TiBTM: Some further applications of this unique retarder/kicker.Recently we reported (ref. 1) the use of N,N,N',N'-tetraisobutylthiuram disulfide di·sul·fide n. A chemical compound containing two sulfur atoms combined with other elements or radicals. Also called bisulfide. (TiBTD) as a low nitrosamine ni·tros·a·mine n. Any of a class of organic compounds present in various foods and other products and found to be carcinogenic and mutagenic in laboratory animals. generating kicker Kicker A right, warrant, or some other feature added to a debt instrument to make it more desirable to potential investors. Notes: The ability to trade a bond or other debt instrument in for stock may entice investors, if they feel the stock will appreciate. for sulfenamides. When used as a kicker for benzothiazole Benzothiazole is a colorless, slightly viscous liquid with a melting point of 2 °C, and a boiling point of 227-228 °C. The density of benzothiazole is 1.238 g/ml (25 °C). It is a heterocyclic organic compound. Benzothiazole has no household use. It is used in industry and research. sulfenamides, this thiuram had better scorch safety than, but cured at the same rate as, TMTD TMTD tetramethylthiuram disulfide. in similar recipes Recipes by category Albanian cuisine
n a chemical added to a substance to slow a chemical reaction, prolong the set of the material, and provide more working time. as well as a kicker for 2-benzothiazole sulfenamides in SBR/BR. In subsequent work (ref. 2), we then demonstrated the efficacy efficacy /ef·fi·ca·cy/ (ef´i-kah-se) 1. the ability of an intervention to produce the desired beneficial effect in expert hands and under ideal circumstances. 2. of low levels of TiBTM as a kicker/retarder for benzothiazole sulfenamides in SBR/BR and NR and how it compares to a prevulcanization inhibitor inhibitor /in·hib·i·tor/ (in-hib´i-tor) 1. any substance that interferes with a chemical reaction, growth, or other biologic activity. 2. (CTP CTP (cytidine triphosphate): see cytosine. (1) (Computer-To-Plate) The production of printing plates directly from the computer without requiring film as an intermediate step. ), with and without a kicker present. Generally, a kicker or secondary 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. increases the cure rate of a primary accelerator but at the same time shortens the scorch time (ref. 3), sometimes an undesirable side effect. Conversely con·verse 1 intr.v. con·versed, con·vers·ing, con·vers·es 1. To engage in a spoken exchange of thoughts, ideas, or feelings; talk. See Synonyms at speak. 2. , a cure retarder will increase the scorch delay but can slow the cure rate of the primary accelerator (ref. 4). A single molecule molecule (mŏl`əky  l) [New Lat.,=little mass], smallest particle of a compound that has all the chemical properties of that compound. possessing the
characteristics of increasing scorch safety while increasing the cure
rate when used with a primary accelerator is certainly unique and
deserves further attention for potential exploitation ExploitationSee also Opportunism. Barnum, P. T. (1810–1891) circus impressario famous for his saying, “Never give a sucker an even break.” [Am. Hist. . Model reaction studies of the interactions of benzothiazole sulfenamides with TiBTD or TiBTM showed that two new chemical species form and that their ratios vary depending upon whether the disulfide or monosulfide is used (ref. 5). These ratios and the importance of the alkyl groups alkyl group (ăl`kĭl), in chemistry, group of carbon and hydrogen atoms derived from an alkane molecule by removing one hydrogen atom (see