r15-3710.qxp 12/5/2007 2:15 PM Page 1

www.rubbernews.com Rubber & Plastics News ● December 10, 2007 15 Technical Winter : Tread material test innovations By Uday Karmarkar Discussion and Edward Terrill As stated in the introduction, com- Akron Rubber Development Laboratory Inc. Executive summary plete analysis of the winter tires used in P.K. Mohamed and Arup K. Chandra This paper presents the development of winter tread formulations using the study provides us with a good under- Apollo Tyres, Limda Village a variety of material testing techniques. standing of the critical components, di- Eight tires were received at Akron Winter compounds have to perform adequately under conditions of mensions and formulations. Rubber Development Laboratory. Each ice and snow. Tread compound formulation strategies encompass several fac- The study also provides a new trac- of the tires is subjected to complete re- tors, such as microscopic analysis, dynamic characteristics, filler interactions, See Winter, page 16 verse engineering reconstruction using and friction testing, geometric conditions of tread design. the techniques of dynamic characteriza- We have focused on obtaining the tread formulation that will provide ade- Fig 2. The remaining six tires used in tion, modulus profiling and chemical de- quate traction under ice and snow conditions using laboratory bench testing the winter tire survey as per Table I. construction. All tests are data analyzed techniques developed in-house. to understand the design philosophy We present the development of the ARDL bench top traction tester to per- with respect to the dynamic properties form testing to duplicate traction at cold temperatures to exact laboratory con- as well as the raw material composition. ditions. Additional testing on the dynamic characteristics of the material provides in- Physical properties sight into the tread rubber formulations. The laboratory testing provides the Tensile testing basis for production of winter tires and testing under ice and snow conditions Dumbbell specimens were die-cut us- by Apollo Tyres, India. ing an ASTM D 638 Type V dumbbell Testing tires for ice and snow performance is done using maneuverability die and tested per ASTM D 412. Sam- testing and braking performance in the field. ples were tested at 2 inches per minute (50.08 cm/minute). 50 percent, 100 percent, 200 percent, strument is used for measuring the TECHNICAL NOTEBOOK 300 percent and 400-percent elongation. transversal relaxation decay curves to Edited by Harold Herzlichh Pulsed proton Nuclear Magnetic probe the changes in the chemical struc- Resonance ture. This in principle can be used to Testing was done in a controlled envi- The ARDL NMR instrument is a identify the changes in the structures ronmental space maintained at 50-per- Bruker Minispec mq 20 MHz Pulsed with aging as well as with changes in cent relative humidity and at 70°F. Test Proton Unit. This instrument has been the formulations of rubber products. output includes elongation to break, used as a chemical structure probe tool. ARDL Benchtop Traction Test stress at break, modulus at 25 percent, The solid state NMR pulsed proton in- The traction tester is used to compare the traction properties of the materials Fig.1 Two tires used in the winter tire survey as identified in Table I. that are used in the tread formulations. The inputs are 65 mph speed axial load that equates to the load based on foot print analysis. See Winter, page 16 Table I. The seven tires used to con- duct a winter tire survey.

Fig 3. The dimensions of the different layers used in the tires.

CUSTOM MIXING • Largest Custom Mixer on West Coast • All Solid Polymers • Black and Non-blacks Table II. Data on three types of compounds formulated designated by letters A, B • Slabs, Strips, Preforms, Calendered Rubber & Fabrics and C differentiating the level of antioxidants used 0.5, 1.25 and 2 phr. All slabs are compression molded to a uniform thickness of 40 thousandths of an inch. • Your Formula or Ours Valley Processing Div. of Mitchell Rubber Prod. V 491 Wilson Way • City of Industry, CA 91744 P (626) 961-0311 • FAX (626) 968-2026 Contact: Sy Hasan or Kevin Sarcon e-mail: [email protected] r16-3710.qxp 12/5/2007 2:29 PM Page 1

