VKRT Payne effect

1 ELASTOMER RESEARCH TESTING the Payne effect in filled rubberVKRT meeting, May 14, 2009 ELASTOMER RESEARCH TESTING RESEARCH TESTING is in the name: ERT provides research and testing facilities in the rubber field for third parties. One of the properties of filled rubber we are working on is the measurement of the Payne effect . The Payne effect is directly related to the dynamic properties of the vulcanized rubber. ELASTOMER RESEARCH TESTING Payne effect in filled rubber is the phenomenon of a strain dependent dynamic carbon black or silica filled rubber we measure a high dynamic modulus at low strains (< 1%) which decreases at higher strains (> 10%).

2 The reason for this phenomenon is the formation of a network formed by filler-filler carbon black the interactions are Van der Waalsforces and for silica the much stronger RESEARCH TESTING Wehmeier, VKRT February 14, 2008. ELASTOMER RESEARCH TESTING (i)the destruction-reformation of a filler network (ii) adsorption-desorption of polymeric chains at the filler interface (iii)disentanglement of bulk polymer from therubber bounded to the surface (iv) strain-softening of the glassy polymer shellsurrounding the particles surfacesIn real life this means an energy loss and the intention is to minimize this effect in filled rubber (but with the reinforcement retained).

3 Possible mechanisms for the Payne RESEARCH TESTING first remark about this phenomenon was in 1942 by Gehman. The Dutch Rubber Stichting played a pronounced roll in the discovery of this phenomenon. In 1954 S. de Meij and van Amerongen presented their results on the DKG Tagung in of these results were published in to measure this filler-filler RESEARCH TESTING device of Seel de RESEARCH TESTING UND GUMMI, 9. Jahrgang, Nr. 3/1956 ELASTOMER RESEARCH TESTING , Payne , RTC 1966, 365 Payne effect : G = [G 0-G ]Loss modulus G tan ELASTOMER RESEARCH TESTING Guy, IRC Lyon, 2006samples were tested in pure shear with a Metravib VA3000 analyzerELASTOMER RESEARCH TESTING Guy, IRC Lyon, 2006 ELASTOMER RESEARCH TESTING Payne effect is difficult to measure in tension (single strain) and measuring in compression means that the test piece has to be glued as is done in the Metravib VA3000 analyzer.

4 The other modes are shear and torsion; ERT has the option make use of an Eplexor and a RPA. Measuring the Payne RESEARCH TESTING measures in torsion shear on samples which are first cured in the die of the instrument. (Wehmeier, VKRT 14-2-2008). Chosen is for 60 C and 1 Hz. The RPA measures from up to 90% strain; below the data are not on bar shaped vulcanized test pieces of 4x4 mm. Chosen is for 60 C and 1 Eplexor measures reliable from to 40% (this is what we did until now).Only two compounds were measured (207-03 and 207-04).

5 ELASTOMER RESEARCH TESTING in shear on the RESEARCH TESTING Payne effect (G') of vulcanized samples0,00,51,01,52,00,1110100strain (%)G' (MPa)207-03207-04 ELASTOMER RESEARCH TESTING G' of vulcaniz ed samples0,00,51,01,52,00,1110100strain (%)G' (MPa)207-03207-04 ELASTOMER RESEARCH TESTING Payne effect (G') measurements0,00,51,01,52,00,1110100stra in (%)G' (MPa)RPA-03 RPA-04 Eplexor-03 Eplexor-04 ELASTOMER RESEARCH TESTING G" of vulcanized samples0,000,050,100,150,200,1110100stra in (%)G" (MPa)207-03207-04 ELASTOMER RESEARCH TESTING G" vulcanized samples0,000,020,040,060,080,100,11,010, 0100,0strain (%)G" (MPa)207-03207-04 ELASTOMER RESEARCH TESTING of G" vs.

6 Strain0,000,050,100,150,200,1110100strai n (%)G" (MPa)RPA-03 RPA-04 Eplexor-03 Eplexor-04 ELASTOMER RESEARCH TESTING tan of vulcaniz ed samples0,000,050,100,150,200,250,300,111 0100strain (%)tan 207-03207-04 ELASTOMER RESEARCH TESTING tan vulcanized (%)tan 207-03207-04 ELASTOMER RESEARCH TESTING of tan vs. strain0,000,050,100,150,200,250,300,1110 100strain (%)tan RPA-03 RPA-04 Eplexor-03 Eplexor-04 ELASTOMER RESEARCH TESTING Payne effect as measured with the RPA on cured samples is higher than measured in shear on the Eplexor (G 1,0 G 20) = MPa for 207-03 and (G 1,0 G 20) = MPa for storage modulus G is also much higher for the RPA the loss modulus and the tan show an unexpected increase at strains over 25%.

7 (Most probably due to slip in the RPA die at higher strains.) ResultsELASTOMER RESEARCH TESTING Payne effect as measured with the RPA on unvulcanized compounds did not show this increase in loss modulus (G ) but the tan curve showed again an : the following curves G and G for unvulcanizedcompounds are smoothened below 1% Payne effect of unvulcanizedcompoundsELASTOMER RESEARCH TESTING G' measured curves0501001502002503000,1110100strain (%)G' (kPa)207-03207-04 ELASTOMER RESEARCH TESTING effect G', unvulcanized compound0501001502002503000,1110100strai n (%)G' (kPa)207-03207-04 ELASTOMER RESEARCH TESTING " vs.

8 Strain; unvulcanized compounds0501001502002503000,1110100stra in (%)G' (kPa)207-03207-04 ELASTOMER RESEARCH TESTING vs. strain; unvulcanized compounds0,00,20,40,60,81,01,21,40,11101 00strain (%)tan 207-03207-04 ELASTOMER RESEARCH TESTING :the Payne effect can not reliably be measured on vulcanized rubberwith the RPA because of unreliability below 1% strain and slip above (at least) 25% strain. For unvulcanizedcompounds the RPA seems to be reliable between and 25% Payne effect of vulcanizedsamples can reliably be measured with the Eplexor in shear between and 40% RESEARCH TESTING Payne effect was defined by Payne as the difference between G 0and G but this is difficult to a measure for the Payne effect in unvulcanizedcompounds, the differences between the G values at 1% and 20% as determined with the RPA in torsion shear can be used in comparative a measure for the Payne effect in vulcanized rubbers.

9 The differences between the G values at and 40% as determined with the Eplexor in pure dynamic shear can be used in comparative studies.