Butyl curatives

Rubber blends with cure rate mismatch is a burning issue for elastomer sandwich products. For example, in a conveyor belt composite structure there is always a combination of two to three special purpose rubbers and, depending on the rubber composition, the curatives are different. Hence, those composite rubber formulations need special processing and formulation to avoid a gross dissimilarity in their cure rate. Recent research in this area indicated that the modification of one or more rubbers with the same cure sites would be a possible solution. Thus, chlorosulfonated polyethylene (CSP) rubber was modified in laboratory scale with 10 wt% of 93% active meta-phenylene bismaleimide (BMI) and 0.5 wt% of dimethyl-di-(/ r/-butyl-peroxy) hexane (catalyst). Mixing was carried out in an oil heated Banbury-type mixer at 150-160°C. The addition of a catalyst was very critical. After 2 min high-shear dispersive melt mix-... 

The system Cl-butyl-cis-polybutadiene has been studied in some detail because it was suitable for the developed differential swelling technique and because this system of blends vulcanized with zinc oxide, sulfur, and thiuram disulfide first revealed the presence of interfacial bonds. This curative system has the feature of a flat cure —i.e.y the two homophases are vulcanized rapidly, and the crosslinked density does not increase radically as vulcanization time is prolonged. This is observed in Table IV by swelling and extractable levels of a series of crosslinked networks cured at increasing times and swollen in a common solvent, cyclohexane. 

Isobutene is used in the field of elastomers, mainly to manufacture a special rubber, butyl rubber, by copolymerization with small amounts of isopiene. It serves essentially for the manufacture of inner tubes, but its production remains modest and accounts for barely 10 per cent of that of SBR (Styrene Butadiene Rubber). Isobutene is also used to produce additives for oils (polyisobutenes), detergents (di- and triisobutylenes) and cur rently for the manufacture of MTBE. 

The direction of activity for disubsdtuted aryl ring compounds was reasonably predicted by averaging the there is no large interactions between the ring substitutents. With the optimum aryl substituent in hand, the hydrophobic sidechain (quadrant II) was re-investigated. Table IV lists the results which verified that the para-chlarophenyl, butyl substituted compound was one of the best Some further verification of the substituent scheme was conducted by preparing other mixed quadrant I, quadrant II variants. The best compounds were subjected to additional studies, including systemic and curative tests, and within the scope of alkyl and alkenyl sidechains, myclobutanil, was determined to be the best compound, overall. 

Cured properties of elastomers with a very low number of cure functional sites such as butyl and EPDM rubbers are independent of curative (accelerators) levels used. However, varying the levels of unsaturation during polymerisation can alter cured physical properties often without processing difficulties. For butyl and EPDM rubbers only a small fraction of the monomer units in a chain take part in the crosslinking reactions. For example, if an average chain contains 10,000 monomer units only about 50-250 would normally be involved in the crosslinking. 

Buthiobate (S-1358) is a dithiocarbonic acid derivative which is very toxic to powdery mildew fungi (22). The fungicide, butyl 4-r-butylbenzyl-N-(3-pyridyl)-dithiocarbonimidate, has an excellent preventive and curative effect against the powdery mildew fungi of many agricultural and horticultural plants (Kato et al.,... 

Butene, a -Butylene ethylethylene. C4HS mol wt 56.10. C 85.637., H 14.377.. CH2CH2CH=CH2. Oc-curs in oil and coal gas. Obtained by cracking of petr oils and by thermal decompn of butane or pentane or isopentane Egloff et al.. Ind. Eng. Chem. 28, 1283 (1936) Calin-gaert, J. Am. Chem. Soc. 45, 130 (1923) from butyl alcohol by treatment with cone H2S04 Compr. Rend. 176, 813 (1923). 

The accelerated-sulfur vulcanization of these rubbers along with the vulcanization of other rubbers, which are vulcanized by closely related technology, comprises more than 90% of all vulcanization. These rubbers include ethylene-propylene-diene-monomer rubber (EPDM), butyl rubber (HR), halobutyl rubbers, and nitrile rubber (NBR). Nevertheless, we give some consideration to vulcanization by the action of other vulcanization agents such as organic peroxides, phenolic curatives, and quinoid curatives. 

N-butyl cyanoacrylate is the most commonly used cerebral AVM embolic material, and is considered by some to be the most effective (Finfante and Wakhloo, 2007). While its drawbacks include tissue adhesiveness and optimization of polymerization time, the main advantage of this material is its permanency. The curative capability of n-BCA, seen both after initial embolization... 

