Improving rolling resistance of NR tread formulations.Energy conservation is of interest on both a national and rubber industry level. High oil prices will increase the desire for conservation. A major source of energy loss in tires is the motive motive or motif (mōtēf`), in music, a short phrase or passage of two or more notes and repeated or elaborated throughout the composition. The term is usually used synonymously with figure. (kinetic kinetic /ki·net·ic/ (ki-net´ik) pertaining to or producing motion. ki·net·ic adj. Of, relating to, or produced by motion. kinetic pertaining to or producing motion. ) energy that is converted to heat in the tire tread tread injury to the coronet of the horse's hoof by treading on it by the opposite hoof, or by another horse when they are being worked in a team. If the coronary matrix is injured there may be a subsequent crack or deformity. as the tire rolls down the road. Low rolling resistance Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when an object such as a ball or tire rolls. It is caused by the deformation of the wheel or tire or the deformation of the ground. can result in significant energy savings. Many manufacturers of passenger car tires have adopted the partial replacement of carbon black by silica silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. , the so-called so-called adj. 1. Commonly called: "new buildings ... in so-called modern style" Graham Greene. 2. "green" tire, to lower rolling resistance. A key to the successful use of silica in automobile automobile, self-propelled vehicle used for travel on land. The term is commonly applied to a four-wheeled vehicle designed to carry two to six passengers and a limited amount of cargo, as contrasted with a truck, which is designed primarily for the transportation of tire tread stock is the use of a silane silane or silicon hydride Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula SinH(2n + 2). coupling agent to improve bonding of the silica to the rubber. Another factor is the creation of special solution styrene-butadiene Styrene-Butadiene (SBR) is an elastomeric copolymer consisting of styrene and butadiene. It has good abrasion resistance and good aging stability. SBR is stable in: mineral oils, fats, aliphatic, aromatic and chlorinated hydrocarbons. rubbers with exact control of microstructure mi·cro·struc·ture n. The structure of an organism or object as revealed through microscopic examination. microstructure Noun a structure on a microscopic scale, such as that of a metal or a cell . Truck tires are based primarily on natural rubber (NR) because of its exceptional resistance to heat build-up build·up also build-up n. 1. The act or process of amassing or increasing: a military buildup; a buildup of tension during the strike. 2. and low cut and chip properties. NR is the polymer polymer (pŏl`əmər), chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond). of choice for truck tire treads because it runs cooler and has lower rolling resistance, which translates to reduced fuel consumption. Furthermore, a decrease in running temperature yields better tire aging resistance and therefore improved retreadability. At the present time, truck tire treads use highly reinforcing re·in·force also re-en·force or re·en·force tr.v. re·in·forced, re·in·forc·ing, re·in·forc·es 1. To give more force or effectiveness to; strengthen: The news reinforced her hopes. carbon black for maximum reinforcement reinforcement /re·in·force·ment/ (-in-fors´ment) in behavioral science, the presentation of a stimulus following a response that increases the frequency of subsequent responses, whether positive to desirable events, or and excellent resistance to abrasion abrasion /abra·sion/ (ah-bra´zhun) 1. a rubbing or scraping off through unusual or abnormal action; see also planing. 2. a rubbed or scraped area on skin or mucous membrane. . A truck tire is expected to last over 400,000 km (250,000 miles). The replacement of carbon black by silica in truck applications has been hampered by incomplete coupling of the silica to the polymer chain ends of the NR. In addition to not obtaining sufficiently lower rolling resistance, abrasion resistance also typically suffers. A survey of global truck tire manufacturers, retread re·tread tr.v. re·tread·ed, re·tread·ing, re·treads 1. To fit (a worn automotive tire) with a new tread. 2. makers and freight The price or compensation paid for the transportation of goods by a carrier. Freight is also applied to the goods transported by such carriers. The liability of a carrier for freight damaged, lost, or destroyed during shipment is determined by contract, statute, or haulers was conducted to obtain a "voice of the customer," to learn customer needs and the important parameters necessary for the adoption of more energy-efficient tires. End users regard cost per mile as the most important criteria criteria (krītēr´ē  ),n. , specifically cost per 0.7 mm (0.03 in.) of tread wear. Tires are the second highest capital expense for trucking companies. Average fuel economy is 2-1/2 to 3-1/2 km/L (6-8 miles/gal.), and it is felt an improvement of 0.1 km/L (0.2 miles/gal.) would be significant. Tire manufacturers indicate wear and rolling resistance are the most important parameters. One-third of fuel cost for trucking companies is simply to roll the tires. A 3% reduction in rolling resistance results in a 1% improvement in fuel costs. Some sacrifice sacrifice [Lat. sacrificare=to make holy], a type of religious offering, or gift to a superior or supreme being, in which the offering is consecrated through its destruction. in tread wear would be acceptable to realize a fuel economy benefit; there are more potential savings in lowering rolling resistance than in increasing tread wear. Measuring loss factor as an indication of rolling resistance Dynamic mechanical testing can be used to measure loss factor as tangent tangent, in mathematics. 