Polyisobutylene oxide

Polyisobutylene has the chemical properties of a saturated hydrocarbon. The unsaturated end groups undergo reactions typical of a hindered olefin and are used, particularly in the case of low mol wt materials, as a route to modification eg, the introduction of amine groups to produce dispersants for lubricating oils. The in-chain unsaturation in butyl mbber is attacked by atmospheric ozone, and unless protected can lead to cracking of strained vulcanizates. Oxidative degradation, which leads to chain cleavage, is slow, and the polymers are protected by antioxidants (75). 

Cross-linking reactions for the polyisobutylene-type polymers depend on adding a reactive site, usually an aHyUc hydrogen or halogen. These reactive sites allow vulcanization with sulfur and accelerators or metal oxides (76,77). 

Polyisobutylene and isobutylene—isoprene copolymers are considered to have no chronic hazard associated with exposure under normal industrial use. Some grades can be used in chewing-gum base, and are regulated by the PDA in 21 CPR 172.615. Vulcanized products prepared from butyl mbber or halogenated butyl mbber contain small amounts of toxic materials as a result of the particular vulcanization chemistry. Although many vulcanizates are inert, eg, zinc oxide cured chlorobutyl is used extensively in pharmaceutical stoppers, specific recommendations should be sought from suppHers. 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

Poly(ethylene terephtlhalate) Phenol-formaldehyde Polyimide Polyisobutylene Poly(methyl methacrylate), acrylic Poly-4-methylpentene-1 Polyoxymethylene polyformaldehyde, acetal Polypropylene Polyphenylene ether Polyphenylene oxide Poly(phenylene sulphide) Poly(phenylene sulphone) Polystyrene Polysulfone Polytetrafluoroethylene Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) Poly(vinyl butyral) Poly(vinyl chloride) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl formal) Polyvinylcarbazole Styrene Acrylonitrile Styrene butadiene rubber Styrene-butadiene-styrene Urea-formaldehyde Unsaturated polyester... 

Polyisobutylene and IIR have chemical resistance expected of saturated hydrocarbons. Oxidative degradation is slow and the material may be further protected by antioxidants, for example, hindered phenols. 

Polyisobutylene rubber Butyl rubber Halobutyl rubber Polyepichlorohydrin Polypropylene Polypropylene oxide... 

Strain-induced crystallization would presumably further improve the ultimate properties of a bimodal network. It would therefore obviously be of considerable importance to study the effect of chain length distribution on the ultimate properties of bimodal networks prepared from chains having melting points well above the very low value characteristic of PDMS. Studies of this type are being carried out on bimodal networks of polyethylene oxide) (55), poly(caprolactone) (55), and polyisobutylene (56). 

Butyl, and the halogenated butyls, can be cured by sulphur, dioxime and resin cure systems. In addition, the halogenated types can be crosslinked with zinc oxide, and diamines. Peroxides cannot be used because they tend to depolymerise the polyisobutylene. 

The simplest motional description is isotropic tumbling characterized by a single exponential correlation time ( ). This model has been successfully employed to interpret carbon-13 relaxation in a few cases, notably the methylene carbons in polyisobutylene among the well studied systems ( ). However, this model is unable to account for relaxation in many macromolecular systems, for instance polystyrene (6) and poly(phenylene oxide)(7,... 

Polyacrylonitrile Poly(ethylene oxide) Poly(ethylene terephthalate) Polyisobutylene Poly(methyl methacrylate) Polypropylene Polystyrene... 

The principal polyolefins are low-density polyethylene (ldpe), high-density polyethylene (hope), linear low-density polyethylene (lldpe), polypropylene (PP), polyisobutylene (PIB), poly-1-butene (PB), copolymers of ethylene and propylene (EP), and proprietary copolymers of ethylene and alpha olefins. Since all these polymers are aliphatic hydrocarbons, the amorphous polymers are soluble in aliphatic hydrocarbon solvents with similar solubility parameters. Like other alkanes, they are resistant to attack by most ionic and most polar chemicals their usual reactions are limited to combustion, chemical oxidation, chlorination, nitration, and free-radical reactions. 

Enhanced radiation cross-linking in polyethylene, polypropylene and polyisobutylene,43 and in copolymers of ethylene and propylene,44 was found when nitrous oxide was incorporated into the polymer matrix. Mechanisms of this process have been proposed by several researchers.45 17... 

Nitrous oxide reduces the amount of radiation degradation of polyisobutylene (5), though this is a typical polymer which degrades under radiation. 