16 Rubber & Plastics News ● December 10, 2007 www.rubbernews.com Technical

gies encompass several factors, such as the usage and application. Five of the NBS abrasion test 1630, and cam- microscopic analysis, dynamic charac- seven tires have cap ply overlays. ber wear testing, flat track testing indi- Winter teristics, filler interactions, traction and Detailed cross sectional microscopy is cated a need for a simultaneous meas- friction testing and geometric conditions essential to accurate measurement of urement of traction and wear on a Continued from page 15 of tread design. the thicknesses. Tire A and C indicate a laboratory scale. tion test that helps with the under- This task was divided into three steps: subtread and tread interface that is only The ARDL test equipment consists of standing of the traction capabilities of 1) winter tire survey, 2) traction and visible with color shaded optical mi- a mechanism to apply a known axial the compounds under dynamic condi- wear and 3) tire prototyping. The first croscopy images assisted with fresh force to the “donut” specimen against a tions. Tire component testing and re- step was conducted on eight tires as cross section visual observations. known frictional surface at a known ro- search can be a very effective tool in de- shown in Table I. Tire A has a subtread that in the cen- tational speed. Footprint analysis of a veloping tire durability tests as well as Dimensional analysis, dynamic test- terline has a physical connection to the typical tire used in service is conducted tire properties to help develop a winter ing and chemical deconstruction were surface. as a basis for the load. tire with superior properties. performed to understand the existing The second step was to conduct a track Polished basalt tiles are used to simu- Winter Tire treads compounds have to ranges of material and sizes used in the able traction and wear test on a labora- late very slick icy conditions. All the test perform adequately under conditions of winter tires. tory materials scale. We focused on ob- parameters are fed to a lab view pro- ice and snow. Tire traction as well as the All tests are data analyzed to under- taining the tread formulation that will gram that allows accurate and high scan tire wear is important to a winter tire stand the design philosophy with re- provide adequate traction under ice and rate monitoring of the torsional force, tread formulation. Understanding of spect to the dynamic properties as well snow conditions using laboratory bench axial load as well as temperature of the tire traction and the transfer of forces on as the raw material composition. testing techniques developed in house. specimen. low coefficient of friction material as Figs. 1 and 2 indicate the different Figs. 4 and 5 shows the development of The sprocket and the sample, the fric- well as regular concrete is important for layers in the tires. The different tires the ARDL Traction and Wear Tester. tion surface and the loading block, and tread formulations. have varying thicknesses as well as con- A survey of the existing techniques the collection pan for wear particles are Tread compound formulation strate- struction characteristics depending on such as Tabor abrasion ASTM 3389, all accurately measured for weight before DIN 53576, ISO 4649, ASTM 5963, and after the 15-second test is complete. Fig. 4. The “ARDL Benchtop Traction Tester” and sample dimensions. PICO Index abrasion ASTM D2228, See Winter, page 20 Fig 6. The data from NMR and traction transferred on the traction and wear tester. Generally the higher the crosslink density, the lower the traction.

Fig 5. The comparative data between the tread formulations based on the winter survey and the two formulations developed. The data indicates an identical trans- fer of torque under dynamic conditions.

Fig 7. The simultaneous measurement of the wear rates indicates that the model compound aged at 70°C has a reversal in trend in comparison to the traction rates. This data demonstrates the capability of the test to differentiate the sample chem- istry.

The authors Uday Prakash Karmarkar is a business development manager for Akron Rubber Development Laboratory Inc. Karmarkar has been active in new test development and aging research in tires. He holds two U.S. patents and has published several scientific articles and presentations on the subject of tires, automotive, aerospace, medical products and predictive materials research. E- mail him at [email protected]. Ed Terrill worked more than 20 years with Goodyear in the Polyester, Tire Physics and Compound Science departments and DuPont n the Textile Fibers Pioneering Research Laboratory. He joined ARDL in March of 2003. He has three patents, two trade secrets and six publications in polymer science. He can be reached at [email protected]. r20-3710.qxp 12/6/2007 12:58 PM Page 1