1 In geometry, the tangent to a circle or sphere is a straight line that intersects the circle or sphere in one and only one point. delta, which is the ratio of viscous viscous /vis·cous/ (vis´kus) sticky or gummy; having a high degree of viscosity. vis·cous adj. 1. Having relatively high resistance to flow. 2. Viscid. response (loss modulus See modulo. ) divided by the elastic elastic Of or relating to the demand for a good or service when the quantity purchased varies significantly in response to price changes in the good or service. response (storage modulus). Loss factor can be used as an indication of relative rolling resistance, with lower tangent delta values indicative indicative: see mood. of lower rolling resistance. The storage modulus is also important, because it determines how much the tread will deform under a given load as the tire rotates through the footprint The amount of geographic space covered by an object. A computer footprint is the desk or floor surface it occupies. A satellite's footprint is the earth area covered by its downlink. See form factor. 1. . Laboratory test data for compounds based on either solution SBR SBR - Spectral Band Replication or NR are shown in table I to illustrate the differences in dynamic mechanical properties. In the SBR/BR passenger tread compound, the data show a large improvement in loss factor by the addition of precipitated silica, from about 0.20 to 0.12. The NR truck tread compound shows less reduction in loss factor by the addition of precipitated silica, from about 0.18 to 0.14. Effect of silica level Precipitated silica was tested as a partial replacement for N220 carbon black in the NR base formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation , and test results are shown in table 2. Higher levels of precipitated silica lead to slightly lower abrasion resistance and modulus. The loss factor of the compounds containing silica is significantly lower than the black-filled compound, with the 60 phr silica compound exhibiting less than half the loss factor of the black-filled compound at 4% double strain amplitude amplitude (ăm`plĭt  d'), in physics, maximum displacement from a zero value or rest position. .The initial addition of silica yields a compound with lower tear strength and shorter scorch and cure times. Increasing levels of silica provide improved tear strength with longer scorch and cure times, becoming comparable to carbon black at the highest silica level. Effect of silane level Holding the silica level constant at 60 phr (with 5 phr N220 carbon black), the level of TESPT silane was varied from 2.4 to 6.0 phr. Formulas and test data are shown in table 3. The results in figures 1-3 show that higher silane levels lead to lower scorch and cure times with higher modulus and abrasion resistance. Loss factor appears to be optimum between 3.6 and 4.8 phr. [FIGURES 1-3 OMITTED] Effect of accelerator accelerator: see particle accelerator. (1) A key combination such as Alt-G or Ctrl-Shift H that is used to activate a task. (2) An incubator that expects to develop the company considerably faster than normal. See incubator. type and level In the base formulation with 60 phr silica, DPG DPG diphosphoglycerate. was compared as a secondary accelerator to Royalac 150 (R-150) with activator activator /ac·ti·va·tor/ (ak´ti-va?ter) 1. a substance that combines with an enzyme to increase its catalytic activity. 2. a substance that stimulates the development of a specific structure in the embryo. . Table 4 contains the formulas and test results, including a black-filled compound as a control. Overall, DPG yields poorer abrasion resistance than the R-150 system. As shown in figures 4-6, higher levels of either secondary accelerator system lead to lower loss factor, shorter scorch and cure times and higher tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. modulus. Although figure 6 shows that the loss factor of DPG is similar to the R-150 system by RPA RPA Remote Patron Authentication RPA Rural Payments Agency (UK Department of Environment, Food and Rural Affairs) RPA Replication Protein A RPA RNAse Protection Assay RPA Regional Plan Association RPA Random-Phase Approximation torsional tor·sion n. 1. a. The act of twisting or turning. b. The condition of being twisted or turned. 2. shear shear: see strength of materials. Shear A straining action wherein applied forces produce a sliding or skewing type of deformation. results, the MTS (1) See Microsoft Transaction Server. (2) (Modular TV System) The stereo channel added to the NTSC standard, which includes the SAP audio channel for special use. 1. MTS - Message Transport System. 2. results in compression compression, external stress applied to an object or substance, tending to cause a decrease in volume (see pressure). Gases can be compressed easily, solids and liquids to a very small degree if at all. of table 4 indicate that the R-150 system is superior to DPG for dynamic properties. [FIGURES 4-6 OMITTED] Effect of activator components The activator is a mixture of several components. The effect of three components was studied in a [2.sup.3] factorial factorial For any whole number, the product of all the counting numbers up to and including itself. It is indicated with an exclamation point: 4! (read “four factorial”) is 1 × 2 × 3 × 4 = 24. design. The formulas and test results are contained in table 5. A low level of component A and a high level of component B gave a desirable combination of scorch and cure times with the best loss factor and abrasion resistance. Regression analysis