Polyisobutylene. The solution viscosity of an irradiated polyisobutylene block was measured in CC14 at 30 °C. to determine the degree of degradation (5). The variation of viscosity-average molecular weight, Mv, with the dose, r, is shown in Figure 3. Nitrous oxide reduced the... 

Polyisobutylene. The viscosity of irradiated polyisobutylene is plotted against N20 pressure in Figure 5. The curve increases monotonically with increasing pressure. If nitrous oxide is effective in reducing the amount of degradation, the behavior of the curve seems to be reasonable since the gas concentration in the polymer solid should increase with the gas pressure. 

Polypropylene. A similar study on polypropylene is interesting because polypropylene has a molecular structure intermediate between polyethylene and polyisobutylene. An atactic polypropylene specimen was prepared by ether extraction and irradiated in a nitrous oxide atmosphere. The changes in gel fraction (insoluble in hot xylene) as a function of N-jO pressure are shown in Figure 6. Gel formation (cross-linking) of polypropylene is also promoted in the presence of nitrous oxide. 

Polyisobutylene and Polypropylene. In a similar way, the material balance of nitrous oxide in the case of polyisobutylene was measured as shown in Table IV. In this case, whereas the enclosed nitrous oxide is not completely consumed during irradiation, the consumption proceeds... 

Nitrous oxide disappears at a high rate in the cases of both polyethylene and polyisobutylene, but no chemical addition to the polymer chain can proceed because the nitrous oxide changes simply to nitrogen and water during irradiation in the polymer solid phase. This behavior of nitrous oxide differs entirely from that of oxygen, chlorine, sulfur dioxide, etc., as an atmosphere during irradiation. In the case of these latter gases, the irradiated polymer should be oxidized, chlorinated, or sulfonated. 

From industry s viewpoint, the action of nitrous oxide should be useful to cut down the dose required for the crosslinking of polyethylene or polypropylene and to keep polyisobutylene from degradation. However, it is a question whether the complexity of processing caused by using nitrous oxide would pay economically. 

K.D. Nelson and F. Plavac, Sulfurized polyisobutylene based wear and oxidation inhibitors, US Patent 7 414 013, assigned to Chevron Oronite Company LLC (San Ramon, CA), August 19, 2008. 

M. Holgerson, Plastic Rocket Propellants , GerP 2006229 (1971) CA 74,113925(1971) [The use of Zn oxide is suggested as an oxygen source in a solid propint which is claimed can be used immediately without being mixed in vacuo to remove air bubbles. Thus, AN (60), polyisobutylene (14), lecithin (1) and Zn oxide (25%) are mixed at 70° to prepare the invented propint]... 

Harada et al. explored the compatibility of CD with various polymeric backbones including polyethylene oxide) (PEG), polypropylene oxide) (PPG), polyisobutylene (PIB), and polyethylene (PE) [77-87]. The corresponding polyrotaxanes (36 to 47) were prepared by Method 2, simply by mixing a solution of CD and the polymer. The cavity size of CD was found to be the main factor in the threading process. While one a-CD (20) was threaded per two repeat units in PEG (m/n=0.50) and every three repeat units for PE (m/n=0.333), it was too small for PIB and PPG. On the other hand, two PPG units complexed per /(-CD (21). Because the upper limit of the min value is controlled by the depth of the CD cavity, the m/n value remained constant for the same type of backbone, irrespective of the end group. However, the nature and concentration, i.e., polymer... 

The question immediately raised is would this technique portray an opposite or negative adhesion response if applied to a polymer blended system where no interfacial bonding could be present Such a system would be cis-polybutadiene and high molecular weight polyisobutylene restricted to that portion of the blend system where polyisobutylene is the minor dispersed phase in cis-polybutadiene. A high molecular weight polyisobutylene [L-300 Vistanex (Enjay Chemical Co.)] was compounded with zinc oxide, sulfur, and TMTDS and then dissolved in hexane. cis-Polybutadiene (Phillips Chemical Co.) was also mixed with... 

Three classes of PSAs used most widely in transdermal systems are polyisobutylene (PIB), polyacrylate, and polydimethylsiloxane (silicone). More recently, hydrophilic adhesive compositions, hydrogels composed of high-molecular-weight polyvinylpyrrolidon (PVP) and oligometric polyethylene oxide (PEO), have been shown to be compatible with a broad range of drugs and are used in several commercial products.60... 

These energy calculations can provide suitable and stable molecular models, and have been successfully utilized for the structure analyses of many other polymers, such as poly(tert-butylethylene oxide) (3 ) and polyisobutylene (35). 

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