Rubber antidegradants

Gotti [95] described a procedure for the identification of antidegradants in vulcanised rubber mixes in which part of an extract of the sample is acetylated and then analysed by GC and the remainder is subjected to thin-layer chromatography. The results of the two analyses are interpreted separately, then, compared with each other. He discusses the characteristics displayed by a range of commercial antidegradants. The technique is suitable for compounds containing amino- or phenolic-hydroxy groups. 

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The product formed in this reaction is a typical sec-alkylaminodiphenylamine (V) which is characteristic of the best rubber antidegradants. No commercial products based on this principle have so far been reported, possibly because of the cost of epoxidation, normally carried out in solution. 

Beilstein Handbook Reference) AI3-14636 BRN 0773905 CCRIS 243 N,N -Diethyl-thiocarbamide 1,3-Diethylthiourea 1,3-Diethyl-2-thiourea N,N -Diethylthiourea N,N-Diethyl-2-thiourea EINECS 203-308-5 HSDB 4106 NCI-C03816 NSC 3507 Pennzone E Thiate H Thiourea, N,N -diethyl- U 15030 Urea, 1,3-diethyl-2-thio- USAF EK-1803. Accelerator for mercaptan-modified chloroprene rubber. Antidegradant for natural, nitrile-butadiene, styrene-butadiene, and chloroprene rubbers. Crystals mp = 78° bp dec. Xm = 234, 265 nm (c = 6310, 7244, MeOH) slightly soluble in CCI4, soluble in H2O (0.1 - 0.5 g/100 ml), EtOH, very soluble in Et20 LDso (rat orl) = 316 mg/kg. ElfAtochem N. Am. 

Synonyms N,N -dibutyl-thiourea N,N-dibutylthiourea N,N -di-n-butylthiourea i,3-dibutyl-2-thiourea 1,3-dibutylthiourea Uses accelerator for mercaptan-modified chloroprene rubber activator for ethylene-propylene-diene terpolymers and natural rubber antidegradant for natural rubber latex and thermoplastic styrene-butadiene rubber A... 

Uses inhibitor of corrosion in metal pickling solutions accelerator for mercaptan-modified chloroprene rubber antidegradant for natural, nitrile-butadiene, styrene-butadiene, and chloroprene rubbers A... 

Antiozonants are a very large part of the rubber antidegradant market. Many times antiozonants are used together with antioxidants in rubber compounds to achieve the best synergistic protection from oxidative degradation while the rubber product is in use. Virtually all chemical antiozonants can act, at least to some extent, as antioxidants. 

ASTM D4676 classifies 6PPD in relation to other rubber antidegradants. 

Rubber processed in latex form accounts for about 10% of new mbber consumption. Rubber latex is a Hquid, oil-in-water emulsion which is used to make foam or thin-walled mbber articles. The same accelerators and antidegradants used in dry mbber are used in latex, with longer-chain versions preferred for greater oil solubiHty. To prepare these and other additives for addition to latex, they must be predispersed in water and the surface of the powder or oil droplet coated with a surface-active agent to prevent destabilization (coagulation) of the latex. 

Rubber Chemicals. Sodium nitrite is an important raw material in the manufacture of mbber processing chemicals. Accelerators, retarders, antioxidants (qv), and antiozonants (qv) are the types of compounds made using sodium nitrite. Accelerators, eg, thiuram [137-26-8J, greatly increase the rate of vulcaniza tion and lead to marked improvement in mbber quaUty. Retarders, on the other hand (eg, /V-nitrosodiphenylamine [156-10-5]) delay the onset of vulcanization but do not inhibit the subsequent process rate. Antioxidants and antiozonants, sometimes referred to as antidegradants, serve to slow the rate of oxidation by acting as chain stoppers, transfer agents, and peroxide decomposers. A commonly used antioxidant is A/,AT-disubstituted Nphenylenediamine which can employ sodium nitrite in its manufacture (see Rubber chemicals). 

Report 79 Rubber Compounding Ingredients - Need, Theory and Innovation, Part I Vulcanising Systems, Antidegradants and Particulate Fillers for General Purpose Rubbers, C. Hepburn, University of Ulster. 

Several studies characterizing the reactions of alkenyl radicals with quinone dumines and quino-neimines were published in the late 1970s. Quinone dumines react with allylic radicals yielding both the reduced PPD and the alkylated product. In these experiments 2-methyl-2-pentene served as a model olefin (model for NR). Samples of the olefin and quinoneimines or quinone diimine were heated to 140°C. Isolation and analysis of products demonstrated that 40%-70% of the imine or diimine was reduced to the corresponding PPD, while 20%-50% was isolated as the alkylated product. This alkylation reaction (via an allylic radical) represents the pathway to the formation of rubber-bound antidegradant. ... 

A-l,3-dimethylbutyl-A -phenyl quinone diimine (6QD1) has been introduced as a multifunctional additive for diene rubbers and provides an advantage in mixing characteristics (functions as peptizer and improves scorch safety) as well as improved performance (better antioxidant activity than paraphenylenediamine antidegradants) of the end products [36]. 

Several of the commonly used rubber chemicals tike accelerators, retarders, antidegradants, etc. are classified as hazardous on account of values of LD50 (lethal dose 50%) [6]. Many of the guanidine... 

Chemical analysis of rubber (specific gravity extract, filler, CB, polymer and sulfur analysis antidegradant and plasticiser analysis)... 

Analysis of natural rubber Analysis of synthetic mbber Oils-characterisation-CC Rubber chemicals-Infrared Rubber chemicals-Ultraviolet Antidegradant-TLC Rubber-Pyrolysis GC Rubber identification by IR spectrophotometry Ct2, Br2, I2 by oxygen flask... 

Plasticiser/oil in rubber is usually determined by solvent extraction (ISO 1407) and FTIR identification [57] TGA can usually provide good quantifications of plasticiser contents. Antidegradants in rubber compounds may be determined by HS-GC-MS for volatile species (e.g. BHT, IPPD), but usually solvent extraction is required, followed by GC-MS, HPLC, UV or DP-MS analysis. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out. The determination of antioxidants in rubbers by means of HPLC and TLC has been reviewed [58], The TLC technique for antidegradants in rubbers is described in ASTM D 3156 and ISO 4645.2 (1984). Direct probe EIMS was also used to analyse antioxidants (hindered phenols and aromatic amines) in rubber extracts [59]. ISO 11089 (1997) deals with the determination of /V-phenyl-/9-naphthylamine and poly-2,2,4-trimethyl-1,2-dihydroquinoline (TMDQ) as well as other generic types of antiozonants such as IV-alkyl-AL-phenyl-p-phenylenediamines (e.g. IPPD and 6PPD) and A-aryl-AL-aryl-p-phenylenediamines (e.g. DPPD), by means of HPLC. 

ASTM Standard D 3156-81, Thin-layer Chromatographic Analysis of Antidegradants (Stabilizers, Antioxidants and Antiozonants) in Raw and Vulcanized Rubbers, Annual Book of ASTM Standards, ASTM, Philadelphia, PA (1990). 

For rubber, a thin layer chromatographic (TLC) method is available ISO 4645 1984 Rubber and rubber products — Guide to the identification of antidegradants — TLC methods. 

Any substance used to prevent premature coagulation of rubber latex the commonest are ammonia, sodium sulphite and formaldehyde. Antidegradant... 

Gas chromatography-mass spectroscopy is used to obtain extensive compositional information on rubbers. It can identify minor components of the sample such as the breakdown products of the cure system and the antidegradants. 

See also Tire compounding antidegradants in, 21 785—790 antioxidants in, 21 789 butyl and halobutyl rubber in, 21 766 elastomers used in, 21 759—772 ethylene-propylene rubber in, 21 765-766... 

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