In statistics, a mathematical method of modeling the relationships among three or more variables. It is used to predict the value of one variable given the values of the others. For example, a model might estimate sales based on age and gender. indicated no highly significant interaction or quadratic quadratic, mathematical expression of the second degree in one or more unknowns (see polynomial). The general quadratic in one unknown has the form ax2+bx+c, where a, b, and c are constants and x is the variable. effects. The main linear effects are shown in table 6. The high level of component C gives improved abrasion resistance with no highly significant effect on other properties. As indicated in table 6, component A detracts from abrasion resistance and lengthens cure time. Component B lowers scorch and cure times and provides the most significant improvement in loss factor. It was felt that the initial activator blend “Blending” redirects here. For alpha blending, see Alpha compositing. In linguistics, a blend is a word formed from parts of two other words. These parts are sometimes, but not always, morphemes. , although providing good technical performance, was in need of improvement. Odor odor (o´der) a volatile emanation perceived by the sense of smell. o·dor n. 1. The property or quality of a thing that affects, stimulates, or is perceived by the sense of smell. and worker health and safety were specific issues of concern. Therefore, alternatives for components A and B were sought. After several analogues were tested, a new blend composition was selected--designated Activator 2. Figures 7 and 8 compare these two activators for dynamic properties, and a good match for loss factor is indicated. [FIGURE 7 OMITTED] Tire build results A tire test was undertaken to evaluate the R-150 system with each activator. A black-filled formulation was used as a control. The three compounds were prepared at a custom mixer mixer, either of two electronic devices in which two or more signals are combined. In the type of mixer used in radio receivers, radar receivers, and similar systems, a signal is translated upward or downward in frequency. , and pre-cured treads were extruded and cured. Sixty drive position tires, size 285/80-R22.5, were purchased and buffed. Twenty tires of each compound were retreaded. The specific formulations and laboratory results are shown in table 7. Tire tests found: * Compound AC yielded a rolling resistance of 18.3 kg (40.4 lbs.). * Compound AD yielded a rolling resistance of 15.8 kg (34.9 lbs.), a 13.6 % reduction. * Compound AE yielded a rolling resistance of 17.6 kg (38.9 lbs), a 3.8 % reduction. Based on the fastest wearing groove from on-tire fleet trials, the projected distance to wear-out showed: * Compound AC gave a tread wear of 417,010 km (259,130 miles). * Compound AD gave a tread wear of 356,600 km (221,590 miles), a 14.5% reduction. * Compound AE gave a tread wear of 377,070 km (234,310 miles), a 9.6% reduction. Assuming a sales price of $450 per tire and a diesel fuel cost of 79 cents/L ($3/gal.), compound AD results in a cost savings of $8,684 in 402,320 km (250,000 miles); compound AE, $2,574. These calculations do not take into account the effect of any raw material cost differences and the possible need to adjust the tire sales price. The unexpectedly poorer rolling resistance results for compound AE were verified ver·i·fy tr.v. ver·i·fied, ver·i·fy·ing, ver·i·fies 1. To prove the truth of by presentation of evidence or testimony; substantiate. 2. by laboratory measurement of loss factor, as shown in figure 9. Comparing figure 9 to figure 8, it is clear that neither factory compound with silica, R-150 and activator achieved the 0.1 loss factor of the laboratory mixed compounds. Why the poorer factory results were obtained is being examined. Our working hypothesis An assumption or theory. During a criminal trial, a hypothesis is a theory set forth by either the prosecution or the defense for the purpose of explaining the facts in evidence. is volatility Volatility 1. A statistical measure of the tendency of a market or security to rise or fall sharply within a period of time. 2. A variable in option pricing formulas that denotes the extent to which the return of the underlying asset will fluctuate between now and the of one or more of the components, because all three factory compounds required hot remilling to bring viscosity down to a workable range. [FIGURES 8-9 OMITTED] For the tires with the lowest rolling resistance, a savings of about $8,600 per 18-wheel rig has been calculated, excluding any differences in the raw material cost of the tires. The laboratory measurement of tangent [delta] in compression is highly correlated cor·re·late v. cor·re·lat·ed, cor·re·lat·ing, cor·re·lates v.tr. 1. To put or bring into causal, complementary, parallel, or reciprocal relation. 2. with rolling resistance of the field tires, as shown in figure 10. If it is possible to approach the tangent [delta] obtained in the more favorable fa·vor·a·ble adj. 1. Advantageous; helpful: favorable winds. 2. Encouraging; propitious: a favorable diagnosis. 3. laboratory tests, we may extrapolate extrapolate - extrapolation that savings in excess of $10,000 per rig might be achieved. [FIGURE 10 OMITTED] Summary Royalac 150 when used with an activator can enhance the performance of the silica/silane system in NR to significantly improve loss factor without major sacrifice in abrasion resistance or other performance properties. Laboratory results were confirmed by rolling resistance and tread wear results from a fleet test of truck tires. The potential economic impact is felt to be sufficient to justify additional technical work to find a practical activator formulation.