radical). , i.e., isobutyl, as shown by model compound evaluations, were used to explain how this unique behavior of TiBTM acting as both a retarder and kicker can occur. A compound of this uniqueness needs to be further evaluated to understand its advantages and limitations in vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. when used with benzothiazole sulfenamides vs. recipes with sulfenamide alone under differing use conditions This work will address some of these issues. Experimental Rubber compounds The SBR/BR masterbatch, weight 214.0, used in this study contains OE-SBR, Ameripol 1712, 55; SBR SBR - Spectral Band Replication , Ameripol 1500, 25; Taktene 1203 (95% cis- cis- a prefix denoting on this side, the same side, or the near side. cis- pref. Having a pair of identical atoms or groups on the same side of a plane that passes through two carbon atoms linked by a double bond: 1,4-polybutadiene, solution polymerized), 35; zinc oxide zinc oxide, chemical compound, ZnO, that is nearly insoluble in water but soluble in acids or alkalies. It occurs as white hexagonal crystals or a white powder commonly known as zinc white. , 3; stearic acid stearic acid /ste·a·ric ac·id/ (ste-ar´ik) a saturated 18-carbon fatty acid occurring in most fats and oils, particularly of tropical plants and land animals; used pharmaceutically as a tablet and capsule lubricant and as an emulsifying , 2; N234 carbon black, 70; Sundex 8125, 20; antioxidant antioxidant, substance that prevents or slows the breakdown of another substance by oxygen. Synthetic and natural antioxidants are used to slow the deterioration of gasoline and rubber, and such antioxidants as vitamin C (ascorbic acid), butylated hydroxytoluene , Agerite Resin D, 2; antiozonant, Antozite 67F, 2. The SBR masterbatches containing 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. were made by replacing the corresponding amounts of carbon black with HiSi1233 from 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. . The natural rubber masterbatch, weight 159.0, used in this study contains SIR natural rubber, 100; N234 carbon black, 45; Sundex 790 oil, 6.0; zinc oxide, 5.0; stearic acid, 2.0; Agerite Resin D, 1.0. The NR masterbatches containing silica were made by replacing the corresponding amounts of carbon black with HiSi1233. These ingredients were combined in a BR 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. , and a masterbatch was obtained by combining a number of batches on a mill. The curatives were added on the mill. ASTM ASTM abbr. American Society for Testing and Materials procedures D 1600, D 1625 and D 2100 were used for determining the cure and vulcanizate properties. TiBTM is supplied as Cure-rite IBM (International Business Machines Corporation, Armonk, NY, www.ibm.com) The world's largest computer company. IBM's product lines include the S/390 mainframes (zSeries), AS/400 midrange business systems (iSeries), RS/6000 workstations and servers (pSeries), Intel-based servers (xSeries) by BFGoodrich Co. Results and discussion Temperature effects - SBR/BR rubber Our previous report demonstrated the usefulness of using TiBTM with benzothiazole sulfenamides as a retarder/kicker in SBR/BR and NR at one vulcanization temperature. Processing and vulcanizate properties can change by changing curing temperatures. In this current work, four different temperatures were used for vulcanization in each of the rubber substrates. Table 1 shows vulcanization data for TBBS/ TiBTM and CBS/TiBTM combinations in SBR at 150, 160, 170 and 180 [degrees] C. Figure 1 schematically sche·mat·ic adj. Of, relating to, or in the form of a scheme