Effect of silica on the viscoelastic properties of a model tread compound.Amorphous Unorganized or vague. A lack of structure. For example, the amorphous state of a spot on a rewritable optical disc means that the laser beam will not be reflected from it, which is in contrast to a crystalline state which will reflect light. See crystalline. precipitated 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. has emerged as a major contributor to the reduction of 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. 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. (refs. 1-5). The challenge of obtaining a low rolling resistance, energy efficient compound with minimal compromise in traction Traction Definition Traction is the use of a pulling force to treat muscle and skeleton disorders. Purpose Traction is usually applied to the arms and legs, the neck, the backbone, or the pelvis. and treadwear has been addressed by emerging silica/coupling agent technology. Because of the increasing use of silica in tread applications, there has been greater emphasis on the mechanistic mech·a·nis·tic adj. 1. Mechanically determined. 2. Of or relating to the philosophy of mechanism, especially one that tends to explain phenomena only by reference to physical or biological causes. understanding of silica-elastomer viscoelastic Adj. 1. viscoelastic - having viscous as well as elastic properties natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" properties. Dynamic mechanical analysis is used to predict the performance of tire compounds especially when time-temperature superposition su·per·po·si·tion n. 1. The act of superposing or the state of being superposed: "Yet another technique in the forensic specialist's repertoire is photo superposition" or "thermorheological simplicity" is most applicable (refs. 6-9). The contribution of inert inert /in·ert/ (in-ert´) inactive. in·ert adj. 1. Sluggish in action or motion; lethargic. 2. fillers to the viscoelastic properties of the resulting polymer-filler composite can be effectively modeled since these effects are primarily rheological rhe·ol·o·gy n. The study of the deformation and flow of matter. rhe  o·log . However, the addition of a
reactive reactive /re·ac·tive/ (re-ak´tiv) characterized by reaction; readily responsive to a stimulus. re·ac·tive adj. 1. Tending to be responsive or to react to a stimulus. 2. filler fill·er 1 n. One that fills, as: a. Something added to augment weight or size or fill space. b. A composition, especially a semisolid that hardens on drying, used to fill pores, cracks, or holes in wood, plaster, to the polymer matrix results in a deviation DEVIATION, insurance, contracts. A voluntary departure, without necessity, or any reasonable cause, from the regular and usual course of the voyage insured. 2. from rheological simplicity, especially in the non-linear region of viscoelastic behavior (ref. 10). In order to predict performance over a broad range the high surface energies of dime reactive fillers require the proper accounting of chemical effects which can change viscoelastic properties. Tan TAN See tax anticipation note (TAN). delta at 0 [degrees] C has been shown to be a predictor of compound wet traction and tan delta at 60 [degrees] C has been shown to be a predictor of compound rolling resistance (refs. 11 and 12). Swor and Taylor Taylor, city (1990 pop. 70,811), Wayne co., SE Mich., a suburb of Detroit adjacent to Dearborn; founded 1847 as a township, inc. as a city 1968. A small rural village until World War II, it developed significantly in the second half of the 20th cent. indicated that the addition of a bi-functional coupling agent to a carbon black filled compound reduced rolling resistance (ref. 13). Okel, Waddell and Evans Ev·ans , Herbert McLean 1882-1971. American anatomist who isolated four pituitary hormones and discovered vitamin E (1922). (refs 14-16) determined that surface area is the primary silica property which predicts compound performance. Tan, et al. (ref. 17) demonstrated the effect of increasing polar-polar interactions between silica and a variety of polymers in changing compound viscoelastic properties relative to carbon black compounds at comparable loadings. Chun chun see tsun. (ref. 18) has shown, using silicas of differing hydrophobic hydrophobic /hy·dro·pho·bic/ (-fo´bik) 1. pertaining to hydrophobia (rabies). 2. not readily absorbing water, or being adversely affected by water. 3. nature, that the morphological mor·phol·o·gy n. pl. mor·phol·o·gies 1. a. The branch of biology that deals with the form and structure of organisms without consideration of function. b. effect of the filler is the controlling mechanism of viscoelasticity Viscoelasticity, also known as anelasticity, is the study of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. at small strains while filler reactivity re·ac·tiv·i·ty n. 1. The property of reacting. 