Table 1--passenger and truck tread compounds and test data
Tire tread type Passenger Truck
Compound A B C D
Solution SBR (Solflex 1216) 75.0 75.0 -- --
Polybutadiene (Budene 1207) 25.0 25.0 -- --
Natural rubber (SIR 20) -- -- 100.0 100.0
N-234 carbon black 72.0 5.0 -- --
N-220 carbon black -- -- 60.0 5.0
Silica (Zeosil 1165) -- 80.0 -- 60.0
Aromatic oil (Sundex 790) 32.5 40.0 7.0 7.0
TESPT silane (Silquest A-1289) -- 3.6 -- 4.8
Second pass
Zinc oxide (Kadox 911) 2.5 2.5 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0 2.0 2.0
Industrene R stearic acid 1.0 1.0 2.0 2.0
Sunproof improved wax 1.5 1.5 1.5 1.5
Final pass
TBBS (Delac NS) 1.5 1.5 1.0 1.0
DPG -- 2.0 -- 1.0
Sulfur 2.0 2.0 2.0 2.0
Mooney at 100[degrees]C
Viscosity, ML 1+4 78.0 91.0 59.0 59.0
Mooney at 135[degrees]C
Scorch, MS t3, minutes 22.1 11.3 13.7 15.2
Rheometer at 160[degrees]C
ML, lb.-in. 7.9 9.8 7.2 6.7
MH, lb.-in. 34.2 36.4 41.7 36.0
Ts2, minutes 5.8 2.6 4.8 4.6
T90, minutes 11.2 14.0 6.5 8.2
Cured at 160[degrees]C
Tensile strength, MPa 17.0 20.6 28.4 27.4
Elongation at break, % 420 420 513.8 587.6
M 100, MPa 2.4 2.3 3.0 1.9
M 300, MPa 11.5 12.3 15.2 9.1
Hardness, A 63.0 59.0 64.0 62.0
M300/M100 4.8 5.3 5.1 4.9
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain,
2 0.184 0.110 0.178 0.140
4 0.198 0.120 0.180 0.145
6 0.201 0.123 0.175 0.139
8 0.204 0.125 0.166 0.142
10 0.205 0.128 0.160 0.138
E', MPa
Peak-to-peak strain,
2 8.1 6.7 7.1 4.4
4 7.1 6.2 6.1 4.1
6 6.5 6.0 5.6 3.9
8 6.2 5.8 5.4 3.9
10 5.9 5.7 5.3 3.9
Table 2--silica as partial replacement for carbon black
Compound E F G H
Natural rubber 100.0 100.0 100.0 100.0
N-220 carbon black 59.0 41.0 23.0 5.0
Precipitated silica - 20.0 40.0 60.0
Aromatic oil 7.0 7.0 7.0 7.0
TESPT silane polysulfide - 1.4 2.8 3.6
Activator - 1.5 2.0 2.5
2nd pass
Zinc oxide 3.0 3.0 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0 2.0 2.0
Industrene R stearic acid 2.0 2.0 2.0 2.0
Sunproof improved wax 1.5 1.5 1.5 1.5
Final pass
TBBS Delac NS 1.00 1.00 1.00 1.00
TATD Royalac 150 - 0.40 0.40 0.40
CTP retarder (Santogard PVI) 0.20 0.20 0.20 0.20
Sulfur 2.00 2.25 2.25 2.25
Mooney at 100[degrees]C
Viscosity, ML 1+4 63 59 61 57
Mooney at 135[degrees]C
Scorch, MS t3, minutes 16.6 11.9 12.8 20.4
Rheometer at 160[degrees]C
ML, lb-in. 7.1 6.7 6.1 5.6
MH, lb-in. 40.4 41.0 38.0 35.6
Ts2, minutes 3.3 2.8 3.2 3.9
T90, minutes 6.8 5.0 5.9 7.1
Cured at 160[degrees]C, minutes 9 7 8 9
Tensile strength, MPa 28.3 28.9 27.9 28.2
Elongation at break, % 541 537 574 618
M 100, MPa 2.8 2.9 2.6 2.3
M 300, MPa 14.7 14.9 12.4 10.9
Hardness, A 66 64 63 61
Die C tear, kN/m 109 97 117 119
M300/M100 5.2 5.1 4.9 4.6
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 27.9 27.0 27.3 28.0
Elongation at break, % 448 447 482 520
M100, MPa 4.4 4.8 4.1 3.8
M300, MPa 19.5 19.3 18.0 16.3
Hardness, A 72 71 67 67
Die C tear, kN/m 89 80 73 63
DIN abrasion index
Average of 3 samples 99.5 101.0 96.3 96.7
RPA test at 1OHz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1.5 0.114 0.074 0.058 0.068
2 0.137 0.085 0.069 0.070
4 0.188 0.113 0.089 0.082
10 0.211 0.136 0.107 0.104
G', MPa
Peak-to-peak strain, %
1.5 5.1 3.4 2.7 2.6
2 4.6 3.2 2.6 2.5
