Effect of precipitated silicas in truck tire treads.The use of 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. as a high quality reinforcing particulate par·tic·u·late adj. Of or occurring in the form of fine particles. n. A particulate substance. particulate composed of separate particles. 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, in rubber compounds continues to receive an increasing amount of attention. This has led to a proliferation proliferation /pro·lif·er·a·tion/ (pro-lif?er-a´shun) the reproduction or multiplication of similar forms, especially of cells.prolif´erativeprolif´erous pro·lif·er·a·tion n. of grades of precipitated silica designed to meet the specific needs of different applications. In 1976, Wagner (ref. 1) reviewed the importance of two fundamental silica properties which dictate TO DICTATE. To pronounce word for word what is destined to be at the same time written by another. Merlin Rep. mot Suggestion, p. 5 00; Toull. Dr. Civ. Fr. liv. 3, t. 2, c. 5, n. 410. the most appropriate end-use: ultimate particle size Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. and the extent of hydration hydration /hy·dra·tion/ (hi-dra´shun) the absorption of or combination with water. hy·dra·tion n. 1. The addition of water to a chemical molecule without hydrolysis. 2. . Silica properties were reported to affect the viscosity, cure rate and time, modulus See modulo. , adhesion adhesion /ad·he·sion/ (ad-he´zhun) 1. the property of remaining in close proximity. 2. the stable joining of parts to one another, which may occur abnormally. 3. , tensile strength tensile strength Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its and 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. resistance of the reinforced rubber. Wagner (ref. 2) later made comparisons which showed that a higher surface area silica, a direct function of smaller ultimate particle size, produced a compound with a higher viscosity but which also had the advantages of higher tensile strength, abrasion resistance and tear strength. These advantages have been put to use in off-the-road (OTR OTR Over The Road (truckers) OTR Other OTR Old Time Radio OTR On The Road OTR Off the Record OTR Outer OTR Over The Rainbow OTR Office of Tax and Revenue OTR Over-The-Rhine ) tire treads which are compounded with natural rubber (NR), carbon black and silica to reduce 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. , increase heat resistance and increase resistance to chipping and chunking chunk n. 1. A thick mass or piece: a chunk of ice. 2. Informal A substantial amount: won quite a chunk of money. 3. A strong stocky horse. (refs. 3-5). In a recent systematic study, Okel and Waddell Waddell is a common surname and may refer to:
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. formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation , illustrating the primary role played by silica surface area and the secondary role played by structure. With the addition 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). coupling agents, silica has become prevalent in passenger tire tread formulations for the reduction of 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. 7-9). Rauline (ref. 10) showed that the benefit of silica in decreasing rolling resistance is a direct function of the silica loading with highly dispersible silicas becoming important for the balance of compound properties at high loadings. The use of the combination of 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)-tetrasulfide (TESPT) and silica to reduce the rolling resistance of truck tire treads was first reported by 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. in 1986 (ref. 11). It was reported that rolling resistance was reduced by as much as 30%, wet 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. remained virtually unchanged and treadwear index decreased only 5% when a silane-modified precipitated silica was used to entirely replace N220 black in a natural rubber truck tread. It is well known that in the absence of silane coupling agent, silica perturbs the sulfur/accelerator cure mechanism resulting in increased scorch time, slower cure rate and decreased crosslink density (refs. 12 and 13). Wolff et al (ref. 14) showed that in the presence of TESPT, the compound Mooney Mooney is family name, which is probably predominantly derived from the Irish Ó Maonaigh. It can also be spelled Moony, Meaney, Mauney, Moon, Money. The word can refer to: Companies
Meaney spelling n. An instrument for measuring the flow of viscous liquids, such as blood. minimum torque of silica-containing compounds are reduced. In addition, cure characteristics are normalized, resulting in an increased rheometer delta torque, reduced 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. , increased high strain modulus and reduced heat build-up, as well as reduced tan delta at 60 [degrees] C, a widely accepted predictor of reduced rolling resistance (refs. 3 and 14). In a recent study of the effects of adding silane coupling agents versus the effects of increasing TBBS TBBS The Bread Board System TBBS The Big Blue Sky (website) 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. in a model black/silica low rolling resistance passenger tread compound, Byers Byers may refer to any of the following places:
adj. 1. Of, relating to, or characteristic of a particular district. 2. Composed of or divided into component sections. n. retreads was equivalent to the all-black control. In a separate study, Cochet et al (ref. 16) increased both accelerator and TESPT levels in a Nit-based tread compound when the surface area of the silica evaluated was increased. A composite model truck tire tread formulation was developed for the present study from a review of the recent patent literature (refs. 17-21) pertaining per·tain intr.v. per·tained, per·tain·ing, per·tains 1. To have reference; relate: evidence that pertains to the accident. 2. to NR truck tread formulations. The purpose of the present study was to quantify Quantify - A performance analysis tool from Pure Software. the effects of silica surface area and of silica loading in perturbing the cure system of this truck tread formulation. Using this information, the effect of silane coupling agent on compound cure, physical and dynamic properties was determined both in the absence and presence of compensation for this cure perturbation perturbation (pŭr'tərbā`shən), in astronomy and physics, small force or other influence that modifies the otherwise simple motion of some object. The term is also used for the effect produced by the perturbation, e.g. with additional accelerator. Experimental Silica physical characteristics Silicas #1, #2 and #3 are specific lots of the commercially available PPG PPG Points Per Game (basketball player statistic) PPG Power Play Goals (hockey) PPG Planning Policy Guidance (UK) PPG Programmable Pulse Generator PPG Power Puff Girls precipitated silicas: Hi-Sil 243LD, Hi-Sil 255G and Hi-Sil 90G, respectively. These three silicas are all granulated gran·u·late v. gran·u·lat·ed, gran·u·lat·ing, gran·u·lates v.tr. 1. To form into grains or granules. 2. To make rough and grainy. v.intr. products. Nitrogen surface areas were determined by the Brunauer, Emmett Emmett or Emmet may refer to: People
prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. ASTM ASTM abbr. American Society for Testing and Materials D3037-92 using a Leeds Leeds, city (1991 pop. 445,242) and metropolitan district, N central England, on the Aire River. It lies between one of England's leading manufacturing regions on the west and south and an agricultural region on the north and east. and Northrup Automatic Surface 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. 4200 for single point determinations and according to ASTM D1993-91 using a Micromeritics The science & technology of small particles is called as micromeritics. The unit of particle size most frequently used in micromeritics is micrometer, also called as a micron. The knowledge & control of the size of particles is of profound importance in pharmacy ASAP (chat) asap - As soon as possible. 2400 for multiple point determinations. Surface area by 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). of 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 ) was determined according to French Standard NF T 45-007 (1987). Sears surface area (ref. 22), related to silica hydroxyl hydroxyl /hy·drox·yl/ (hi-drok´sil) the univalent radical OH. hy·drox·yl n. The univalent radical or group OH, a characteristic component of bases, certain acids, phenols, alcohols, carboxylic content, was determined as previously described by Okel and Waddell (ref. 6). Dibutyl phthalate Dibutyl phthalate (DBP) is a commonly used plasticizer. It is also used as an additive to adhesives or printing inks. It is soulble in various organic solvents, e.g. in alcohol, ether and benzene. (DBP DBP Diastolic Blood Pressure DBP Development Bank of the Philippines DBP Database Project (Visual Studio File Extension) DBP DNA Binding Protein DBP Disinfection Byproduct DBP Deutsche Bundespost ) absorption was determined according to ASTM D2414-92 with the following modifications: the sample was dried at 105 [degrees] C for two hours; a test weight of 10-15 g of the dried silica was used; dampening was set at 1 s; and the absorption volume was determined by the intersection intersection /in·ter·sec·tion/ (-sek´shun) a site at which one structure crosses another. intersection a site at which one structure crosses another. of tangents drawn on the baseline The horizontal line to which the bottoms of lowercase characters (without descenders) are aligned. See typeface. baseline - released version and curve. Silica pH was determined using a Markson Selectro Mark Analyzer 4503 with an Orion Orion, in Greek mythology Orion (ōrī`ən), in Greek mythology, Boeotian hunter. When Oenopion delayed giving his daughter Merope to him, Orion, when drunk, violated her. Ross Ross , Sir Ronald 1857-1932. British physician. He won a 1902 Nobel Prize for proving that malaria is transmitted to humans by the bite of the mosquito. combination pH electrode electrode, terminal through which electric current passes between metallic and nonmetallic parts of an electric circuit. In most familiar circuits current is carried by metallic conductors, but in some circuits the current passes for some distance through a by dispersing 5 g of silica in 100 [cm.sup.3] of deionized water Deionized water (DI water or de-ionized water; also spelled deionised water, see spelling differences) is water that lacks ions, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. , stirring the solution for one minute and recording the measurement after one additional minute. Mercury total intruded in·trude v. in·trud·ed, in·trud·ing, in·trudes v.tr. 1. To put or force in inappropriately, especially without invitation, fitness, or permission: volume and pore pore (por) a small opening or empty space. alveolar pores openings between adjacent pulmonary alveoli that permit passage of air from one to another. diameter were determined using a Quantochrome Autoscan-33 Porosimeter operated in the high pressure range from 103 KPa to 227 MPa, absolute. Pore diameter is reported for the maximum of the volume pore size distribution. The physical properties of the three precipitated silicas studied are summarized in table 1. These three silicas were selected for study as the main difference in their physical characteristics arises from differences in surface area. Table 1 -- silica physical characteristics Property #1 #2 #3 Surface area, [m.sup.2]/g 1-pt [N.sub.2] BET 149 176 220 5-pt [N.sub.2] BET 138 167 201 CTAB absorption 134 143 166 Sears 337 348 330 DBP absorption, ml/100g 172 179 203 % moisture loss 105 [degrees] C 5.7 5.6 5.6 pH, 5% solution 6.7 6.3 7.0 Mercury porosimetry Total intruded volume, [cm.sup.3]/g 1.53 1.57 1.67 Pore diameter, nm 28.6 27.7 17.5 Residual [Na.sub.2] [SO.sup.4] content, wt. % <0.007 1.31 0.339 Residual NaCl consent' wt. % 1.61 0.0315 0.0244 Rubber compound properties The natural rubber-based model truck tread formulation consisting of a N220 carbon black-based control and silica-containing modifications is presented in table 2. Initially, the three silicas were substituted into the control formulation at 8, 16 and 24 phr loadings, keeping the filler volume loading constant and the accelerator, benzothiazyl-2-cyclohexyl sulfenamide (CBS (Cell Broadcast Service) See cell broadcast. ), level constant at 1.2 pier. A constant level of TESPT of 8.0 weight % relative to the weight of silica was maintained. In addition, at the 24 phr loading of the three silicas, the CBS level was also increased to 1.6 phr for the three silicas. From these studies, the relative influence of silica loading and curative curative /cur·a·tive/ (kur´ah-tiv) tending to overcome disease and promote recovery. cu·ra·tive adj. 1. Serving or tending to cure. 2. level on compound physical properties was determined for each silica surface area. Table 2 -- control and model truck tread formulations Ingredient Black control Compound Natural rubber (CV-60) 100 100 N220 carbon black 50 43.0, 35.5, 28.5 Precipitated silica 0 8.0, 16.0, 24.0 SI-69 0 0.64, 1.28, 1.92 Santoflex 13 1.0 1.0 Wingstay 100 0.5 0.5 Sundex 8125 2.0 2.0 Stearic acid 2.0 2.0 Zinc oxide 4.0 4.0 Sulfur 1.5 1.5 Santocure 1.0 1.2, 1.6 Precipitated silica = HiSil 243LD, Hi-Sil 225G, Hi-Sil 190G; the SI-69 level was held fixed at 8.0 wt. % relative to the weight of silica; the filler volume was kept constant; the three silica loadings were compounded at each of 1.2 and 1.6 phr CBS. In a subsequent series of 2-variable, 2-level statistically designed experiments, the effects of silica loading and silane (TESPT) level were evaluated for each of the three silicas. These studies were conducted both at constant accelerator (CBS) level and with the accelerator level increased as silica loading increased. The degree of adjustment of the accelerator level was dependent upon the silica surface area. The design scheme is illustrated in figure 1. The two variables, silica loading and weight % silane relative to silica weight are completely independent of one another. 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 Version 3.1.5 software (ref. 23). [Figure 1 ILLUSTRATION OMITTED] All compounds were mixed using a two-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 standard mix cycle employed is presented in table 3 which presents the centerpoint Centerpoint is used in several senses:
Table 3 -- model truck tread formulation design centerpoint
Addition Ingredient PHR
Time, min Silica #1
Non-productive
0 Natural rubber
(CV-60) 100
1.0 Silica 16
SI-69 1.28
2.0 N220 carbon black 35.5
Santoflex 13 1.0
Wingstay 100 0.5
Sundex 8125 2.0
Stearic acid 2.0
Dump @ 6 min.165 [degrees] C max.
Productive
0 Masterbatch 158.3
0.5 Zinc oxide 4.0
Sulfur 1.5
CBS 1.2, 1.4
Dump @ 3 min. 125 [degrees] C max.
Addition PHR
Time, min Silica #2 Silica #3
Non-productive
0
100 100
1.0 16 16
1.28 1.28
2.0 35.5 35.5
1.0 1.0
0.5 0.5
2.0 2.0
2.0 2.0
Productive
0 158.3 158.3
0.5 4.0 4.0
1.5 1.5
1.2, 1.45 1.58, 1.8
Compound test specimens were cured at 150 [degrees] C for [T.sub.90] appropriate 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 time. 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. tests were used to determine the physical properties of the rubber compounds (ref. 6). Dynamic properties were determined with a Rheometrics RDS-11 mechanical spectrometer spectrometer Device for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emission (as of electromagnetic radiation or particles) is spread out according to some , using a parallel plate sample 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. at 2% strain. Temperature sweep curves were obtained between 75 [degrees] C and -45 [degrees] C at a 1 Hz oscillating os·cil·late intr.v. os·cil·lat·ed, os·cil·lat·ing, os·cil·lates 1. To swing back and forth with a steady, uninterrupted rhythm. 2. frequency. Results and discussion The objective of the first phase of the study was to determine the degree of influence of silica surface area and loading on the perturbation of the cure system relative to an all-black control. The compound properties obtained for the formulations presented in table 2, are summarized in table 4 for a constant silica loading of 24 phr and in table 5 for a constant CBS accelerator level of 1.2 pier. In each case, the TESPT level was kept at a constant 8.0 weight % relative to the amount of silica compounded.
Table 4 -- truck head compound performance as a function of
accelerator level
Carbon Silica #1
black
control
CBS level, phr 1.2 1.6
Properties
[M.sub.L], dNm 4.12 3.8 3.8
[M.sub.H] - [M.sub.L] dNm 22.7 22.5 26.1
[Ts.sub.2], min. 3.5 3.5 3.4
[T.sub.50], min. 5.0 5.6 5.3
[T.sub.90], min. 8.1 9.0 7.8
Hardness @ 23 [degrees] C 66 62 65
Tensile, MPa 31.6 31.6 31.6
Elongation, % 514 548 516
100% modulus, MPa 2.7 2.4 2.9
300% modulus, MPa 16.0 13.6 15.8
Rebound @ 23 [degrees] C, % 50.4 56.6 58.2
Rebound @ 100 [degrees] C, % 63.4 70.0 72.2
Silica #2 Silica #3
CBS level, phr
1.2 1.6 1.2 1.6
Properties
[M.sub.L], dNm 4.2 3.8 4.0 4.1
[M.sub.H] - [M.sub.L] dNm 20.5 24.5 18.5 23.3
[Ts.sub. 2],min. 3.4 3.5 3.3 3.3
[T.sub.50], min. 5.2 5.2 5.8 5.3
[T.sub.90], min. 8.2 7.6 9.3 7.8
Hardness @ 23 [degrees] C 62 64 60 63
Tensile, MPa 31.0 32.4 30.1 32.2
Elongation, % 559 530 580 556
100% modulus, MPa 2.3 2.7 2.0 2.4
300% modulus, MPa 12.8 15.2 11.0 13.6
Rebound @ 23 [degrees] C, % 57.0 55.4 54.4 56.8
Rebound @ 100 [degrees] C, % 68.8 68.4 63.8 68.0
Silica loading = 24phr; silane level = 8.0 wt. % of silica wt.