2. The process of reacting. reactivity, n the degree to which a being responds to a stimulus. is a significant contributor to changes in moduli In theoretical physics, moduli are scalar fields whose different values are equally good (each one such scalar field is called a modulus). The reason is that the potential energy for moduli is constant, which can be guaranteed, for example, by supersymmetry (with in the nonlinear A system in which the output is not a uniform relationship to the input. nonlinear - (Scientific computation) A property of a system whose output is not proportional to its input. viscoelastic region. Voet, Morawski and Donnet (ref. 19) reported on the effect of various morphological parameters of silicas on static and dynamic mechanical properties of SBR SBR - Spectral Band Replication vulcanizates. Silica surface area can be measured by a variety of methods. The two primary methods use either nitrogen or cetyltrimethylammonium bromide bromide, any of a group of compounds that contain bromine and a more electropositive element or radical. Bromides are formed by the reaction of bromine or a bromide with another substance; they are widely distributed in nature. (CTAB CTAB Clear to auscultation bilaterally, see there ) as the absorbate. The latter method is reported to measure the specific surface area exclusive of that contained in micropores which sterically hinder hin·der 1 v. hin·dered, hin·der·ing, hin·ders v.tr. 1. To be or get in the way of. 2. To obstruct or delay the progress of. v.intr. CTAB adsorption adsorption, adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see adhesion and cohesion). . The difference between CTAB and nitrogen surface areas has been defined as the micropore micropore, n 1. microscopic pores created by enamel etching in order to increase sealant adhesion. n 2. an organelle in certain protozoa that develops at the site of a damaged membrane. surface area, which comes from pores whose diameters are [is less than] 2 nm (refs. 20 and 21). Reportedly SBR elastomer elastomer (ĭlăs`təmər), substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic rubbers and rubberlike plastics from natural rubber. , with a molecular weight of 300,000, can only access pores with diameters [is greater than] 2 run (ref. 22). This article focuses on the effects of coupling agent, silica as percent of total filler loading, and silica surface area on the dynamic mechanical properties of a model SBR/BR tread under varying strain and temperature conditions. Experimental Table 1 summarizes the normalized surface areas of the five experimental silicas used in this study. Single point nitrogen BET surface area was determined using ASTM ASTM abbr. American Society for Testing and Materials D3037-92. Silica CTAB surface area was determined using French Standard NF T 45-007 5.12 Method A (1987). The surface area range covered by these silicas is representative of those used in tire compounds. This systematic variation provided the ability to separate the effect of silica nitrogen surface area (A -vs- D or B -vs- E) from the effect of CTAB surface area (C -vs- D -vs- B). Table 1 also indicates that these silicas provided a wide range in micropore surface area. Witco's LH30 high structure, low hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. N351 type carbon black was also used ([N.sub.2] BET surface area = 93 [m.sup.2]/g; dibutylthalate absorption = 135 mL/100g, crushed dibutylthalate absorption = 104 mL/100g). The coupling agent used was Degussa's X50S (50% N330, 50% TESPT: bis- bis- pref. 1. Two; twice: bisalbuminemia. 2. Having two identical but separated complex chemical groups in one molecule: 1,4-bis(5-phenyloxazol-2-yl)-benzene. (3-triethoxysilylpropyl)-tetrasulfane). Table 1 - normalized silica surface area Silica 1 pt. N2 BET CTAB Micropore A 1.66 1.53 0.13 B 1.95 1.65 0.30 C 1.99 1.00 0.99 D 2.04 1.49 0.55 E 2.41 1.69 0.72 (*) Micropore = 1 pt. N2 BET - CTAB All compounds were mixed using a three-stage procedure in a laboratory-scale internal 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. . The model all-silica passenger tire tread compound (ref. 23) used is presented in table 2. Each silica was compounded at 0, 50 and 100% of the total filler loading. Note that all compounds had a constant filler volume loading. For the silica containing compounds, the coupling agent was added at 0 or 10 weight % of the TESPT relative to the weight of the silica. The carbon black control was also compounded with and without coupling agent. The amount of coupling agent added was equal to the amount added in the all silica compound. All compounds were cured at T90 (time to 90% cure) + 5' (mold mold, name for certain multicellular organisms of the various classes of the kingdom Fungi, characteristically having bodies composed of a cottony mycelium. The colors of molds are caused by the spores, which are borne on the mycelium. lag/heat transfer considerations) at 150 [degrees] C. Table 2 - all-silica all-silica passenger tread model Time Ingredient phr 0' SSBR 1216 75.0 " BR 1207 25.0 0.5' Filler 32.5 1.5' Filler 32.5 3.5' Sundex 8125 25.0 " Stearic acid 2.0 " Zinc oxide 2.5 Mix 5'/maximum temperature: 165-175 [degrees] C 0' Masterbatch 0.5' X50S Varied 2' Sunolite 240 1.5 " Wingstay 100 2.0 Mix 4'/maximum temperature: 150-160 [degrees] C 0' Masterbatch 0.5' Sulfur 1.4 " TBBS 1.7 " DPG 2.0 Mix 2.5/maximum temperature: 125 [degrees] C Dynamic viscoelastic properties - G', G" and 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 were obtained with a Rheometrics RDA RDA abbr. recommended daily allowance Recommended Dietary Allowance (RDA) The Recommended Dietary Allowances (RDAs) are quantities of nutrients in the diet that are required to maintain good health in people. II dynamic analyzer analyzer /ana·ly·zer/ (an´ah-li?zer) 1. a Nicol prism attached to a polarizing apparatus which extinguishes the ray of light polarized by the polarizer. 