4 3.6 2.7 2.3 2.3
10 2.4 2.1 1.9 1.9
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1 0.151 0.080 0.069 0.054
2 0.182 0.101 0.086 0.083
4 0.185 0.113 0.099 0.088
6 0.176 0.113 0.101 0.092
8 0.171 0.112 0.100 0.089
10 0.163 0.110 0.097 0.088
E', MPa
Peak-to-peak strain, %
1 8.5 6.9 5.7 5.3
2 7.4 6.4 5.5 5.1
4 6.4 6.0 5.3 4.9
6 6.0 5.8 5.3 4.9
8 5.8 5.7 5.2 4.9
10 5.7 5.7 5.3 4.9
Table 3--effect of silane level
Compound I J K
Natural rubber 100.0 100.0 100.0
N-220 carbon black 59.0 5.0 5.0
Precipitated silica - 60.0 60.0
Aromatic oil 7.0 7.0 7.0
TESPT silane - 6.0 4.8
Activator - 2.5 2.5
2nd pass
Zinc oxide 3.0 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0 2.0
Industrene R stearic acid 2.0 2.0 2.0
Sunproof improved wax 1.5 1.5 1.5
Final pass
Delac NS 1.00 1.00 1.00
Royalac 150 - 0.40 0.40
CTP retarder 0.20 0.20 0.20
Sulfur 2.00 2.00 2.00
Mooney at 100[degrees]C
Viscosity, ML 1+4 56 58 62
Mooney at 135[degrees]C
Scorch, MS t3, minutes 17.1 11.8 14.2
18 pt. rise time, minutes 21.1 19.7 22.1
Rheometer at 160[degrees]C
ML, lb.-in. 6.2 6.0 6.5
MH, lb.-in. 38.6 38.1 37.4
Ts2, minutes 3.5 3.3 3.5
T90, minutes 7.2 6.3 6.7
Cured at 160[degrees]C, minutes 9 8 9
Tensile strength, MPa 28.8 29.0 28.5
Elongation at break, % 566 588 586
M 100, MPa 2.7 2.7 2.2
M 300, MPa 13.8 12.7 11.8
Hardness, A 64 63 61
M300/M100 5.2 4.7 5.3
Die C tear, kN/m 108 125 124
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 28.6 27.7 27.9
Elongation at break, % 462 448 482
M100, MPa 4.3 4.6 4.3
M300, MPa 19.2 19.1 18.2
Hardness, A 69 70 70
Die C tear, kN/m 98 94 89
DIN abrasion index
Average of 3 samples 95.5 101.0 95.8
RPA test at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1.5 0.116 0.054 0.059
2 0.129 0.062 0.067
4 0.172 0.068 0.073
10 0.190 0.080 0.093
G', MPa
Peak-to-peak strain, %
1.5 4.3 2.6 2.7
2 3.9 2.5 2.6
4 3.0 2.2 2.4
10 2.2 2.0 2.0
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1 0.144 0.099 0.079
2 0.169 0.101 0.085
4 0.180 0.103 0.093
6 0.174 0.108 0.091
8 0.158 0.105 0.093
10 0.154 0.101 0.092
E', MPa
Peak-to-peak strain, %
1 7.2 4.8 5.6
2 6.3 4.7 5.3
4 5.5 4.5 5.1
6 5.1 4.5 5.1
10 4.9 4.6 5.1
Compound L M
Natural rubber 100.0 100.0
N-220 carbon black 5.0 5.0
Precipitated silica 60.0 60.0
Aromatic oil 7.0 7.0
TESPT silane 3.6 2.4
Activator 2.5 2.5
2nd pass
Zinc oxide 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0
Industrene R stearic acid 2.0 2.0
Sunproof improved wax 1.5 1.5
Final pass
Delac NS 1.00 1.00
Royalac 150 0.40 0.40
CTP retarder 0.20 0.20
Sulfur 2.25 2.40
Mooney at 100[degrees]C
Viscosity, ML 1+4 61 65
Mooney at 135[degrees]C
Scorch, MS t3, minutes 17.6 22.4
18 pt. rise time, minutes 25.3 27.5
Rheometer at 160[degrees]C
ML, lb.-in. 6.5 7.7
MH, lb.-in. 36.8 38.9
Ts2, minutes 3.8 3.7
T90, minutes 7.0 7.3
Cured at 160[degrees]C, minutes 9 9
Tensile strength, MPa 28.9 28.2
Elongation at break, % 623 647
M 100, MPa 2.2 2.1
M 300, MPa 10.9 9.8
Hardness, A 62 59
M300/M100 4.9 4.7
Die C tear, kN/m 109 115
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 28.2 27.1
Elongation at break, % 469 488
M100, MPa 4.1 3.9
M300, MPa 17.7 16.7
Hardness, A 68 71
Die C tear, kN/m 85 69
DIN abrasion index