Table 5 -- truck tread compound performance as a function of
silica loading
Carbon Silica #
black
control
Silica loading, phr 8 24
Properties
[M.sub.L], dNm 4.1 3.8 3.8
[M.sub.H]-[M.sub.L] dNm 22.7 23.6 22.5
[Ts.sub.2], min 3.5 3.3 3.5
[T.sub.50], min 5.0 4.8 5.6
[T.sub.90], min 8.1 7.9 9.0
Hardness @ 23 [degrees] C 66 65 62
Tensile, MPa 31.6 30.4 31.6
Elongation, % 514 507 548
100% modulus, MPa 2.7 2.8 2.4
300% modulus, MPa 16.0 15.5 13.6
Rebound @ 23 [degrees] C, % 50.4 53.2 56.6
Rebound @ 100 [degrees] C, % 63.4 67.4 70.0
Silica #2 Silica #3
Silica loading, phr 8 24 8 24
Properties
[M.sub.L], dNm 3.9 4.2 4.1 4.0
[M.sub.H]-[M.sub.L] dNm 23.4 20.5 22.6 18.5
[Ts.sub.2], min 3.0 3.4 3.1 3.3
[T.sub.50], min 4.5 5.2 4.6 5.8
[T.sub.90], min 7.1 8.2 7.2 9.3
Hardness @ 23 [degrees] C 65 62 64 60
Tensile, MPa 31.3 31.0 31.3 30.1
Elongation, % 508 559 520 580
100% modulus, MPa 2.8 2.3 2.6 2.0
300% modulus, MPa 15.9 2.8 15.2 11.0
Rebound @ 23 [degrees] C, % 54.0 57.0 53.2 54.4
Rebound @ 100 [degrees] C, % 67.4 68.8 65.4 63.8
CBS level = 1.2 phr; silane level = 8.0 wt. % of silica wt. From table 4, it is apparent that for a given accelerator level, crosslink density as predicted by rheometer delta torque decreases as silica surface area increases. This is accompanied by increases in elongation, decreases in higher strain modulus and to a lesser extent decreases in 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 . The inverse relationship A inverse or negative relationship is a mathematical relationship in which one variable decreases as another increases. For example, there is an inverse relationship between education and unemployment — that is, as education increases, the rate of unemployment between silica CTAB surface area and compound 300% modulus is illustrated for each accelerator level in figure 2. From the 300% modulus values obtained at the two accelerator levels, it was possible to extrapolate extrapolate - extrapolation the amount of accelerator required for compounds containing a 24 phr loading of each silica to match the 300% modulus of the all-carbon black control compound. This was estimated to be 1.6, 1.7 and 2.0 phr of CBS accelerator for silica CTAB surface areas of 134, 143 and 166 [m.sup.2]/g, respectively. [Figure 2 ILLUSTRATION OMITTED] The compounding data presented in table 5 show that there is not much influence of silica surface area on the cure-related compound physical properties at a loading of 8 pier. However, as illustrated for 300% modulus in figure 3, the influence of silica surface area on compound physical properties becomes progressively more pronounced with silica loading. Also from table 5, it is apparent that even at a silica loading of only 8 pier, a significant increase in rebound at 100 [degrees] C was observed for each silica relative to the carbon black control compound. At a 24 phr silica loading, the highest rebound at 100 [degrees] C was obtained for the lowest surface area silica, which also provided the least perturbation to the cure system. [Figure 3 ILLUSTRATION OMITTED] Based on these results, a series of 2-variable, 2-level designed experiments (figure 1) was initiated to determine the influence of silica loading and of silane coupling agent level on compound physical properties. For the two lower surface area silicas, these studies were conducted at a constant accelerator level and then repeated with the accelerator level increased with increased silica loading to maintain a constant 300% modulus. Since silica #3 had a significantly higher surface area with a much greater perturbation of the cure system than the other two silicas, the decision was made to not conduct a study at a constant, relatively low level of accelerator. Instead, two design studies were conducted with two different ranges of accelerator adjustment for increases in silica loading. The accelerator levels used with each silica at each loading are tabulated in table 6.
