibleness Lack of flexibleness in modulating singe and optimal remedy clipInferior tensile, tear and flex public presentation,Inferior cole oppositionHigher cost,Sensitivity to oxygen during vulcanization,Smells of peroxide decomposition merchandises.Peroxide remedy of EPDMPeroxide-cured EPDM gum elastics are being widely used for many old ages. They are no rmally used in window seals, automotive hosieries, roof sheeting, tanking liner, electrical insularities, steam hosieries, roll coverings moldings and so on 42 .Mechanism of peroxide remedy of EPDM gum elasticThe mechanism of peroxide remedy of EPDM gum elastic and the subsequent practical effects have been reviewed by new wave Duin and colleagues 17, 44, 45 . In the by and large accepted mechanism of peroxide remedy of EPDM, the major stairss are illustrated in Figure 9.Figure 9 Mechanism for peroxide remedy of EPDM 17, 44, 45 Thermal debasement of the peroxide initiated by procedure triggered a concatenation of free-radical reactions, taking to the formation of primary alkoxy ( ROa? ) or secondary alkyl groups ( Ra? ) . Then the abstraction of H-atoms from the EPDM polymer outputs EPDM macro-radicals ( EPDMa? ) . The following measure is the combination of two EPDM macro-radicals, or the incorporation of a macro-radical to an EPDM unsaturation. If a yoke agent, such as vinyls ilanes mentioned in Section 4.2.1.1 ( TAC, trimethylolpropane or m-phenylenbis ( maleimide ) ) , is present, the peroxide remedy efficiency can be increased, as they can heighten the H-atoms abstraction and the undermentioned reactions are repressed 1, 17 EPDMa? + ROa? a EPDM RO ( No crosslinking )EPDMa? aEPDMa? + ( I?-Scission )The issues of the elaborate mechanism of peroxide vulcanization of EPDM gum elastic remain unfastened, chiefly having to the complexness of the system. Several surveies have been conducted to see far apprehension of the chemical mechanism of peroxide remedy of EPDM 46, 47 .Matching agents for peroxide remedy of silica-filled EPDM gum elasticAs antecedently stated, vinylsilanes are normally incorporated in peroxide remedy systems for silica-filled EPDM gum elastic to better vulcanization efficiency and mechanical public presentation of vulcanisates. The effectivity of TAC as a yoke agent for peroxide vulcanization of silica-filled EPDM gum elastic was investigated by Abtahi et al 1 and concluded that TAC matching agent improved some belongingss such as tensile strength, scratch and resiliency opposition with a proper preparation. They besides used SEM to hold a deep penetration in the interaction between silica filler and gum elastic in the presence of TAC and found that the grade of support was chiefly affected by the grade of wettability.New DevelopmentsReducing the sulfur content consequences in vulcanisates with better thermal opposition throughout service life, nevertheless, this is at the disbursal of decrease in mechanical public presentations such as dynamic weariness opposition and tear opposition. This via media can be eliminated by utilizing two additives, viz. hexamethylene-1, 6-bisthiosulphate ( HTS ) , a station vulcanization stabilizer and 1, 3-bis ( citraconimidomethyl ) benzine, an anti-reversion agent 42 .Vulcanization techniques have effects on EPDM gum elastics. Das 4 studied the efficiency of one-stage and two-stage sulfur vulcanization techniques of silica- filled EPDM gum elastics and reported that alteration of EPDM gum elastic by two-stage vulcanization technique enhanced the interactions between EPDM rubber and silicon oxide.Furthermore, assorted remedy systems can besides be employed to heighten the public presentation of vulcanisates.Undertaking PlanThe overall purpose of this undertaking is to prove some sulfur and peroxide remedy systems to bring around silanised silica-filled EPDM gum elastic to bring forth a gum elastic with good mechanical belongingss utilizing a suited hardening system. The undertaking programs arePrepare silanised silica-filled EPDM gum elastic compounds with peroxide and bring around the gum elastic with gas pedal and activator via the sulfur in the silane Use C black and silanised silicon oxide nanofillers in EPDM gum elastic to measure their effects on the mechanical belongingss of the gum elastic Remedy and step the mechanical belongingss of fill ed EPDM gum elastic to set up consequence of the bring arounding systems and fillers on the gum elastic belongingss.