Average of 3 samples 93.7 88.0
RPA test at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1.5 0.058 0.067
2 0.069 0.076
4 0.076 0.095
10 0.095 0.108
G', MPa
Peak-to-peak strain, %
1.5 2.7 3.3
2 2.5 3.2
4 2.3 2.8
10 2.0 2.3
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1 0.068 0.095
2 0.085 0.101
4 0.093 0.113
6 0.094 0.112
8 0.091 0.114
10 0.086 0.113
E', MPa
Peak-to-peak strain, %
1 5.1 4.0
2 4.9 4.1
4 4.8 4.0
6 4.7 3.9
10 4.8 3.9
Table 4--effect of secondary accelerator type and level
Compound N O P
Natural rubber 100.0 100.0 100.0
N-220 carbon black 59.0 5.0 5.0
Precipitated silica - 60.0 60.0
Aromatic oil 7.0 7.0 7.0
TESPT silane - 4.8 4.8
Activator - - -
2nd pass
Zinc oxide 3.0 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0 2.0
Industrene R stearic acid 2.0 2.0 2.0
Sunproof improved wax 1.5 1.5 1.5
Final pass
Delac NS 1.00 1.00 1.00
Royalac 150 - - -
CTP retarder 0.20 - 0.20
DPG - 0.50 1.00
Sulfur 2.00 2.12 2.00
Mooney at 100[degrees]C
Viscosity, ML 1+4 57 65 54
Mooney at 135[degrees]C
Scorch, MS t3, minutes 14.4 14.4 13.6
18 pt. rise time, minutes 17.5 19.6 19.4
Rheometer at 160[degrees]C
ML, lb.-in. 6.8 7.5 6.7
MH, lb.-in. 40.7 32.1 36.1
Ts2, minutes 3.3 3.3 3.1
T90, minutes 6.7 10.1 6.9
Cured at 160[degrees]C, minutes 9 12 9
Tensile strength, MPa 28.4 22.6 27.4
Elongation at break, % 537 592 617
M 100, MPa 2.9 1.5 2.0
M 300, MPa 14.8 7.7 10.0
Hardness, A 64 61 62
M300/M100 5.1 5.1 5.3
Die C tear, kN/m 125.0 114.0 124.0
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 27.9 27.3 27.9
Elongation at break, % 446 544 537
M100, MPa 4.6 2.9 3.3
M300, MPa 19.7 13.9 15.0
Hardness, A 72 70 68
Die C tear, kN/m 98 - 103
DIN abrasion index
Average of 3 samples 94.2 71.2 76.3
RPA test at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1.5 0.110 0.084 0.066
2 0.129 0.095 0.071
4 0.181 0.127 0.090
10 0.202 0.156 0.110
G', MPa
Peak-to-peak strain, %
1.5 5.0 4.4 3.4
2 4.5 4.2 3.2
4 3.4 3.5 2.8
10 2.4 2.6 2.3
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1 0.147 0.136 0.110
2 0.175 0.148 0.134
4 0.180 0.156 0.138
6 0.175 0.156 0.134
8 0.163 0.154 0.135
10 0.158 0.151 0.132
E', MPa
Peak-to-peak strain, %
1 7.9 4.9 4.8
2 6.8 4.6 4.5
4 5.9 4.3 4.2
6 5.5 4.2 4.1
8 5.3 4.2 4.0
10 5.2 4.2 4.0
Compound Q R
Natural rubber 100.0 100.0
N-220 carbon black 5.0 5.0
Precipitated silica 60.0 60.0
Aromatic oil 7.0 7.0
TESPT silane 3.6 3.6
Activator 2.5 2.5
2nd pass
Zinc oxide 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0
Industrene R stearic acid 2.0 2.0
Sunproof improved wax 1.5 1.5
Final pass
Delac NS 1.00 1.00
Royalac 150 0.25 0.40
CTP retarder 0.20 0.20
DPG - -
Sulfur 2.30 2.25
Mooney at 100[degrees]C
Viscosity, ML 1+4 63 62
Mooney at 135[degrees]C
Scorch, MS t3, minutes 16.3 15.4
18 pt. rise time, minutes 19.2 21.1
Rheometer at 160[degrees]C
ML, lb.-in. 7.0 7.3
MH, lb.-in. 39.4 39.9
Ts2, minutes 3.5 3.5
T90, minutes 6.8 6.5
Cured at 160[degrees]C, minutes 9 9
Tensile strength, MPa 27.6 29.0
Elongation at break, % 625 606
M 100, MPa 2.1 2.3
M 300, MPa 10.3 11.6
Hardness, A 65 62
M300/M100 5.0 5.1
Die C tear, kN/m 116.0 128.0
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 28.7 27.9
Elongation at break, % 509 489