Table 6 -- accelerator levels in relation to silica loadings
Silica #1 Silica #2
Silica loading, phr 8 16 24 8 16 24
CBS level, phr (1) 1.2 1.2 1.2 1.2 1.2 1.2
(2) 1.2 1.4 1.6 1.2 1.45 1.7
Silica #3
Silica loading, phr 8 16 24
CBS level, phr (1) 1.3 1.6 1.85
(2) 1.5 1.8 2.1
Correlation coefficients Correlation Coefficient A measure that determines the degree to which two variable's movements are associated. The correlation coefficient is calculated as: of silica loading and of weight % silane relative to weight of silica, with compound cure, physical and dynamic properties, are presented in tables 7 and 8 for silica #1 and silica #2, respectively. These coefficients were determined at constant accelerator level and for accelerator level increased with increased silica loading. Correlation coefficients are presented in table 9 for silica #3 for the lower and higher ranges of accelerator level confounded with silica loading. Properties with absolute correlation coefficients greater than 0.5 are included in the tables. Only one cure time, one modulus value and one DeMattia cut growth value are presented since all cure times are 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 each other as are all modulus values and all cut growth values. In addition, of the G', G" and tan delta values obtained at 0 [degrees] C and 60 [degrees] C, only tan delta at 60 [degrees] C is tabulated since these properties were also all highly correlated with each other. Positive values reported in tables 7-9 indicate 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 , while negative values indicate 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. The nearer the absolute correlation coefficient is to 1.00, the higher is the degree of association. At a constant accelerator level, increased silica loading showed a number of strong associations such as decreased rheometer maximum torque and therefore delta torque, decreased hardness, modulus, cut growth and tan delta at 60 [degrees] C, as well as increased scorch time, cure time, elongation and rebound at 100 [degrees] C. The changes in rheometer maximum torque, hardness and modulus were counterbalanced coun·ter·bal·ance n. 1. A force or influence equally counteracting another. 2. A weight that acts to balance another; a counterpoise or counterweight. tr.v. by increased levels of silane but with a lesser degree of association. As will be described in greater detail, a number of these associations with silica loading were diminished di·min·ish v. di·min·ished, di·min·ish·ing, di·min·ish·es v.tr. 1. a. To make smaller or less or to cause to appear so. b. when the accelerator level was confounded with silica loading.
Table 7 -- correlation coefficients for tread compounds
containing silica #1
CBS=1.2 phr
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+ 4(100 [degrees] C) -0.56
[M.sub.H], dNm -0.92
[M.sub.H]-[M.sub.L], dNm -0.84
[Ts.sub.2], min. 0.98
[T.sub.90], min. 0.99
Hardness @ 23 [degrees] C -0.81 0.58
Tensile strength, MPa -0.78
Elongation, % 0.86
50% modulus, MPa -0.78 0.49
300% modulus, MPa -0.96
Tear, kN/m 0.59
Cut growth @ 54 kc, mm -0.71 0.55
Heat build-up, [degrees] C 0.60
Permanent set, % 0.70 -0.48
Rebound @ 23 [degrees] C, % 0.96
Rebound @ 100 [degrees] C, % 0.74
Tan [Delta] @ 60 [degrees] C, MPa -0.92
CBS varied(*)
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+ 4(100 [degrees] C)
[M.sub.H], dNm 0.66 0.72
[M.sub.H]-[M.sub.L], dNm 0.61 0.73
[Ts.sub.2], min. 0.99
[T.sub.90], min. 0.96
Hardness @ 23 [degrees] C 0.87
Tensile strength, MPa -0.58
Elongation, % -0.77
50% modulus, MPa 0.92
300% modulus, MPa -0.66 0.50
Tear, kN/m
Cut growth @ 54 kc, mm
Heat build-up, [degrees] C -0.89
Permanent set, % -0.94
Rebound @ 23 [degrees] C, % 0.78
Rebound @ 100 [degrees] C, % 0.91
Tan [Delta] @ 60 [degrees] C, MPa -0.97
(*) Reference table 6
Table 8 -- correlation coefficients for tread
compounds containing silica #2
CBS = 1.2 phr
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+4(100 [degrees] C) 0.89
[M.sub.H], dNm -0.83 0.51
[M.sub.H]-[M.sub.L], dNm, -0.83 0.51
[Ts.sub.2] min. 0.69
[T.sub.90], min. 0.98
Hardness @ 23 [degrees] C -0.94
Tensile strength, MPa
Elongation, % 0.85
50% modulus, MPa -0.75
300% modulus, MPa -0.86 0.58
Tear, kN/m 0.68 -0.68
Cut growth @ 54 kc, mm -0.66
Heat build-up, [degrees] C 0.44 -0.75
Permanent set, % 0.52 -0.63
Rebound @ 23 [degrees] C, % 0.79
Rebound @ 100 [degrees] C, % 0.49 0.64
Tan [Delta] @ 60 [degrees] C, MPa -0.98
CBS varied(*)
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+4(100 [degrees] C) 0.79 -0.50
[M.sub.H], dNm 0.89
[M.sub.H]-[M.sub.L], dNm, 0.88
[Ts.sub.2] min. 0.73
[T.sub.90], min.
