الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
ABSTRACT Rest .1’esis’tan”t_rub~ blends at 50 pbr* fran na1iural .1’Il1>be:l:l om> end 50 pbr from s1iyrene -- bu’llf>die116rubber (Smi - l502) bave been prgpered according 1io 1ihe stendard 1iecbniques. These blends were incurpora1ied wi1ih differentconcentra1iions end 1iypes at carbon black end sUbJected 1io electirical and 1ihermal conduc1iivi1iies measurements~ For
de conduc1iiviiiy , t7” , i1i was found iihaii c-r’ depends on the carbon black concen1iraiiion , F , according to 1ihe
6D1pirical formula on the form.
In ( d’1?) = In ~o&/crK) I [ 1 + exp ((”1’;- t)~F)] wb$re <%’ is 1ille ini1iial oonduc’liiv.1:liyQf the host rubber material , ~:Il is tbe conc:luciiiviiiy of ’libe extreameLy carbon loaded rubber matirix end F0 is a cri’liical carbon black concentiro’liion arround which Large change of conduc’liivi1o;y
was appeared __within ’lihe concen1ira’liion range OF !
The above empirical formula was also found ’lio be in good
agreeman’li with tha1i previously sugges’lied 1)yAmin e1i al (47) !
r! Tbe ’liempera’liuredependance of C’for the above rubber blends showed ’libermally aciiiva’lied conduciiion mechanism for
low carbon black coniien’li! For high as well as moderate concentra’liions of carbon black, however, a decreasing in
conduc’liivi’liy wi1ih iiempera1iure bas been obtia:i.ned! The.
conduc’liion mechanism at such canpos11ies was suggesiied ’lio be
due ”to hopping or ’liunneling mechanisms. The descending
behaviour at the elec’lirioal conductivi1iies is a”ttribu’lied
tio ’lihe thermal expansion of hopping poths due to the higher values at ’lihe ’lihermal expansion coefficien’li of iihe insula’liing rubber, - 3 - The CClIIlpe1ii1ioiofnthe above conduo1i1onmechaniSlllSe,1i
rele,’t1vel.,yhigh temperatures results in the appearence of m1.nimumconductivity value, This minimumwas found to be dependen’t on ’the carbon black concentration, It is shif’ted towards the bo’th higher values of conductivities and
temperatures as the carbon black oonoentration increases, the dc conductivity of differen1i types of oarbon blaoltloaded lm/SBa blends was found to be dependen1ion bo1ih
ohemical and physical properties of carbon black used, Six types of carbon black (with 100 phr) were used far 1ihis
s’tudy neae13 , :I.SAli’ , IUJI’ , li’1I1II’ , GPJ’. smr and EI?O. It
was found ’that IS4.’U’, HAP and JIlE’O blaokSwhicl1 have’ 8ma]} plL;Cticlesize endconsequen1;l,yhigh 1iendencyof aggregate forma1i1onsincre.e me.:akedly”the dc conductivity of the
rubber blend w11i1rlespec”t ”to other ”types of black, Tile ac oonductiv11iymeasurementsfor J’JJBblaok ; leaded Ni/SBRshowa frequency dependence on the form.,
().J 0( vP w1’bh0,5 -( n < l this confirms according to JonscharGO)
1ihehopping conduc1iionmeohanism’through the carbon filled ~ubber _1ir~”’1i rele:tively higher frequencies approxime1il.1
quadra1i1cdependence on 1ihefrequency has been observed whiCha1i’tributed ’to 1iheintar - chain llopp1J:lglIleohanism”
J’ina1l3, ’the ’therIaal conduc’tivi1iy, K, or all above
ccmposi1iesa’t dj,ftden1i 1i.pera’tures ~as been measured 1181 ••••
’the s1i_4y sta’t6 !low ’techniques. Tbe de~ease of ’theraaal conduc’tivi’tl wi’th ’the fncrease of ’tempera’ture was found to be ’the predomina’tefea’ture of ’the It (T) relatiClD. !l!b:Liss. at1iributed ’to ’the increase of ’the pbQnon- phononin’terac’t1an,
whioh is in good &greemen’twith tha’t sl1ggec1iedin ’the previous publications.