M100, MPa 4.2 4.4
M300, MPa 17.6 18.0
Hardness, A 73 73
Die C tear, kN/m 69 89
DIN abrasion index
Average of 3 samples 86.2 99.9
RPA test at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1.5 0.063 0.057
2 0.077 0.064
4 0.103 0.082
10 0.133 0.101
G', MPa
Peak-to-peak strain, %
1.5 5.3 3.6
2 5.0 3.4
4 4.2 3.0
10 3.1 2.4
MTS at 10 Hz and 60[degrees]C
Tangent delta
Peak-to-peak strain, %
1 0.082 0.091
2 0.103 0.111
4 0.116 0.112
6 0.115 0.112
8 0.112 0.111
10 0.107 0.109
E', MPa
Peak-to-peak strain, %
1 6.4 5.6
2 6.2 5.5
4 5.8 5.1
6 5.5 5.0
8 5.4 5.0
10 5.4 5.0
Table 5--effect of activator components
Compound S T U V
Natural rubber 100.0 100.0 100.0 100.0
N-220 carbon black 5.0 5.0 5.0 5.0
Precipitated silica 60.0 60.0 60.0 60.0
Aromatic oil 7.0 7.0 7.0 7.0
TESPT Silane 3.6 3.6 3.6 3.6
2nd pass
Activator 1 2.50 0.00 0.00 0.00
Component A 0.00 0.55 0.15 0.15
Component B 0.00 0.68 0.20 0.20
Component C 0.00 0.17 0.17 1.60
Zinc oxide 3.0 3.0 3.0 3.0
Flexzone 7P 2.0 2.0 2.0 2.0
Industrene R 2.0 2.0 2.0 2.0
Sunproof improved 1.5 1.5 1.5 1.5
Final pass for all. 1.00 Delac NS; 0.40 Royalac 150; 0.20 CTP retarder;
2.25 sulfur
Mooney at 135[degrees]C
Scorch, MS t3, min. 17 15 15 16
Rheometer at 160[degrees]C
ML, lb.-in. 6.2 5.8 5.9 5.8
MH, lb.-in. 39.9 35.2 39.7 39.4
Ts2, minutes 4.3 5.0 4.2 4.0
T50, minutes 6.6 7.5 7.3 6.7
T90, minutes 7.7 8.8 8.6 7.7
Cured at 160[degrees]C, minutes 13.0 14.0 15.0 13.0
Tensile strength, Mpa 26.6 25.4 25.2 26.4
Elongation at break, % 532.0 549.0 541.0 544.0
M 100, MPa 2.4 2.1 2.2 2.2
M 300, MPa 12.4 10.9 11.0 12.0
Hardness, A 64.0 63.0 61.0 62.0
DIN abrasion index
Average of 3 samples 104.9 89.8 101.4 105.4
RPA test at 10 Hz and 60[degrees]C
Tangent S PtP Strain, %
1.5 0.051 0.057 0.055 0.056
2 0.065 0.069 0.067 0.055
4 0.079 0.083 0.081 0.080
10 0.101 0.104 0.104 0.097
G', MPa PtP Strain, %
1.5 3.1 2.5 3.1 3.0
2 3.0 2.4 2.9 2.9
4 2.7 2.2 2.6 2.6
10 2.3 1.9 2.2 2.2
Compound W X Y Z
Natural rubber 100.0 100.0 100.0 100.0
N-220 carbon black 5.0 5.0 5.0 5.0
Precipitated silica 60.0 60.0 60.0 60.0
Aromatic oil 7.0 7.0 7.0 7.0
TESPT Silane 3.6 3.6 3.6 3.6
2nd pass
Activator 1 0.00 0.00 0.00 0.00
Component A 0.55 0.55 0.35 0.55
Component B 0.68 0.20 0.44 0.20
Component C 1.60 1.60 0.89 0.17
Zinc oxide 3.0 3.0 3.0 3.0
Flexzone 7P 2.0 2.0 2.0 2.0
Industrene R 2.0 2.0 2.0 2.0
Sunproof improved 1.5 1.5 1.5 1.5
Final pass for all. 1.00 Delac NS; 0.40 Royalac 150; 0.20 CTP retarder;
2.25 sulfur
Mooney at 135[degrees]C
Scorch, MS t3, min. 14 22 23 24
Rheometer at 160[degrees]C
ML, lb.-in. 5.5 5.4 5.6 5.5
MH, lb.-in. 41.0 36.1 34.2 32.8
Ts2, minutes 3.8 4.9 5.1 5.3
T50, minutes 6.4 7.9 7.6 7.8
T90, minutes 7.4 9.2 8.8 9.2
Cured at 160[degrees]C, minutes 13.0 14.0 14.0 14.0
Tensile strength, Mpa 26.1 25.2 24.0 25.0
Elongation at break, % 502.0 532.0 554.0 552.0
M 100, MPa 2.5 2.1 1.9 2.0
M 300, MPa 13.1 11.3 10.2 10.4
Hardness, A 62.0 62.0 62.0 62.0
DIN abrasion index
Average of 3 samples 106.9 95.0 96.8 75.0
RPA test at 10 Hz and 60[degrees]C
Tangent S PtP Strain, %
1.5 0.045 0.056 0.055 0.057
2 0.052 0.063 0.070 0.070
4 0.064 0.083 0.083 0.091
10 0.084 0.102 0.107 0.114
G', MPa PtP Strain, %