Hardness @ 23 [degrees] C -0.66 0.66
Tensile strength, MPa 0.74
Elongation, %
50% modulus, MPa 0.67
300% modulus, MPa
Tear, kN/m -0.58
Cut growth @ 54 kc, mm 0.62
Heat build-up, [degrees] C -0.96
Permanent set, % -0.89
Rebound @ 23 [degrees] C, % 0.98
Rebound @ 100 [degrees] C, % 0.98
Tan [Delta] @ 60 [degrees] C, MPa -0.96
(*) Reference table 6
Table 9 -- correlation coefficients for tread
compounds containing silica #3
CBS varied (1)(*)
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+4(100 [degrees] C)
[M.sub.H], dNm 0.76 0.51
[M.sub.H]-[M.sub.L], dNm, 0.69 0.55
[Ts.sub.2] min. 0.91
[T.sub.90], min. 0.67
Hardness @ 23 [degrees] C -0.54 0.82
Tensile strength, MPa
Elongation, % 0.60
50% modulus, MPa
300% modulus, MPa -0.80 0.59
Tear, kN/m 0.72
Cut growth @ 54 kc, mm 0.96
Heat build-up, [degrees] C -0.81
Permanent set, %
Rebound @ 23 [degrees] C, %
Rebound @ 100 [degrees] C, % 0.72
Tan [Delta] @ 60 [degrees] C, MPa -0.96
CBS varied (2)(*)
Silica Wt. %
loading silane
Silica loading, phr 1.0 0.0
Wt. % silane 0.0 1.0
Properties
[M.sub.L]-1+4(100 [degrees] C) -0.79
[M.sub.H], dNm 0.82
[M.sub.H]-[M.sub.L], dNm, 0.74 0.62
[Ts.sub.2] min. 0.83
[T.sub.90], min. 0.92
Hardness @ 23 [degrees] C -0.65 0.65
Tensile strength, MPa
Elongation, % 0.81
50% modulus, MPa -0.47 0.77
300% modulus, MPa -0.75
Tear, kN/m -0.94
Cut growth @ 54 kc, mm
Heat build-up, [degrees] C -0.84
Permanent set, % -0.62
Rebound @ 23 [degrees] C, % 0.95
Rebound @ 100 [degrees] C, % 0.74
Tan [Delta] @ 60 [degrees] C, MPa -0.94
(*) Reference table 6 Using screening models, equations were developed for key compound physical properties for each of the six designed experiments. These equations, along with their coefficients of determination, [r.sup.2], are presented in tables 10-11 for silicas #1 and #2. Note that [r.sup.2] correlation coefficient values [is greater than] 98% are considered to be predictive, values [is greater than] 90% are considered to represent significant relationships while values between 80% and 90% are considered indicative of general trends.
Table 10 -- model equations for tread compounds containing
silica #1
Property Intercept [C.sub.1]
(loading)
[M.sub.L]-1+4 (100 [degrees] C) 1 67.2 -0.22
2 69.2 -0.062
[M.sub.H]-[M.sub.L], dNm 1 22.6 -0.11
2 20.3 0.058
[Ts.sub.2], min. 1 3.69 0.040
2 3.46 0.025
[T.sub.90], min. 1 7.57 0.11
2 7.52 0.048
Hardness @ 23 [degrees] C 1 62.7 -0.22
2 63.7 0.0
Elongation, % 1 539 2.10
2 637 61.59
50% modulus, MPa 1 1.61 -0.012
2 1.28 -0.00090
300% modulus, MPa 1 17.0 -0.17
2 12.8 -0.054
HBU, [degrees] C 1 29 0.41
2 26 -0.19
Rebound @ 100 [degrees] C, % 1 62.8 0.11
2 69.0 0.15
Tan [Delta] at 60 [degrees] C, MPa 1 0.111 -0.0015
2 0.135 -0.0020
Property [C.sub.2] [r sup. 2]
(silane)
[M.sub.L]-1+4 (100 [degrees] C) 0.37 0.37
0.25 0.061
[M.sub.H]-[M.sub.L], dNm 0.22 0.89
0.28 0.90
[Ts.sub.2], min. -0.012 0.96
-0.0038 0.99
[T.sub.90], min. 0.025 0.99
0.041 0.96
Hardness @ 23 [degrees] C 0.62 0.98
0.25 0.75
Elongation, % -1.2 0.75
-9.1 0.89
50% modulus, MPa 0.030 0.85
0.021 0.87
300% modulus, MPa 0.13 0.96
0.16 0.68
HBU, [degrees] C -1.1 0.52
-0.25 0.87
Rebound @ 100 [degrees] C, % 0.050 0.55
0.050 0.83
Tan [Delta] at 60 [degrees] C, MPa 0.0017 0.91
-0.00058 0.95
C1 = coefficient coefficient /co·ef·fi·cient/ (ko?ah-fish´int) 1. an expression of the change or effect produced by variation in certain factors, or of the ratio between two different quantities. 2. of silica loading; C2 = coefficient of wt % silane 1 = CBS constant @ 1.2 pier; 2 = CBS level confounded with silica loading Bold = significant effect, probability t<0.05.
Table 11 -- model equations for tread compounds containing
silica #2
Property Intercept [C.sub.1]
(loading)
[M.sub.L]-1+4 (100 [degrees] C) 1 60.8 0.28
2 60.3 0.34
[M.sub.H]-[M.sub.L], dNm 1 21.1 -0.16
2 19.9 0.14
[Ts.sub.2], min. 1 3.71 0.023
2 3.20 0.0060
[T.sub.90], min. 1 7.15 0.070
2 7.26 -0.0090
Hardness @ 23 [degrees] C 1 66.7 -0.28
2 61.3 -0.12
Elongation, % 1 562 1.9
2 552 0.34
50% modulus, MPa 1 1.32 -0.018
2 1.28 0.0028
300% modulus, MPa 1 13.7 -0.15
2 13.0 0.028
HBU, [degrees] C 1 44 0.44
2 29 -0.47
Rebound @ 100 [degrees] C, % 1 57.3 0.16
2 61.6 0.34
Tan [Delta] @ 60 [degrees] C, MPa 1 0.122 -0.0010
2 0.127 -0.0028
Property [C.sub. 2] (silane) [r.sup.2]
[M.sub.L]-1+4 (100 [degrees] C) -0.12 0.81
-0.88 0.87
[M.sub.H]-[M.sub.L], dNm 0.39 0.95
0.27 0.97
[Ts.sub.2], min. -0.075 0.80
-0.010 0.61
[T.sub.90], min. -0.025 0.96
0.030 0.25
Hardness @ 23 [degrees] C 0.12 0.90
0.50 0.86
Elongation, % -3.0 0.84
-1.1 0.05
50% modulus, MPa 0.059 0.95
0.024 0.54
300% modulus, MPa 0.37 0.99
0.11 0.14
HBU, [degrees] C -3.0 0.75
-0.12 0.93
Rebound @ 100 [degrees] C, % 0.82 0.65
0.22 0.98
Tan [Delta] @ 60 [degrees] C, MPa -0.00070 0.97
0.00070 0.93
C1 = coefficient of silica loading; C2 = coefficient of wt. % silane 1 = CBS constant @ 1.2 phr; 2 = CBS level confounded with silica loading Bold = significant effect, probability t <0.05. As shown in table 10, for the silica with the lowest surface area, silica #1, neither silica loading or silane level had a significant effect on compound Mooney viscosity. The adjustment of accelerator level with the silica loading to maintain 300% modulus was successful. This is indicated by comparing rows 1 and 2 for 300% modulus. At a constant accelerator level (row 1), the fit of the model for 300% modulus has a highly significant r2 Of 0.96 with a significant decline in 300% modulus occurring with increased silica loading. In the presence of the accelerator adjustment (row 2), the fit of the model drops to an insignificant [r.sup.2] Of 0.68 with no significant influence of silica loading. This accelerator adjustment resulted in a decline in the influence of silica loading on a number of other properties as well; rheometer delta torque, scorch time, [T.sub.90], hardness, elongation and 50% modulus. In the presence of the accelerator adjustment, heat build-up declined and % rebound at 100 [degrees] C increased with increasing silica level. The only compound physical properties which continued to be significantly influenced by increasing level of silane coupling agent were the rheometer delta torque and the 50% modulus. In these experiments, both in the absence and presence of accelerator adjustment, only the increase in silica loading was significant in reducing the tan delta at 60 [degrees] C. A similar pattern of compound physical property behavior was found for silica #2, as shown in table 11 and presented in figures 4-7. In these figures, a variable is only truly significant in influencing the compound physical property if the error bars on the trend line do not overlap o·ver·lap n. 1. A part or portion of a structure that extends or projects over another. 2. The suturing of one layer of tissue above or under another layer to provide additional strength, often used in dental surgery. v. the horizontal line (Descriptive Geometry & Drawing) a constructive line, either drawn or imagined, which passes through the point of sight, and is the chief line in the projection upon which all verticals are fixed, and upon which all vanishing points are found. See also: Horizontal representing the average response. The closer the trend line to horizontal, the less significant is the variable. For silica #2, a trend of increasing Mooney viscosity with increased silica loading was observed. No significant effect of level of silane coupling agent on Mooney viscosity was determined. The decline in rheometer delta torque with increased silica loading is actually reversed with the adjustment in accelerator level, indicating that the degree of accelerator adjustment was somewhat greater than necessary. As illustrated in figure 6, 300% modulus significantly declined as the loading of silica #2 increased at a constant accelerator level. Under these conditions, increasing silane coupling agent was significant in increasing 300% modulus. However, in the presence of increasing accelerator level with increasing loading of silica #2, 300% modulus is no longer significantly influenced by either silica loading or silane level. As illustrated (figures 4-7), confounding confounding when the effects of two, or more, processes on results cannot be separated, the results are said to be confounded, a cause of bias in disease studies. confounding factor accelerator level with silica loading was also successful in removing from significance the effect of increasing silica loading on increasing scorch time, cure time, elongation and in decreasing hardness and modulus. Correlating accelerator level with increased silica loading had the effect of significantly reducing heat build-up and increasing rebound at 100 [degrees] C. In the presence of this accelerator adjustment, the only remaining significant effect was the direct relationship of silane level with the rheometer delta torque. As with silica #1, these two designed experiments for silica #2 showed that only the increase in silica loading was significant in reducing tan delta at 60 [degrees] C. [Figure 4-7 ILLUSTRATION OMITTED] The same pattern of compound physical property dependence was found with the highest surface area silica, silica #3. A much greater degree of accelerator adjustment was required to maintain 300% modulus with increased silica loading. The higher degree of adjustment, with the CBS level ranging from 1.5 phr at 8 phr silica to 2.1 phr at 24 phr silica, was effective at removing silica loading as a significant factor in affecting 300% modulus and other cure-related compound physical properties Again, only increased silica loading had the significant effect of reducing tan delta at 60 [degrees] C. Of the three silicas studied, all were equally effective at reducing tan delta at 60 [degrees] C with a similar decline in tan delta with increased loading observed in each case. As a test of the validity of these models, the three silicas were compounded at a silica loading of 24 phr, a silane coupling agent level of 8 weight % relative to the silica weight and the CBS level required to compensate for the silica surface area. Considering the degree of error associated with compounding and testing properties, the predictions were in excellent agreement with the actual physical properties obtained. A number of key results were obtained. Mooney viscosity is lower for the silica containing compounds and only shows a slight increasing trend with increasing silica surface area. For an equivalent elongation at break, a higher rheometer delta torque was obtained for the silica containing compounds. As expected, the 300% modulus was essentially equivalent for all compounds as was scorch time, cure time, tensile strength, modulus at various strains and 300/100% modulus ratio. Cut growth was excellent for all compounds. Tear strength was perhaps increased for the highest surface area silica, even at constant elongation. Heat build-up, % rebound at 100 [degrees] C and tan delta at 60 [degrees] C all indicated significantly reduced 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. for the silica-containing compounds. While % rebound at 23 [degrees] C was also increased and accompanied by a decrease in tan delta at 0 [degrees] C for the silica-containing compounds, the change in tan delta between 0 [degrees] C