Polyisobutene properties

Nylon-6,6 can be made into articles with tensile strengths around 12,000 psi or into other articles with tensile strengths around 120,000 psi. What is the basic difference in the processes used to form these two different articles Why do polyisobutene properties not respond in the same manner to different forming operations ... 

Pathmamanoharan C and Philipse A P 1998 Preparation and properties of monodisperse magnetic cobalt colloids grafted with polyisobutene J. Colloid Interface Sol. 205 304-53... 

Whilst polyisobutene is a non-rubbery polymer exhibiting high cold flow (see Section 11.3), the copolymer containing about 2% isoprene can be vulcanised with a powerful accelerated sulphur system to give moderately rubbery polymers. The copolymers were first developed in 1940 by Esso and are known as butyl rubbers and designated as HR. As they are almost saturated they have many properties broadly similar to the EPDM terpolymers. They do, however, have two properties that should be particularly noted ... 

Standard-grade PSAs are usually made from styrene-butadiene rubber (SBR), natural rubber, or blends thereof in solution. In addition to rubbers, polyacrylates, polymethylacrylates, polyfvinyl ethers), polychloroprene, and polyisobutenes are often components of the system ([198], pp. 25-39). These are often modified with phenolic resins, or resins based on rosin esters, coumarones, or hydrocarbons. Phenolic resins improve temperature resistance, solvent resistance, and cohesive strength of PSA ([196], pp. 276-278). Antioxidants and tackifiers are also essential components. Sometimes the tackifier will be a lower molecular weight component of the high polymer system. The phenolic resins may be standard resoles, alkyl phenolics, or terpene-phenolic systems ([198], pp. 25-39 and 80-81). Pressure-sensitive dispersions are normally comprised of special acrylic ester copolymers with resin modifiers. The high polymer base used determines adhesive and cohesive properties of the PSA. 

Plastic Propellant The Tensile Properties of the Polyisobutene Binder , ERDE Tech Memo No 15/M/64, Waltham Abbey (Engl) (1964)... 

To get a better insight into the chlorination reaction, we wanted to avoid a heterogeneous process. Instead of polyethylene or polypropylene, we used polyisobutene, which is soluble in carbon tetrachloride, as are its chlorination products. In addition, we were interested in the structure and properties of the chlorinated products, especially in comparison with polyvinyl chloride (PVC) and vinyl chloride/isobutene (VC/IB) copolymers. 

The rubbery character and particular physical and chemical properties of polyisobutene stem from its paraffinic origins. Its outstanding properties are its low glass transition temperature, very low water vapor permeability and resistance to many chemicals. At room temperature polyisobutene is resistant to dilute and concentrated mineral acids and bases, as well as hydrogen peroxide. 

However, no indications are given of the molecular weights nor of the compositional heterogeneity of the graft copolymers, their properties or potential applications. The existence of a microphase separation was evidenced however on methyl metha-crylate/polyisobutene graft copolymers by means of DSC measurements. Two glass transitions were observed at —68 °C (polyisobutene) and at 102 °C (PMMA), i.e. at the same temperatures at which they occur in the corresponding hono-polymers. 

The main use of MTBE is as an octane booster in gasoline formulations. Table 2.1 (above) compares octane number and boiling points of some tertiary ethers and hydrocarbons. The volatility is another important property of gasoline components. In fact, the lower volatility of ETBE is an advantage with respect to MTBE. Another (smaller scale) application of MTBE is the synthesis of high purity isobutene by cracking MTBE over amorphous silica-alumina. This isobutene serves as a monomer for polyisobutene. 

Jessup, R. S., "Some Thermodynamic Properties of the Systems Polybutadiene-Benzene and Polyisobutene-Benzene," J. Res. Nat. Bur. Stand., 60, 47 (1958). 

Polyethylene and polyisobutene are both hydrocarbon polymers and have intermolecular forces of similar magnitude. Yet, one polymer is a plastic and fiber-former and the other is an elastomer. Comment briefly on the reason for this difference in properties,... 

Richards, J. R., K. Ninomiya, and J. D. Ferry Viscoelastic properties of concentrated solutions of polyisobutene in cetane. I. Dynamic measurements. 

The properties of bitumen paints (Section 2.14.2) can be favorably modified and adjusted to suit practical requirements by combination with other film-forming substances. For example, the thermoplasticity can be reduced and/or mechanical properties (e.g., hardness, extensibility) can be improved by adding polymers such as polyethylene, polypropylene, polyisobutene, and styrene-butadiene copolymers. The chemical resistance can also be improved high-quality corrosion protection coatings can be obtained by combination with alkyd resins. 

Ethyl glycol acetate [111-15-9] (2-ethoxyethyl acetate) is a colorless, neutral liquid that is partially miscible with water and readily miscible with organic solvents. It has a slight odor. Ethyl glycol acetate dissolves many natural and synthetic resins. Cellulose acetate is swollen. Poly(vinyl chloride), rubber, and polyisobutene are insoluble. It is no longer used in paints due to its teratogenic properties. 

The extent of the non-equilibrium region II of polymer retention diagrams in the glassy state is dependent, as proved above, on experimental conditions. In addition, this extent is strongly affected by the polymer properties. A case in point is polyisobutene, whose non-equilibrium region extends over a considerable temperature range between — 70(Tj,) and -f-.50 [216]. Althor h no chromatographic data at very low temi)cratures are available, there is evidence that the equilibrium bulk sorption is achieved below room temperature for natural rubber (T, — 70°0) [96] and for styrene-butadiene copolymer (T, — 60°C) [199] stationary phases. 

The physical properties of polyisobutene are very dependent on molecular weight. Polymers with average molecular weight (M ) of about 15 000 are sticky viscous liquids whilst those with molecular weight of 100 000—200 000 are rubber-like, resembling unmilled crepe rubber. 

Unvulcanized butyl rubber resembles polyisobutene of comparable molecular weight in many properties. It is soluble in hydrocarbons and chlorinated hydrocarbons and shows considerable cold flow. 

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