or diagram. n. A structural or procedural diagram, especially of an electrical or mechanical system. shows a comparison of the percent changes in the cure rates as a function of only changes in temperature, additives, and both temperature and additive additive In foods, any of various chemical substances added to produce desirable effects. Additives include such substances as artificial or natural colourings and flavourings; stabilizers, emulsifiers, and thickeners; preservatives and humectants (moisture-retainers); and . The percent cure rate enhancements observed ob·serve v. ob·served, ob·serv·ing, ob·serves v.tr. 1. To be or become aware of, especially through careful and directed attention; notice. 2. in using the sulfenamide alone compared to the combination of sulfenamide/TiBTM are about equal at all four temperatures, i.e., about 20-25% with TBBS TBBS The Bread Board System TBBS The Big Blue Sky (website) and about 15% with CBS (Cell Broadcast Service) See cell broadcast. . The cure rate enhancement seen in raising a given temperature 10 [degrees] C is about the same with the sulfenamide alone as with the sulfenamide/TiBTM combination and these increases become smaller as the temperatures become greater. In circumstances CIRCUMSTANCES, evidence. The particulars which accompany a fact. 2. The facts proved are either possible or impossible, ordinary and probable, or extraordinary and improbable, recent or ancient; they may have happened near us, or afar off; they are public or where a compounder would prefer to increase the cure rate without substantially increasing the temperature of vulcanization so as to avoid the detrimental det·ri·men·tal adj. Causing damage or harm; injurious. det  ri·men effects of the increase, a plot of temperature
vs. cure rates could be used to predict a lower use temperature for a
sulfenamide/TiBTM combination that would give the same cure rate.[Figure 1 ILLUSTRATION OMITTED]
Table 1 - effect of temperature on TBBS/CBS/TiBTM cure in SBR/BR
Ingredients Recipes
1 2
SBR/BR masterbatch 214.00 214.00
TBBS 1.30 1.00
CBS
TiBTM 0.23
Sulfur 1.80 1.82
Total 217.10 217.05
SBR cure and vulcanizate
properties Monsanto rheometer,
1 [degree] arc, 150 [degrees] C
Mh-MI, Nxm 3.1 3.2
Scorch time (t2), min. 8.3 8.8
Cure time (t90), min. 17.8 16.7
Cure time (t95), min. 20.8 19.5
Cure rate index 9.1 11.1
Mooney scorch, ML at
130 [degrees] C
t5, min. 22.6 24.2
t35, min. 26.2 27.6
Cure index 3.6 3.4
Stress-strain, opt. Cure
(t95) at 150 [degrees] C
Tensile strength, MPa 21.3 22.0
Elongation, % 557 558
300% modulus, MPa 9.7 10.3
Monsanto rheometer,
1 [degree] arc, 150 [degrees] C
Mh-MI, Nxm 2.9 3.0
Scorch time (t2), min. 5.1 5.4
Cure time (t90), min. 10.9 10.0
Cure time (t95), min. 12.6 11.4
Cure rate index 15.2 19.4
Mooney scorch, ML at 138 [degrees] C
t5, min. 13.5 14.8
t35, min. 16.1 17.1
Cure index 2.6 2.3
Stress-strain, opt. cure 1 2
(t95) a t 160 [degrees] C
Tensile strength, MPa 21.3 22.1
Elongation, % 579 586
300% Modulus, MPa 9.0 9.4
Monsanto rheometer,
1 [degree] arc, 170 [degrees] C
Mh-MI, Nxm 2.8 2.8
Scorch time (t2), min. 3.3 3.5
Cure time (t90), min. 6.6 6.3
Cure time (t95), min. 7.5 7
Cure rate index 26.3 31.3
Mooney scorch, ML at
147 [degrees] C
t5, min. 7.7 8.5
t35, min. 9.3 9.9
Cure index 1.6 1.4
Stress-strain, opt. Cure
(t95) at 170 [degrees] C
Tensile strength, MPa 21.4 20.8
Elongation, % 606 572
300% modulus, MPa 8.5 9
Monsanto rheometer,
1 [degree] arc, 180 [degrees] C
Mh-MI, Nxm 2.6 2.6
Scorch time (t2), min. 2.2 2.4
Cure time (t90), min. 4.3 4.1
Cure time (t95), min. 4.7 4.5
Cure rate index 41.3 49.7
Mooney scorch, ML at
155 [degrees] C