20 Rubber & Plastics News ● December 10, 2007 www.rubbernews.com Technical

trations that the lower change in cross Conclusion The next phase of this study is to linking for these specimens also is A new test method is under develop- manufacture tires with this tread for- Winter matched by a lower drop in traction ment at ARDL to measure traction mulation and conduct on the road ice forces. The greater the thermo oxidative forces transferred. and snow testing for correlations Continued from page 16 aging, the greater the loss of traction. Testing of winter tire tread material Studies were conducted on compound- The wear rate, however, depends on the formulations can be performed on mold- References ed rubber samples aged in tire reactors temperature of aging. This might possi- ed model compounds as well as on sam- 1. Shoop, S., Kestler, K. and Haehnel, R., “ Finite under various conditions of thermo ox- bly be from the formation of certain sul- ples from tires. Element Modelling of Tires on Snow, “ Tire Science and Technology. TSTCA, Vol. 34, No. 1, January- idative aging. fur linkages compared with others. New winter tires are being developed March 2006, pp.2-37 Table II shows the comparison of The third step of novel tire tread com- with material testing 2. Lacombe, James, “Tire Model for simulations of pulsed proton NMR data and traction. pound prototyping was started using the The ARDL Benchtop Traction tester vehicle motion on high and low friction road sur- Figs. 6 and 7 indicate the unusual phe- traction and wear tester. Fig. 5 indi- can be used to measure information on faces., US ARMY REL, Hannover, N.H. 3. Nakajima, Yukio, “Analytical model of longitudinal nomenon where the high temperature cates comparison of the traction rates traction and wear and to study wear tire traction in snow,” Journal of Terramechanics, aged sample and a trend reversal be- for two tires compared to two experi- particle morphology. Vol. 40, Issue 1, January 2003. pp. 63-82. tween traction and wear compared to mental tread formulations. A variety of Detailed cross section analysis, dy- 4. Hofstetter, K.; Grohs, Ch.; Eberhardsteiner, J.; crosslink density. techniques will be utilized for compar- namic testing and winter traction test- Mang, H.A.; “Sliding behaviour of simplified tire tread patterns investigated by means of FEM Com- The blue shaded symbols indicate ing the new formulations to existing ing are used to develop a benchmarked puters and Structures,” Vol. 84, Issue 17-18, June samples aged in lower oxygen concen- tread formulations. winter tire formulation 2006. pp. 1151-1163 Classifieds

Equipment For Sale SPARESPARE PARTSPARTS • 16"x40" FARREL Silicone Mill SPAREPARTS (chromed rolls and cutting bar) - Rebuilt in 1999 • 3-1/2" DAVIS-STANDARD 10.5:1 Spare Parts Spare Parts Silicone Extruder - New in 1996, 32ft conveyorized curing oven - New in 1996 • SCOTT L-6 Tensile Tester RRR DEVELOPMENT SPARE PARTS OFFERINGS • Versa Puller/Cutter w/ 2" wide belts • RRR USA supplies many universal spare parts for first stage shoulder set tire and single knife building machines and servicers from their Ohio Design and Build Job Shop Facility. • 2 - 14"x14" (2 openings) ALBERT • RRR USA also purchased 25 Akron Standard tire plant product designs to continue Hydraulic presses w/ 6" or 8" ram exclusive spare parts and product support of their large installed base. - Rebuilt 1998 • New MILLER Hydraulic unit - never • RRR Asia(Vietnam) is a wholly owned RRR USA subsidiary with 25 employees equipped with new CNC machines and PRO-E design stations to provide Asian used priced spare parts for RRR plus other OEMs. Please give us an opportunity to quote • 8"x8" PHI hand-pump press the fabrication and distribution of your parts. OEM fabrication is kept confidential. • Versa Puller - 4" wide belts (non-oper- ational) • This could be a good opportunity for you to safely expand your product offerings in the Asian region, as well as have more accessible spare parts and technical sup- • 2 - BLUE M Model 806 post-cure port directly from Asia. We are working hard to provide American quality at Asian ovens (inside dimensions: 48"W x 48"D prices. x 60"H) Email: • Please contact Ashley Roberts ([email protected]) 330-966-8855 or visit RRR’s website (www.rrrdev.com) for more information. [email protected] for details. ★ ★ RUBBER EQUIPMENT FOR SALE • ALPHA ORD 2000 RHEOMETER, NEW 2001 • FARREL F 80 UNIDRIVE 600/300HP COMPLETE • 3 LITER LAB TILT DISPERSION MIXER Happy Holidays • 13”x6” FARREL MILL 7.5HP DRIVE from • 30”x12” RELIABLE MILL DUEL 25HP DRIVE • 42”x14” BOLLING MILL VARIABLE SPEED Rubber & Plastics News • 84”x26” FARREL MILL DRILLED ROLLS, TWIN DRIVE Classifieds! EAGLE POLYMER EQUIPMENT, INC. PH: 330-706-0552 FAX: 330-706-0546 Spare Parts WWW.POLYMEREQUIPMENT.COM SPARE PARTS?? Does your company offer Spare Parts? Are you looking for a way to promote this to the rubber industry? A sure way to do so is with an ad in RPN’s NEW SPARE PARTS Classifieds Section. This Special Section of RPN Valves classifieds will be dedicated solely to the Spare Parts segment of the rubber industry. Your ad in print, digital and web QUALITY HIGH PRESSURE VALVES Serving The Rubber Industry Since 1947 for one low price! www.valv-trol.com 800-497-2136 Call today for Special Introductory and Color Rates! 800-429-0948 • [email protected]