Butyl rubber solvents

Table 2. Polymer—Solvent Interaction Parameters for Polyisobutylene and Butyl Rubber...

Chemical and Other Specialty Manufacture A wide variety of products may be derived from petroleum feed stocks, including such diverse materials as alcohols, butyl rubber, sulfur, additives, and resins. Other specialties such as solvent naphthas, white oils, Isopars, Varsol, may also be produced. As indicated previously the respective chemical affiliate usually has responsibility for products broadly classified as petrochemicals. 

TPEs from blends of rubber and plastics constitute an important category of TPEs. These can be prepared either by the melt mixing of plastics and rubbers in an internal mixer or by solvent casting from a suitable solvent. The commonly used plastics and rubbers include polypropylene (PP), polyethylene (PE), polystyrene (PS), nylon, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), butyl rubber, nitrile rubber, etc. TPEs from blends of rubbers and plastics have certain typical advantages over the other TPEs. In this case, the required properties can easily be achieved by the proper selection of rubbers and plastics and by the proper change in their ratios. The overall performance of the resultant TPEs can be improved by changing the phase structure and crystallinity of plastics and also by the proper incorporation of suitable fillers, crosslinkers, and interfacial agents. 

Experiments have been made in which uncross-linkable polymer rubbers have been added to a similar rubber that is subsequently cross-linked (199). As an example, polyisobutylene was added to butyl rubber before it was cross-linked. The polyisobutylene molecules were not attached to the network structure, so they could be extracted by a solvent. As expected, the polyisobutylene greatly increased the creep compliance over that of the pure butyl rubber. 

The most industrially significant polymerizations involving the cationic chain growth mechanism are the various polymerizations and copolymerizations of isobutylene. In fact, about 500 million pounds of butyl rubber, a copolymer of isobutylene with small amounts of isoprene, are produced annually in the United States via cationic polymerization [126]. The necessity of using toxic chlorinated hydrocarbon solvents such as dichloromethane or methyl chloride as well as the need to conduct these polymerizations at very low temperatures constitute two major drawbacks to the current industrial method for polymerizing isobutylene which may be solved through the use of C02 as the continuous phase. 

Uses Coolant and refrigerant herbicide and fumigant organic synthesis-methylating agent manufacturing of silicone polymers, pharmaceuticals, tetramethyl lead, synthetic rubber, methyl cellulose, agricultural chemicals and nonflammable films preparation of methylene chloride, carbon tetrachloride, chloroform low temperature solvent and extractant catalytic carrier for butyl rubber polymerization topical anesthetic fluid for thermometric and thermostatic equipment. 

Figure 10 shows a spectrum of butyl rubber gum stock obtained on the solid at 80°C using normal pulsed FT techniques. Clearly it could be identified as a component in fabricated materials by direct nmr spectral analysis. Figure 11 shows spectra obtained from various portions of typical rubber products. These samples were cut from the rubber product, placed in an nmr tube without solvent, and spectra obtained at an elevated temperature. The data show how polyisoprene, a polyisoprene/polybutadiene blend and a polyisobutylene/polyisoprene/polybutadiene rubber blend are quickly identified in the materials. Figure 11a shows processing oil was present, and which was confirmed by solvent extraction. 

Polymers with solubility parameters differing from those of the solvent by at least 2.0 H, will not dissolve in the solvent at room temperature. Thus although unvulcanized natural rubber (NR), unvulcanized styrene-butadiene elastomer (SBR), unvulcanized butyl rubber, and EPDM dissolve in gasoline or benzene, the vulcanized (cross-linked) polymers are swollen but will not dissolve due to the presence of the crosslinks. 

Skin should be protected by gloves (preferably nitrile or butyl rubber), boots, and long-sleeve clothing. For the protection of eyes, safety glasses with side shields or splash goggles are the best choice when handling liquid chemicals. If spray equipment is used, proper respiratory protection may be needed. If any contact with the chemical occurs, the affected area has to be washed with soap and water immediately solvents should not be used. In extreme cases, proper medical help may be required. 

Because of their widespread use in the American workplace, butyl rubber, nitrile latex, neoprene latex, poly(vinyl alcohol), surgical rubber latex, and Viton elastomer were chosen for the present studies. The composite/bonded substances of this study were not in all cases presently available as commercial material for protective garments, but rather were chosen to determine their potential for resistance to solvent permeation. Likewise, Teflon gloves were included in these studies simply because they are commercially available. 

Methyl chloride is used in the production of tetramethyllead antiknock compounds for gasoline and methyl silicone resins and polymers, and as a catalyst carrier in low-temperature polymerization (e g., butyl rubber), a refrigerant, a fluid for thermometric and thermostatic equipment, a methylating agent in organic synthesis, an extractant and low-temperature solvent, a herbicide, a topical antiseptic, and a slowing agent (lARC, 1986 Lewis, 1993). 

Known as MR. butyl rubber is a copolymer of isobutylene and isoprene. The elastomers contain only (1.5 2.5 mole 9r of isoprene. This is introduced to effect sufficient unsaturatinn to make the rubber vulcanizublc. Polymerizations are usually earned out at low temperature (-80 to -1(KJ C) with methyl chloride as solvent. Anhydrous aluminum chloride and a trace of water serve as catalyst. 

Propane is a good solvent for other hydrocarbons and the plasticizers4 used in elastomers. It is important that the right fuel hoses be used for propane. Hoses made from butyl rubber are not compatible with propane and will swell and leak. Hoses made from nitrile or neoprene should be used and are compatible with LP gas. However, even in hoses made from compatible materials, residues may result from these hoses primarily from two sources grease inside the hose from manufacturing and plasticizers present in the hose that are leached out by the propane upon first contact. (The extent of leach-out can be a function of the... 

Adhesives on the basis of a rubber are applied as watery dispersions, as solvents, or as solvent-free fluids. Sometimes the rubber is vulcanised after the gluing process, sometimes it remains uncured. Polymers often used are butyl rubber, polyisobutylene, and polychloroprene. A more recent development is the use of... 

Several organic sealants such as epoxy resins, butyl rubber or silicones prove to be more or less permeable and the tiny amount of solvent in the cell is rapidly lost. Suitable organic sealing materials for this technology turn out to be thermoplastic materials, like polyethylene/carboxylate copolymers. So far, Surlyn 1702 ionomer from Dupont has been the main substance used to optimize cell performance and build module prototypes. However, the softening point of Surlyn is rather low (65° C) and at elevated temperatures (> 70°C), serious solvent loss is observed because the bond between Surlyn and TCO-coated glass is substantially weakened [7]. 

Surface treatments consist of washing with solvent, abrading, or, in the most demanding applications, cyclizing with acid. The most common elastomers to be bonded in this way include nitrile, neoprene, urethane, natural rubber, SBR, and butyl rubber. It is more difficult to achieve good bonds with silicones, fluorocarbons, chlorosulfonated polyethylene, and polyacrylate. 

Prime with butyl rubber adhesive in an aliphatic solvent. 

Disks faced with PTFE should be used in the head-space vials as some solvents may be absorbed by butyl-rubber caps. Contamination of samples with chloroform, usually from the laboratory environment, is common. An artefact eluting with a retention time of 33.2 minutes derives from the gas-chromatograph septa. 

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