t5, min. 5.2 5.7
t35, min. 6.5 6.8
Cure index 1.3 1.1
Stress-strain, opt. cure
(t95) at 180 [degrees] C
Tensile strength, MPa 19.7 19.7
Elongation, % 619 586
300% modulus, MPa 7.2 8.1
Ingredients Recipes
3 4
SBR/BR masterbatch 214.00 214.00
TBBS
CBS 1.44 1.15
TiBTM 0.23
Sulfur 1.80 1.82
Total 217.24 217.20
SBR cure and vulcanizate
properties Monsanto rheometer,
1 [degree] arc, 150 [degrees] C
Mh-MI, Nxm 3.0 3.1
Scorch time (t2), min. 7.5 8.2
Cure time (t90), min. 16.2 15.5
Cure time (t95), min. 19.0 18.2
Cure rate index 10.3 12.0
Mooney scorch, ML at
130 [degrees] C
t5, min. 20.4 22.5
t35, min. 23.2 25.5
Cure index 2.8 3.0
Stress-strain, opt. Cure
(t95) at 150 [degrees] C
Tensile strength, MPa 22.1 21.7
Elongation, % 591 545
300% modulus, MPa 9.3 10.1
Monsanto rheometer,
1 [degree] arc, 150 [degrees] C
Mh-MI, Nxm 2.9 2.9
Scorch time (t2), min. 4.8 5.2
Cure time (t90), min. 9.7 9.3
Cure time (t95), min. 11.3 10.6
Cure rate index 18.2 21.3
Mooney scorch, ML at 138 [degrees] C
t5, min. 12.6 13.8
t35, min. 14.4 15.7
Cure index 1.8 1.9
Stress-strain, opt. cure 3 4
(t95) a t 160 [degrees] C
Tensile strength, MPa 20.4 22.6
Elongation, % 571 605
300% Modulus, MPa 8.7 9.2
Monsanto rheometer,
1 [degree] arc, 170 [degrees] C
Mh-MI, Nxm 2.7 2.8
Scorch time (t2), min. 3.2 3.2
Cure time (t90), min. 6.1 5.8
Cure time (t95), min. 6.8 6.5
Cure rate index 31.0 34.5
Mooney scorch, ML at
147 [degrees] C
t5, min. 7.3 7.9
t35, min. 8.5 9.1
Cure index 1.2 1.2
Stress-strain, opt. Cure
(t95) at 170 [degrees] C
Tensile strength, MPa 20.4 21.0
Elongation, % 585 585
300% modulus, MPa 8.2 8.7
Monsanto rheometer,
1 [degree] arc, 180 [degrees] C
Mh-MI, Nxm 2.5 2.6
Scorch time (t2), min. 2.2 2.3
Cure time (t90), min. 4.0 3.9
Cure time (t95), min. 4.4 4.3
Cure rate index 47.8 54.0
Mooney scorch, ML at
155 [degrees] C
t5, min. 5.2 5.6
t35, min. 6.2 6.5
Cure index 1 0.9
Stress-strain, opt. cure
(t95) at 180 [degrees] C
Tensile strength, MPa 19.4 18.10
Elongation, % 614 583
300% modulus, MPa 6.9 6.9
The 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 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 300% modulus See modulo. with the sulfenamide/TiBTM combinations tend to parallel those with the corresponding sulfenamide alone, although the values tend to run slightly greater overall with the TiBTM combinations. Thus, the use of TiBTM with the sulfenamides does not contribute to any detrimental effects with tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. and modulus. Natural rubber The vulcanization data for sulfenamide and sulfenamide/TiBTM recipes at four different temperatures are shown in table 2. The cure rates vs. temperature are schematically shown in figure 2. Again, similar cure rate changes are occurring in all the recipes in natural rubber. The major difference in NR vs. SBR/BR is that the rate enhancement at any temperature in NR in changing from the sulfenamide to the sulfenamide/TiBTM combination is comparable in size to making a 10 [degrees] C increase in temperature for the sulfenamide alone. The effect is more marked with TBBS than with CBS combinations with TiBTM. A compounder could thus achieve a rate enhancement comparable to a 10 [degrees] C rise in vulcanization temperature using TiBTM without having to contend with the detrimental effects of the increased temperature. As higher temperatures are used, however, the rate enhancement lessens at any given temperature in changing from sulfenamide to sulfenamide/TiBTM and this becomes more pronounced with CBS than with TBBS. [Figure 2 ILLUSTRATION OMITTED]
Table 2 - effect of temperature on TBBS/CBS/TiBTM cure in NR
Ingredients Recipes
1 2