2. using 0.2% strain, 1 Hz frequency and parallel plate geometry geometry [Gr.,=earth measuring], branch of mathematics concerned with the properties of and relationships between points, lines, planes, and figures and with generalizations of these concepts. in temperature sweep mode (75 [degrees] C to -45 [degrees] C), and 1 Hz frequency at 60 [degrees] C in strain sweep mode (0.1% to 25%). Other compound properties measured included stress/strain, Zwick rebound rebound (rē´bownd), n/v 1. a recovery from illness. n 2. an outbreak of fresh reflex activity after withdrawal of a stimulus rebound adjective and Mooney viscosity. All test procedures were executed in conformance con·for·mance n. Conformity. Noun 1. conformance - correspondence in form or appearance conformity agreement, correspondence - compatibility of observations; "there was no agreement between theory and with standard ASTM and ISO (1) See ISO speed. (2) (International Organization for Standardization, Geneva, Switzerland, www.iso.ch) An organization that sets international standards, founded in 1946. The U.S. member body is ANSI. methods (ref. 14). Statistical analyses were performed using JMP JMP Jump JMP Java Memory Profiler JMP Joint Manpower Program JMP Joint Management Plan JMP Joint Marketing Program JMP JCL Manipulation Program JMP Joint Mission Planning (US DoD) JMP Joint Military Program statistical analysis software (ref. 24). Results and discussion The strain-dependent dynamic moduli of silicas A through E at 60 [degrees] C, the temperature typically used to characterize the dynamic response at the frequencies associated with typical highway speeds (~ 1 Hz), show significant deviation from linear viscoelasticity at strains greater than approximately 0.4% (figures 1-3). Loss modulus See modulo. . (G"). Indicative of the hysteretic hys·ter·e·sis n. pl. hys·ter·e·ses The lagging of an effect behind its cause, as when the change in magnetism of a body lags behind changes in the magnetic field. contribution, and tangent delta values go through a maximum at around 5% strain and then begin to converge con·verge v. con·verged, con·verg·ing, con·verg·es v.intr. 1. a. To tend toward or approach an intersecting point: lines that converge. b. with increasing strain. Storage modulus (G') generally shows an inverse (mathematics) inverse - Given a function, f : D -> C, a function g : C -> D is called a left inverse for f if for all d in D, g (f d) = d and a right inverse if, for all c in C, f (g c) = c and an inverse if both conditions hold. correlation with strain and also begins to converge at the higher strains. [Figures 1-3 ILLUSTRATION OMITTED] The magnitude of the effects of the three variables covered in this study is strain dependent. However, generally the strain-dependent dynamic moduli of the silicas are significantly below the carbon black control. In particular, the significantly lower tan delta values indicate that the silica compounds would provide significantly lower rolling resistance than a low hysteresis carbon black. Figure 2 indicates that the dynamic moduli of silica C are significantly lower than the other silica and carbon black compounds. As shown in figures 1 through 3 for the carbon black filled compound (silica = 0 phr), the addition of coupling agent (C.A.) slightly reduced G" in the 1-10% strain region while having a minimal effect on G'. This provides a slight decrease in tan delta in the 1-10% strain region which may relate to the reported beneficial effect of a coupling agent in reducing the rolling resistance of a carbon black filled compound (ref. 13). However, for the silica containing compounds the presence of the coupling agent is significantly different. This difference is typified by silica A for the 50% and 100% filler loadings, respectively. The addition of coupling agent for these compounds results in a significant increase in both G" and G' independent of silica loading. While this effect is opposite the effect seen for the carbon black filled compound, the significantly greater increase in G', relative to G", results in a significantly lower tangent delta over the range of strains tested. As expected, the increase in G', or the reduction in tan delta, for the intermediate silica loading is lower than that for the all-silica compound. The effect of surface area on the strain-dependent dynamic moduli at different silica loadings with or without coupling agent is typified by silica B ([N.sub.2]-BET = 1.95, CTAB = 1.65, micropore (Delta) = 0.30). silica C ([N.sub.2]-BET = 1.99, CTAB = 1.00, micropore (Delta) = 0.99). and silica E ([N.sub.2]-BET = 2.41, CTAB = 1.69. micropore (Delta) = 0.72) as shown in figures 4 through 7. Without coupling agent (figures 4 and 5) a change in CTAB surface area at constant [N.sub.2]-BET surface area has a much greater impact on the strain-dependent dynamic moduli than a change in [N.sub.2]-BET surface area at constant