Peptizer influence on rubber-to-steel cord adhesion.For long life truck tires and high performance passenger car tires, a good rubber-to-steel cord adhesion is essential. From the literature (ref. 1) it is known that the rubber-to-steel cord adhesion depends not only on the type of steel cord used, but also on the different ingredients of the skim compound. The NR, necessary for the production of the skim compound, will usually be masticated to ensure a good flowability of the compound. Besides a good flowability of the rubber compound, a sufficiently long scorch time is imperative for obtaining good penetration of the interstices of the steel cord. The mastication mastication /mas·ti·ca·tion/ (mas?ti-ka´shun) chewing; the biting and grinding of food. mastication (mas´tikā´sh reduces the molar mass Molar mass, symbol M,[1] is the mass of one mole of a substance (chemical element or chemical compound).[2] It is a physical property which is characteristic of each pure substance. of the macromolecules Macromolecules A large molecule composed of thousands of atoms. Mentioned in: Gene Therapy macromolecules and thus enables improved processing. Today, for economic reasons, the mastication process is performed in an internal mixer in the presence of a peptizer (reft 2). With regard to masticated NR for skim compounds, the question is often raised as to whether the peptizer has any effect on the aging properties and especially on the rubber-to-steel cord adhesion properties of the vulcanizates. This study deals with the in vestigation of the highly active peptizer Renacit 11/WG. It is composed of 2,2`-dibenzami-dodiphenyldisulfide (DBD DBD DNA binding Domain (nuclear receptors) DBD Database Design DBD Day-By-Day DBD Database Description dBd Decibels (dipole antenna) DBD Death Before Dishonor (gaming clan) ), a small amount of a specific activator, an inactive filler and a binder for the production of dust-flee granules Granules Small packets of reactive chemicals stored within cells. Mentioned in: Allergic Rhinitis, Allergies and was developed as a substitute for the discontinued dis·con·tin·ue v. dis·con·tin·ued, dis·con·tin·u·ing, dis·con·tin·ues v.tr. 1. To stop doing or providing (something); end or abandon: peptizer Renacit 7/WG, which was based on activated pentachloro-thiophenol (PCTP PCTP Partido Comunista dos Trabalhadores Portugueses PCTP Payload Complement Training Plan PCTP Push Channel Tire Pressure PCTP Private Communication Transport Protocol ). Experiments Mastication The mastication trials were performed in a separate step on the laboratory scale using a Werner & Pfieiderer internal mixer (Model GK 1.5 E) with a volume of 1.5 liters and inter-locking rotors. The NR grade used was TSR (Terminate and Stay Resident) Refers to a program that remains in memory when the user exits it in order that it be immediately available at the press of a hotkey. 5 with an original Mooney viscosity of 89. The peptizers used were Renacit 7/WG (0.125 pbw), Renacit 11/WG (0.1 pbw) and pure, non-activated DBD (0.1 pbw). The mixer was filled to 65%. The speed was set at 60 rpm and the ram pressure In physics, ram pressure is a pressure exerted on a body which is moving through a fluid medium. It causes a strong drag force to be exerted on the body. For example, a meteor traveling through the Earth's atmosphere produces a shock wave generated by the extremely rapid at 8 bar. The heating medium temperature was 85 [degrees] C. Exactly 10 seconds after loading the mixer with NR and peptizer, the ram was lowered. The total mixing time was three minutes "Three Minutes" is the 46th episode of Lost. It is the twenty-second episode of the second season. The episode was directed by Stephen Williams, and written by Edward Kitsis and Adam Horowitz. It first aired on May 17, 2006 on ABC. . In all cases, the maximum temperature and the discharge temperature of the rubber were approximately 148 [degrees] C. In the case of using no peptizer, the mastication time was 16 minutes. The maximum temperature of the rubber was again approximately 148 [degrees] C. However, the discharge temperature was in this case only 139 [degrees] C. In this way, samples of masticated NR having a Mooney viscosity of 54 [+ or -] 1 were obtained. Compounding The various skim compounds were produced in a mixer of the same model as described above. The formulation used is outlined in table 1. The setting of the mixer was the same as for mastication, however, the speed was increased to 65 rpm and the heating medium temperature was decreased to 60 [degrees] C. After 30 seconds of warming up the masticated rubber, while the ram was down, all ingredients with the exception of the curatives and the HMMM HMMM Hexamethoxymethylmelamine formulation (hexamethylolmelamine ether ether, in chemistry ether, any of a number of organic compounds whose molecules contain two hydrocarbon groups joined by single bonds to an oxygen atom. on filler) were added. During the mixing, the shaft was brushed down twice. The compound was discharged after five minutes. The sulfur, the accelerator and the methylene methylene /meth·y·lene/ (meth?i-len) the bivalent hydrocarbon radical —CH2— or CH2dbond. meth·yl·ene n. component of the bonding system were added on the open mill. The samples for the determination of the Mooney viscosity and the cure characteristics were taken from the remaining part of the compound after sheeting out for the preparation of the various test specimens. Table 1 - formulation NR (masticated TSR 5) 100.00 pbw Carbon black N 326 50.00 pbw Silica 10.00 pbw Zinc oxide 6.00 pbw Tackifier resin 3.00 pbw 6PPD 1.00 pbw Resorcinol formulation (66.6%) 3.00 pbw Cobalt salt (22.5% Co) 0.44 pbw Aromatic mineral oil 3.00 pbw Insoluble sulfur (80%) 6.50 pbw DCBS 1.30 pbw HMMM formulation (50%) 4.00 pbw 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. In each case, the vulcanization temperature was 150 [degrees] C. The vulcanization time was a combination of the t90-value and a mold-related warming up time. The resulting period was then rounded to the nearest five minutes. In the case of the tests for the rubber-to-steel cord adhesion, a separate overcure series was performed with a further 60 minutes of vulcanization time. Aging The aging tests of the vulcanizates were performed as follows: Hot air aging with circulation: DIN 53508, 70 [degrees] C, seven and 14 days. Oxygen bomb aging: DIN 53508, 70 [degrees] C, 21 bar 02, four days. Steam aging: 105 [degrees] C, four days. Moisture aging: 70 [degrees] C, 100% humidity, 28 days. Testing The following testing standards/devices were applied: Mooney viscosity: DIN 53523 large rotor, 100 [degrees] C, warming up time one minute, testing time four minutes. Rheometer rhe·om·e·ter n. An instrument for measuring the flow of viscous liquids, such as blood. : ASTM ASTM abbr. American Society for Testing and Materials D 2084, Monsanto 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 E, 150 [degrees] C. Stress/strain: DIN 53504. Hardness: DIN 53505, 23 [degrees] /70 [degrees] C. Rebound resilience: DIN 53512, 23 [degrees] / 70 [degrees] C. Dynamic properties: DIN 53533, Goodrich Flexometer, 100 [degrees] /25 min, pre-strain 1 MPa, stroke 4.45 mm. Viscoelastic Adj. 1. viscoelastic - having viscous as well as elastic properties natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" properties: DIN 53513/ISO 4664, Roelig-test, 10 Hz, 23 [degrees] /60 [degrees] C. Rubber-to-steel cord adhesion (pull out strength F (N), steel cord coverage): internal test method (ref. 3) of Bayer AG Bayer AG German chemical and pharmaceutical company. Founded in 1863 by Friedrich Bayer (1825–1880), it now operates plants in more than 30 countries. Bayer has originated scores of pharmaceuticals, chemicals, and synthetic materials; it was the first developer and , 80 [degrees] C, dimension of the test specimen 20 x 15 x 6 mm, brass plated steel cord of the construction 3+9x0.22+0.15 (N.V. Bekaert S.A.), copper content 67.5%, testing arrangement 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. figure 1, number of samples tested: eight, assessment of the steel cord coverage after pulling out the cord according to: 1: steel cord uncovered; 2: poor coverage of the steel cord; 3: good coverage of the steel cord; 4: tear within the rubber. [Figure 1 ILLUSTRATION OMITTED] Results The theological compound data obtained are shown in table 2. Considering that each masticated NR sample used had a Mooney viscosity of 54 [+ or -] 1, it can be concluded that the rubber must have been further masticated during the compounding step and the subsequent sheeting out for the preparation of test specimens. Otherwise, viscosities of the final rubber compounds of between 41 and 52 would not have been obtained.
Table 2 - rheological compound data
None 7/WG 11/WG DBD
ML(1+4)
100 [degrees] C (MU) 44 52 47 41
ts01 (min.) 1.77 1.78 1.85 1.97
t90 (min.) 19.40 19.32 23.22 22.62
S'max (dNm) 33.32 31.55 32.53 35.12
The basic vulcanizate properties before aging are outlined in table 3. According to these data, the three peptizers have practically no effect on the vulcanizate properties.
Table 3 - basic vulcanizate properties
None 7/WG 11/WG DBD
Tensile strength (MPa) 21 25 25 24
Elongation at
break (%) 350 384 374 381
Modulus 100 (MPa) 5.1 5.0 4.8 4.9
Modulus 200 (MPa) 11.4 11.7 11.7 11.2
Modulus 300 (MPa) 18.4 19.2 19.2 18.4
Hardness,
23[degrees]C (Shore A) 78 77 77 77
Hardness,
70[degrees]C (Shore A) 73 73 72 74
Rebound res.,
23 [degrees]C (%) 38 38 40 36
Rebound res.,
70[degrees]C (%) 50 50 53 52
From the residual 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 the residual elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. at break represented in figures 2 and 3, respectively, it can be seen that after hot air aging all peptizer-containing vulcanizates behave very similarly, especially after 14 days of aging. However, it seems that the peptizer-containing vulcanizates perform slightly worse than the peptizer-free control. This may be due to the very small amount, 1 pbw, of 6PPD (1) (Parallel Presence Detect) The method used by earlier SIMM memory modules to communicate their capacity to the computer. A binary number coming from a parallel set of pins was read by the system, with each pin representing one bit. Contrast with SPD. which was used as the antidegradant. The small antidegradant loading was specifically selected in order to have a sensitive tool for detecting any influence of the peptizer on the aging behavior of the vulcanizates. From other investigations (ref. 4) it can be concluded that 2 to 3 pbw of 6PPD, which is a typical loading in practice, will overcome the observed aging deficit. [Figures 2-3 ILLUSTRATION OMITTED] All the other testing data obtained alter hot air aging are more or less the same and in no case noticeably different. The dynamic vulcanizate properties according to the Gooodrich Flexometer test are shown in figure 4. Judged by the lowest temperature increase, the lowest permanent set and the lowest creep, the vulcanizates, which contain the peptizers 7/WG and l l/WG, respectively, performed the best, followed by the DBD containing vulcanizate, while the peptizer-free vulcanizate trails behind. [Figure 4 ILLUSTRATION OMITTED] Obviously, the compounds which contain activated peptizers generate a very favorable network structure providing the lowest temperature increase in this test. The viscoelastic properties under compressive stress Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume). When a material is subjected to compressive stress, then this material is under compression. Usually, compressive stress applied to bars, columns, etc. leads to shortening. according to the Roelig-Test are outlined in figures 5 and 6. The two vulcanizates, which contain the activated peptizers, yield approximately the same 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. E', loss modulus See modulo. E" and dissipation factor In physics, the dissipation factor (DF) is a measure of loss-rate of power of a mechanical mode, such as an oscillation, in a dissipative system. For example, electric power is lost in all dielectric materials, usually in the form of heat. tan 15. In terms of the lowest hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. , these vulcanizates performed the best, followed by the DBD containing vulcanizate. In this case, the poorest performance is shown by the peptizer-free control. [Figures 5-6 ILLUSTRATION OMITTED] The steel cord pull out strength [F.sub.0] of the unaged, optimum cured samples is shown in figure 7. When compared with the peptizer-free control, the pull out strength is reduced by approximately 9% in the case of DBD, by approximately 13% in the case of 11/WG and by approximately 18% in the case of 7/WG. In total, however, the peptizer-containing, unaged vulcanizates provide a pull out strength level which is still sufficient if one considers the steel cord coverage (table 4). For the 11/WG containing vulcanizate, the steel cord coverage was assessed to be 3 to 4. In all the other cases the assessment made was 3, including the peptizer-free control. [Figure 7 ILLUSTRATION OMITTED]
Table 4 - steel cord coverage after aging
(optimun cured)
None 7/WG 11/WG DBD
Unaged 3 3 3-4 3
Hot air,
70[degrees]C/14 days 4 3 3-4 3
Oxygen,
70[degrees]C/4 days 3-4 3-4 3-4 3
Moisture,
70[degrees]C/28 days 3 3 3 3
Steam,
105[degrees]C/4 days 2 2-3 2 2-3
The residual pull out strength F/[F.sub.0] x 100 of the optimum cured compounds after aging is outlined in figure 8. In all cases, the peptizer-containing vulcanizates yield a better residual pull out strength than the peptizer-free control. It should be mentioned that a significant variation of the standard deviation In statistics, the average amount a number varies from the average number in a series of numbers. (statistics) standard deviation - (SD) A measure of the range of values in a set of numbers. of the pull out strength F before and after aging of the respective samples was not observed. [Figure 8 ILLUSTRATION OMITTED] The assessment of the respective steel cord coverage after aging is summarized in table 4. It can be seen that all samples within the specific test series yield more or less the same steel cord coverage. The pull out strength of the steel cord of the overcured (t90-value + mold-related warming up time + 60 minutes), unaged compounds is shown in figure 9. In this investigation the peptizer-free control and the 7/WG containing vulcanizate perform the best, while the 11/WG and the DBD containing vulcanizates yield a pull out strength poorer by approximately 14%. However, the steel cord coverage assessment was 3 in all cases (table 5). [Figure 9 ILLUSTRATION OMITTED]
Table 5 - steel cord coverage after aging
(overcured)
None 7/WG 11/WG DBD
Unaged 3 3 3 3
Hot air,
70[degrees]C/14 days 3-4 4 3-4 3-4
Oxygen,
70[degrees]C/4 days 3-4 3-4 4 4
Moisture,
70[degrees]C/28 days 3 3 3 3
Steam,
105[degrees]C/4 days 2 3-4 3 (*))
(*) Results of the DBD containing vulcanisate could not be evaluated due to an experimental error The residual pull out strength after aging of the overcured compounds is shown in figure 10. It can be seen that the peptizer-containing vulcanizates differ from the peptizer-free control. In total, however, the 11/WG containing vulcanizate performed best in this test. [Figure 10 ILLUSTRATION OMITTED] The assessment of the steel cord coverage after aging is outlined in table 5. According to this, all samples give more or less the same steel cord coverage. Conclusion The study shows that the granulated gran·u·late v. gran·u·lat·ed, gran·u·lat·ing, gran·u·lates v.tr. 1. To form into grains or granules. 2. To make rough and grainy. v.intr. , dust-free peptizer 11/WG, which is based on specifically activated DBD, is an appropriate substitute for the discontinued peptizer 7/WG, which was based on activated PCTP. In NR skim compounds for rubber-to-steel cord adhesion, the behavior of 11/WG is similar to that of 7/WG in terms of the basic mechanical vulcanizate properties before and after aging, the heat build-up build·up also build-up n. 1. The act or process of amassing or increasing: a military buildup; a buildup of tension during the strike. 2. , the viscoelastic and the adhesion properties. The 11/WG containing vulcanizate yields a lower heat build-up and a smaller dissipation factor tan [Delta] than vulcanizates which include non-activated DBD or no peptizer. In addition, due to the greater efficiency of 11/WG compared with the discontinued 7/WG, approximately 25% less is needed for the NR mastication in a separate step. References [1.] J. Orband, G. Anthoine and H. Roebuck (1986), Verbesserte Haftung von Naturgummi an vermessingtem Stahlcord, Kautschuk+Gummi Kunststoffe 39 (1), 37. [2.] H.-W. Engels and M. Abele (1991), "Improved economics in the production of NR goods through the use of peptizers," Rubber World 204 (5), 14. [3.] Internal test method no. PV 210 of Bayer AG, Rubber Business Group, Leverkusen, Germany. [4.] H. Buding, N. Upadhyay, H. Fries and H.W. Engels, "A new optimized peptizer for economic mastication of natural rubber," paper presented at the International Rubber Conference `94 in Moscow (26.09-01.10.1994). Acknowledgements "Peptizer influence on rubber-to-steel cord adhesion" is based on a paper given at the International Rubber Conference `97." "Silicone rubber Noun 1. silicone rubber - made from silicone elastomers; retains flexibility resilience and tensile strength over a wide temperature range synthetic rubber, rubber - any of various synthetic elastic materials whose properties resemble natural rubber bladder coating system as a process aid for curing tires" is based on a paper given at the May 1998 Rubber Division meeting. "Silane silane or silicon hydride Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula SinH(2n + 2). coupling agents for enhanced silica performance" is based on a paper given at the May 1998 Rubber Division meeting. |
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