and 60 [degrees] C was significantly greater, indicating the potential for an improved balance between wet traction and rolling resistance. All three silicas were found to significantly reduce tan delta at 60 [degrees] C relative to the all-carbon black control. The two higher surface area silicas were equivalent in reducing tan delta at 60 [degrees] C to a slightly greater extent. Conclusions For this all-natural rubber low rolling resistance truck tread formulation at a constant level of accelerator, increasing silica surface area or increasing the loading of silica significantly reduces the cure-related compound physical properties. This effect becomes progressively more pronounced as silica surface area is increased. These effects are counter-balanced adj. 1. brought into equipoise by means of a weight or force that offsets another. by the presence of bis Second version. It means twice in Old Latin, or encore in French. Ter means three. For example, V.27bis and V.27ter are the second and third versions of the V.27 standard. (3-triethoxylsilylpropyl) tetrasulfide coupling agent. If the perturbation of the cure system by silica is adequately compensated with increased accelerator for either increased silica surface area or increased silica loading, the effects of the silane coupling agent are significantly diminished over a range of coupling agent level from 6 to 10 weight % relative to silica weight. For this coupling agent range, only the increase of rheometer delta torque with increasing silane level remained significant. With accelerator compensation, reduction in heat build-up and increased rebound at 100 [degrees] C become positively influenced by increased silica loading. Therefore, with the appropriate level of accelerator to compensate for the surface area and the loading of silica, the perturbation of the cure system due to the 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. nature of the silica relative to carbon black is overcome, allowing a reduction in the level of silane required to achieve the desired balance of cure-related properties. For this natural rubber-based tread formulation, no highly significant effect of either silica loading or of level of silane on Mooney viscosity was found at the levels studied. Tan delta at 60 [degrees] C was significantly reduced by the replacement of carbon black with silica, regardless of accelerator level. The degree of improvement was a direct function of silica loading with all three silicas giving a similar rate of decline in tan delta at 60 [degrees] C. This would indicate that the replacement of carbon black with silica will lead to reduced rolling resistance in an all natural rubber based truck tread formulation. References (1.) M.P. Wagner, Rubber Chem. Technol. 49, 703 (1976). (2.) M.P. Wagner, Elastomerics 113 (8), 40 (1981). (3.) S. Wolff; Rubber Chem. Technol. 55, 967 (1982). (4.) L.A. Walker, Kautsch. Gummi Kunstst. 38, 494 (1985). (5.) W.H. Waddell and J.R. Parker, Rubber World 207, 29 (1992). (6.) T.A. Okel and W.H. Waddell, Rubber Chem. Technol. 67, 217 (1994). (7.) R.H. Hess Hess , Walter Rudolf 1881-1973. Swiss physiologist. He shared a 1949 Nobel Prize for his research on the brain's control of the body. , H.H. Hockje, J.R. Creasey and F. Strain (to PPG Industries PPG Industries (NYSE: PPG) was founded in 1883 as the Pittsburgh Plate Glass Company. PPG is an American manufacturer of glass and chemical products, including automotive safety glass. , Inc.), US 3,768,537 (1973). (8.) S. Ahmad Ahmad. For Ottoman sultans thus named, use Ahmed. and R.J. Schaefer Schäfer is German language word for shepherd. It is also a common surname, alternatively spelled Schaefer or Schaeffer (or anglicised to Shafer or Shaffer). (to B.F. Goodrich Goodrich is a surname, and may refer to:
(9.) S. Wolff, Tire Sci. Technol., 15, 276 (1987). (10.) R. Rauline (to Michelin), US 5,227,425 (1993). (11.) S. Wolff, paper no. 46 presented at a meeting of the Rubber Division, American Chemical Society The American Chemical Society (ACS) is a learned society (professional association) based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has over 160,000 members at all degree-levels and in , New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of , New York, April 8-11, 1986. (12.) J.H. Bachmann, J.W. Sellers, M.P. Wagner and R.F. Wolff; Rubber Chem. Technol. 32, 1286 (1959). (13.) S. Wolff, K. Burmester and E.-H. Tan, Kautsch. Gummi Kunstst. 29, 691 (1976). (14.) 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. (15.) J.T. Byers, Tire Technol. Int. '93, 58 (1993). (16.) Ph. Cochet, P. Barruel, L. Barriquand, J. Grobert, Y. Bomal and E. Prat, paper No. 162, presented at a meeting of the Rubber Division of the American Chemical Society, Orlando, Florida The city of Orlando is a major city in central Florida and is the county seat of Orange County, Florida. According to the 2000 census, the city population was 185,951. A 2006 U.S. , October 26-29, 1993. (17.) M. Ohashi and T. Kusano (to Bridgestone), EP 0 608 892 A1 (1994). (18.) P.H. Sandstrom, T.J. Segatta and J.D. Massle, II (to Goodyear Tire and Rubber Co.), EP 0 538 723 Al (1993). (19.) S. Misono (to Tokai Carbon), US 5,225,475 (1991). (20.) J.M. Branan, Jr. and C.H. Shieh (to Cabot Carbon), US 5,124,396 (1990). (21.) E. Minekl and H. Takahashi (to Bridgestone), EP 0 209 125 A2 (1987). (22.) R.K. Iler, "The chemistry of silica," John Wiley John Wiley may refer to:
(23.) 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., JMP User's Guide, Version 3.1, Cary, NC (1 995). |
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