CTAB surface area. As might be expected, this impact is greater for the all silica compound (figure 5) than the 50/50 silica/carbon black compound (figure 4). [Figures 4 through 7 ILLUSTRATION OMITTED] With coupling agent addition the effect of surface area becomes much more pronounced (figures 6 and 7). An increase in CTAB surface area at constant [N.sub.2]-BET surface area resulted in an increase in the strain-dependent dynamic moduli. However, an increase in [N.sub.2]-BET surface area at constant CTAB surface area resulted :-in a decrease in the strain-dependent dynamic moduli. The effect of the [N.sub.2]-BET surface area was not only opposite the effect seen for CTAB but also appeared to have a smaller impact. Also there is an inverse correlation between silica micropore surface area (Delta) and the strain-dependent dynamic moduli. The influence of surface area was seen for both loadings. These same relationships also held for tan delta. Figure 8 illustrates the effects of silica loading and coupling agent on tangent delta in temperature sweep mode at 0.2% strain and 1 Hz frequency. The effects are typified by summarizing both tan delta at 60 [degrees] C (td@60C) and the difference between tan delta at 0 [degrees] C and tan delta at 60 [degrees] C (delta tan delta: td[0C-60C]) for silica C. An optimum compound would have the lowest rolling resistance with the highest wet traction. Therefore, an optimum compound would have the lowest tan delta with the highest delta tan delta. This type of comparison is shown for 10% coupling agent (65/13). 2) 100% silica with 0% coupling agent (65/0), 3) 50% silica with 10% coupling agent (32.5/6.5), 4) 50% silica with 0% coupling agent (32.5/0), 5) 0% silica with 0% coupling agent (0/0). and 6) 0% silica with equivalent amount of coupling agent as is in the all silica compound (0/13). [Figure 8 ILLUSTRATION OMITTED] For the low hysteresis carbon black control, the addition of coupling agent increases the tan delta at 600C (at this low strain region) and decreases delta tan delta (0/0 -vs- 0/13). The addition of silica decreases tan delta at 60 [degrees] C and increases delta tan delta compared to the low hysteresis carbon black control compound (0/0 -vs- 32.5/0 -vs- 65/0 or 0/ 13 -vs- 32.5/6.5 -vs- 65/13). The addition of coupling agent to the silica containing compounds decreases tan delta at 60 [degrees] C and may slightly increase delta tan delta (32.5/0 -vs- 32.5/6.5 or 65/0 -vs- 65/13). However, note that delta tan delta appears to be more related to silica loading than to coupling agent addition. The compound with the lowest tan delta at 60 [degrees] C and the highest delta tan delta contained 100% silica and 10% coupling agent (65/13). Figure 9 compares the all silica filled coupled compounds for the five silicas studied to the all carbon black filled, both non-coupled and coupled compounds. The all silica filled coupled compounds have significantly lower tan delta at 60 [degrees] C and significantly higher delta tan delta than the all carbon black filled compounds. Silica C showed the best combination of low tan delta at 60 [degrees] C and high delta tan delta. [Figure 9 ILLUSTRATION OMITTED] The effect of silica surface area is typified by the all silica compounds (figures 10 and 11). These figures show that silica [N.sub.2]-BET surface area, at relatively constant CTAB surface area (silicas A, B and D), does not correlate with either tan delta at 600C or with delta tan delta. In contrast, silica CTAB surface area, at relatively constant [N.sub.2]-BET surface area (silicas B, C, and D), showed a direct correlation Noun 1. direct correlation - a correlation in which large values of one variable are associated with large values of the other and small with small; the correlation coefficient is between 0 and +1 positive correlation with tan delta at 60 [degrees] C and an inverse correlation with delta tan delta. The silica micropore area for all the silicas studied showed an inverse correlation with tan delta at 60 [degrees] C and a direct correlation with delta tan delta. These relationships held for both non-coupled and coupled formulations. [Figures 10 and 11 ILLUSTRATION OMITTED] The effect of coupling agent on the overall balance of properties is summarized in table 3. Adding the amount of 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). used in the all silica compound to the carbon black control did not show any significant effect on performance. Addition of silane in the all silica compounds significantly reduced ML1 +4" (100 [degrees] C). ML. [T.sub.2], [T.sub.50], elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. , tan delta at 0 [degrees] C, and tan delta at 60 [degrees] C and significantly increased hardness, rebound, tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. , modulus, 300%/100% modulus ratio and delta tan delta. The impact of the silane addition appeared to be dependent on the silica CTAB surface area. For instance, the magnitude of the reduction in elongation due to the addition of silane was greater when there was a change in CTAB at constant [N.sub.2]-BET surface area (silica B -VS- silica C) than when there was a change in [N.sub.2]-BET at constant CTAB surface area (silica B -vs- Silica E).