Raman microimaging is used to estimate the effect of the siUca filler on phase separation in binary polymer blends composed of brominated poly(isobutylene-co-para-methyl) styrene (BIMS) and butyl rubber (HR). The domain sizes, relative concentration of polymer components within domains, and distribution of particulate silica filler and zinc stearate curative are characterised for blends of different compositions and history of ageing treatments. The presence of increased concentrations of precipitated silica results in better... 

PP was blended with 5-50 parts of chlorinated butyl rubber, CBR, in the presence of a non-peroxide curative (e.g., oxides or sulfides of Zn, Cd, Mn, Fe, or Pb) on a roll mill at 138-157 °C. The dynamic vulcanization resulted in materials useful for high tensile strength applications... 

When the crosslinked rubber level in the blend is high, the blends are rubbery with good elastic recovery properties, have low compression set values at elevated temperatures, and are processable as plastics. At low crosslinked rubber levels (<25%), these blends are tough and have very good impact resistance. Dynamic vulcanization was first practiced by Gessler [23] around 1958, when he described the preparation ofhalogenated butyl mbber and polypropylene on a heated roll mill. Most of the blends in the examples had only a small amount of rubber (20 wt%) and the curative used was a metal oxide. The mixing time was about 20 min at 320 ° F. It was shown that the dynamically vulcanized blends had better tensile properties than identical blends vulcanized at 320 °F under static conditions. Fischer [24] prepared... 

Additives used in final products Fillers calcium carbonate, calcium hydroxide, calcium oxide, carbon black, polymeric beads, polystyrene particles, zinc oxide Plasticizers 1-isobutyrate benzyl phthalate, 2,2,4-tri-methyl-1,3-pentanediol, alkyl sulfonic acid esters of phenol and/or cresol, benzyl butyl phthalate, chlorinated paraffins, hydrogenated perphenyl, isooctyl benzyl phthalate Curatives metal peroxides, oxy salts (e.g., dioxides of lead, manganese, calcium, etc.) ... 

Various product forms may occur during storage (typical for fatty acid derivatives) or production. DSC has been used for detection of polymorphism of butylated hydroxyanisole (BHA) [91]. Similarly, DSC has allowed to detect various product forms of the hindered phenolic antioxidant octade-cyl 3-(3, 5 -di-f-butyl-4 -hydroxyphenyl) propionate (Anox PP 18), which caused handling problems during production [92]. The DSC method for purity determination as used for curatives, such as 2,2 -benzothiazyldisulfide (MBTS) [93], and for sulfur and accelerators [79], is also applicable to other additives, such as antioxidants and antiozonants. DSC and TGA have been used to establish the oxidation and weight loss characteristics of commercially available triaryl, trialkyl and alkyl-aryl phosphate esters, which are widely used as plasticisers and flame retardants in the polymer industry [94]. 

Polypropylene Butyl rubber Butyl rubber curatives... 

Methylol-terminated para-alkyl-substituted phenol formaldehyde resin is used as the vulcanizing agent for compounds based on butyl and EPDM rubber. The alkyl group is usually octyl. It is commonly used to cure butyl rubber where superior heat resistance is needed. Therefore, this vulcanizing agent is commonly used as the curative to make butyl bladders for repetitive curing of tires. It is also sometimes used in dynamic vulcanization with a tin chloride activator to make thermoplastic vulcanizates (TPVs). 

Partially cure butyl rubber. This can best be done by adding a carefully measured amount of curative and fully curing to the extent of the curative present, or by using one of the available precured grades. 

Blend either PIB or butyl with halogen-ated butyl and cure only the halogenated butyl portion by utilizing the halogen functionality. As an example, a curative that will react with chlorobutyl and not with butyl is zinc oxide. This technique is also of interest in blends of halogenated butyl with either SBR or natural rubber for pressure sensitive adhesives. 

Once the mbber solutions are made, further compounding is carried on either in the same equipment, as has been noted, or in another unit. One example of two different pieces of equipment being used is in the preparation of butyl textile laminating adhesives. The butyl is first pigmented and curative is added on either a mbber mill or in a Banbury. The compounded stock is then solvated in an adhesives chum where resins and other soluble ingredients can also be added. 

Reclaim Rubber. Rubber recovered from scrap rubber goods, primarily by digestion or mastication at elevated temperatures, consists of soluble hydrocarbon, crosslinked rubber, and about 30% carbon black, plus minor amounts of oil, tackifiers, and curative residues. The rubber content of reclaim derived from tires is a mixture of SBR and NR, while butyl reclaim is derived from inner tubes. One of the principal virtues of reclaim is price. It is used for black friction tape but to a larger extent for duct tapes and pipe wrap tapes. 

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