Interactions between Copper Atoms and Rubber Molecules by X-ray Diffraction

D0I:10.13374/j.iss1001-053x.1991.02.010 第13卷第2期 北京科技大学学报 Vol,13 No,2 1991年3月 Journal of University of Science and Technology Beijing March 1991 Interactions between Copper Atoms and Rubber Molecules by X-ray Diffraction Liu Jinlin Mu Chengzhang Lu Yugiu (刘金裤) (穆承章) (卢于) ABSTRACT:In order to determine the interactions between copper atoms and rubber molecules,this article used X-ray diffraction to analyse the cure spe- cimen of size materials mixed with copper powder for the first time,found the atomic nucleus distances between copper and atoms in rubber molecules were equal to 0,23169nm and 0,3043nm,0.3043nm reflected the atomic distance between Cu and S under the action of Van der Waals force.0.23169nm stated that there was chemical interaction between Cu atoms and rubber molecules. KEY WORDS:rubber,copper,interaction,X-ray diffraction While bonding to rubber,tyre wire must be plated with copper or copper alloy in order to obtain good bond strength.The states of the element copper play a very important role in bonding.The studies of interactions between copper and S,C atoms in rubber molecules were a great help to revealing the secrets of bonding and advancing convincing bonding theory. There were several bonding mechanisms of brass to rubber having been put forward(),but the main reasons of bond formation,i.e.,chemical bonds, physical bonds or mechanical mesh force,were still unclear and waiting for further studies.Measuring atomic nucleus distance between Cu and S,C in rubber can accurately determine the interactions between them,thus finding out the real reasons of bonding. 1 Experimental 1.1 X-ray Diffraction of Amorphous Materials Because amorphous materials haven't any structure regularity on the whole, 1990-05-09收稿 "压力加工系(Department of Metal Forming) 156

第 卷第 期 年 月 北 京 科 技 大 学 学 报 。 ‘ 一 ‘ ” 之 夕 “ “ 刘 金麟 穆承章 卢于 逮 扭 ， 一 扭 ， 一 。 。 。 让 。 节了 廿 ， ， ， 一 了 ， 、犷 五 ， 军犷 一 〕 ， ， ， ， ， ， ， 。 一 ’ ， 一 一 收稿 压 力加工 系 王与办 DOI ：10．13374／j ．issn1001－053x．1991．02．010

it often gives out a diffusion diffraction hump.If there is strong short-order structure,some simple and casual diffraction peaks may be obtained.These diffraction peaks relate to atomic distances appearing frequently in the disor- dered material.Using Bragg equation: d=1/2·元/sin0 (1) to describe them only has approximate meaning. The theory treatment to radial distribution function reflecting atomic distance Ris),is very complicated.After simplified deduction,to the amor- phous materials made up by chain hydrocarbon such as rubber: R=7/4π·元/sin0=1.11·d (2) This equation means:atomic distancc R appearing frequently produce strong extreme value at angle of diffraction pattern.R is cqual to 1.11 limes as value as d calculated by Bragg equationt6). 1.2 Experimental methods Add 18g (1 sample)copper powder into most primary size compound (2 sample): Natural rubber 200g MBT 1.4g Stearic acid 1.0g ZnO 10g Sulfur 6g obtain two compound sample,roll to slice and cure 30 min at 143C. Experiments were made on Japan Science 12kW rotating anode X-ray diffraction instrument. 2 Results and Discussion 1*and 2*sample's results of X-ray diffraction were shown in Figure 1,2. 2*sample's diffraction peaks were caused by rubber and ZnO.The peaks in amorphous diffusion hump and three peaks,0.94nm,3.116nm and 0.135nm which two samples both had,were caused by rubber.The other peaks were all caused by ZnO (5-664*ASTM card). Among 1*samplc's diffraction peaks,there were 4 peaks caused by copper (4-836*ASTM card),2 peaks by Cu 1,8S (23-962*ASTM card),besides that by rubber and ZnO.The other two peaks,d were equal to 0.1954nm,0.277nm were created by the interactions between copper atoms and rubber molecules. According to equation (2),the atomic dislances R were equal to 0.2169nm and 0.3079nm. 151

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15.00f Sample Name:LJL1 7.5 5.00 20.00 40.00 60.00 50.00 100.00 120.00 Fig.1 1'sample /s result of X-ray diffraction 10.00 Serrple Name:ILJ2 N 5.00 P- 5.0020.00 40.00 60.00 80.00 100.00 120.00 Fig.22.sample/s result of X-ray diffraction There were only S and C atoms in cured rubber.The atomic radiuses of Cu and S were 0,120nm and 0,185nm,the sum of them was 0.305nm.This stated that 0,305 9nm reflected the atomic distance between Cu and S under the action of van der walls force. The another atomic distance 0.2169nm reflected the interaction between Cu and C.Cu and C was impossible to attract each other by physical intera- ction.The atomic radiuses of Cu and S were 0.128nm and 0.180nm respectively. The sum of them was 0.30 8nm,which was much larger than 0.216 9nm.This stated that strong chemical bond was formed between Cu and C. 152

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Metal atoms,such as Cu,Ag,Pt,can form stable alkene coordinate compound(7).This stated that Cu H atoms was possible to form o-co- H 23 ordinate bonds with C=C in rubber 91.2 232.7 137 molecules chain. 216= 89.43 At the same time,atomic dista- 2c0.5 nce 0.216 9nm between Cu and C was H H approximate 0.21 6nm (Fig.3)be- tween Pt and C in Zeise's salt,KPt Fig.3 Structure of (Pt(C2H4)C133 Cl2 C2-H4.H2Ot8).Therefore,it was concluded that strong chemical interaction took place between Cu and C atoms,Cu and C=C formed o-z coordinate bond. 3 Conclusions (1)Cu and S in cured rubber can casily attract each other by Van der Waals force. (2)Cu and C=C in rubber molecule chain formed strong o-coordinate bond. References 1 Buchan,Rubber to Metal Bonding,Crosby Lockwood and Sons,London, 1959 2 van Ooij W J.Rubber Chemistry and Technology,1979,52:605 3 van Ooij W J.Rubber Chemistry and Technology,1984,57:421 4 haemers G.Rubber Would,1980,(9):26 5 Xiaozeng You.Guide to Structure Analysis,Academic Press,Beijing: 1980,179 6 Klug H P,Alexander L E.X-ray Diffraction Procedures for Polycrystal- line and Amorphous Materials,John wiley and Sons,New York:1974, 849 7 Xianglin Zhang and Heng Kang.Coordination Chemistry,Centre-South Technology University Press,Hunan,China:1986,709 8 Jarvis J A J.et cl Acta Cryst,1971;B27:366. 153

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