Xanthate accelerators in vulcanizing isobutylene-based elastomers.Isobutylene-based elastomers include butyl rubber butyl rubber: see rubber. and halogenated halogenated pertaining to a substance to which a halogen is added. halogenated salicylanilides see rafoxanide, clioxanide. butyl rubber, and their respective star-branched versions. Due to their impermeability im·per·me·a·ble adj. Impossible to permeate: an impermeable membrane; an impermeable border. im·per and resistance to heat and oxidation oxidation /ox·i·da·tion/ (ok?si-da´shun) the act of oxidizing or state of being oxidized.ox·idative ox·i·da·tion n. 1. The combination of a substance with oxygen. 2. , these polymers find application in tire innerliners and innertubes, curing bladders and envelopes, and other applications where air retention and resistance to heat and oxidation are desired. Butyl rubbers are produced via a cationic cationic having qualities dependent on having free cations available. cationic detergents are wetting agents that disrupt or damage cell membranes, denature proteins and inactivate enzymes. polymerization polymerization Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same. in methyl chloride methyl chloride n. An explosive gas, CH3Cl, used in organic synthesis and polymerization, as a refrigerant, and an anesthetic. at temperatures between -90[degrees]C and -100[degrees]C. These unique attributes and difficult manufacturing requirements place butyl rubbers in the special purpose elastomers category, distinct from general-purpose gen·er·al-pur·pose adj. Designed for or suitable to more than one use; broadly useful: a general-purpose loan. general-purpose Adjective rubbers such as polybutadiene Polybutadiene is a synthetic rubber that has a high resistance to wear and is used especially in the manufacture of tires. It has also been used to coat or encapsulate electronic assemblies, offering extremely high electrical resistivity. (BR), natural rubber (NR) and styrene-butadiene rubbers (SBR SBR - Spectral Band Replication ) (ref. 1). The 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. of butyl butyl /bu·tyl/ (bu´t'l) a hydrocarbon radical, C4H9. bu·tyl n. A hydrocarbon radical, C4H9. butyl a hydrocarbon radical, C4H9. or isobutylene-co-isoprene rubber (IIR IIR - Infinite Impulse Response ), brominated isobutylene-co-isoprene rubber (BIIR BIIR Baylor Institute for Immunology Research (Dallas, Texas) BIIR Basic Imagery Interpretation Report BIIR Brominated Isobutylene-Isoprene Rubber ) and chlorinated chlorinated /chlo·ri·nat·ed/ (klor´i-nat?ed) treated or charged with chlorine. chlorinated charged with chlorine. chlorinated acids some, e.g. isobutylene-co-isoprene rubber (CIIR CIIR Catholic Institute for International Relations CIIR Center for Intelligent Information Retrieval CIIR counterintelligence information report (US DoD) CIIR Canadian International Information Resource ) differs from that of general-purpose rubbers. Butyl rubber has approximately 2% unsaturation un·sat·u·rat·ed adj. 1. Of or relating to an organic compound, especially a fatty acid, containing one or more double or triple bonds between the carbon atoms. 2. Capable of dissolving more of a solute at a given temperature. in the backbone. Halobutyl rubbers Halobutyl rubber is mainly used for tire inner liner compounds, because of its low air permeability. Bromobutyl is superior to Chlorobutyl, but is more expensive. The halogen radical permits the rubber to bond to the other elastomers in the carcass compound (BIIR and CIIR) incorporate a butyl backbone with either bromine bromine (brō`mēn, –mĭn) [Gr.,=stench], volatile, liquid chemical element; symbol Br; at. no. 35; at. wt. 79.904; m.p. –7.2°C;; b.p. 58.78°C;; sp. gr. of liquid 3.12 at 20°C;; density of vapor 7. or chlorine chlorine (klōr`ēn, klôr`–) [Gr.,=green], gaseous chemical element; symbol Cl; at. no. 17; at. wt. 35.453; m.p. −100.98°C;; b.p. −34.6°C;; density 3.2 grams per liter at STP; valence −1, +1, +3, +5, +7. , which increases the 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. of the isoprenyl units located in the butyl polymer backbone. Utilization of the unique attributes of butyl rubber and halobutyl rubber with their minimal backbone unsaturation can be found in many areas of industry. These properties offer excellent impermeation to gas and vapor vapor /va·por/ (va´por) pl. vapo´res, vapors [L.] 1. steam, gas, or exhalation. 2. an atmospheric dispersion of a substance that in its normal state is liquid or solid. , resistance to heat degradation DEGRADATION, punishment, ecclesiastical law. A censure by which a clergy man is deprived of his holy orders, which he had as a priest or deacon. , and improved chemical resistance as compared to general-purpose rubbers. However, this low amount of reactivity will require special consideration to vulcanize vul·ca·nize tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat the isobutylene-based elastomers. The selection of a vulcanization system type is a function of the mission profile for the final product, composite structure in which it may be used, and the product performance demands. Therefore, vulcanization systems may include organic accelerators along with resins resins, n.pl complex, insoluble, sticky substances secreted by plants. Used as astringents, antimicrobials, and antiinflammatories, and are burned as incense. Can cause oral ulcers and epidermal irritations. , 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. , zinc oxide and 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. , and quinoid quin·oid n. A substance resembling quinone in structure or physical properties. systems. This article will discuss xanthate xan·thate n. A salt of a xanthic acid, especially a simple xanthic acid salt, as of sodium or potassium, used as a flotation collector for copper, silver, and gold. Noun 1. accelerators in vulcanization systems for isobutylene-based elastomers. Composition of isobutylene Noun 1. isobutylene - used also in making gasoline components butene, butylene - any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers butyl - a hydrocarbon radical (C4H9) polymers Butyl rubber is the copolymer copolymer: see polymer. of isobutylene and a small amount of isoprene isoprene or 2-methyl-1,3-butadiene (ī`səprēn, by  'tədī`ēn), colorless liquid organic compound. , typically in the order of 2%. Figure 1 is a schematic A graphical representation of a system. It often refers to electronic circuits on a printed circuit board or in an integrated circuit (chip). See logic gate and HDL. of butyl
rubber.
[FIGURE 1 OMITTED] Chlorobutyl and bromobutyl rubbers are manufactured similar to butyl rubber, but with an added halogenation Halogenation A chemical reaction or process which results in the formation of a chemical bond between a halogen atom and another atom. Reactions resulting in the formation of halogen-carbon bonds are especially important. step. Due to the nearly equivalent reactivity ratios of the monomers and low concentration of isoprene, the isoprenyl units in these polymers are randomly distributed along the polymer chain. Figure 2 illustrates the isomers isomers (ī´sōmurz), n.pl 1. organic compounds having the same empirical formula–i.e. of the isoprenyl units found in bromobutyl rubber (ref. 1). The majority of the isoprenyl units is in the trans-configuration. [FIGURE 2 OMITTED] Structure II is the predominant pre·dom·i·nant adj. 1. Having greatest ascendancy, importance, influence, authority, or force. See Synonyms at dominant. 2. configuration (approximately 50%-60%). Structure I is typically around 30%-40%. Structure III is approximately 5%-15%. Structure IV is typically only 1%-3%. Vulcanization of isobutylene-based elastomers In butyl rubber, the hydrogen atoms positioned alpha ([alpha]) to the isoprenyl unit carbon-carbon double bond permits vulcanization with sulfur and organic accelerators. The low degree of unsaturation The degree of unsaturation (also known as the Index of Hydrogen Deficiency or IHD) formula is used in organic chemistry to help draw chemical structures. The formula lets the user determine how many rings, double bonds, and triple bonds are present in the compound to has traditionally required the use of ultra-accelerators, such as thiurams or thiocarbamates thiocarbamates herbicides (allate, diallate, ETPC) which are poisonous causing clinical signs including tremor, dyspnea, salivation, vomiting and bloat. . Phenolic resins Noun 1. phenolic resin - a thermosetting resin phenolic, phenoplast synthetic resin - a resin having a polymeric structure; especially a resin in the raw state; used chiefly in plastics and quinone quinone Any member of a class of cyclic organic compounds comprising a six-membered unsaturated ring (see saturation) to which two oxygen atoms are bonded as carbonyl groups (−C=O; see functional group). derivatives derivatives In finance, contracts whose value is derived from another asset, which can include stocks, bonds, currencies, interest rates, commodities, and related indexes. Purchasers of derivatives are essentially wagering on the future performance of that asset. can also be employed. Vulcanization introduces a chemical crosslink approximately every 250 carbon atoms Noun 1. carbon atom - an atom of carbon atom - (physics and chemistry) the smallest component of an element having the chemical properties of the element along the polymer chain. Polysulfidic crosslinks have limited stability at elevated temperature, and in many instances can rearrange re·ar·range tr.v. re·ar·ranged, re·ar·rang·ing, re·ar·rang·es To change the arrangement of. re to form mono- mono- or mon- pref. 1. One; single; alone: monomorphic. 2. Monomolecular; monatomic: monolayer. 3. and disulfidic crosslinks. This rearrangement re·ar·range tr.v. re·ar·ranged, re·ar·rang·ing, re·ar·rang·es To change the arrangement of. re results in permanent set and reduction in creep for vulcanizates exposed to high temperatures for long periods of time. Resin cure systems such as alkyl alkyl /al·kyl/ (al´k'l) the monovalent radical formed when an aliphatic hydrocarbon loses one hydrogen atom. al·kyl n. phenol-formaldehyde derivatives can provide carbon-carbon crosslinks resulting in heat-stable vulcanizates (ref. 2). Halobutyl rubber can be crosslinked by the same curatives used for butyl rubber such as zinc oxide, bismaleimides, diamines, peroxides and dithiols. Halogens See Chlorine are good leaving groups A leaving group is an atom or group of atoms that detaches from a chemical substance. The remaining molecule or fragment remaining is known as the residual or main part. The term leaving group is dependent on the context of the statement. in nucleophilic substitution In organic and inorganic chemistry, nucleophilic substitution is a fundamental class of substitution reaction in which an "electron rich" nucleophile selectively bonds with or attacks the positive charge of a group or atom called the leaving group; rarely referred to as an reactions due to low carbon-halogen bond energies (table 1). When zinc oxide is used to crosslink halobutyl rubber, carbon-carbon bonds A carbon-carbon bond is a covalent bond between two carbon atoms. The most common form is the single bond – a bond composed of two electrons, one from each of the two atoms. are formed through dehydrohalogenation which result in a compound with a very stable crosslink system, good retention of aged properties and a low compression set. The primary difference in properties between chlorobutyl rubber and bromobutyl rubber is due to the higher reactivity of the C-Br bond compared to that of C-Cl bond. Bromine has the lowest bond energy and the longest bond length in the series (table 1). Bromobutyl rubber has faster cure rates and a shorter scorch or cure induction period induction period n. The interval between an initial injection of an antigen and the appearance of demonstrable antibodies in the blood. , requires lower levels of curatives, and in turn enables use of a wider range of accelerators than might be possible when curing chlorobutyl rubber. A broad range of accelerators can be found in formulations for isobutylene-based elastomers, including cyclohexyl-benzothiazole sulfenamide (CBS (Cell Broadcast Service) See cell broadcast. ), benzothiazole sulfide sulfide, chemical compound containing sulfur and one other element or sulfur and a radical. Sulfides may be salts or esters of hydrogen sulfide, H2S, or may be formed directly, e.g., by heating a metal with sulfur. (MBTS MBTS 2-Mercaptobenzothiazyl Disulfide MBTS Missile Bit Test Set MBTS Missile Bench Test Set ), tetramethyl thiuram disulfide Thiuram disulfides are a class of organic compounds that have the general structural formula shown to the right. (TMTD TMTD tetramethylthiuram disulfide. ), diphenyl diphenyl /di·phen·yl/ (di-fen´il) a toxic compound comprising two linked benzene rings, used as a fungistat in containers for shipping citrus fruits. di·phen·yl n. See biphenyl. guanidine guanidine /gua·ni·dine/ (gwah´ni-den) the compound NHdbondC(NH2)2, a strong base found in the urine as a result of protein metabolism and used in the laboratory as a protein denaturant. (DPG DPG diphosphoglycerate. ) and zinc zinc, metallic chemical element; symbol Zn; at. no. 30; at. wt. 65.38; m.p. 419.58°C;; b.p. 907°C;; sp. gr. 7.133 at 25°C;; valence +2. Zinc is a lustrous bluish-white metal. It is found in Group 12 of the periodic table. dimethyl di·meth·yl n. An organic compound, especially ethane, containing two methyl groups. dithiocarbamate (ZDMC). Effective use of new cure systems requires an understanding of the mechanism of vulcanization and how the materials in question participate in the reaction. This has been the subject of an earlier review (ref. 3). Vulcanization of butyl rubber has typically required the use of ultra-fast accelerators, such as thiurams and dithiocarbamates dithiocarbamates fungal seed dressing unlikely to be poisonous for animals. . Such accelerators are reported to generate secondary nitrosamines nitrosamines highly hepatotoxic compounds formed in the rumen by the combination of amines and nitrite. They do not appear to occur naturally in large quantities. Nitrosamine poisoning has also been caused by feeding nitrite-treated fishmeal and Solanum incanum. , which may be undesirable. One means to overcome this issue is through use of xanthate accelerators. Due to the absence of a nitrogen atom in the xanthate structure, such as in zinc diisopropylxanthate, nitrosamines cannot be formed during compound vulcanization. Furthermore, cure systems containing xanthates could enable vulcanization over a broader range of temperatures. In combination with MBTS, the use of xanthates may enable rapid vulcanization. This third in a series of studies on the vulcanization of isobutylene elastomers (refs. 3 and 4) will review the physical properties which can be obtained by use of such cure system accelerators when used in place of thiurams and dithiocarbamates. Experimental methods Table 2 illustrates a model butyl rubber formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation that was used for evaluating the xanthate accelerators. In table 3, a model bromobutyl rubber compound is illustrated that was also used for cure system evaluations. A comprehensive set of properties for these compounds, including fundamental mechanical properties and cure characteristics, may be found at: www.butylrubber.com. An MDR MDR, n See multidrug resistance. MDR, n the abbreviation for minimum daily requirement, specifically the Minimum Daily Requirements for Specific Nutrients compiled by the United States Food and Drug Administration. 2000 rheometer rhe·om·e·ter n. An instrument for measuring the flow of viscous liquids, such as blood. (Alpha Technologies) was used to determine compound cure kinetics kinetics: see dynamics. Kinetics (classical mechanics) That part of classical mechanics which deals with the relation between the motions of material bodies and the forces acting upon them. according to according to 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 D5289. The rheometer report gave the rate of vulcanization, which was calculated from the 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. of the curve at t50. A cure rate index was calculated from equation 1. This is a simple calculation, but readily permits a relative ranking of cure rates. C.R.I = 100 / ([t.sub.90] - [t.sub.10]) (1) In earlier work at 140[degrees]C, the rate of reaction was slow, most likely due to the low saturation saturation, of an organic compound saturation, of an organic compound, condition occurring when its molecules contain no double or triple bonds and thus cannot undergo addition reactions. of the butyl polymer when compared to general purpose elastomers. Thus, in order to obtain insight into the mechanism of vulcanization, an 'apparent' activation energy activation energy, in chemistry, minimum energy needed to cause a chemical reaction. A chemical reaction between two substances occurs only when an atom, ion, or molecule of one collides with an atom, ion, or molecule of the other. was calculated from the vulcanization kinetic kinetic /ki·net·ic/ (ki-net´ik) pertaining to or producing motion. ki·net·ic adj. Of, relating to, or produced by motion. kinetic pertaining to or producing motion. data generated at 160[degrees]C and 170[degrees]C or 180[degrees]C using the Arrhenius equation The Arrhenius equation is a simple, but remarkably accurate, formula for the temperature dependence of a chemical reaction rate, more correctly, of a rate coefficient, as this coefficient includes all magnitudes that affect reaction rate except for concentration. which is typically written as, k = [Ae.sup.-Ea/RT] (2) where k is the rate constant, A is a constant, Ea is the energy of activation Noun 1. energy of activation - the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur; "catalysts are said to reduce the energy of activation during the transition phase of a reaction" activation energy , R is the gas constant (cal [mole.sup.-1] [degree.sup.-1]), and T is the absolute temperature in [degrees]K. For determination of the apparent activation energy, this equation is rearranged to give, Ea = 4.576 [T.sub.2][T.sub.1] (log k" - log k') / ([T.sub.2] - [T.sub.1]) (3) Mooney viscosity and Mooney scorch values were determined as described in ASTM D1646. 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 tear strength values where measured according to ASTM D412 and D624, respectively. Test samples were vulcanized vul·ca·nize tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat at 160[degrees]C and compound cure times were set by adding two minutes to the rheometer [t.sub.90] cure time. Permeability permeability /per·me·a·bil·i·ty/ (per?me-ah-bil´i-te) the property or state of being permeable. per·me·a·bil·i·ty n. 1. The property or condition of being permeable. 2. was measured using a Mocon Ox-Tran Model 2/61 oxygen transmission rate test apparatus. There are six cells per instrument where gas transmission through each test sample in a cell is measured individually. A zero reading to establish a baseline The horizontal line to which the bottoms of lowercase characters (without descenders) are aligned. See typeface. baseline - released version and test samples is then measured at 40[degrees]C and 60[degrees]C. Oxygen transmission is measured with an [O.sub.2] detector detector: see particle detector. . Data are reported as a permeation per·me·a·tion n. The process of spreading through or penetrating, as in the extension of a malignant neoplasm by continuous proliferation of the cells along the blood or lymph vessels. 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. in [cc.sup.*]mm/ ([m.sup.2]-day) and permeability coefficient in [cc.sup.*]mm/ ([m.sup.2]-daymmHg). Permeability is then expressed as a rating relative to the control compound. The model compound illustrated in table 3 is assigned as·sign tr.v. as·signed, as·sign·ing, as·signs 1. To set apart for a particular purpose; designate: assigned a day for the inspection. 2. a rating of 100. This control compound has a nominal permeation coefficient at 40[degrees]C of 200 to 220 [cc.sup.*]mm/([m.sup.2]-day). Two Xanthate accelerators were studied in the model formulations shown in tables 2 and 3. Accelerators studied were zinc isopropyl isopropyl denotes the 1-methylethyl group, -CH(CH3)2. isopropyl alcohol rubbing alcohol, used as a solvent and rubefacient. Formed naturally in the rumen of the cow in nervous acetonemia. xanthate and isopropyl xanthate tetrasulfide. The structures of these two accelerators are shown in figure 3. [FIGURE 3 OMITTED] Results To investigate the performance of the two xanthate accelerators, a series of fundamental studies were conducted with both butyl and bromobutyl rubbers using the respective model formulations illustrated in tables 2 and 3. Screening of ZIX and [IXS (Integrated XSeries Server) An x86-based xSeries server (motherboard and memory) from IBM that plugs into an iSeries or i5 midrange computer. Running Windows or Linux, the IXS shares disk storage, server management, user administration with its iSeries/i5 host. .sub.4] in butyl rubber The two xanthate accelerators, [IXS.sub.4] and ZIX, were evaluated at 2.0 and 4.0 phr levels in a model butyl rubber compound in place of TMTD, as shown in the experimental layout in table 4. Rheometer and Mooney viscosity data are presented in table 5. Isopropylxanthate tetrasulfide ([ISX ISX InstallShield Express (Setup software) ISX Internet Service Exchange (Abovenet) ISX Insoluble Starch Xanthate ISX Information Superiority Experiments ISX Infrastructure ISX Incisive Software Extensions .sub.4]) and zinc diisopropylxanthate (ZIX) were evaluated in place of TMTD and MBTS in order to assess their reactivity in vulcanizing butyl rubber. These accelerators were also evaluated at 2.0 phr, along with 0.5 phr MBTS, in order to identify any benefits of using a binary Meaning two. The principle behind digital computers. All input to the computer is converted into binary numbers made up of the two digits 0 and 1 (bits). For example, when you press the "A" key on your keyboard, the keyboard circuit generates and transfers the number 01000001 to the 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. cure system. A number of points can be noted: * In comparison with the control compound (compound 1), addition of 2.0 phr of [ISX.sub.4] (compound 2) results in an increase in rheometer [t.sub.90] cure time and a decrease in cure state as measured by the rheometer delta torque. Cure rate is also slower due to the larger induction induction, in electricity and magnetism induction, in electricity and magnetism, common name for three distinct phenomena. Electromagnetic induction time and extended [t.sub.90] cure time. * Addition of 4.0 phr of [ISX.sub.4] (compound 3) results in a significant increase in Mooney scorch and a decrease in cure state (delta torque). * In combination with MBTS, use of 2.0 phr of [IXS.sub.4] in place of TMTD (compound 4) still results in an increase in Mooney scorch, [t.sub.90] cure time and delta torque values. Compound 4 has more desirable cure properties than does compound 2, indicating the benefits of using MBTS in combination with [IXS.sub.4]. * ZIX use at any level afforded a significant reduction in Mooney scorch and cure state (delta torque). Use of the higher 4.0 phr level of ZIX caused cure reversion reversion: see atavism. and a further drop in the cure state. Figure 4 illustrates the rheometer profiles for butyl rubber compounds when using these two accelerators, with and without MBTS. ZIX shows a faster cure rate (peak rate at [t.sub.50]). However, at the 4.0 phr level, reversion can be observed (compound 6). To explore this further, simple studies of the effect of varying both ZIX and MBTS were performed. [FIGURE 4 OMITTED] ZIX/MBTS study The levels of ZIX were assessed from initial screening work and formulations are presented in table 6. Data were imported into SAS (1) (SAS Institute Inc., Cary, NC, www.sas.com) A software company that specializes in data warehousing and decision support software based on the SAS System. Founded in 1976, SAS is one of the world's largest privately held software companies. See SAS System. 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 and regression analysis In statistics, a mathematical method of modeling the relationships among three or more variables. It is used to predict the value of one variable given the values of the others. For example, a model might estimate sales based on age and gender. performed using the simple relationship shown in equation 4. Dependent variable = a + b + [a.sup.2] + [b.sup.2] + ab + constant (4) This model allows identification of any potential interactions and by use of squared terms it is possible to describe response patterns of the dependent variables that may not be linear. Data are shown in table 6. Three-dimension contour contour or contour line, line on a topographic map connecting points of equal elevation above or below mean sea level. It is thus a kind of isopleth, or line of equal quantity. plots were constructed to enable identification and visualization Using the computer to convert data into picture form. The most basic visualization is that of turning transaction data and summary information into charts and graphs. Visualization is used in computer-aided design (CAD) to render screen images into 3D models that can be viewed from all of trends in compound cure properties (figure 5). A number of observations may be made: [FIGURE 5 OMITTED] * With the MBTS level fixed at 1 phr, increases in ZIX concentrations cause reductions in Mooney scorch [t.sub.5] and [t.sub.35] times. * Increases in cure state (delta torque, [DELTA]T) resulted from increases in both MBTS and ZIX levels. * An increase in the activation energy and decrease in cure rate results with increasing ZIX concentration; MBTS levels had relatively no effect upon these cure parameters. Screening of ZIX and [IXS.sub.4] in bromobutyl rubber The two xanthate accelerators, [ISX.sub.4] and ZIX, were evaluated at 2.0 phr and 4.0 phr in place of TMTD and MBTS accelerators in order to assess their reactivity in vulcanizing bromobutyl rubber (table 7). These accelerators were also evaluated at the 2.0 phr level, along with MBTS, to identify any benefits of using a binary accelerator cure system. A number of points were noted: * In comparison with the control compound (compound 17), addition of 2.0 phr of [IXS.sub.4] results in significant increases in Mooney scorch and rheometer [t.sub.90] cure time. * Addition of 4.0 phr of [IXS.sub.4] results in slight increases in Mooney scorch, and significant increases in rheometer [t.sub.90] cure time. * Cure rates were also slower, thought to be due to the large induction time and extended [t.sub.90] cure times. * Compounds with [IXS.sub.4] showed reversion. * Increases in cure state were observed based upon increases in rheometer delta torque values. * In combination with MBTS, use of 2.0 phr of [IXS.sub.4] (compound 20) has only slight changes compared to compound 18. * ZIX use resulted in very significant reductions in Mooney scorch values and large increases in rheometer [t.sub.90] cure times. * In combination with MBTS, ZIX use still results in decreased Mooney scorch values, increased [t.sub.90] cure times, and reduced cure states. Figure 6 illustrates the rheometer profiles for the bromobutyl rubber compounds using the two xanthate accelerators, with and without MBTS. Reversion associated with [ISX.sub.4] use (compounds 18, 19 and 20) is evident. [FIGURE 6 OMITTED] In a follow-up follow-up, n the process of monitoring the progress of a patient after a period of active treatment. follow-up subsequent. follow-up plan study, the two xanthate accelerators [IXS.sub.4] and ZIX were re-evaluated at 2.0 and 4.0 phr levels with 1.0 phr MBTS present in the model bromobutyl rubber compound (table 8). The data confirmed the earlier conclusions regarding the effects of the two xanthate accelerators. Figure 7 illustrates the rheometer profiles at 180[degrees]C for these two accelerators in the presence of 1.0 phr of MBTS. The reversion condition found with [ISX.sub.4] (compounds 25, 26 and 27) is evident. To explore this further, a simple factorial factorial For any whole number, the product of all the counting numbers up to and including itself. It is indicated with an exclamation point: 4! (read “four factorial”) is 1 × 2 × 3 × 4 = 24. design was constructed to explore the effect of varying both [IXS.sub.4] and MBTS. [FIGURE 7 OMITTED] Optimization optimization Field of applied mathematics whose principles and methods are used to solve quantitative problems in disciplines including physics, biology, engineering, and economics. of [IXS.sub.4] level in bromobutyl rubber A three-variable multiple regression Multiple regression The estimated relationship between a dependent variable and more than one explanatory variable. was constructed with MBTS, isopropylxanthate tetrasulfide ([IXS.sub.4]) and sulfur using the model bromobutyl rubber compound whose formulation is shown in table 3. The design was (the phr range from minimum, center point to maximum): MBTS - 0.50, 1.00 and 1.50; [IXS.sub.4] - 1.50, 3.00 and 4.50; and sulfur - 0.25, 0.625 and 1.00. Rheometer, Mooney scorch, tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. , tear strength and dynamic property data are shown in table 9. The tabulated compound data were imported to SAS JMP, and regression equations Regression equation An equation that describes the average relationship between a dependent variable and a set of explanatory variables. calculated using the relationship shown in equation 5: Dependent variable = aX + bY + cZ + d[X.sup.2] + e[Y.sup.2] + f[Z.sup.2] + gXY + hXZ + jYZ + constant (5) This quadratic quadratic, mathematical expression of the second degree in one or more unknowns (see polynomial). The general quadratic in one unknown has the form ax2+bx+c, where a, b, and c are constants and x is the variable. model allows identification of any potential interactions. By use of squared terms in such models, it is possible to describe response patterns of the dependent variables that may not be linear. Furthermore, this three-variable rotatable ro·tate v. ro·tat·ed, ro·tat·ing, ro·tates v.intr. 1. To turn around on an axis or center. 2. central composite design In statistics, a central composite design is an experimental design, useful in response surface methodology, for building a second order (quadratic) model for the response variable without needing to use a complete three-level factorial experiment. with star points (figure 8) requires a minimum of 15 compounds and is more efficient than performing a full factorial design, which may use up to 27 compounds (ref. 6). [FIGURE 8 OMITTED] Using SAS JMP, contour plots were constructed to illustrate the effect of changing the amounts of isopropylxanthate tetrasulfide, MBTS and sulfur on compound properties. Figure 9 is a series of graphs plotting MBTS and [IXS.sub.4]. Sulfur level has been fixed at the center point of the design (0.6 phr). From these graphs: [FIGURE 9 OMITTED] * Increasing [IXS.sub.4] and MBTS concentrations cause a reduction in rheometer [t.sub.90] cure time and an increase in cure rate. * MBTS had little effect on cure state (delta torque, [DELTA]T). * The computer fits predict a 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. dependence of cure properties on accelerators. Maintaining the MBTS level at 1.0 phr (figure 10) illustrates the effects of varying [IXS.sub.4] and sulfur: [FIGURE 10 OMITTED] * Increasing the [IXS.sub.4] level results in a reduction in 300% modulus See modulo. and tear strength values. * Cure state (delta torque) decreases with increasing [IXS.sub.4] levels, whereas sulfur has little effect. * Rheometer [t.sub.90] cure time decreases and cure rate increases with increasing [IXS.sub.4]. * The computer fits predict a nonlinear dependence of cure and physical properties on [IXS.sub.4] and sulfur levels. There was very little effect on oxygen permeability Oxygen permeability, abbreviated Dk, is a parameter of a contact lens. Another parameter, the transmissibility level, abbreviated DK/t; the Dk per thickness of the lens, is generally more used. Typical values are from 25 to 50. or compound hardness values (table 9). At the fixed [IXS.sub.4] level of 3.0 phr, MBTS was plotted versus sulfur (figure 11): [FIGURE 11 OMITTED] * Increasing MBTS levels result in a decrease in 300% modulus, but little effect upon compound tear strength. * Rheometer [t.sub.90] cure time decreases and cure rate increases with added MBTS levels. * As in the case with [IXS.sub.4], the fits predict a non-linear dependence upon 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. ingredients. With MBTS-accelerated sulfur vulcanization, a sulfurating agent is formed which is the species that creates crosslinks in the compound. On this basis, it is reasonable to assume that the curvature curvature Measure of the rate of change of direction of a curved line or surface at any point. In general, it is the reciprocal of the radius of the circle or sphere of best fit to the curve or surface at that point. noted in sulfur and [IXS.sub.4] contour plots similarly suggests interactions between these two independent variables, consequent con·se·quent adj. 1. a. Following as a natural effect, result, or conclusion: tried to prevent an oil spill and the consequent damage to wildlife. b. formation of a sulfurating species and then crosslink generation. This mechanism should be similar to that found with thiuram accelerators such as TMTD. The SAS JMP Prediction Profiler was used to illustrate how changes in the level of the independent curative variables can affect compound properties. Figure 12a shows the independent variables at the center point of the design. In this instance, a compound with 1.0 phr of MBTS, 3.0 phr of [IXS.sub.4] and 0.60 phr of sulfur is computed to have a 300% modulus value of 4.3 MPa. For illustrative il·lus·tra·tive adj. Acting or serving as an illustration. il·lus  tra·tive·ly adv.Adj. 1. purposes, lowering the [IXS.sub.4] level from 3.0 phr to 1.5 phr results in an increase in the 300% modulus value to 5.2 MPa, (figure 12b. Thus, by varying the xanthate accelerator level, compound properties can be optimized for any specific set of in-service in-service In-service training adjective Referring to any form of on-the-job training noun In-service training of an employee targets that might be required. [FIGURE 12 OMITTED] Discussion and conclusions This work is a series of experiments where both isopropylxanthate tetra-sulfide and zinc diisopropylxanthate were first screened as a replacement for the nitrosamine-generating TMTD accelerator in both butyl rubber and bromobutyl rubber formulations. A preferred accelerator was then studied further in a statistically designed experiment in order to identify any empirical trends. These trends may provide an illustration of the cure and cured physical properties that can be achieved with isobutylene-based elastomers and also provide a starting point Noun 1. starting point - earliest limiting point terminus a quo commencement, get-go, offset, outset, showtime, starting time, beginning, start, kickoff, first - the time at which something is supposed to begin; "they got an early start"; "she knew from the for further development work using xanthate accelerators as curatives. Thus, a number of observations has been noted: * In butyl rubber compounds, ZIX tends to show a higher cure rate than does [IXS.sub.4]. * In combination with MBTS, the state of cure obtained with both ZIX and [IXS.sub.4] increases. * Increasing MBTS levels increase the Mooney scorch [t.sub.5] and [t.sub.35] times. * As in the generally understood mechanism for MBTS and TMTD binary cure systems, there may be little to no interaction between MBTS and xanthate accelerator levels. * The cure systems studied in this work did not show any significant effect on compound permeability. * As [IXS.sub.4] concentrations increase, the vulcanization activation energy also increases. * Increases in the sulfur level used decrease the vulcanization activation energy, suggesting that the preferred mechanism of xanthate curing of isobutylene-based elastomers may be via formation of sulfurating complexes rather than as a sulfur donor The party conferring a power. One who makes a gift. One who creates a trust. donor n. a person or entity making a gift or donation. DONOR. He who makes a gift. (q.v.) (figure 13). [FIGURE 13 OMITTED] * [IXS.sub.4] cure systems tend to show reversion; as a tetrasulfide, long polysulfidic crosslinks are most likely formed in vulcanization, and such reversion might then be anticipated. Palaty and Joseph have reported that xanthate accelerators can vulcanize natural rubber at temperatures as low as 25[degrees]C (ref. 7). However, at elevated temperatures (150[degrees]C), less desirable properties may be obtained, possibly due to the onset of the competing reversion and crosslink formation reactions, or decomposition decomposition /de·com·po·si·tion/ (de-kom?pah-zish´un) the separation of compound bodies into their constituent principles. de·com·po·si·tion n. 1. of the xanthate at the higher temperature. This may not be the case for curing isobutylene-based elastomers, due to the very low level of back bone unsaturation (about 2%) compared to general-purpose rubbers. ZIX was also reported to be the more effective accelerator when compared to either zinc ethylxanthate or zinc butylxanthate. In this instance, ZIX was the preferred accelerator for butyl rubber. The absence of an activating halogen halogen (hăl`əjĕn) [Gr.,=salt-bearing], any of the chemically active elements found in Group 17 of the periodic table; the name applies especially to fluorine (symbol F), chlorine (Cl), bromine (Br), and iodine (I). site in butyl rubber renders it considerably less 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. . The greater activity of ZIX compared to [IXS.sub.4], which would be analogous analogous /anal·o·gous/ (ah-nal´ah-gus) resembling or similar in some respects, as in function or appearance, but not in origin or development. a·nal·o·gous adj. to that of zinc dimethyl dithiocarbamate (ZDMC) and TMTD, would therefore be preferred. Versloot, Haasnoot and Reedijk also noted that room temperature vulcanization was feasible using highly reactive accelerators such as xanthates, and reported the formation of crosslink precursors precursors, (prēkur´s  rz),n.pl particles or compounds that precede something. that are readily converted to crosslinks in the presence of zinc dithiocarbamates (ref. 8). As illustrated in figure 13, sulfur rich complexes are formed by insertion insertion n. the addition of language at a place within an existing typed or written document, which is always suspect unless initialled by all parties. of sulfur into the zinc dimethyldithiocarbamate molecule, which in turn is an active sulfurating complex. Rubber bound intermediates are subsequently formed, followed by crosslinking, to form initial polysulfidic crosslinks. These later evolve into mono- and disulfidic crosslinks (refs. 9 and 10). It is suggested that xanthates will form similar sulfurating complexes. The zinc diisopropylxanthate may form a soluble soluble /sol·u·ble/ (sol´u-b'l) susceptible of being dissolved. sol·u·ble adj. Capable of being dissolved, especially easily dissolved. internally chelated che·late adj. Zoology Having chelae or resembling a chela. n. Chemistry A chemical compound in the form of a heterocyclic ring, containing a metal ion attached by coordinate bonds to at least two nonmetal ions. species where oxygen can donate its lone pair A lone pair is a (valence) electron pair without bonding or sharing with other atoms. They are found in the outermost electron shell of an atom, so lone pairs are a subset of a molecule's valence electrons. of electrons (figure 14). Nitrogen in the dithiocarbamate complex can donate its lone pair of electrons more readily than oxygen. The ionization ionization: see ion. ionization Process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) by the removal or addition of negatively charged electrons. energy of nitrogen is 64.3 J/mol compared to 84.1 kJ/mol for oxygen. The positive charge on the carbon atom of the C=S bond in dithiocarbamates will, therefore, be less than for xanthates. This decreases the polarity (1) The direction of charged particles, which may determine the binary status of a bit. (2) In micrographics, the change in the light to dark relationship of an image when copies are made. of the S-Zn bond in dithiocarbamates, thereby increasing the breaking strength. In xanthates, this S-Zn bond is thus relatively weak, rendering See render. (graphics, text) rendering - The conversion of a high-level object-based description into a graphical image for display. For example, ray-tracing takes a mathematical model of a three-dimensional object or scene and converts it into a bitmap image. the xanthate a more effective, faster accelerator. Alternative explanations for the activity of xanthates has centered on better solubility solubility Degree to which a substance dissolves in a solvent to make a solution (usually expressed as grams of solute per litre of solvent). Solubility of one fluid (liquid or gas) in another may be complete (totally miscible; e.g. of this material versus other accelerators (ref. 11). [FIGURE 14 OMITTED] The present data suggest that xanthate-accelerated vulcanizates may be more susceptible to reversion, with [IXS.sub.4] compounds showing more reversion than does ZIX. This may be due to the presence of four sulfur atoms in [IXS.sub.4] (figure 14) versus two sulfur atoms in ZIX. Hence, formation of higher polysulfide pol·y·sul·fide n. A sulfide compound containing at least two sulfur atoms per molecule. crosslinks may leave the vulcanizate prone to reversion. It may, therefore, be deduced that ZIX might react in a similar manner to zinc diethyldithiocarbamates, with xanthate accelerators also forming an activated complex In chemistry an activated complex is a transitional structure in a chemical reaction that results from an effective collision between molecules and that persists while old bonds are breaking and new bonds are forming. that can then be readily sulfurated sulfurated /sul·fu·rat·ed, sul·fu·ret·ed/ (sul´fu-rat?ed) combined with or charged with sulfur. sulfurated combined with sulfur. (figure 15). This is in agreement with our observations that the activation energy decreases with increasing sulfur levels. [FIGURE 15 OMITTED] In conclusion, [IXS.sub.4] and ZIX accelerator systems in combination with MBTS can be used to vulcanize isobutylene-isoprene elastomers at temperatures between 160[degrees]C and 180 degrees]C. Results do not indicate a significant interaction between the xanthate accelerators and MBTS. Identification of the optimum cure temperature requires further elucidation e·lu·ci·date v. e·lu·ci·dat·ed, e·lu·ci·dat·ing, e·lu·ci·dates v.tr. To make clear or plain, especially by explanation; clarify. v.intr. To give an explanation that serves to clarify. for in-service specific applications. This article is based on a paper presented at a meeting of the Rubber Division, ACS (Asynchronous Communications Server) See network access server. . References (1.) E.N. Kresge, R.H. Schatz and H.-C. 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. , "Isobutylene polymers," Encyclopedia encyclopedia, compendium of knowledge, either general (attempting to cover all fields) or specialized (aiming to be comprehensive in a particular field). Encyclopedias and Other Reference Books of Polymer Science Polymer science or macromolecular science is the subfield of materials science concerned with polymers, primarily synthetic polymers such as plastics. The field of polymer science includes researchers in multiple disciplines including chemistry, physics, and engineering. & Engineering, Vol 8, 2nd edition, pp. 423-448, John Wiley John Wiley may refer to:
(2.) W.H. Waddell and A.H. Tsou, "Butyl rubber," in Rubber Compounding, Chemistry and Applications, Ed. M.B. Rodgers, Marcel Dekker Marcel Dekker is a well-known encyclopedia publishing company with editorial boards found in New York, New York. They are part of the Taylor and Francis publishing group. Initially a textbook publisher, they went to encyclopedia publishing in the late 1990's. , Inc., 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 , 2004. (3.) S.C. Solis Solis Diazepam, see there , M.B. Rodgers, N.K. Tambe, B.B. Sharma and W.H. Waddell, "A review of the vulcanization of isobutylene-based elastomers, "presented at a meeting of the ACS, Rubber Division, San Antonio San Antonio (săn ăntō`nēō, əntōn`), city (1990 pop. 935,933), seat of Bexar co., S central Tex., at the source of the San Antonio River; inc. 1837. , 2005. (4.) M.B. Rodgers, S.C. Solis, N.K. Tambe, B.B. Sharma and W.H. Waddell, "Thiourea thiourea a goitrogenic agent used in industry as a photographic fixative. Mode of action is as for thiouracil. accelerators in the vulcanization of butyl 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. ," Rubber World, 233-6, March 2006. (5.) www.butylrubber.com. (6.) R.J. DelVecchio, Understanding Design of Experiments, Hanser, Cincinnati, 1997. (7.) S. Palaty and R. Joseph, "Xanthate accelerators for low temperature curing of natural rubber," J. Appl. Polymer Science, 78, pp. 1,769-1,775 (2000). (8.) P. Versloot, J.G. Haasnoot and J. Reedijk, "Sulfur vulcanization of simple model olefins, part IV. Vulcanization of 2,3-dimethyl-2-butene with TMTD and activated activated a state of being more than usually active. In biological systems this is usually brought about by chemical or electrical means. Commonly said of pharmaceutical and chemical products. zinc dithiocarbamate/xanthate accelerators at different temperatures, "Rubber Chem. Technol., 68, pp. 563-572 (1995). (9.) L. Batman, C.G. Moore Moore, city (1990 pop. 40,761), Cleveland co., central Okla., a suburb of Oklahoma City; inc. 1887. Its manufactures include lightning- and surge-protection equipment, packaging for foods, and auto parts. , M. Porter and B. Saville, "Chemistry of vulcanization," in Chemistry and Physics of Rubber-Like Substances, chapter 15, p. 465, Maclaren Press, London, 1963. (10.) A.D. Roberts, Natural Rubber Science and Technology, Oxford University Press, Oxford, 1988. (11.) S. Palaty and R. Joseph, "Studies on xanthate-zinc diethyl dithiocarbamate accelerator combination in natural rubber," Plastics Rubber and Composites, 30(6), 270-274 (2001). by Nitin Tambe, Scott Solis, Brendan Rodgers, Bharat B. Sharma and Walter H. Waddell, ExxonMobil Chemical (www.butylrubber.com) Table 1 - carbon-halogen bond energies and bond lengths (ref. 3) Bond Energy J/mol Length nm -C - C- 346 0.154 -C - H 413 0.109 -C - F 452 0.138 -C - C1 327 0.177 -C - Br 209 0.194 Table 2--model butyl rubber screening compound (ref. 5) Material Phr Butyl rubber (Exxon butyl 268) 100 Carbon black (N660) 70 Paraffinic oil 25 Phenolic tackifying resin 4 Stearic acid 1 Zinc oxide 5 Tetramethylthiuram disulfide (TMTD) 1 Mercaptobenzothiazole disulfide (MBTS) 0.50 Sulfur 2 Table 3 - model bromobutyl screening compound (ref. 5) Material Phr Exxon bromobutyl 2222 100 Carbon black (N660) 60 Naphthenic oil 8 Aromatic hydrocarbon resin 7 Phenolic tackifying resin 4 Stearic acid 1 Zinc oxide 1 Mercaptobenzothiazole disulfide (MBTS) 1.25 Sulfur 0.50 Table 4 - butyl rubber screening formulations Compound 1 2 3 4 Butyl rubber 100 100 100 100 Carbon black N660 70 70 70 70 Paraffinic oil 25 25 25 25 Phenolic tackfier resin 4 4 4 4 Stearic acid 1 1 1 1 ZnO 5.0 5.0 5.0 5.0 TMTD 1.0 MBTS 0.5 0.5 Sulfur 2.0 2.0 2.0 2.0 IX[S.sub.4] 2.0 4.0 2.0 ZIX Total 208.5 209.0 211.0 209.5 Compound 5 6 7 Butyl rubber 100 100 100 Carbon black N660 70 70 70 Paraffinic oil 25 25 25 Phenolic tackfier resin 4 4 4 Stearic acid 1 1 1 ZnO 5.0 5.0 5.0 TMTD MBTS 0.5 Sulfur 2.0 2.0 2.0 IX[S.sub.4] ZIX 2.0 4.0 2.0 Total 209.0 211.0 209.5 Table 5 - rheometer result at 180[degrees]C Mooney scorch 125[degrees]C 1 2 3 Minimum viscosity MU 17.3 14.6 12.7 [t.sub.5] min 16.1 44.4 Rheorneter MDR 180[degrees]C ML dNm 1.1 1.0 0.9 MH dNm 12.8 6.5 6.7 Delta torque dNm 11.7 5.5 5.8 [t.sub.10] Mins. 0.8 1.6 1.6 [t.sub.90] Mins. 5.5 11.2 5.8 Peak rate dNnVmin. 8.7 2.3 1.9 Cure rate index (CRI) % 21 10 24 Mooney scorch 4 5 6 7 Minimum viscosity 13.7 17.9 18.3 18.9 [t.sub.5] 55.9 4.9 4.6 5.4 Rheorneter MDR ML 0.9 1.2 1.1 1.2 MH 8.4 5.6 4.7 7.2 Delta torque 7.5 4.4 3.6 6.0 [t.sub.10] 1.4 0.4 0.3 0.5 [t.sub.90] 8.5 13.6 2.3 Peak rate 2.6 4.8 6.8 3.7 Cure rate index (CRI) 14 8 51 10 Table 6 - study of MBTS and FIX levels N Compound 8 9 Butyl rubber 100 100 Carbon black N660 70 70 Paraffinic oil 25 25 Phenolic tackifier resin 4 4 Stearic acid 1 1 Zinc oxide 5.0 5.0 MBTS 0.65 1.35 ZIX 1.44 1.44 Sulfur 2.00 2.00 Total 209.09 209.79 Mooney viscosity 100[degrees]C ML 1+4 MU 47.5 48.2 Mooney scorch 125[degrees]C Mooney viscosity MU 35.7 35.1 [t.sub.5] mins. 20.6 64.2 [t.sub.35] mins. 46.4 101.3 Rheometer ODR 160[degrees]C ML dNm 7.9 7.4 MH dNm 25.1 28.9 Delta torque dNm 17.2 21.6 [t.sub.90] mins. 40.6 40.4 Cure rate index 2.8 3.0 Rheometer ODR 180[degrees]C ML dNm 7.0 6.4 MH dNm 26.6 30.5 Delta torque dNm 19.6 24.1 [t.sub.90] mins. 15.2 14.8 Cure rate index 7.5 8.0 Rheometer MDR 160[degrees]C ML dNm 1.4 1.4 MH dNm 4.7 5.4 Delta torque dNm 3.3 4.1 [t.sub.90] mins. 39.0 37.9 Cure rate index 4.0 3.8 Stress-strain properties tc90+2 mins. Tensile MPa 7.7 8.7 Elongation % 795.0 780.0 1000% modulus MPa 0.6 0.6 2000% modulus MPa 1.0 1.1 3000% modulus MPa 1.6 1.8 Energy at break Joules 6.5 7.4 Hardness Duro. A 34 38 Tear resistance Die B KN/m 34.0 36.8 Die C KN/m 34.9 31.1 Compound 10 11 12 Butyl rubber 100 100 100 Carbon black N660 70 70 70 Paraffinic oil 25 25 25 Phenolic tackifier resin 4 4 4 Stearic acid 1 1 1 Zinc oxide 5.0 5.0 5.0 MBTS 0.65 1.35 0.50 ZIX 3.56 3.56 2.50 Sulfur 2.00 2.00 2.00 Total 211.21 211.91 210.00 Mooney viscosity ML 1+4 47.7 48.0 47.6 Mooney scorch Mooney viscosity 37.3 36.6 37.1 [t.sub.5] 6.0 7.2 7.0 [t.sub.35] 8.3 10.4 10.4 Rheometer ODR ML 8.6 8.3 8.4 MH 28.5 31.6 25.5 Delta torque 19.9 23.2 17.0 [t.sub.90] 34.7 37.1 37.2 Cure rate index 3.0 2.9 2.9 Rheometer ODR ML 8.1 7.7 7.7 MH 28.6 31.8 26.2 Delta torque 20.5 24.2 18.5 [t.sub.90] 14.5 14.3 15.0 Cure rate index 7.4 7.7 7.3 Rheometer MDR ML 1.4 1.4 1.4 MH 5.2 5.8 4.7 Delta torque 3.8 4.4 3.4 [t.sub.90] 37.7 38.6 39.1 Cure rate index 3.3 3.2 3.6 Stress-strain properties tc90+2 mins. Tensile 8.5 9.4 7.7 Elongation 780.0 775.0 755.0 1000% modulus 0.6 0.6 0.6 2000% modulus 1.1 1.3 1.0 3000% modulus 1.8 2.1 1.7 Energy at break 7.4 8.4 6.4 Hardness 35 38 34 Tear resistance Die B 37.8 36.5 35.0 Die C 33.8 35.8 33.9 Compound 13 14 Butyl rubber 100 100 Carbon black N660 70 70 Paraffinic oil 25 25 Phenolic tackifier resin 4 4 Stearic acid 1 1 Zinc oxide 5.0 5.0 MBTS 1.50 1.00 ZIX 2.50 1.00 Sulfur 2.00 2.00 Total 211.00 209.00 Mooney viscosity ML 1+4 47.3 48.3 Mooney scorch Mooney viscosity 36.2 35.4 [t.sub.5] 15.9 71.6 [t.sub.35] 30.7 112.6 Rheometer ODR ML 8.0 7.4 MH 30.6 26.4 Delta torque 22.7 19.0 [t.sub.90] 37.9 41.0 Cure rate index 3.0 2.9 Rheometer ODR ML 7.0 6.4 MH 31.7 28.3 Delta torque 24.6 21.9 [t.sub.90] 14.0 14.5 Cure rate index 8.2 8.2 Rheometer MDR ML 1.4 1.4 MH 5.7 5.1 Delta torque 4.3 3.7 [t.sub.90] 38.0 38.8 Cure rate index 3.6 3.8 Stress-strain properties tc90+2 mins. Tensile 8.7 7.1 Elongation 770.0 770.0 1000% modulus 0.6 0.5 2000% modulus 1.2 0.9 3000% modulus 1.9 1.5 Energy at break 7.3 5.9 Hardness 37 35 Tear resistance Die B 31.8 31.3 Die C 33.2 33.0 Compound 15 16 Butyl rubber 100 100 Carbon black N660 70 70 Paraffinic oil 25 25 Phenolic tackifier resin 4 4 Stearic acid 1 1 Zinc oxide 5.0 5.0 MBTS 1.00 1.00 ZIX 4.00 2.50 Sulfur 2.00 2.00 Total 212.00 210.50 Mooney viscosity ML 1+4 47.5 47.8 Mooney scorch Mooney viscosity 36.9 37.1 [t.sub.5] 6.1 9.2 [t.sub.35] 8.5 14.8 Rheometer ODR ML 8.6 8.2 MH 30.9 28.8 Delta torque 22.3 20.6 [t.sub.90] 36.5 37.7 Cure rate index 2.9 2.9 Rheometer ODR ML 8.0 7.4 MH 30.7 29.6 Delta torque 22.7 22.2 [t.sub.90] 14.5 14.4 Cure rate index 7.4 7.7 Rheometer MDR ML 1.4 1.4 MH 5.5 5.3 Delta torque 4.1 3.9 [t.sub.90] 37.7 39.1 Cure rate index 3.2 3.5 Stress-strain properties tc90+2 mins. Tensile 8.7 8.3 Elongation 750.0 755.0 1000% modulus 0.7 0.6 2000% modulus 1.2 1.1 3000% modulus 2.0 1.8 Energy at break 7.3 6.9 Hardness 36 35 Tear resistance Die B 34.4 34.0 Die C 33.5 34.6 Table 7 - screening of IX[S.sub.4] and ZIX in bromobutyl Compound 17 18 Bromobutyl rubber 100 100 Carbon black N660 60 60 Naphthenic oil 8 8 Phenolic tackifier resin 4 4 Aromatic hydrocarbon resin 7 7 Stearic acid 2 2 MgO 0.15 0.15 ZnO 1.00 1.00 Sulfur 0.50 0.50 MBTS 1.00 TMTD 1.00 IX[S.sub.4] 2.00 ZIX Total 184.65 184.65 Mooney scorch 125[degrees]C Mooney viscosity MU 19.8 18.5 [t.sub.5] mins. 8.6 19.3 [t.sub.10] mins. 9.7 22.7 Rheometer MDR 160[degrees]C ML dNm 1.2 1.2 MH dNm 4.8 7.1 Delta torque dNm 3.6 6.0 [t.sub.10] mins. 1.1 1.6 [t.sub.90] mins. 4.4 9.7 Peak rate dNrrVmin. 2.0 1.2 Cure rate index (CRI) 29.7 12.3 Rheometer MDR 180[degrees]C ML dNm 1.0 1.0 MH dNm 4.3 6.7 Delta torque dNm 3.4 5.7 [t.sub.10] mins. 0.5 0.7 [t.sub.90] mins. 2.2 2.4 Peak rate dNm/min. 4.8 4.2 Cure rate index (CRI) 59.5 56.8 Compound 19 20 21 Bromobutyl rubber 100 100 100 Carbon black N660 60 60 60 Naphthenic oil 8 8 8 Phenolic tackifier resin 4 4 4 Aromatic hydrocarbon resin 7 7 7 Stearic acid 2 2 2 MgO 0.15 0.15 0.15 ZnO 1.00 1.00 1.00 Sulfur 0.50 0.50 0.50 MBTS 1.00 TMTD IX[S.sub.4] 4.00 2.00 ZIX 2.00 Total 186.65 185.65 184.65 Mooney scorch Mooney viscosity 17.1 17.7 30.9 [t.sub.5] 10.8 20.7 1.4 [t.sub.10] 12.4 23.7 1.6 Rheometer MDR ML 1.0 1.1 1.7 MH 6.4 6.8 5.6 Delta torque 5.4 5.7 3.9 [t.sub.10] 1.3 1.9 0.3 [t.sub.90] 9.2 8.6 17.4 Peak rate 1.3 1.3 4.2 Cure rate index (CRI) 12.6 14.8 5.9 Rheometer MDR ML 0.9 0.9 1.8 MH 5.6 6.5 5.5 Delta torque 4.8 5.6 3.7 [t.sub.10] 0.6 0.7 0.2 [t.sub.90] 1.8 2.0 4.0 Peak rate 5.0 5.6 6.4 Cure rate index (CRI) 79.4 76.3 26.2 Compound 22 23 Bromobutyl rubber 100 100 Carbon black N660 60 60 Naphthenic oil 8 8 Phenolic tackifier resin 4 4 Aromatic hydrocarbon resin 7 7 Stearic acid 2 2 MgO 0.15 0.15 ZnO 1.00 1.00 Sulfur 0.50 0.50 MBTS 1.00 TMTD IX[S.sub.4] ZIX 4.00 2.00 Total 186.65 185.65 Mooney scorch Mooney viscosity 31.5 26.0 [t.sub.5] 1.2 2.5 [t.sub.10] 1.4 2.9 Rheometer MDR ML 1.9 1.5 MH 3.1 4.8 Delta torque 1.2 3.3 [t.sub.10] 0.3 0.5 [t.sub.90] 55.0 14.7 Peak rate 1.7 2.0 Cure rate index (CRI) 1.8 7.0 Rheometer MDR ML 1.9 1.4 MH 3.0 4.5 Delta torque 1.1 3.1 [t.sub.10] 0.2 0.3 [t.sub.90] 20.3 3.7 Peak rate 1.4 3.4 Cure rate index (CRI) 5.0 29.3 Table 8 - screening of IX[S.sub.4] and ZIX with MBTS in bromobutyl rubber Compound 24 25 26 Bromobutyl rubber 100 100 100 Carbon black N660 60 60 60 Naphthenic oil 8 8 8 Phenolic tackifier resin 4 4 4 Aromatic hydrocarbon resin 7 7 7 Stearic acid 2 2 2 MgO 0.15 0.15 0.15 ZnO 1.00 1.00 1.00 Sulfur 0.50 0.50 0.50 MBTS 1.00 1.00 1.00 TMTD 1.00 IX[S.sub.4] 2.00 4.00 ZIX Total 184.65 185.65 187.65 Mooney scorch 125[degrees]C Mooney viscosity MU 19.3 17.6 15.7 [t.sub.5] Mins. 8.4 19.4 17.1 [t.sub.10] Mins. 9.5 22.1 19.4 Rheometer MDR 180[degrees]C ML dNm 0.9 0.9 0.8 MH dNm 4.3 6.4 5.2 Delta torque dNm 3.4 5.5 4.3 [t.sub.10] Mins. 0.5 0.7 0.6 [t.sub.90] Mins. 2.3 2.0 5.0 Peak rate dNrn/min. 5.0 5.8 4.5 Cure rate index (CRI) 57.1 76.3 22.5 Compound 27 28 29 30 Bromobutyl rubber 100 100 100 100 Carbon black N660 60 60 60 60 Naphthenic oil 8 8 8 8 Phenolic tackifier resin 4 4 4 4 Aromatic hydrocarbon res 7 7 7 7 Stearic acid 2 2 2 2 MgO 0.15 0.15 0.15 0.15 ZnO 1.00 1.00 1.00 1.00 Sulfur 0.50 0.50 0.50 0.50 MBTS 1.00 1.00 1.00 1.00 TMTD 1.00 1.00 IX[S.sub.4] 2.00 ZIX 2.00 4.00 2.00 Total 186.65 185.65 187.65 186.65 Mooney scorch Mooney viscosity 17.4 25.2 28.6 20.9 [t.sub.5] 8.0 2.3 1.4 5.4 [t.sub.10] 9.0 2.6 1.6 6.2 Rheometer MDR ML 0.9 1.4 1.5 1.1 MH 3.3 4.6 3.2 2.9 Delta torque 2.5 3.1 1.6 1.9 [t.sub.10] 0.5 0.3 0.3 0.4 [t.sub.90] 1.5 3.2 13.5 1.4 Peak rate 2.9 3.7 0.8 2.1 Cure rate index (CRI) 98.0 35.0 7.6 95.2 Table 9 - study of IX[S.sub.4], MBTS and sulfur in a three-variable Central composite design Compound 31 32 Bromobutyl rubber 100 100 Carbon black N660 60 60 Naphthenic oil 8 8 Aromatic hydrocarbon resin 7 7 Phenolic tackifier resin 4 4 Stearic acid 2 2 MgO 0.2 0.2 ZnO 1.0 1.0 MBTS 0.7 1.3 IX[S.sub.4] 2.1 2.1 Sulfur 0.4 0.4 Mooney scorch 125[degrees]C Mooney viscosity MU 25.8 26.2 [t.sub.5] Mins. 22.4 21.9 Rheometer MDR 160[degrees]C ML dNm 1.6 1.6 MH dNm 7.8 7.8 Delta torque dNm 6.2 6.2 [t.sub.10] Mins. 2.0 2.0 [t.sub.90] Mins. 9.7 9.0 Peak rate dNnVmin. 1.4 1.4 Cure rate index (CRI) 13.0 14.3 Rheometer MDR 170[degrees]C ML dNm 1.5 1.4 MH dNm 7.5 7.4 Delta torque dNm 6.1 6.0 [t.sub.10] mins. 1.2 1.2 [t.sub.90] mins. 5.0 4.5 Peak rate dNm/min. 2.5 2.6 Cure rate index (CRI) 26.4 30.4 Stress-strain properties [t.sub.90] + 2 min. Tensile MPa 11.6 11.4 Elongation % 694 705 100% modulus MPa 1.5 1.3 200% modulus MPa 3.4 3.0 300% modulus MPa 5.2 4.7 Energy at break Joules 12.4 12.3 Hardness Duro. A 50 50 Tear resistance Die B KN/m 61 57 Die C KN/m 31 31 Oxygen permeability rating @ 65[degrees]C Permeation % 100 100 Permeability % 100 100 Dynamic properties @ 2% 1 Hz Strain Tan delta 0[degrees]C 0.34 0.36 Tan delta 60[degrees]C 0.16 0.21 Dynamic properties @ 2% 10 Hz Strain Tan delta 0[degrees]C 0.64 0.63 Tan delta 60[degrees]C 0.20 0.22 Compound 33 34 35 Bromobutyl rubber 100 100 100 Carbon black N660 60 60 60 Naphthenic oil 8 8 8 Aromatic hydrocarbon resin 7 7 7 Phenolic tackifier resin 4 4 4 Stearic acid 2 2 2 MgO 0.2 0.2 0.2 ZnO 1.0 1.0 1.0 MBTS 0.7 1.3 0.7 IX[S.sub.4] 3.9 3.9 2.1 Sulfur 0.4 0.4 0.9 Mooney scorch Mooney viscosity 24.9 24.8 26.1 [t.sub.5] 21.3 19.8 21.8 Rheometer MDR ML 1.5 1.5 1.6 MH 7.5 7.3 7.8 Delta torque 5.9 5.8 6.2 [t.sub.10] 1.9 1.8 1.9 [t.sub.90] 8.9 8.1 9.3 Peak rate dNnVmin. 1.4 1.5 1.5 Cure rate index (CRI) 14.2 15.7 13.6 Rheometer MDR ML 1.4 1.4 1.5 MH 7.3 7.2 7.6 Delta torque 5.9 5.8 6.2 [t.sub.10] 1.1 1.1 1.2 [t.sub.90] 4.5 4.1 4.7 Peak rate 2.7 2.9 2.7 Cure rate index (CRI) 29.6 33.3 28.4 Stress-strain properties [t.sub.90] + 2 min. Tensile 11.0 11.1 11.4 Elongation 703 740 675 100% modulus 1.3 1.2 1.5 200% modulus 3.0 2.7 3.5 300% modulus 4.6 4.2 5.3 Energy at break 12.0 12.2 12.3 Hardness 49 49 50 Tear resistance Die B 57 56 59 Die C 30 30 33 Oxygen permeability rating @ 65[degrees]C Permeation 105 104 89 Permeability 105 104 89 Dynamic properties @ 2% Strain Tan delta 0.38 0.38 0.36 Tan delta 0.20 0.20 0.17 Dynamic properties @ 2% Strain Tan delta 0.67 0.65 0.63 Tan delta 0.22 0.23 0.19 Compound 36 37 38 Bromobutyl rubber 100 100 100 Carbon black N660 60 60 60 Naphthenic oil 8 8 8 Aromatic hydrocarbon resin 7 7 7 Phenolic tackifier resin 4 4 4 Stearic acid 2 2 2 MgO 0.2 0.2 0.2 ZnO 1.0 1.0 1.0 MBTS 1.3 0.7 1.3 IX[S.sub.4] 2.1 3.9 3.9 Sulfur 0.9 0.9 0.9 Mooney scorch Mooney viscosity 26.4 25.5 24.9 [t.sub.5] 21.7 20.3 19.8 Rheometer MDR ML 1.5 1.5 1.5 MH 7.7 7.4 7.3 Delta torque 6.1 5.9 5.8 [t.sub.10] 2.0 1.8 1.8 [t.sub.90] 8.8 8.6 8.4 Peak rate dNnVmin. 1.4 1.5 1.4 Cure rate index (CRI) 14.6 14.7 15.1 Rheometer MDR ML 1.7 1.4 1.4 MH 7.7 7.2 7.1 Delta torque 6.0 5.8 5.7 [t.sub.10] 1.8 1.1 1.0 [t.sub.90] 8.1 4.4 4.2 Peak rate 1.4 2.7 2.7 Cure rate index (CRI) 15.8 30.4 31.8 Stress-strain properties [t.sub.90] + 2 min. Tensile 11.3 11.3 11.5 Elongation 714 739 751 100% modulus 1.4 1.3 1.3 200% modulus 3.0 2.7 2.9 300% modulus 4.7 4.2 4.3 Energy at break 12.0 12.2 12.4 Hardness 48 47 47 Tear resistance Die B 58 56 56 Die C 31 29 30 Oxygen permeability rating @ 65[degrees]C Permeation 101 100 97 Permeability 101 100 97 Dynamic properties @ 2% Strain Tan delta 0.38 0.36 0.37 Tan delta 0.22 0.21 0.23 Dynamic properties @ 2% Strain Tan delta 0.67 0.62 0.65 Tan delta 0.24 0.23 0.24 Compound 39 40 41 Bromobutyl rubber 100 100 100 Carbon black N660 60 60 60 Naphthenic oil 8 8 8 Aromatic hydrocarbon resin 7 7 7 Phenolic tackifier resin 4 4 4 Stearic acid 2 2 2 MgO 0.2 0.2 0.2 ZnO 1.0 1.0 1.0 MBTS 0.5 1.5 1.0 IX[S.sub.4] 3.0 3.0 1.5 Sulfur 0.6 0.6 0.6 Mooney scorch Mooney viscosity 25.8 27.5 28.7 [t.sub.5] 22.0 19.3 21.1 Rheometer MDR ML 1.6 1.7 1.7 MH 7.6 7.7 7.8 Delta torque 6.1 6.0 6.1 [t.sub.10] 2.0 1.8 2.0 [t.sub.90] 9.3 8.1 9.8 Peak rate dNnVmin. 1.3 1.5 1.2 Cure rate index (CRI) 13.7 15.8 12.8 Rheometer MDR ML 1.5 1.6 1.6 MH 7.5 7.5 7.7 Delta torque 6.0 6.0 6.0 [t.sub.10] 1.2 1.1 1.2 [t.sub.90] 4.7 4.0 4.9 Peak rate 2.5 2.8 2.4 Cure rate index (CRI) 28.6 34.0 27.3 Stress-strain properties [t.sub.90] + 2 min. Tensile 11.1 10.5 11.1 Elongation 625 665 656 100% modulus 1.8 1.4 1.5 200% modulus 3.8 3.0 3.5 300% modulus 5.6 4.6 5.4 Energy at break 11.5 10.8 12.1 Hardness 49 49 51 Tear resistance Die B 58 56 60 Die C 32 31 32 Oxygen permeability rating @ 65[degrees]C Permeation 96 97 105 Permeability 96 97 105 Dynamic properties @ 2% Strain Tan delta 0.34 0.34 0.35 Tan delta 0.16 0.17 0.15 Dynamic properties @ 2% Strain Tan delta 0.63 0.60 0.64 Tan delta 0.20 0.19 0.18 Compound 42 43 Bromobutyl rubber 100 100 Carbon black N660 60 60 Naphthenic oil 8 8 Aromatic hydrocarbon resin 7 7 Phenolic tackifier resin 4 4 Stearic acid 2 2 MgO 0.2 0.2 ZnO 1.0 1.0 MBTS 1.0 1.0 IX[S.sub.4] 4.5 3.0 Sulfur 0.6 0.3 Mooney scorch Mooney viscosity 27.1 28.6 [t.sub.5] 18.5 19.4 Rheometer MDR ML 1.6 1.7 MH 7.4 7.7 Delta torque 5.7 6.0 [t.sub.10] 1.7 1.8 [t.sub.90] 8.4 8.8 Peak rate dNnVmin. 1.5 1.5 Cure rate index (CRI) 15.0 14.3 Rheometer MDR ML 1.5 1.6 MH 7.3 7.6 Delta torque 5.8 6.0 [t.sub.10] 1.1 1.1 [t.sub.90] 4.3 4.4 Peak rate 2.8 2.8 Cure rate index (CRI) 30.6 30.4 Stress-strain properties [t.sub.90] + 2 min. Tensile 10.5 11.4 Elongation 654 668 100% modulus 1.3 1.4 200% modulus 2.9 3.2 300% modulus 4.5 5.0 Energy at break 10.5 12.3 Hardness 48 48 Tear resistance Die B 56 58 Die C 30 30 Oxygen permeability rating @ 65[degrees]C Permeation 104 105 Permeability 103 105 Dynamic properties @ 2% Strain Tan delta 0.37 0.37 Tan delta 0.19 0.31 Dynamic properties @ 2% Strain Tan delta 0.64 0.64 Tan delta 0.20 0.30 Compound 44 45 Bromobutyl rubber 100 100 Carbon black N660 60 60 Naphthenic oil 8 8 Aromatic hydrocarbon resin 7 7 Phenolic tackifier resin 4 4 Stearic acid 2 2 MgO 0.2 0.2 ZnO 1.0 1.0 MBTS 1.0 1.0 IX[S.sub.4] 3.0 3.0 Sulfur 1.0 0.6 Mooney scorch Mooney viscosity 27.9 26.0 [t.sub.5] 19.6 21.7 Rheometer MDR ML 1.7 1.5 MH 7.8 7.5 Delta torque 6.1 5.9 [t.sub.10] 1.8 1.9 [t.sub.90] 8.8 9.3 Peak rate dNnVmin. 1.4 1.3 Cure rate index (CRI) 14.4 13.5 Rheometer MDR ML 1.5 1.4 MH 7.6 7.4 Delta torque 6.1 6.0 [t.sub.10] 1.1 1.1 [t.sub.90] 4.4 4.6 Peak rate 2.7 2.5 Cure rate index (CRI) 30.3 28.7 Stress-strain properties [t.sub.90] + 2 min. Tensile 10.4 10.9 Elongation 637 701 100% modulus 1.3 1.2 200% modulus 2.9 2.7 300% modulus 4.6 4.2 Energy at break 9.9 11.2 Hardness 48 49 Tear resistance Die B 58 57 Die C 31 31 Oxygen permeability rating @ 65[degrees]C Permeation 98 98 Permeability 98 97 Dynamic properties @ 2% Strain Tan delta 0.38 0.37 Tan delta 0.21 0.20 Dynamic properties @ 2% Strain Tan delta 0.69 0.65 Tan delta 0.23 0.22 |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion