Thiophosphates - helpful in the design of nitrosamine-free accelerator systems.Dithiophosphates have been known to function since the late 1960s (ref. 1). The dithiophosphates are chemically similar to the dithiocarbamates (figure 1)(ref. 2). Due to this similarity in structure, they can be substituted for dithiocarbamates in diene Dienes are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes. Classes Dienes can be divided into three classes:
[ILLUSTRATION OMITTED] The thiophosphates are preferred in EPDM EPDM Ethylene-Propylene-Diene-Monomer EPDM Enterprise Product Data Management EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components) EPDM Engineering Product Data Management compounds. The possibility of bloom can be greatly reduced by partially substituting thiophosphates for dithiocarbamates. The longer scorch times seen with the dithiophosphates can be made shorter using small amounts of other accelerators, increasing the amount of sulfur or adding a sulfur donor (ref. 4). The thiophosphates generally decrease the tendency towards reversion reversion: see atavism. of natural rubber compounds that is commonly seen in conventional accelerator systems (ref. 5). In addition to being more soluble soluble /sol·u·ble/ (sol´u-b'l) susceptible of being dissolved. sol·u·ble adj. Capable of being dissolved, especially easily dissolved. in certain elastomers, the thiophosphates do not form toxic N-nitrosamines (ref. 6). These two qualities have created a new interest in the thiophosphates. Usage of thiophosphates in EPDM compounds. Examples of some accelerator systems are shown in table 1. Example A is a recipe for an injection molding injection molding n. A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold. compound that exhibits extremely good storage stability and no bloom. The mixture is proofed under the specification for underwater seals DIN 4060. Comparable U.S. specification would be ASTM ASTM abbr. American Society for Testing and Materials D 2000 (SAE sae abbr (BRIT) (= stamped addressed envelope) → sobre con las propias señas de uno y con sello 200) 3BA410 A 14; B 13; C 12; F 17. The compound was processed at temperatures about 200 - 220[degrees]C (392-428[degrees]F). Table 1 - ZDBP cure systems for EPDM
Compound ingredients Injection Extrusion
molding
Vistalon 4507 - 100
Buna AP 451 100 -
Carbon black N 550 60 -
Carbon black N 539 - 30
Carbon black N 762 - 130
Sillitin Z - 50
ZnO active 6 10
Stearic acid 1.5 2
Paraffinic oil 75 80
CaO (80% active) - 5
Sulfur 0.8 1.5
TMTM 0.8 -
MBS 3.0 -
ZDBP 1.5 3.8
MBT - 1.5
Physical properties
Hardness (ShA) 46 72
Tensile strength (MPa) 12 9
Elongation at break (%) 540 325
Compression set
(40% deflect./22 hrs/70[degrees]C) (%) 15
25% deflect./22 hrs. /70[degrees]C) (%) 20
Example B (ref. 7) is a recipe for automotive profiles that do not form carcinogenic carcinogenic having a capacity for carcinogenesis. N-nitrosamines. The profiles have a hardness of 70 Shore A and overall good physical properties. Looking at isolated examples as shown in table 1 does not lead to a basic understanding of the function of the thiophosphates. Comparison of thiophosphates in EPDM For the comparison of thiophosphates, a test compound with a standard accelerator system was selected. The comparison was made between ZDBP, zinc-aminodithiophosphates (ZADP) and copper-dibutyl-dithiophosphate (CuDBP). The data were presented in table 2. The biggest difference between these accelerators is in the rate of cure. ZADP has the fastest cure rate, CuDBP has the slowest cure rate and ZDBP is in between. The modulus See modulo. values indicate that the crosslink density is independent of the chemical nature of the thiophosphates. Compression is seen to be better for the CuDBP accelerated stock than for the stocks accelerated with ZDBP and ZADP. Table 2 - comparison of thiophosphates
Physical properties(1) A B C
3 phr 3 phr 3phr
ZDBP(2) AZDP(3) CuDBP(4)
Mooney scorch 120[degrees]C
t5 (min) 17.49 13.37 30.40
t35 (min) 22.25 17.49 31.28
Stocks cured 10 min/180[degrees]C
Hardness (ShA) 58 59 58
Modulus 100% (MPa) 2.9 3.1 3.0
Modulus 300% (MPa) 10.1 10.6 6.9
Tensile strength (MPa) 12.0 10.5 10.8
Elongation at break (%) 365 310 310
After aging 7 d/120[degrees]C
Hardness (ShA) 67 67 66
Modulus 100% (MPa) 5.0 5.4 5.6
Modulus 300% (MPa) 11.1 11.2 11.4
Elongation at break (%) 195 195 180
Compression set DIN 53517
24 h/RT (%) 5 4 4
24 h/120[degrees]C (%) 34 37 29
70 h/120[degrees]C (%) 39 40 35
(1)Masterbatch: EPDM (Buna bu·na n. A synthetic rubber made from the polymerization of butadiene and sodium. [Originally a trademark.] Noun 1. AP451) 100; carbon black N550 100; paraffinic oil 75; 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. 5; Aflux 42 5; Rhenogran S-80 2; Rhenocure CBS-80 2.5. (2)Rhenocure TP/S TP/S Test Plans & Specifications . (3)Rhenocure ZAT ZAT Zinc Atmospheric Tracer ZAT Zone Air Temperature (4)Rhenocure CUT. It is known that the ratio of sulfur to accelerator level and the sum of accelerators is important for crosslink density. This can be seen in table 3 where the sulfenamide level is varied. One can see that the scorch time at 120[degrees]C shows a small decrease as the concentration of CBS (Cell Broadcast Service) See cell broadcast. goes from 0.9 phr to 2.5 phr. This indicates that CBS has only a little acceleration effect compared to ZDBP. Considering that compression set at higher temperatures is decreasing without a similar effect on modulus indicates that the crosslink density is increasing. Table 3 - influence of CBS on ZDBP
Physical properties(1) A B C
0.9 phr 1.5 phr 2.5phr
CBS(2) CBS(2) CBS(2)
Mooney scorch 120[degrees]C
t5 (min) 18.37 17.38 17.49
t35 (min) 23.10 22.00 22.25
Stocks cured 10 min/180[degrees]C
Hardness (ShA) 57 58 58
Modulus 100% (MPa) 2.6 3.0 2.9
Modulus 300% (MPa) 10.0 10.6 10.1
Tensile strength (MPa) 12.3 12.4 12.0
Elongation at break (%) 370 365 365
After aging 7 d/120[degrees]C
Hardness (ShA) 67 67 67
Modulus 100% (MPa) 5.6 5.0 5.0
Modulus 300% (MPa) 12.9 10.2 11.1
Elongation at break (%) 210 180 195
Compression set DIN 53517
24 h/RT (%) 4 4 5
24 h/120[degrees]C (%) 38 37 34
70 h/120[degrees]C (%) 51 48 39
(1)Masterbatch: EPDM (Buna AP451) 100; carbon black N550 100; paraffinic oil 75; zinc oxide 5; Aflux 42 5; Rhenogran S-80 2; Rhenocure TP/S 3. (2)Rhenogran CBS-80. A comparison of the scorch data in table 4 shows that CBS behaves as a retarder retarder, n a chemical added to a substance to slow a chemical reaction, prolong the set of the material, and provide more working time. in the presence of ZADP. There is no effect on compression set at higher temperatures. Age resistance is also unaffected. Table 4 - influence of CBS on ZADP
Physical properties(1) A B C
0.9 phr 1.5 phr 2.5phr
CBS(2) CBS(2) CBS(2)
Mooney scorch 120[degrees]C
t5 (min) 11.50 12.36 13.37
t35 (min) 14.40 15.48 17.49
Stocks cured 10 min/180[degrees]C
Hardness (ShA) 57 58 59
Modulus 100% (MPa) 2.9 3.0 3.1
Modulus 300% (MPa) 10.2 10.3 10.5
Tensile strength (MPa) 12.4 12.1 10.5
Elongation at break (%) 370 360 310
After aging 7 d/120[degrees]C
Hardness (ShA) 66 67 67
Modulus 100% (MPa) 5.2 5.7 5.4
Modulus 300% (MPa) 11.8 12.6 11.2
Elongation at break (%) 205 205 195
Compression set DIN 53517
24 h/RT (%) 4 4 4
24 h/120[degrees]C (%) 35 36 37
70 h/120[degrees]C (%) 45 41 40
(1)Masterbatch: EPDM (Buna AP451) 100; carbon black N550 100; paraffinic oil 75; zinc oxide 5; Aflux 42 5; Rhenogran S-80 2; Rhenocure ZAT 3. (2)Rhenogran CBS-80. The conclusion of this study could be that a mixture of ZDBP with ZADP would help to adjust the scorch and cure times without adversely influencing the physical properties. With the assistance of the statistic statistic, n a value or number that describes a series of quantitative observations or measures; a value calculated from a sample. statistic a numerical value calculated from a number of observations in order to summarize them. experimental design (ref. 8) a four variable study was made 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. a Box Behnken design. A great variation in the cure data was found between the upper and lower limits in this study (table 5). This variation is mainly dependent on the concentration of the thiophosphate and the ratio of the two thiophosphates. The CBS and sulfur only make small contributions to the variations in the cure data. At the shortest possible cure rate, the construction of a cure time window (figure 2) leads to a certain accelerator level. Table 5 - experimental design with thiophosphates in EPDM
Range Lower and upper limits
Rhenogran S-80 1.5-2.5
Rhenogran CBS-80 2-3
Rhenocure TP/G + Rhenocure ZAT/G 2-4
Rhenocure TP/G/Rhenocure ZAT/G 0-1
Physical properties(1) A B
lower limit upper limit
Mooney scorch 120[degrees]C
t5 (min) 118.50 32.10
t35 (min) 24.00 41.20
Rheometer data (ODR)
180[degrees]C/1 Nm
t10 (min) 0.96 1.28
t50 (min) 1.44 1.92
t90 (min) 3.52 4.44
MH - ML (Nm) 0.431 0.492
Stocks cured 10 min/180[degrees]C
Hardness (ShA) 53 56
Modulus 100% (MPa) 1.78 2.28
Modulus 300% (MPa) 6.66 7.9
Tensile strength (MPa) 10.5 12.1
Elongation at break (%) 270 420
After aging 3 d/120[degrees]C
Hardness (ShA) 63 67
Modulus 100% (MPa) 4.79 3.59
Tensile strength (MPa) 5.5 8.4
Elongation at break (%) 130 170
Compression set DIN 53517
24 h/RT (%) 6 8
24 h/90[degrees]C (%) 45 64
70 h/120[degrees]C (%) 73 92
(1)Masterbatch: EPDM (Polysar 865) 100; carbon black N550 60; carbon black N330 40; paraffinic oil 90; zinc oxide 5; stearic acid stearic acid /ste·a·ric ac·id/ (ste-ar´ik) a saturated 18-carbon fatty acid occurring in most fats and oils, particularly of tropical plants and land animals; used pharmaceutically as a tablet and capsule lubricant and as an emulsifying 1; Aflux 42 3. [ILLUSTRATION OMITTED] The optimized physical properties give another window. The best combination was figured out by considering 300% modulus, 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. after aging at 120[degrees]C and 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 (figure 3). Both windows have an intersection. The accelerator levels shown in table 6 are common in both windows, i.e. at the intersection of both windows. [ILLUSTRATION OMITTED] Table 6 Acceleration for EPDM as found with the experimental design - fastest cure rate Rhenogran S-80 1.60 Rhenogran CBS-80 2.40 Rhenogran TP/G 1.60 Rhenogran ZAT/G 2.40 To improve the physical properties of such an EPDM stock one might add an additional accelerator such as a thiazole thi·a·zole n. 1. A colorless or pale yellow liquid, C3H3NS, containing a five-member ring composed of a nitrogen atom, a sulfur atom, and three carbon atoms, used in making dyes and fungicides. 2. accelerator like MBTS MBTS 2-Mercaptobenzothiazyl Disulfide MBTS Missile Bit Test Set MBTS Missile Bench Test Set . In the following study the optimum concentrations of sulfur (1.5 phr) and CBS (2.4 phr) were used. A three variable design was made with the MBTS and the thiophosphates to show the influence of the MBTS on thiophosphate mixtures (table 7). The influence of the MBTS on physical properties can easily be seen by comparing the data shown in tables 7 and 5, i.e. stocks cured with and without the added MBTS. Table 7 - experimental design with thiophosphates/MBTS combination
Range Lower and upper limits
Rhenogran MBTS-80 1.0-2.0
Rhenogran TP/S + Rhenogran ZAT/G 2.0-4.0
Rhenocure ZAT/(TP + ZAT) 0.0-1.0
Physical properties(1) A B
lower limit upper limit
Mooney scorch 120[degrees]C
t5 (min) 17.43 29.35
t35 (min) 23.60 39.90
Rheometer data (ODR) 180[degrees]C/1 Nm
t10 (min) 0.96 1.20
t50 (min) 1.48 1.84
t90 (min) 2.84 3.72
Stocks cured 10 min/180[degrees]C
Hardness (ShA) 57 55
Modulus 100% (MPa) 1.58 1.90
Modulus 300% (MPa) 5.4 6.6
Tensile strength (MPa) 7.3 9.5
Elongation at break (%) 400 500
After aging 3 d/120[degrees]C
Hardness (ShA) 66 69
Modulus 100% (MPa) 3.5 4.75
Tensile strength (MPa) 7.4 9.0
Elongation at break (%) 165 220
Compression set DIN 53517
24 h/90[degrees]C (%) 32 40
70 h/120[degrees]C (%) 49 62
(1)Masterbatch: EPDM (Polysar 865) 100; carbon black N550 60; carbon black N330 40; paraffinic oil 90; zinc oxide 5; stearic acid 1; Aflux 42 3; Rhenogran S-80 1.5; Rhenogran CBS-80 2.4. Using the experimental design results shown in figure 4, where the MBTS level is held constant at 1.2 phr, the window for the fastest cure rate was found. On the other hand, using the experimental design results shown in figure 5, where the MBTS level is held constant at 1.80 phr, the window for the optimum physical properties was found. [ILLUSTRATION OMITTED] To summarize sum·ma·rize intr. & tr.v. sum·ma·rized, sum·ma·riz·ing, sum·ma·riz·es To make a summary or make a summary of. sum , the addition of MBTS shortens both the scorch time and cure time, which is not undesirable here. The optimum level of MBTS-80 was observed at 1.0 phr; however, this does mean that this is an optimum cure system for EPDM. The compound might not have the optimum sulfur level. Also, it is quite possible that a different blend of accelerators might provide even better properties. Additional improvements could probably be obtained by substituting a sulfur donor for some sulfur or by adding a dithiocarbamate like ZBEC instead of a sulfenamide like CBS. The object here was to show that practical cure systems could be achieved using thiophosphates in combination with other accelerators. Dithiophosphates in other elastomers The activating effect of dithiophosphates is also useful in other elastomers also in EPDM. Very little experimentation has been done in this area. Rhein Chemie is now starting studies to show the influence of thiophosphates on cure rate and vulcanizate properties of polymers and applications. Efficient 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 NBR NBR Number NBR Nightly Business Report (PBS show) NBR National Business Review (New Zealand weekly business newspaper) NBR National Bureau of Asian Research NBR National Board of Review It is the goal here to find the alternate cure system for an NBR compound based on TMTD TMTD tetramethylthiuram disulfide. and DTDM DTDM Do The Damn Mission DTDM Deterministic Time Division Multiplexing for heat resistance (table 8). Table 8 - experimental design parameters Compounding Control Upper Lower ingredients limit limit NBR masterbatch 171 171 171 Rhenocure S/G - 4 3 