1.5 2.7 2.6 2.4 2.6
2 2.7 2.5 2.3 2.5
4 2.4 2.3 2.1 2.2
10 2.1 1.9 1.8 1.9
Compound AA AB
Natural rubber 100.0 100.0
N-220 carbon black 5.0 5.0
Precipitated silica 60.0 60.0
Aromatic oil 7.0 7.0
TESPT Silane 3.6 3.6
2nd pass
Activator 1 0.00 0.00
Component A 0.15 0.15
Component B 0.68 0.68
Component C 0.17 1.60
Zinc oxide 3.0 3.0
Flexzone 7P 2.0 2.0
Industrene R 2.0 2.0
Sunproof improved 1.5 1.5
Final pass for all. 1.00 Delac NS; 0.40 Royalac 150; 0.20 CTP retarder;
2.25 sulfur
Mooney at 135[degrees]C
Scorch, MS t3, min. 16 13
Rheometer at 160[degrees]C
ML, lb.-in. 6.1 5.6
MH, lb.-in. 37.7 40.5
Ts2, minutes 4.0 3.4
T50, minutes 6.2 5.8
T90, minutes 7.2 6.7
Cured at 160[degrees]C, minutes 12.0 12.0
Tensile strength, Mpa 25.1 22.8
Elongation at break, % 513.0 570.0
M 100, MPa 2.1 1.7
M 300, MPa 11.8 9.1
Hardness, A 62.0 62.0
DIN abrasion index
Average of 3 samples 99.0 116.8
RPA test at 10 Hz and 60[degrees]C
Tangent S PtP Strain, %
1.5 0.055 0.046
2 0.058 0.057
4 0.074 0.075
10 0.097 0.093
G', MPa PtP Strain, %
1.5 2.9 3.0
2 2.8 2.9
4 2.5 2.6
10 2.2 2.3
Table 6--regression analysis for activator component effects
Component
Constant A B
t3 at 135[degrees]C 25.6 1.0 * -14.6 (b)
P value 0.77 0.00
t90 at 160[degrees]C 9.18 1.27 (b) -2.75 (a)
P value 0.01 0.00
RPA tan [delta] - 4% 0.100 -0.020 (a) -0.028 (a)
P value 0.04 0.00
RPA tan [delta] - 10% 0.125 -0.020 (a) -0.028 (a)
P value 0.02 0.00
DIN abr. index 93.4 -34.9 (b) 18.6 (a)
P value 0.01 0.05
Component
C [R.sup.2]
t3 at 135[degrees]C 0.0 * 73.3
P value 0.63
t90 at 160[degrees]C -0.50 (a) 78.9
P value 0.07
RPA tan [delta] - 4% -0.005 62.9
P value 0.36
RPA tan [delta] - 10% -0.007 (a) 71.7
P value 0.09
DIN abr. index 10.3 (a) 89.0
P value 0.01
Color code for above: (a) Green = good, (b) Blue = bad
* Strikethrough = Not significant, P>0.5, due to random
chance more than 50% of time.
** Bold = Highly significant, P<0.01, due to random change
less than 1% of time.
Table 7--testing of compounds for tire tests
Compound AC AD AE
Natural rubber 100.0 100.0 100.0
N-220 carbon black 59.0 5.0 5.0
Precipitated silica - 60.0 60.0
Aromatic oil 7.0 7.0 7.0
TESPT silane polysulfide - 4.8 4.8
2nd pass
Activator 1 - 2.5 -
Activator 2 - - 2.1
Zinc oxide 3.0 3.0 3.0
Flexzone 7P antiozonant 2.0 2.0 2.0
Industrene R stearic acid 2.0 2.0 2.0
Sunproof improved wax 1.5 1.5 1.5
Final pass
Delac NS 1.0 1.0 1.0
Royalac 150 - 0.6 0.6
CTP retarder 0.2 0.2 0.2
Sulfur 2.0 2.3 2.3
Mooney at 100[degrees]C
Viscosity, ML 1+4 54.0 83.0 87.0
Mooney at 135[degrees]C
Scorch, MS t3, minutes 18.3 5.5 9.1
Rheometer at 160[degrees]C
ML, lb.-in. 7.2 9.5 8.2
MH, lb.-in. 39.3 44.8 45.1
Ts2, minutes 4.2 2.2 2.9
T50, minutes 6.1 3.8 4.8
T90, minutes 7.7 5.9 6.9
Cured at 160[degrees]C, minutes 10.0 8.0 9.0
Tensile strength, MPa 26.2 26.9 26.6
Elongation at break, % 506.0 516.0 510.0
M 100, MPa 2.7 3.1 3.4
M 300, MPa 13.9 14.6 14.7
Hardness, A 65.0 65.0 65.0
Aged 2 weeks at 70[degrees]C
Tensile strength, MPa 27.0 25.2 23.4
Elongation at break, % 405.0 414.0 380.0
M100, MPa 4.6 4.9 5.2
M300, MPa 20.1 19.2 19.2
Hardness, A 72.0 72.0 74.0
DIN abrasion index 105.6 105.1 99.3
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