Table 3 - organic rubber performance effect of coupling agent
Compound # 1 2 3 4
Silica B 100% 100%
Silica C
Silica E
Carbon black 100% 100%
X50S 0% 10% 0% 10%
Mooney
ML 1+4' (100 [degrees] C) 68 70 92 62
MDR 2000
ML, dNm 3.5 3.8 5.6 3.3
MH. dNm 23.4 24.4 24.4 25.5
[T.sub.2], minutes 1.5 1.7 5.0 4.3
[T.sub.50], minutes 2.6 3.0 13.4 7.9
Zwick resiliometer
Hardness (23[degrees] C) 64 65 57 67
Hardness (100[degrees] C) 61 62 52 64
Rebound (23[degrees] C), % 46 45 45 48
Rebound (100[degrees] C), % 64 61 57 69
Stress/strain
Tensile, MPa 21.4 24.3 16.1 19.5
Elongation, % 456 477 980 444
100% Modulus, MPa 2.7 3.0 1.0 2.5
300% Modulus, MPa 12.8 14.0 2.0 11.4
Ratio 300%/100% 4.7 4.7 2.0 4.6
Rheometrics dynamic data
(0.2% strain, 1Hz)
Tan delta, 0[degrees] C 0.111 0.115 0.129 0.105
Tan delta, 60[degrees] C 0.067 0.075 0.109 0.055
Delta tan delta
(0-60 [degrees] C) 0.044 0.040 0.020 0.049
Compound # 5 6 7 8
Silica B
Silica C 100% 100%
Silica E 100% 100%
Carbon black
X50S 0% 10% 0% 10%
Mooney
ML 1+4' (100 [degrees] C) 52 56 92 64
MDR 2000
ML, dNm 2.8 2.7 5.6 3.5
MH. dNm 19.6 25.1 23.8 25.0
[T.sub.2], minutes 12.3 3.1 5.0 3.8
[T.sub.50], minutes 15.1 5.3 13.4 7.4
Zwick resiliometer
Hardness (23[degrees] C) 49 61 54 63
Hardness (100[degrees] C) 47 60 44 63
Rebound (23[degrees] C), % 49 56 42 51
Rebound (100[degrees] C), % 70 74 52 70
Stress/strain
Tensile, MPa 11.2 16.5 13.0 21.4
Elongation, % 614 369 942 483
100% Modulus, MPa 1.3 2.5 0.9 2.3
300% Modulus, MPa 3.7 12.4 1.8 10.9
Ratio 300%/100% 2.8 5.0 2.0 4.7
Rheometrics dynamic data
(0.2% strain, 1Hz)
Tan delta, 0[degrees] C 0.119 0.101 0.129 0.109
Tan delta, 60[degrees] C 0.054 0.039 0.103 0.052
Delta tan delta
(0-60 [degrees] C) 0.065 0.062 0.026 0.057
The effect of the silica loading is shown in table 4 for the coupled formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation as typified for silicas B, C and E. Replacing carbon black with silica decreases ML1+4" (100 [degrees] C), tensile, tan delta at 0 [degrees] C and tan delta at 600C and increases MH. [T.sub.2], [T.sub.50], rebound and delta tan delta- Again, the impact of the silica loading appeared to be dependent on the silica CTAB surface area. For instance, the magnitude of the reduction in elongation due to the increase in silica loading was greater when there was a change in CTAB at constant [N.sub.2]-BET surface area (silica B -vs- silica C) than when there was a change in [N.sub.2]-BET at constant CTAB surface area (silica B -vs- silica E). Table 4 - organic rubber performance effect of silica loading Compound# 1 2 3 4 Silica B 50% 100% Silica C Silica E Carbon black 100% 100% X50S 0% 10% 10% 10% Mooney ML 1+4'(100 [degrees] C) 68 70 62 62 MDR 2000 ML, dNm 3.5 3.8 3.1 3.3 MH, dNm 23.4 24.4 23.6 25.5 T2, minutes 1.5 1.7 2.9 4.3 T50, minutes 2.6 3.0 5.1 7.9 Zwick resiliometer Hardness (23 [degrees] C) 64 65 63 67 Hardness (100 [degrees] C) 61 62 60 64 Rebound (23 [degrees] C) % 46 45 47 48 Rebound (100 [degrees] C) % 64 61 65 69 Stress/strain Tensile, MPa 21.4 24.3 19.4 19.5 Elongation, % 456 477 485 444 100% Modulus, MPa 2.7 3.0 2.5 2.5 300% Modulus, MPa 12.8 14.0 10.8 11.4 Ratio 300%/100% 4.7 4.7 4.3 4.6 Rheometrics dynamic data (0.2% strain, 1 Hz) Tan delta, 0 [degrees] C 0.111 0.115 0.109 0.105 Tan delta, 60 [degrees] C 0.067 0.075 0.058 0.065 Delta tan delta (0-60 [degrees] C) 0.044 0.040 0.051 0.050 Compound# 5 6 7 8 Silica B Silica C 50% 100% Silica E 50% 100% Carbon black X50S 10% 10% 10% 10% Mooney ML 1+4'(100 [degrees] C) 60 56 70 64 MDR 2000 ML, dNm 2.9 2.7 3.5 3.5 MH, dNm 23.0 25.1 24.3 25.0 T2, minutes 2.2 3.1 2.3 3.8 T50, minutes 3.8 5.3 4.1 7.4 Zwick resiliometer Hardness (23 [degrees] C) 60 61 62 63 Hardness (100 [degrees] C) 58 60 60 63 Rebound (23 [degrees] C) % 50 56 48 51 Rebound (100 [degrees] C) % 66 74 64 70 Stress/strain Tensile, MPa 19.1 16.5 21.0 21.4 Elongation, % 438 369 460 483 100% Modulus, MPa 2.6 2.5 2.7 2.3 300% Modulus, MPa 12.0 12.4 12.3 10.9 Ratio 300%/100% 4.6 5.0 4.6 4.7 Rheometrics dynamic data (0.2% strain, 1 Hz) Tan delta, 0 [degrees] C 0.108 0.101 0.112 0.109 Tan delta, 60 [degrees] C 0.053 0.039 0.058 0.052 Delta tan delta (0-60 [degrees] C) 0.055 0.062 0.054 0.057 A comparison of all silica loaded versus all carbon black loaded compounds with silane coupling is shown in table 5 for all five silicas used in this stud). In comparison to the all low hysteresis carbon black compound, the all silica compounds were lower in ML1+4" (100 [degrees] C), ML, tensile, modulus, tan delta at 0 [degrees] C and tan delta at 60 [degrees] C. and higher in MH, [T.sub.2], [T.sub.50], rebound and delta tan delta. Silica CTAB surface area, at relatively constant [N.sub.2]-BET surface area (silicas B, C and D), con-elate better than silica [N.sub.2]-BET surface area, at relatively constant CTAB surface area (silicas A. B and D) for the rubber properties studied. The compound filled with silica C appeared to provide the best balance of properties. This compound, in comparison to the all low hysteresis carbon black compound, provided lower viscosity, slightly longer cure time, equal hardness, higher rebound, equivalent modulus and lower tan delta at 60 [degrees] C with higher delta tan delta. Table 5 - coupled organic rubber performance all silica - vs all carbon black Compound# 1 2 3 4 Silica A 100% Silica 3 100% Silica C Silica D Silica E Carbon black 100% 100% X50S 0% 10% 10% 10% Mooney ML 1+4'(100 [degrees] C) 68 70 52 62 MDR 2000 ML, dNm 3.5 3.8 2.6 3.3 MH, dNm 23.4 24.4 24.4 25.5 T2, minutes 1.5 1.7 5.8 4.3 T50, minutes 2.6 3.0 8.9 7.9 Zwick resiliometer Hardness (23 [degrees] C) 64 65 61 67 Hardness (100 [degrees] C) 61 62 60 64 Rebound (23 [degrees] C) % 46 45 54 48 Rebound (100 [degrees] C) % 64 61 71 69 Stress/strain Tensile, MPa 21.4 24.3 18.2 19.5 Elongation, % 456 477 552 444 100% Modulus, MPa 2.7 3.0 2.1 2.5 300% Modulus, MPa 12.8 14.0 7.8 11.4 Ratio 300%/100% 4.7 4.7 3.7 4.6 Rheometrics dynamic data (0.2% strain, 1Hz) Tan delta, 0 [degrees] C 0.111 0.115 0.105 0.105 Tan delta, 60 [degrees] C 0.067 0.075 0.058 0.055 Delta tan delta (0-60 [degrees] C) 0.044 0.040 0.047 0.049 Compound# 5 6 7 Silica A Silica 3 Silica C 100% Silica D 100% Silica E 100% Carbon black X50S 10% 10% 10% Mooney ML 1+4'(100 [degrees] C) 56 58 64 MDR 2000 ML, dNm 2.7 3.0 3.5 MH, dNm 25.1 25.5 25.0 T2, minutes 3.1 3.8 3.8 T50, minutes 5.3 6.8 7.4 Zwick resiliometer Hardness (23 [degrees] C) 61 65 63 Hardness (100 [degrees] C) 60 63 63 Rebound (23 [degrees] C) % 56 51 51 Rebound (100 [degrees] C) % 74 70 70 Stress/strain Tensile, MPa 16.5 18.2 21.4 Elongation, % 369 433 483 100% Modulus, MPa 2.5 2.4 2.3 300% Modulus, MPa 12.4 10.9 10.9 Ratio 300%/100% 5.0 4.5 4.7 Rheometrics dynamic data (0.2% strain, 1Hz) Tan delta, 0 [degrees] C 0.101 0.101 0.109 Tan delta, 60 [degrees] C 0.039 0.051 0.052 Delta tan delta (0-60 [degrees] C) 0.062 0.050 0.058 Conclusions Addition of carbon black or silica to this model tread formulation resulted in significant deviations from linear viscoelasticity at shear strains shear strain or shearing strain See under strain. greater than approximately 0.4%. Loss modulus (G") and tangent delta displayed a maximum at around 5% strain and then converged with increasing strain. The magnitude of the effects of coupling agent addition, silica loading and surface area were strain dependent. The strain-dependent dynamic moduli of the silica filled compounds were lower than the carbon black filled compounds. The significantly lower tan delta -values suggest that the silica compounds would provide lower rolling resistance than a low hysteresis carbon black at comparable loading. The addition of coupling agent to the silica filled compounds resulted in a significant increase in both G" and G'. Moreover, this effect was opposite the effect seen for the carbon black filled compound, thus confirming chemical interactions between the coupling agent, silica and polymer system. Increasing silica loading reduced both the dynamic moduli and tan delta. While silica [N.sub.2]-BET surface did not correlate, both silica CTAB and micropore surface area did correlate with both the dynamic moduli and tan delta. An all silica filled coupled compound containing the silica with the lowest CTAB surface area and the highest micropore surface area provides a better wet traction/rolling resistance response than the low hysteresis carbon black filled compound as tested in this series. Acknowledgements "Effect of silica on the viscoelastic properties of a model tread compound" is based on a paper given at the May, 1997 Rubber Division meeting. "Effects of filler compatability of NR" is based on a paper given at the October, 1997 Rubber Division meeting "Silica wet masterbatch: A new process for pre-dispersion of silica in emulsion emulsion: see colloid. emulsion Mixture of two or more liquids in which one is dispersed in the other as microscopic or ultramicroscopic droplets (see colloid). Emulsions are stabilized by agents (emulsifiers) that (e.g. polymers" is based on a paper given at the October, 1997 Rubber Division meeting. References (1.) R. Rauline, U.S. 5,227,425 (7/13/93). (2.) F. Bomo, Y. Chevallier, P. Lamy and J.-C. Morawski, U.S. 5,089,554 (2/18/92). (3.) Ph. Cochet, L. Barriquand, Y. Bomal and S. Touzet, "Precipitated silica in tire tread," presented at the ACS (Asynchronous Communications Server) See network access server. Rubber Division Meeting, Cleveland, OH, October, 1995. (4.) W.H. Waddell, P.A. Beauregard and L.R. Evans, Tire Technol. Int. '95, 14 (1995). (5.) L.R. Evans and W.H. Waddell, Kautsch, Gummi Kunstst, 48, 718 (1995). (6.) J. Collins, W. Jackson Jackson. 1 City (1990 pop. 37,446), seat of Jackson co., S Mich., on the Grand River; inc. 1857. It is an industrial and commercial center in a farm region. and P. Oubridge, Transactions of the Institute of the Rubber Industry, 40, 6 (1964). (7.) L.F. Gatti and R.J. Huffcut, "Applying dynamic mechanical properties for tire compound development," presented at the 2nd International Tire Exhibition and Conference, Akron, OH, 09/1996. (8.) S. Futamura, Tire Sci. Tech., 18, 1 (1990), pp. 2-12. (9.) S. Futamura and M.L. Englehardt, "Developing a high-performance tire tread," Rubber & Plastics News, 0511986. (10.) R.G. Stacer, D.M. Husband and H.L. Stacer, Rubber Chem. Technol., 60 (2), 227-44, 1987. (11.) S. Wolff Wolff , Kaspar Friedrich 1733-1794. German anatomist noted for his pioneering work in embryology. His chief work, Theoria Generationis (1759), refuted the theory of preformation, which held that the embryo is a fully formed miniature adult. , Rubber Chem. Technol. 55, 967 (1982). (12.) S. Wolff, U. Gorl, M.-J. Wang (Wang Laboratories, Inc., Lowell, MA) A computer services and network integration company. Wang was one of the major early contributors to the computing industry from its founder's invention that made core memory possible, to leadership in desktop calculators and word processors. and W. Wolff, "Silica-based tread compounds: Background and performance," presented at TyreTech '93, Basel, Switzerland, October 1993. (13.) R.A. Swor and R.L. Taylor, U.S. 5,494,955, (2/27/96). (14.) T.A. Okel and W.H. Waddell, Rubber Chem. Technol., 67 (2), 217, 1994. (15.) W.H. Waddell, L.R. Evans and T.A. Okel, Tire Technology International '94, 22, 1994. (16.) L.R. Evans and WK. Waddell, Rubber & Plastics News, April 25, 1994, p. 16. (17) E. W. Tan, S. Wolff, M. Haddeman, P.H. Grewatta and J.M. Wang, Rubber Chem Technol., 66 (4), 594-604, 1993. (18.) D.S D.S Drainage Structure (flood protection) . Chun, "The role of surface activity of silica on viscoelastic behavior of elastomeric vulcanizates," Dissertation dis·ser·ta·tion n. A lengthy, formal treatise, especially one written by a candidate for the doctoral degree at a university; a thesis. dissertation Noun 1. , University of Akron Enrollment in fall 2006 was 23,539 students.[1] The school offers more than 200 undergraduate degrees [2] and 100 graduate degrees [3]. The University's best-known program is its College of Polymer Science and Polymer Engineering, which is located in a , 1989. (19.) A. Voet, J.C. Morawski, J.B. Donnet, Rubber Chem. Technol., 50 (2), 342, 1977. (20.) J. C. Abram and M. C. Bennett, J. Col. Inter. Sci., 27(1), 1968. (21.) S.H. Hansen Han·sen , Gerhard Henrik Armauer 1746-1845. Norwegian physician and bacteriologist who discovered (1869) the leprosy bacillus. , P. Helboe and M. Thomsen, J. Chrom., 360,53 (1986). (22.) NF T 45-007, 5.12, November, 1987. (23.) S.D. Patkar, L.R. Evans and W.H. Waddell, "Mixing studies for improved performance and processability of silica-based compounds," presented at the 2nd International Tire Exhibition and Conference, Akron, Ohio Akron is a city in the U.S. state of Ohio and the county seat of Summit County.GR6 The municipality is located in northeastern Ohio on the Cuyahoga River between Cleveland to the north and Canton to the south, approximately 60 miles (96 km) west of , 09/1996. (24.) JMP Statistics and Graphics Guide, Version 3. 1, SAS Institute SAS Institute Inc., headquartered in Cary, North Carolina, USA, has been a major producer of software since it was founded in 1976 by Anthony Barr, James Goodnight, John Sall and Jane Helwig. Inc., Cary, NC, USA, 1995. |
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