NR masterbatch 159.00 159.00
TBBS 1.00 0.80
TiBTM 0.18
CBS
Sulfur 2.00 2.02
Total 162.00 162.00
NR cure and vulcanizate properties
Monsanto rheometer, 1 [degrees]
arc, 140 [degrees] C
Mh-MI, Nxm 3.8 3.8
Scorch time (t2), min. 9.8 10.7
Cure time (t90), min. 19.0 15.6
Cure time (t95), min. 21.3 16.6
Cure rate index 9.6 17.9
Reversion (%) 3.6 2.4
Mooney scorch, ML at 121 [degrees] C
t5, min. 31.3 32.8
t35, min. 35.2 35.0
Cure index 3.8 2.2
Stress-strain, opt. cure (t95)
at 140 [degrees] C
Tensile strength, MPa 29.8 30.6
Elongation, % 504 520
300% modulus, MPa 15.5 15.5
Monsanto rheometer, 1 [degrees]
arc, 150 [degrees] C
Mh-MI, Nxm 3.7 3.7
Scorch time (t2), min. 5.7 5.9
Cure time (t90), min. 11 8.8
Cure time (t95), min. 12.3 9.4
Cure rate index 17 29
Reversion (%) 4 4
Mooney scorch, ML at 130 [degrees] C
t5, min. 14.3 16.7
t35, min. 16.7 18.0
Cure index 2.3 1.3
Stress-strain, opt. cure 1 2
(t95) a t 150 [degrees] C
Tensile strength, MPa 30.6 30.3
Elongation, % 526 535
300% Modulus, MPa 14.9 14.4
Monsanto rheometer, 1 [degrees]
arc, 160 [degrees] C
Mh-MI, Nxm 3.6 3.6
Scorch time (t2), min. 3.4 3.8
Cure time (t90), min. 6.4 5.5
Cure time (95), min. 7.0 5.8
Cure rate index 30 48.3
Revision (%) 14 9
Mooney scorch, ML at 139 [degrees] C
t5, min. 8 8.9
t35, min. 9.3 9.7
Cure index 1.3 0.8
Stress-strain, opt. cure (t95)
at 160 [degrees] C
Tensile strength, MPa 29.7 28.3
Elongation, % 546 532
300% modulus, MPa 13.3 13.0
Monsanto rheometer, 1 [degrees]
arc, 170 [degrees] C
Mh-MI, Nxm 3.4 3.5
Scorch time (t2), min. 2.3 2.3
Cure time (t90), min. 3.9 3.4
Cure time (t95), min. 4.3 3.5
Cure rate index 52.1 80.6
Reversion (%) 23 16
Mooney scorch, ML at 149 [degrees] C
t5, min. 5.1 5.8
t35, min. 6.1 6.5
Cure index 1 0.8
Stress-strain, opt cure (t95)
at 170 [degrees] C
Tensile strength, MPa 28.8 28.5
Elongation, % 556 551
300% modulus, MPa 12.3 12.3
Recipes
Ingredients
3 4
NR masterbatch 159.00 159.00
TBBS
TiBTM 0.18
CBS 1.11 0.89
Sulfur 2.00 2.02
Total 162.11 162.09
NR cure and vulcanizate properties
Monsanto rheometer, 1 [degrees]
arc, 140 [degrees] C
Mh-MI, Nxm 3.7 3.8
Scorch time (t2), min. 8.6 9.8
Cure time (t90), min. 16.1 14.2
Cure time (t95), min. 18.3 15.3
Cure rate index 12.2 20.0
Reversion (%) 5.5 3.6
Mooney scorch, ML at 121 [degrees] C
t5, min. 25.8 29.7
t35, min. 27.8 31.5
Cure index 2.0 1.8
Stress-strain, opt. cure (t95)
at 140 [degrees] C
Tensile strength, MPa 31.7 30.4
Elongation, % 560 518
300% modulus, MPa 14.7 15.5
Monsanto rheometer, 1 [degrees]
arc, 150 [degrees] C
Mh-MI, Nxm 3.7 3.7
Scorch time (t2), min. 5 5.4
Cure time (t90), min. 9 8
Cure time (t95), min. 10.2 8.4
Cure rate index 23 35
Reversion (%) 6 6
Mooney scorch, ML at 130 [degrees] C
t5, min. 13 15.1
t35, min. 14.3 16.1
Cure index 1.3 1
Stress-strain, opt. cure 3 4
(t95) at 150 [degrees] C
Tensile strength, MPa 31.1 30.2
Elongation, % 548 537
300% Modulus, MPa 14.4 14.4
Monsanto rheometer, 1 [degrees]
arc, 160 [degrees] C
Mh-MI, Nxm 3.6 3.6
Scorch time (t2), min. 3.2 3.5
Cure time (t90), min. 5.6 5
Cure time (95), min. 6.2 5.3
Cure rate index 37.5 56.8
Revision (%) 14 14
Mooney scorch, ML at 139 [degrees] C
t5, min. 7.4 8.5
t35, min. 8.3 9
Cure index 0.8 0.5
Stress-strain, opt. cure (t95)
at 160 [degrees] C
Tensile strength, MPa 29.4 29.5
Elongation, % 533 551
300% modulus, MPa 13.6 13.0
Monsanto rheometer, 1 [degrees]
arc, 170 [degrees] C
Mh-MI, Nxm 3.4 3.5
Scorch time (t2), min. 2.2 2.4
Cure time (t90), min. 3.6 3.4
Cure time (t95), min. 3.9 3.5
Cure rate index 63.7 81.3
Reversion (%) 26 19
Mooney scorch, ML at 149 [degrees] C
t5, min. 4.8 5.3
t35, min. 5.5 5.8
Cure index 0.8 0.4
Stress-strain, opt cure (t95)
at 170 [degrees] C
Tensile strength, MPa 29.2 28.4
Elongation, % 555 551
300% modulus, MPa 12.6 12.2
The Mooney scorch data in NR, as in SBR/BR, all fairly well parallel each other, indicating that the changes in any one series are comparable in magnitude magnitude, in astronomy, measure of the brightness of a star or other celestial object. The stars cataloged by Ptolemy (2d cent. A.D.), all visible with the unaided eye, were ranked on a brightness scale such that the brightest stars were of 1st magnitude and the with those in another corresponding series. The loss in scorch safety in going to a higher temperature in any one series is greater in NR compared to a similar series in SBR/BR. The percent improvement in scorch safety at any given temperature in going from the sulfenamide to the sulfenamide/TiBTM is comparable in both rubbers. The tensile and modulus data generally trend the same within experimental error for all the recipes and no surprises should occur when TiBTM is used with the sulfenamides. It is well known that reversion reversion: see atavism. in natural rubber becomes more pronounced at higher vulcanization temperatures. Percent reversion is shown in table 2. Sulfenamide/ TiBTM recipes show better reversion resistance than those corresponding recipes using straight sulfenamide. In independent examinations, this trend was just the opposite when TMTM TMTM The Muppets Take Manhattan (movie) TMTM The More, the Merrier was used in place of TiBTM. Sulfur sulfur or sulphur (sŭl`fər), nonmetallic chemical element; symbol S; at. no. 16; at. wt. 32.06; m.p. 112.8°C; (rhombic), 119.0°C; (monoclinic), about 120°C; (amorphous); b.p. 444.674°C;; sp. gr. at 20°C;, 2. level effects The levels of sulfur in rubber recipes can have effects on the crosslink density and length of sulfur crosslinks Crosslinks is an evangelical Anglican missionary society, drawing its support mainly from parishes in the Church of England and Church of Ireland. It was known as the Bible Churchmen's Missionary Society (BCMS) until 1992 The Society's foundation . These factors would manifest manifest 1) adj., adv. completely obvious or evident. 2) n. a written list of goods in a shipment. MANIFEST, com. law. A written instrument containing a true account of the cargo of a ship or commercial vessel. 2. themselves in tensile and modulus of the vulcanizates. Data were obtained with recipes at three different sulfur levels (1.80, 2.00 and 2.20 parts) at 160 and 180 [degrees] C in SBR/BR with TBBS and TBBS/TiBTM as accelerators. There appears to be little differences in trends in tensile and modulus when comparing TBBS to TBBS/TiBTM cures at a given temperature. Silica effects Recent trends have been to replace some carbon black by silica (ref. 6) to improve various properties of the vulcanizate, e.g., 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. and tear strength. Silica has the effect of deactivating the accelerator system and thus slowing the cure rate. Higher levels of accelerator must be used to recover that loss in cure rate. Since TiBTM is used in such low levels with benzothiazole sulfenamides, it is possible that the TiBTM could be totally deactivated to the extent that no cure rate enhancement or scorch safety would be observed compared to straight sulfenamide. Table 3 shows curing data for recipes in which various amounts of carbon black have been replaced by corresponding amounts of silica in SBR/BR for TBBS and TBBS/TiBTM cured systems. One can see that the cure rates decrease as more and more silica is used in place of carbon black, as expected. But it is noteworthy that TiBTM does not lose its ability to enhance the cure rate of TBBS relative to straight TBBS recipes. While there is a two minute absolute difference in cure rates for the two vulcanization systems at each silica level, the percent enhancement of the cure rate increases at higher levels of silica. This suggests that TiBTM is not deactivated by the silica as is TBBS. The Mooney scorch data reflects the ability of TiBTM to enhance scorch safety for sulfenamide recipes even in the presence of silica. The trend to longer scorch safety at higher silica levels probably just reflects the trend of slower cure rates due to deactivated TBBS. Table 3 - effect of HiSiL on cure characteristics of TBBS/TiBTM in SBR/BR Ingredients 1 2 3 4 SBR/BR masterbatch 0 parts HiSil 214.00 214.00 14 parts HiSil 214.00 214.00 21 parts HiSil 28 parts HiSil TBBS 1.30 1.00 1.30 1.00 TiBTM 0.23 0.23 Sulfur 2.00 2.04 2.00 2.04 Total 217.30 217.27 217.30 217.27 SBR cure and vulcanizate properties Monsanto rheometer, 1 [degrees] arc, 160 [degrees] C Mh-MI, Nxm 3.1 3.2 2.7 2.8 Scorch time (t2), min. 5.8 6.6 5.6 6.2 Cure time (t90), min. 11.7 11.7 13.4 12.7 Cure time (t95), min. 13.5 13.3 15.5 14.6 Cure rate index 14.5 16.5 11.5 13.8 Mooney scorch, ML at 138 [degrees] C t5, min. 16.2 17.8 15.1 17.5 t35, min. 19.3 20.3 18.8 20.8 Cure index 3.2 2.5 3.7 3.3 Ingredients 5 6 7 8 SBR/BR masterbatch 0 parts HiSil 14 parts HiSil 21 parts HiSil 214.00 214.00 28 parts HiSil 214.00 214.00 TBBS 1.30 1.00 1.30 1.00 TiBTM 0.23 0.23 Sulfur 2.00 2.04 2.00 2.04 Total 217.30 217.27 217.30 217.27 SBR cure and vulcanizate properties Monsanto rheometer, 1 [degrees] arc, 160 [degrees] C Mh-MI, Nxm 2.5 2.6 2.2 2.4 Scorch time (t2), min. 6.0 6.6 6.5 6.9 Cure time (t90), min. 15.1 14.1 18.0 15.8 Cure time (t95), min. 17.5 16.3 20.9 18.3 Cure rate index 10.0 12.0 8.0 10.2 Mooney scorch, ML at 138 [degrees] C t5, min. 15.3 18.5 15.8 19.2 t35, min. 19.8 22.2 21.3 23.6 Cure index 4.4 3.7 5.4 4.4 The cure rates and Mooney scorch were also examined in NR recipes with some carbon black being replaced with silica. Similar trends in cure rates and scorch were seen in NR compared to SBR/BR, except that the magnitudes were different. Conclusions Increases in cure temperature, various levels of sulfur and the presence of silica do not affect the ability of TiBTM to enhance the cure rates and scorch times of sulfenamide accelerators in SBR or NR. Trends in the physical properties of the vulcanizates parallel those that occur in straight sulfenamide cured systems under the above influences. However, TiBTM does improve reversion resistance compared to NR recipes without it. Acknowledgements "High temperature curing and high heat resistance compounding" is based on a paper given at the May, 1997 meeting of the Rubber Division. "Novel processing agents for silica-filled rubber" is based on a paper given at the May, 1997 meeting of the Rubber Division. "TiBTM: Some further applications of this unique retarder/kicker" is based on a paper given at the October October: see month. , 1997 meeting of the Rubber Division. References (1.) R.W. Layer and D.W. Chasar, Rubber Chem. Technol., 67, 299 (1994). (2.) D.W. Chasar, Rubber World, 214 (5), 25 (1996). (3.) M.A. Fath fath or fath. abbr. fathom , Rubber World, 209 (1), 22 (1993). (4.) M.A. Fath, Rubber World, 209 (3), 17(1993). (5.) D.W. Chasar, Rubber Chem. Technol., 70, 634 (1997). (6.) W.H. Waddell Waddell is a common surname and may refer to:
American anatomist who isolated four pituitary hormones and discovered vitamin E (1922). , Rubber Chem. Technol., 69, 377 (1996). |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion