Cure system effect on low temperature dynamic shear modulus of natural rubber.Natural rubber (NR) is used in many dynamic applications. Its ability to strain crystallize crys·tal·lize also crys·tal·ize v. crys·tal·lized also crys·tal·ized, crys·tal·liz·ing also crys·tal·iz·ing, crys·tal·liz·es also crys·tal·iz·es v.tr. 1. imparts high physical properties. These properties can develop at light levels of loading, which along with polymer polymer (pŏl`əmər), chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond). structure, can result in low levels of damping damping In physics, the restraint of vibratory motion, such as mechanical oscillations, noise, and alternating electric currents, by dissipating energy. Unless a child keeps pumping a swing, the back-and-forth motion decreases; damping by the air's friction opposes the , ideal for rubber isolators. Cure systems are known to affect low temperature properties. In natural rubber, modulus See modulo. increases with progressive levels of crystallization Crystallization The formation of a solid from a solution, melt, vapor, or a different solid phase. Crystallization from solution is an important industrial operation because of the large number of materials marketed as crystalline particles. . The degree of crosslinking is known to affect the amount of crystallization (ref. 1). Service temperature of natural rubber is limited at the high end to approximately ap·prox·i·mate adj. 1. Almost exact or correct: the approximate time of the accident. 2. 80[degrees]C, depending on cure system. At the lower end, natural rubber has a glass transition temperature The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state). of -72[degrees]C, but it becomes effectively non-compliant much before this. A designer desires constant spring rates for critical applications. Unfortunately, rubber properties, including modulus, are affected by time, temperature, strain history, frequency, etc. The rapid increase in modulus at lower temperatures may be avoided, to a degree, in formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation development by using polymers with very low Tgs 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) or silicone silicone, polymer in which atoms of silicon and oxygen alternate in a chain; various organic radicals, such as the methyl group, CH3, are bound to the silicon atoms. (MVQ MVQ Motion Vector Quantization MVQ Methyl Vinyl Silicone MVQ Martin Vallely Quartet ). However, these polymers do not possess the strength and fatigue fatigue, in engineering fatigue, in engineering, microscopic cracking of materials, especially metals, after repeated applications of stress. Fissures may be formed within pieces of metal during their manufacture when, while cooling from the molten state, resistance properties of NR. Lower temperature properties of NR can be improved by polymer blending A polymer blend, polymer alloy, or polymer mixture is a member of a class of materials analogous to metal alloys, in which two or more polymers are blended together to create a new material with different physical properties. , use of plasticizing oils, or by varying the cure system. The methodology for measuring lower temperature shear modulus shear modulus See under modulus of elasticity. was explored on a servohydraulic dynamic tester. Also, a variety of cure systems was studied in lightly filled natural lubber. The shear modulus changes can be applied in engineering applications where time and temperature dependent changes in modulus are important. A 48 hour soak (exposure at temperature) is the primary evaluation period Evaluation period The time interval over which funds assess a money manager's performance. , simulating a weekend of exposure at temperature without use. Large 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 , 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. or various longer crosslinks, show a marked delay in modulus increase as compared to short crosslinks formed with lightly crosslinked peroxide peroxide (pərŏk`sīd), chemical compound containing two oxygen atoms, each of which is bonded to the other and to a radical or some element other than oxygen; e.g. and EV sulfur cure systems. High crosslink density cure systems are still best at minimizing the crystallization induced induced /in·duced/ (in-dldbomacst´) 1. produced artificially. 2. produced by induction. induced, adj artificially caused to occur. induced induction. modulus increase at low temperatures (ref. 2). Several alternate alternate /al·ter·nate/ (awl´ter-nit) 1. following in turns. 2. pertaining to every other one in a series. 3. occurring in place of another; acting as a substitute. cure systems and variations on traditional sulfur cure systems exist today. These systems ale used for a variety of intended purposes, including heat resistance, fatigue and reversion reversion: see atavism. resistance. An evaluation of the low temperature vs. room temperature modulus change was made for these crosslink systems. Some of these introduce large molecules into the crosslink. These large molecules could interfere with some crystallization and thereby minimize In a graphical environment, to hide an application that is currently displayed on screen. For example, in Windows and Mac, the application's window is removed from the screen and represented by an icon on the Windows Taskbar. In the Mac, the icon is placed in the Dock. See Win Minimize windows. modulus increase. Most of the studied systems are shown in table 1. * Sulfur cured systems at various sulfur levels; * peroxide cure system (DCP DCP - definitional constraint programming ); * peroxide cure system with coagent Co`a´gent n. 1. An associate in an act; a coworker. TMPTMA; * low sulfur systems with Na-HMT; * low sulfur systems with CIMB CIMB Commerce International Merchant Bankers Berhad CIMB Current Issues in Molecular Biology (periodical) CIMB Corporate Information Management Branch (British Columbia, Canada) ; * low sulfur systems with BDBzTH; and * low sulfur systems with NPDI NPDI New Product Development and Introduction (core business process) or urethane urethane (yoor´ithān´), n ethyl carbamate used as an anesthetic agent for laboratory animals, formerly used as a hypnotic in humans. . The cure system components CIMB, Na-HMT, BDBZTH and in some cases urethane are primarily intended to reduce reversion during cure in high sulfur systems. They become part of the crosslink system. Since the molecules are so bulky bulk·y adj. bulk·i·er, bulk·i·est 1. Having considerable bulk; massive. 2. Of large size for its weight: a bulky knit. 3. Clumsy to manage; unwieldy. , it was decided to examine their influence on lower sulfur cure systems, and their influence on crystallization. The urethane cure system introduces a very large molecule molecule (mŏl`əky  l) [New Lat.,=little mass], smallest particle of a compound that has all the chemical properties of that compound. into the
crosslink. Similarly, during peroxide 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. , the coagent TMPTMA
can become part of the crosslink system.Experimental Simple base formulations were used for the evaluation and are shown in table 2. Formulations were mixed in two passes on a laboratory 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. . Modulus measurements were made using dual lap shear shear: see strength of materials. Shear A straining action wherein applied forces produce a sliding or skewing type of deformation. samples on a servohydraulic dynamic test machine (ref. 3). Samples were cured and bonded 30 minutes at 160[degrees]C. The rubber cross-sectional cross section also cross-sec·tion n. 1. a. A section formed by a plane cutting through an object, usually at right angles to an axis. b. A piece so cut or a graphic representation of such a piece. 2. dimensions were 50.8 mm x 6.35 mm x 12.7 mm for each shear rubber portion. A 15 minute 100[degrees]C soak and a 15 minute 23[degrees]C cool down was used prior to indicated soak conditions to remove residual Residual See:Residual value crystallization. The samples were then immediately subjected to the soak temperature, with no ramping or stepping of temperature. Samples strained to [+ or -] 10% displacement displacement, in psychology: see defense mechanism. Same as offset. See base/displacement. at 20 Hz were noted to have little detected change in dynamic modulus Dynamic modulus is the ratio of stress to strain under vibratory conditions (calculated from data obtained from either free or forced vibration tests, in shear, compression, or elongation). It is a property of viscoelasticity materials. . This contradicted quasi [Latin, Almost as it were; as if; analogous to.] In the legal sense, the term denotes that one subject has certain characteristics in common with another subject but that intrinsic and material differences exist between them. static test results from load displacement tests. The high damping at low temperature results in immediate internal heat generation, and therefore an almost immediate decrease in modulus. This rate of change will be a function of energy input into the system. Figure 1 shows how quickly the modulus changes with each sinusoidal sinusoidal /si·nus·oi·dal/ (si?nu-soi´dal) 1. located in a sinusoid or affecting the circulation in the region of a sinusoid. 2. shaped like or pertaining to a sine wave. cycle. When the sample is forced to a specified spec·i·fy tr.v. spec·i·fied, spec·i·fy·ing, spec·i·fies 1. To state explicitly or in detail: specified the amount needed. 2. To include in a specification. 3. 10% amplitude amplitude (ăm`plĭt d'), in physics, maximum displacement from a zero value or rest position. in
displacement control, the percent modulus change is rapid. Instead, if
measurements are taken for forces of [+ or -] 222 N, the rate of change
is minimal, especially during the first 20 cycles. In order to reflect a
real world application, all further testing was revised. Instead of a
displacement based amplitude, a force based amplitude was chosen.
Samples were strained to [+ or -] 222 N at 20 Hz. Dynamic modulus
measurements with the servohydraulic system were made through a sine
regression regression, in psychology: see defense mechanism. regression In statistics, a process for determining a line or curve that best represents the general trend of a data set. calculation over the first eight cycles. Measurements were taken at described temperatures and compared with room temperature (23[degrees]C) results. [FIGURE 1 OMITTED] Discussion The focus of this article is the effect of the crosslink system on dynamic modulus change with decreasing temperature. It is known that there is an inverse relationship A inverse or negative relationship is a mathematical relationship in which one variable decreases as another increases. For example, there is an inverse relationship between education and unemployment — that is, as education increases, the rate of unemployment between state of cure and degree of crystallization (ref. 1). Highly crosslinked systems result in a delayed increase in modulus. This has been attributed to steric steric /ste·ric/ (ster´ik) pertaining to the arrangement of atoms in space; pertaining to stereochemistry. ster·ic or ster·i·cal n. interference interference, in physics, the effect produced by the combination or superposition of two systems of Waves, in which these waves reinforce, neutralize, or in other ways interfere with each other. with crystallite crys·tal·lite n. Any of numerous minute rudimentary, crystalline bodies of unknown composition found in glassy igneous rocks. crys formation. Indeed, measurements of dynamic modulus in the base formulation with varying sulfur levels show a marked difference in modulus at lower temperatures (figure 2). The decreasing state of cure with less sulfur shows more dramatic increases in modulus, especially at the lowest 0.5 phr level. [FIGURE 2 OMITTED] Low sulfur and urethane systems Figure 2 showed that the most pronounced changes in modulus occurred with the lowest sulfur formulation. It was decided to modify this 0.5 phr sulfur level cure system with the cure components Na-HMT, CIMB, BDBzTH and NPDI, and to test a no sulfur NPDI cure system. Figure 3 and table 3 show the resulting changes in modulus. [FIGURE 3 OMITTED] All of the modified mod·i·fy v. mod·i·fied, mod·i·fy·ing, mod·i·fies v.tr. 1. To change in form or character; alter. 2. cure systems show a much smaller change in modulus with decreasing temperature. The system with a high level of BDBzTH was influenced by temperature the least. Table 3 shows these data. The 100% and 300% modulus and G * can be an indicator Indicator Anything used to predict future financial or economic trends. Notes: In the context of technical analysis, an indicator is a mathematical calculation based on a securities price and/or volume. The result is used to predict future prices. of cure state changes. The indication is that for most the cure state changes little, but the modulus change is greatly affected. Figure 3 shows that BDBzTH at 3 phr performs the best. However, table 3 clearly shows that at the high 3 phr level, BDBzTH has an increased state of cure. The 1 phr BDBzTH, 3 phr CIMB and 1 phr Na-HMT all show improvements at low temperature with similar cure states. Na-HMT at higher levels (3 phr) does not perform as well as when used at the lower 1 phr level. 1.0 phr sulfur level A similar improvement in change with temperature is noted at the higher 1.0 sulfur level (figure 4). The CIMB and BDBzTH perform slightly better than the Na-HMT. Material properties from table 4 indicate cure state is similar for most, but begins to increase at the higher level of BDBzTH. Again, the high 3 phr level Na-HMT does not perform as well as the other modified crosslinks. [FIGURE 4 OMITTED] Peroxide cure system An experimental design and results are shown in table 5, examining the effect of dicumyl peroxide level and TMPTMA coagent level on modulus. Figure 5 illustrates the effect on room temperature modulus. Regression coefficients Regression coefficient Term yielded by regression analysis that indicates the sensitivity of the dependent variable to a particular independent variable. See: Parameter. regression coefficient are shown in table 6 with Rsq = 99.2%, and are based on the coded levels of table 5. [FIGURE 5 OMITTED] Figure 6 illustrates the effect on change in modulus at -30[degrees]C. Similar changes were noted at -10[degrees]C and at -40[degrees]C. Increasing peroxide or coagent significantly reduces changes in modulus at low temperatures. This is expected as the crosslink density increases in either case. Regression coefficients of table 7 show that the peroxide levels have a greater influence at low temperature. Peroxide level has a greater impact than coagent level. [FIGURE 6 OMITTED] If a comparison is attempted at similar states of cure, it appears that the coagent effect is limited to increasing the state of cure, and hence modulus change. Compare table 5 formulations C and E. Both have similar cure state (as measured my 100%, 300% tensile tensile, adj having a degree of elasticity; having the ability to be extended or stretched. modulus and room temperature shear modulus). However, the low temperature modulus change is less pronounced for the higher peroxide level formulation E. A similar example is a comparison of formulations B and D. Change in modulus over time Samples were given a 48 hour soak and then held for longer periods of time to evaluate longer-term modulus change. Figure 7 shows that the very low sulfur level of recipe R1.1 (table 8) is very, stiff Stiff may refer to:
Albanian cuisine
tr. & intr.v. stiff·ened, stiff·en·ing, stiff·ens To make or become stiff or stiffer. stiff as much. The high sulfur recipes remain much softer. Data are compiled in table 8. [FIGURE 7 OMITTED] Conclusion Formulating for applications requiring high strength, high fatigue natural rubber compounds operating in temperature regions less than 0[degrees]C can require careful consideration of the cure system. Higher sulfur systems will provide comparatively smaller dynamic modulus increases at lower temperatures. However, applications that require improved heat and aging resistance can be served by semi-EV cure systems or very low sulfur systems with long chain crosslink modifiers. These longer chain crosslink modifications can serve to minimize changes in dynamic modulus with temperature and time. Similarly, higher crosslink densities in peroxide cure systems, through coagents or increased peroxide, can also minimize changes in dynamic modulus with temperature and time. For sulfur crosslink systems, modification A change or alteration in existing materials. Modification generally has the same meaning in the law as it does in common parlance. The term has special significance in the law of contracts and the law of sales. with CIMB or BDBzTH offers the best low temperature performance. Crosslink modification is one tool that can be used for low temperature natural rubber optimization optimization Field of applied mathematics whose principles and methods are used to solve quantitative problems in disciplines including physics, biology, engineering, and economics. . References (1.) Vulcanization of Elastomers, ed. F. Alliger and I.J. Sjothun, Reinhold Reinhold is a surname and given name, and may refer to: As a surname:
(2.) Natural Rubber Science and Technology; ed. A.D. Roberts. Oxford University Press 1988, Ch. 18, A. Stevenson. (3.) "Comparison of dynamic test methods and machines for elastomers," R.J. Del Vecchio Del Vecchio is a surname, and may refer to:
Table 1
Name Chemical name
DCP Dicumyl peroxide
TMPTMA Trimethylolpropane trimethacrylate
Na-HMT Hexamethylene-1,6-bisthiosulfate
disodium salt, dihydrate
CIMB 1,2-bis (citraconimidomethyl)benzene
BDBzTH 1,6-Bis (N,N'-dibenzylthiocarbamoyldithio)
hexane
NPDI Nitrosophenol/methylene di-isocyanate
or urethane adduct
Table 2--formulations
Sulfur Peroxide
and urethane
CV-60 natural rubber 100 100
N550 carbon black 1 1
Stearic acid 2 --
Zinc oxide 3 --
PTMQ 1.5 1.5
IPPD 1.5 --
Wax 2 2
Z-MB2 -- 2
70% dicumyl peroxide -- Variable
72% TMPTMA -- Variable
CBS Variable --
Sulfur Variable --
Table 3--formulations and results for 0.5 phr sulfur experiments
Low sulfur level
ID R1.1 R1.2 R1.3
CV-60 100 100 100
N550 1 1 1
Stearic Acid 2 2 2
ZnO 3 3 3
PTMQ 1.5 1.5 1.5
IPPD 1.5 1.5 1.5
Wax 2 2 2
Second cycle ingredients
CBS 2 2 2
Sulfur 0.5 0.5 0.5
Na-HMT -- -- --
CIMB -- 1 3
BDBzTH -- -- --
NPDI -- -- --
ZDMC -- -- --
TMTM -- -- --
Total 113.5 114.5 116.5
Hardness (durometer A) 32 34 34
Tensile (MPa) 10.6 10.2 10.9
Elongation (%) 791 712 791
100% modulus (MPa) 0.59 0.63 0.61
300% modulus (MPa) 1.5 1.4 1.3
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 445 442 457
G' (kPa) 445 442 456
Tan delta 0.05 0.06 0.06
G* % change, 48 hrs. soak at temperature
4[degrees]C 6% 4%
-10[degrees]C 19% 27% 22%
-20[degrees]C 259% 98% 64%
-30[degrees]C 481% 165% 107%
-40[degrees]C 830% 250% 200%
ID R1.4 R1.5 R1.6
CV-60 100 100 100
N550 1 1 1
Stearic Acid 2 2 2
ZnO 3 3 3
PTMQ 1.5 1.5 1.5
IPPD 1.5 1.5 1.5
Wax 2 2 2
Second cycle ingredients
CBS 2 2 2
Sulfur 0.5 0.5 0.5
Na-HMT 1 3 --
CIMB -- -- --
BDBzTH -- -- --
NPDI -- -- 4
ZDMC -- -- --
TMTM -- -- --
Total 114.5 116.5 115.7
Hardness (durometer A) 35 35 32
Tensile (MPa) 11.9 11.8 9.7
Elongation (%) 745 764 596
100% modulus (MPa) 0.63 0.58 0.68
300% modulus (MPa) 1.4 1.1 1.5
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 459 451 449
G' (kPa) 459 450 448
Tan delta 0.05 0.06 0.07
G* % change, 48 hrs. soak at temperature
4[degrees]C 4% 13%
-10[degrees]C 21% 55% 17%
-20[degrees]C 99% 96%
-30[degrees]C 114% 269% 117%
-40[degrees]C 225% 370% 242%
ID R1.7 R1.8 R1.9
CV-60 100 100 100
N550 1 1 1
Stearic Acid 2 2 2
ZnO 3 3 3
PTMQ 1.5 1.5 1.5
IPPD 1.5 1.5 1.5
Wax 2 2 2
Second cycle ingredients
CBS 2 2 --
Sulfur 0.5 0.5 --
Na-HMT -- -- --
CIMB -- -- --
BDBzTH 1 3 --
NPDI -- -- 6.7
ZDMC -- -- 2
TMTM -- -- 1
Total 114.5 116.5 120.7
Hardness (durometer A) 36 39 35
Tensile (MPa) 13.8 14.3 13.0
Elongation (%) 517 479 527
100% modulus (MPa) 0.68 0.83 0.79
300% modulus (MPa) 2.0 2.7 2.0
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 437 520 488
G' (kPa) 437 520 487
Tan delta 0.04 0.02 0.06
G* % change, 48 hrs. soak at temperature
4[degrees]C
-10[degrees]C 15% 11% 23%
-20[degrees]C 25% 21%
-30[degrees]C 92% 42% 231%
-40[degrees]C 195% 77% 420%
Table 4--formulations, results for 1.0 phr sulfur experiments
Sulfur level at 1 phr
ID R2.1 R2.2 R2.3
CV-60 100 100 100
N550 1 1 1
Stearic acid 2 2 2
ZnO 3 3 3
PTMQ 1.5 1.5 1.5
IPPD 1.5 1.5 1.5
Wax 2 2 2
Second cycle ingredients
CBS 1.6 1.6 1.6
Sulfur 1 1 1
CIMB -- 3 --
Na-HMT -- -- 3
BDBzTH -- -- --
Total 113.6 116.6 116.6
Hardness (durometer A) 36 36 35
Tensile (MPa) 13.7 12.3 13.7
Elongation (%) 857 835 856
100% modulus (MPa) 0.72 0.70 0.69
300% modulus (MPa) 1.74 1.59 1.54
G* (23[degrees]C) (kPa) 474 442 491
G' (23[degrees]C) (kPa) 474 491 490
Tan delta (23[degrees]C) 0.04 0.05 0.05
G* % change, 48 hrs. soak at temperature
4[degrees]C 3% 4% 9%
-10[degrees]C 12% 13% 19%
-20[degrees]C 47% 26% 39%
-30[degrees]C 103% 39% 75%
-40[degrees]C 141% 60% 87%
ID R2.4 R2.5
CV-60 100 100
N550 1 1
Stearic acid 2 2
ZnO 3 3
PTMQ 1.5 1.5
IPPD 1.5 1.5
Wax 2 2
Second cycle ingredients
CBS 1.6 1.6
Sulfur 1 1
CIMB -- --
Na-HMT -- --
BDBzTH 1 3
Total 114.6 116.6
Hardness (durometer A) 38 42
Tensile (MPa) 15.6 12.9
Elongation (%) 430 408
100% modulus (MPa) 0.84 1.05
300% modulus (MPa) 2.66 3.81
G* (23[degrees]C) (kPa) 499 597
G' (23[degrees]C) (kPa) 499 597
Tan delta (23[degrees]C) 0.02 0.02
G* % change, 48 hrs. soak at temperature
4[degrees]C
-10[degrees]C 13% 11%
-20[degrees]C
-30[degrees]C 30% 33%
-40[degrees]C 44% 43%
Table 5--experimental design and results for peroxide/coagent experiment
Peroxide/coagent design Perox./ Perox./ Perox./
coa. coa. coa.
A B C
CV-60 100 100 100
N550 1 1 1
PTMQ 1.5 1.5 1.5
Wax 2 2 2
Z-MB2 2 2 2
Second cycle ingredients
70% dicumyl peroxide 1.43 1.43 1.43
SR 350-72% 0 5 10
Total: 107.93 112.93 117.93
Hardness (durometer A) 27 35 39
Tensile (MPa) 4.51 14.04 14.78
Elongation (%) 593 544 479
100% modulus (MPa) 0.46 0.74 0.86
300% modulus (MPa) 0.93 2.12 3.49
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 324 429 508
G' (kPa) 322 428 508
Tan delta 0.10 0.07 0.07
G* % change, 48 hr. soak at temperature
-10[degrees]C 584% 98% 46%
-30[degrees]C 743% 639% 328%
-40[degrees]C 903% 661% 407%
Coded perox. level -1 -1 -1
Coded coagent level -1 0 1
Peroxide/coagent design Perox./ Perox./ Perox./
coa. coa. coa.
D E F
CV-60 100 100 100
N550 1 1 1
PTMQ 1.5 1.5 1.5
Wax 2 2 2
Z-MB2 2 2 2
Second cycle ingredients
70% dicumyl peroxide 2.714 2.714 2.714
SR 350-72% 0 5 10
Total: 109.214 114.214 119.214
Hardness (durometer A) 35 39 44
Tensile (MPa) 9.51 15.23 12.20
Elongation (%) 533 452 375
100% modulus (MPa) 0.72 0.97 1.23
300% modulus (MPa) 1.73 3.37 6.32
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 399 509 646
G' (kPa) 398 508 646
Tan delta 0.06 0.05 0.05
G* % change, 48 hr. soak at temperature
-10[degrees]C 27% 18% 17%
-30[degrees]C 296% 58% 46%
-40[degrees]C 474% 116% 159%
Coded perox. level 0 0 0
Coded coagent level -1 0 1
Peroxide/coagent design Perox./ Perox./ Perox./
coa. coa. coa.
G H I
CV-60 100 100 100
N550 1 1 1
PTMQ 1.5 1.5 1.5
Wax 2 2 2
Z-MB2 2 2 2
Second cycle ingredients
70% dicumyl peroxide 4 4 4
SR 350-72% 0 5 10
Total: 109.5 114.5 119.5
Hardness (durometer A) 35 42 46
Tensile (MPa) 7.08 10.46 7.45
Elongation (%) 374 349 259
100% modulus (MPa) 0.79 1.13 1.50
300% modulus (MPa) 1.92 4.43
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 452 630 785
G' (kPa) 452 630 785
Tan delta 0.04 0.03 0.03
G* % change, 48 hr. soak at temperature
-10[degrees]C 15% 10% 11%
-30[degrees]C 108% 31% 22%
-40[degrees]C 132% 53% 41%
Coded perox. level 1 1 1
Coded coagent level -1 0 1
Peroxide/coagent design Perox./
coa. Rep E
J E2
CV-60 100 replicate
N550 1 of E
PTMQ 1.5
Wax 2
Z-MB2 2
Second cycle ingredients
70% dicumyl peroxide 2
SR 350-72% 10
Total: 117.5
Hardness (durometer A) 39
Tensile (MPa) 13.49 14.90
Elongation (%) 442 444
100% modulus (MPa) 1.01
300% modulus (MPa) 4.12
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 610 506
G' (kPa) 609 505
Tan delta 0.05 0.05
G* % change, 48 hr. soak at temperature
-10[degrees]C 21% 17%
-30[degrees]C 112% 55%
-40[degrees]C 185% 110%
Coded perox. level -0.5 0
Coded coagent level 1 0
Peroxide/coagent design
Rep E
E2
CV-60 replicate
N550 of E
PTMQ
Wax
Z-MB2
Second cycle ingredients
70% dicumyl peroxide
SR 350-72%
Total:
Hardness (durometer A)
Tensile (MPa) 15.30
Elongation (%) 459
100% modulus (MPa)
300% modulus (MPa)
Dynamic @ 20 Hz, [+ or -] 222 N amplitude
G* (kPa) 508
G' (kPa) 508
Tan delta 0.05
G* % change, 48 hr. soak at temperature
-10[degrees]C 20%
-30[degrees]C 58%
-40[degrees]C 111%
Coded perox. level 0
Coded coagent level 0
Table 6--regression analysis peroxide/coagent design of table 5 for
room temperature (23[degrees]) complex modulus (G*)*--levels are
coded according to table 5
Stat. Regr. coefficients; Var.: GRTCOMPL; R-sqr = .99217;
adj.:98565
Experimental 2 factors, 1 block, 12 runs; MS residual = 225.0564
Design DV. GRTCOMPL
Regressn.
Factor Coeff. Std. Err. t(6) p
Mean/Interc. 515.127 * 7.65 * 67.30 * .000000 *
1. PeroxLV (L) 99.005 * 6.04 * 16.39 * .000003 *
PeroxLV ^2 (Q) 3.656 9.21 0.40 0.705108
2. CoagLV (L) 131.358 * 5.78 * 22.74 * .000000 *
CoagLV ^2 (Q) 5.646 9.07 0.62 0.556431
1L by 2L 34.098 * 7.34 * 4.64 * .003529 *
-95.00% -95.00%
Factor cnf. limit cnf. limit
Mean/Interc. 496.4 * 533.9 *
1. PeroxLV (L) 84.2 * 113.8 *
PeroxLV ^2 (Q) -18.9 26.2
2. CoagLV (L) 117.2 * 145.5 *
CoagLV ^2 (Q) -16.5 27.8
1L by 2L 16.1 * 52.1 *
Table 7--regression analysis peroxide/coagent design of table 5 for
-30[degrees]C percent change in complex dynamic modulus (G*)--levels
are coded according to table 5
Stat. Regr. Coefficients; Var.: C_30BIG; R-sqr. = .96915;
adj.:.94344
Experimental 2 factors, 1 block, 12 runs; MS residual = 3464.149
Design DV: C_30BIG
Regressn
Factor Coeff. Std. Err. t(6) p
Mean/Interc. 87.211 * 30.03 * 2.90 * .027180 *
1. PeroxLV (L) -256.630 * 23.69 * -10.83 * .000037 *
PeroxLV ^2 (Q) 202.436 * 36.13 * 5.60 * .001377 *
2. CoagLV (L) -128.037 * 22.66 * -5.65 * .001318 *
CoagLV ^2 (Q) 32.112 35.57 0.90 0.401476
1L by 2L 84.243 * 28.81 * 2.92 * .026495 *
-95.00% -95.00%
Factor Cnf. limit Cnf. limit
Mean/Interc. 13.7 * 160.7 *
1. PeroxLV (L) -314.6 * -198.7 *
PeroxLV ^2 (Q) 114.0 * 290.8 *
2. CoagLV (L) -183.5 * -72.6 *
CoagLV ^2 (Q) -54.9 119.2
1L by 2L 13.7 * 154.7 *
Table 8--change in modulus with time--samples exposed -30[degrees]C for
indicated time--actual modulus (G*) and percent change shown
ID: R1.1 SM SH SHH
CV-60 100 100 100 100
N550 1 1 1 1
Stearic acid 2 2 2 2
ZnO 3 3 3 3
PTMQ 1.5 1.5 1.5 1.5
IPPD 1.5 1.5 1.5 1.5
Wax 2 2 2 2
Second cycle ingredients
CBS 2 1.6 0.8 0.4
Sulfur 0.5 1 2 2.5
Na-HMT -- -- -- --
CIMB -- -- -- --
BDBzTH -- -- -- --
Total 113.5 113.6 113.8 113.9
G* Modulus (kPa)
23[degrees]C 445 477 553 531
48 hrs. at -30[degrees]C 2,586 969 716 727
312 hrs. at -30[degrees]C 2,948 2,276
336 hrs. at -30[degrees]C 727 740
288 hrs. at -30[degrees]C
432 hrs. at -30[degrees]C 3,268 2,405
Percent change
48 hrs. at -30[degrees]C 481 103 30 37
312 hrs. at -30[degrees]C 562 378
336 hrs. at -30[degrees]C 32
288 hrs. at -30[degrees]C
432 hrs. at -30[degrees]C 634
ID: R1.2 R1.3 RI.4 R1.5
CV-60 100 100 100 100
N550 1 1 1 1
Stearic acid 2 2 2 2
ZnO 3 3 3 3
PTMQ 1.5 1.5 1.5 1.5
IPPD 1.5 1.5 1.5 1.5
Wax 2 2 2 2
Second cycle ingredients
CBS 2 2 2 2
Sulfur 0.5 0.5 0.5 0.5
Na-HMT -- -- 1 3
CIMB 1 3 -- --
BDBzTH -- -- -- --
Total 114.5 116.5 114.5 116.5
G* Modulus (kPa)
23[degrees]C 442 457 459 451
48 hrs. at -30[degrees]C 1,173 944 983 1,663
312 hrs. at -30[degrees]C
336 hrs. at -30[degrees]C
288 hrs. at -30[degrees]C 1,724 3,378
432 hrs. at -30[degrees]C 2,850 2,501
Percent change
48 hrs. at -30[degrees]C 165 107 114 269
312 hrs. at -30[degrees]C
336 hrs. at -30[degrees]C
288 hrs. at -30[degrees]C 276 649
432 hrs. at -30[degrees]C 545 448
ID: R1.7 R1.8
CV-60 100 100
N550 1 1
Stearic acid 2 2
ZnO 3 3
PTMQ 1.5 1.5
IPPD 1.5 1.5
Wax 2 2
Second cycle ingredients
CBS 2 2
Sulfur 0.5 0.5
Na-HMT -- --
CIMB -- --
BDBzTH 1 3
Total 114.5 116.5
G* Modulus (kPa)
23[degrees]C 437 520
48 hrs. at -30[degrees]C 839 739
312 hrs. at -30[degrees]C
336 hrs. at -30[degrees]C
288 hrs. at -30[degrees]C
432 hrs. at -30[degrees]C 2,454 1,268
Percent change
48 hrs. at -30[degrees]C 92 42
312 hrs. at -30[degrees]C
336 hrs. at -30[degrees]C
288 hrs. at -30[degrees]C
432 hrs. at -30[degrees]C 462 144
Figure 5--particle size distribution NDR 47085--Lot
RC0426SDDD
Sieve size (mm)
%
% of total distribution Running total
3.35 9.7
2.35 18.2
1.68 28.6
1.19 41
0.84 52.1
0.59 64.6
0.42 76.2
0.30 85
0.21 90.9
0.15 94.8
0.11 99.7
0.08 99.4
0.05 100
Note: Table made from bar graph.
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