Rhenogran MBTS - 2.4 1.2 Rhenocure ZAT/G - 3.6 1.2 Rhenogran TMTD-80 2 - - Rhenocure M/G 1.5 - - The calculated amount of available sulfur in the control system gives 0.38 phr. The calculated amount of available sulfur from R-S/G is 0.26 phr (lower limit/3 phr R-S/G) or 0.35 phr (upper limit/4 phr R-S/G). From these calculations a lower crosslink density of the compounds containing R-S/G is expected if the MBTS doesn't influence the crosslink density as was the case in EPDM. From the crosslink dependence data shown in figure 6, it is obvious that both the R-S/G and the R-ZAT/G have a surprisingly strong influence on crosslink density while MBTS has a relatively weak effect on crosslink density. All properties of the control could be obtained using the combination of R-S/G with R-ZAT/G except compression set at higher temperatures (tables 9 and 10). The best compression set value for the R-S/G system was 30% as opposed to 25% for the control. These results are not clear and need further investigation. Even with the moderate retardation retardation: see mental retardation. effect of MBTS in comparison to ZADP, the cure rate is still faster than that of the control stock. The closest approximation approximation /ap·prox·i·ma·tion/ (ah-prok?si-ma´shun) 1. the act or process of bringing into proximity or apposition. 2. a numerical value of limited accuracy. is with the following system: R-S/G 3.3; R-MBTS-80 1.4; and R-ZAT/G 3.6 [ILLUSTRATION OMITTED] Table 9
Control Lower Upper
limit limit
't10/170[degrees]C 1.68 0.8 1.64
't50/170[degrees]C 3.96 1.48 2.76
'90/170[degrees]C 5.92 2.4 4.32
Table 10
Control Lower Upper
limit limit
Modulus 100 2.2 3 1.6
Modulus 300 9.5 11.3 7.1
Tensile strength 20 20 17
Elongation at break 600 790 485
DVR 72 h/125[degrees]C 33 63 40
DVR 25 h/125[degrees]C 23 54 28
Thiophosphates in chloroprene chloroprene (klōr`əprēn') or 2-chloro-1,3-butadiene, colorless liquid organic compound used in the synthesis of neoprene and certain other rubbers. (CR) Ethylenethiourea (ETU ETU Electrical Trades Union ETU Ethylene Thiourea (pesticide & fungicide) ETU European Taekwondo Union ETU Educational Technology Unit ETU Elementary Time Unit (SIM card timing unit) ) is the most common accelerator for CR. However, due to its hazardous potential (refs. 9, 10 and 12), a less hazardous alternative is wanted. In sulfur (mercapto) modified CR, the ETU activates the vulcanization in conjunction with TMTD or with CBS (ref. 11). The reaction isn't fully understood (ref. 13). It has been found that ZABP or ADBP ADBP Agriculture Development Bank of Pakistan can replace ETU (tables 11 and 12). Although the properties are similar to those of the control, it is obvious there is room for improvement. Table 11 - thiophosphates on polychloroprene Compound ingredients A B C D E F Neoprene WK 100 100 100 100 100 100 Rhenomag 2150 2 2 2 2 2 2 Vulkanox OCD 2 2 2 2 2 2 Vulkanox AFS/LG 1 1 1 1 1 1 Antilux 654 2 2 2 2 2 2 Stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 PE wax 3 3 3 3 3 3 Carbon black N 550 20 20 20 20 20 20 Carbon black N 330 10 10 10 10 10 10 Durex O 15 15 15 15 15 15 Dioctyl sebacate 5 5 5 5 5 5 HAR 15 15 15 15 15 15 Rhenosorb C/GW 6 6 6 6 6 6 Rhenogran ZnO-80 6 6 6 6 6 6 Rhenocure GE 1228 1 1 2 2 - - Rhenocure EPG 118 0.9 2.7 0.9 2.7 1.8 1.8 Rhenogran ZAT/G - - - - 1 2 Stocks cured 10 min / 170[degrees]C Hardness (ShA) 57 65 57 65 61 57 Elasticity(%) 44 48 44 49 45 45 Tear strength (graves) (N/mm) 19.24 14.81 19.22 14.95 17.90 20.11 Modulus 100% (MPa) 2.23 3.22 2.22 3.47 2.68 2.36 Modulus 300% (MPa) 10.05 10.30 9.10 11.09 9.82 8.80 Tensile strength (MPa) 14.15 12.28 12.90 10.97 12.59 12.05 Elongation at break (%) 433 368 428 300 397 414 After aging 7 d / 100[degrees]C Hardness (ShA) 63 71 62 70 66 64 Elasticity (%) 45 48 45 47 46 46 Tear strength (graves) (N/mm) 19.84 15.05 19.72 16.04 16.56 19.12 Modulus 100% (MPa) 3.15 5.02 3.30 4.88 3.87 3.62 Modulau 300% (MPa) 10.97 - 10.92 - - - Tensile strength (MPa) 12.10 9.62 10.82 9.24 8.87 10.44 Elongation at break (%) 337 203 300 202 224 282 Table 12 - accelerator systems for SBR SBR - Spectral Band Replication & NR Compounding A B C D ingredients Rhenocure S/G 2 2 2 2 Rhenogran CBS-80 2 2 2 2 Rhenogran TBzTD-80 3 3 - - Rhenogran ZBEC-70 - - 3.5 3.5 Rhenocure ZAT/G - 1 - 1 If the CR is not modified with sulfur, crosslinking can take place with zinc oxide/ETU alone. DTDC/ZADP or DTDC/ADBP are not able to provide the same crosslink density as the ETU acceleration system. An experimental additive additive In foods, any of various chemical substances added to produce desirable effects. Additives include such substances as artificial or natural colourings and flavourings; stabilizers, emulsifiers, and thickeners; preservatives and humectants (moisture-retainers); and is developed to solve this problem. The results obtained with the new additive can be seen in the vulcameter study (figure 7). [ILLUSTRATION OMITTED] Thiophosphates in SBR and NR The first study was an attempt to replace a typical sulfur donor/carbamate cure system in an SBR compound. The influence of TBzTD and ZBEC on the cure with CBS can be seen in this study (table 13). ZADP accelerates CBS in SBR. If CBS is replaced with ZBEC, there is no additional effect on acceleration except that the cure time becomes a little faster. All the acceleration systems produced vulcanizates with similar physical properties. Table 13 - cure system for butyl rubber butyl rubber: see rubber. Compound A B C ingredients Butyl 301 100 100 100 Carbon black N 660 65 65 65 Paraffinic oil 22 22 22 Rhenogran ZnO-80 6 6 6 Stearic acid 1 1 1 Rhenogran S-80 2.2 2.2 2.2 Rhenogran MBTS-80 0.6 0.6 0.6 Rhenogran TMTD-80 1.2 - - Rhenocure S/G - 2 - Rhenocure ZAT/G - 2 2 Rhenocure TBzTD-80 - - 6 Stocks cured 10 min / 180[degrees]C Hardness (ShA) 51 48 51 Tear strength (N/mm) 26.3 28.8 23.4 Modulus 100% (MPa) 1.9 1.6 1.2 Modulus 300% (MPa) 5.8 5.3 4.1 Modulus 500% (MPa) 10.8 10.6 8.2 Tensile strength (MPa) 11.5 11.8 11.9 Elongation at break (%) 530 545 665 Compression set DIN 53517 24 h / 70[degrees]C (%) 12 22 16 24 h / 100[degrees]C (%) 58 70 60 Thiophosphates in IIR IIR - Infinite Impulse Response If IIR was cured with a sulfur/-MBTS/TMTD accelerator system, then alternately a sulfur/MBTS/CBS/ZADB or sulfur/MBTS/ZBEC/ZADB can be used. The first study shows the dependence of the crosslink densities on each of the three systems (tables 14 and 15). [TABULAR tab·u·lar adj. 1. Having a plane surface; flat. 2. Organized as a table or list. 3. Calculated by means of a table. tabular resembling a table. DATA OMITTED] Thiophosphates for accelerator systems free of zinc There are several reasons for using a zinc-free cure system. Zinc salts have some degree of 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. in wate; therefore, they can be extracted from a product used in water. In automotive applications with gasoline gasoline or petrol, light, volatile mixture of hydrocarbons for use in the internal-combustion engine and as an organic solvent, obtained primarily by fractional distillation and "cracking" of petroleum, but also obtained from natural gas, by , zinc salts can form greases in the hoses. Finally zinc salts that find their way to water treatment plants tend to kill the bacteria. On the other hand, zinc free cure systems yield significantly different cure rates and vulcanizate properties (ref. 14). For such systems, to improve cure rates and vulcanizate properties, ADBP is recommended. Studies are in progress to explore this potential application. Toxicology toxicology, study of poisons, or toxins, from the standpoint of detection, isolation, identification, and determination of their effects on the human body. Toxicology may be considered the branch of pharmacology devoted to the study of the poisonous effects of drugs. of thiophosphates and its derivatives Bis(diethoxythiophosphoryl)trisulfan had been considered as a potential substitute for TMTD (ref. 15); however, this chemical was found to produce toxic by-products during vulcanization. Although the higher homologues of the alkyl alkyl /al·kyl/ (al´k'l) the monovalent radical formed when an aliphatic hydrocarbon loses one hydrogen atom. al·kyl n. substituents produced less toxic by-products during thermal decomposition For the biological process, see Decomposition. For chemical decomposition in general, see Chemical decomposition. Thermal decomposition is a chemical reaction whereby a chemical substance breaks up into at least two chemical substances when heated. (refs. 16-18). On the other hand, GC-MS GC-MS Gas chromatography-mass spectroscopy. See there. studies show no significant levels of O,O',S-trialkyldithiophosphates with ADBP, which contains a [C.sub.8] alkyl group alkyl group (ăl`kĭl), in chemistry, group of carbon and hydrogen atoms derived from an alkane molecule by removing one hydrogen atom (see radical). (ref. 20). ZDPD and ZADP contain [C.sub.4]-alkyl groups. Some minor levels of O,O',S-trialkyldithiophosphates were found in the 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 these products (ref. 21). Even so, [C.sub.4]-alkyl dithiophosphates have been used for decades without any known adverse effects. As a precaution, efficient local exhaust systems Noun 1. exhaust system - system consisting of the parts of an engine through which burned gases or steam are discharged exhaust automobile engine - the engine that propels an automobile may minimize any potential exposure. Summary Thiophosphates have a greater potential for use in EPDM applications. Their high solubility in most elastomers allows for bloom free accelerator systems. ZADP alone or in combination with ZDBP has the capability of performing as a delayed action Noun 1. delayed action - a mechanism that automatically delays the release of a camera shutter for a fixed period of time so that the photographer can appear in the picture accelerator. Such new strong accelerators are now being considered as replacements for the traditional accelerator systems that can potentially cause Nnitrosamines. There is much work to be done. Hopefully this article has stirred the imagination. References (1.)H. Ehrend; Uber die wirkung von thiophosphaten als beschleuniger in vernetzungssystemen fur dienkautschuke; Gummi Asbest Kunststoffe, 30 2 (1977), p. 68-71. (2.)I.G. Pimblott, et al.; Bis- (diisopropyl) thiophosphorylsulfides in vulcanization reactions; J. Appl. Polym. Sci. 23 (1979), p. 3621 ff. (3.)H. Ehrend; Uber die wirkung von dithiophosphaten in vernetzungssystemen fur dienkautschuke, SGF SGF Svenska Golfförbundet (Swedish Golf Federation) SGF Société Générale de Financement (Quebec, Canada) SGF Smart Game Format SGF Simulated Gastric Fluid 76, Kopenhagen, Denmark. (4.)W. Hofmann; Rubber Technology Handbook, Hanser Publishers, 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 , 1989. (5.)Compounders pocket book, chemicals for the rubber industrie, publication of Monsanto, USA, November 1981. (6.)H. Lohwasser, 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. in the rubber industry (germ.); Gummi Asbest Kunststoffe, 39 (1986), p. 385-391. (7.)Vistalon selected compounds for automotive, building and mechanical goods; technical publication of Exxon Chemicals, printed in Belgium 1992. (8.)G.E.P. Box, W.G. Hunter, J.S. Hunter, Statistics for experimenters; John Wiley John Wiley may refer to:
(9.)Sixth Annual Report on carcinogens Carcinogens Substances in the environment that cause cancer, presumably by inducing mutations, with prolonged exposure. Mentioned in: Colon Cancer, Rectal Cancer , summary 1991; U.S. Department of Health and Human Services Noun 1. Department of Health and Human Services - the United States federal department that administers all federal programs dealing with health and welfare; created in 1979 Health and Human Services, HHS ; editor: Technical Resources, Inc. (10.)Toxikologische bewertung, ausgabe 02/89; ethylenethioharnstoff Nr. 1; Druckschrift der berufsgenossenschaft der chemischen industrie (BG Chemie). (11.)J.C. Bament, Richtlinien fur den mischungsaufbau und die verarbeitung von Neoprene neoprene: see rubber. neoprene Any of a class of elastomers (rubberlike synthetic organic compounds of high molecular weight) made by polymerization of the monomer 2-chloro-1,3-butadiene and vulcanized (cross-linked, like rubber), by sulfur, plus rezepturempfehlungen; Firmenschrift Du Pont Du Pont (d  pŏnt), family notable in U.S. industrial history. The Du Pont family's importance began when Eleuthère Irénée Du Pont established a gunpowder mill on the .(12.)H.C. Beadle BEADLE. Eng. law. A messenger or apparitor of a court, who cites persons to appear to what is alleged against them, is so called. , D.W. Gorman, "Non-thiourea Neoprene accelerator," Elastomerics September 1980, p. 39-42. (13.)T. Kempermann; Schwefelfreie vulkanisationssysteme - eine ubersicht; Kautschuk Gummi Kunstst. 40 8 (1987) p. 741. (14.)N.L. Hewitt, "Zinc-free curing systems for silica silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. ," Rubber World 206 6/Sept. (1992) p. 24-27. (15.)H.-W. Engels; Nitrosamine ni·tros·a·mine n. Any of a class of organic compounds present in various foods and other products and found to be carcinogenic and mutagenic in laboratory animals. in der gummiindustrie: herausforderung fur kautschukchemikalien-anbieter; Kautschuk Gummi Kunstst. 43 11(1990) p. 992-996. (16.)H. Luther and S.K. Sinha; Zur reaktionskinetik der thermischen zersetzung von zinkdialkyldithiophosphaten; Erdol und Kohle Erdgas Petrochemie, 17 Febr. (1964) p. 91-97. (17.)H. Luther and E. Baumgarten, K. Ul-Islam; Gaschromatographische untersuchungen uber die thermische zersetzungen von zink-dibutyl-dithiophosphaten; Erdol und Kohle Erdgas Petrochemie, 26 9(1973) p. 509-511. (18.)T. Rumpf and H. Schindbauer; Matrixeinflusse auf die thermische zersetzung von zink (O,O -dialkyldithiophosphat) bei der analyse an·a·lyse v. Chiefly British Variant of analyze. analyse or US -lyze Verb [-lysing, -lysed] or -lyzing, von schmieroladditiven; Fresenius Z. Anal anal (a´n'l) relating to the anus. a·nal adj. 1. Of, relating to, or near the anus. 2. . Chem., 315 (1983) p. 350-352. (20.)H. Schafer, Rhein Chemie; private communication. (21.)Monsanto; private communications. |
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