Hoechst Celanese Corporation

Holechst Celanese Corporation

William M Pleban

George L Collins

Paul Zema

Milton J Hayes

Helmut Eckhardt

John A Flint

George Collins

Hongkyu Kim

Frank Haimbach, Iv

Lak M Walpita

Milton J Hayes, Jr

Polymeric compositions having a high dielectric constant are made from a thermotropic liquid crystalline and a ceramic having a dielectric constant which is greater than about 50 at a frequency of 1.0 GHz. The compositions have a dielectric constant of at least about 4, and preferably at least about 6. Preferred compositions also have a low loss tangent.

Liquid crystalline polymer composites having high dielectric constant

The tensile modulus of fibers made from liquid crystalline polymers comprising 6-oxy-2-naphthoate and 4-oxybenzoate monomer units that have been heat treated can be increased by applying and then releasing a stress at room temperature in the range of about 25% to about 90% of the tensile strength of the heat treated fiber to yield a 'pre-stressed' fiber.

Pre-stressing of heat treated liquid crystalline polymer fiber to

A crosslinked elastomeric acetal polymer is synthesized from 1,3-dioxolane, 1,3-dioxepane, and a polyfunctional crosslinking compound having two or more functional groups that react under conditions of cationic polymerization, such as 1,4-divinyloxybutane or poly(butadiene oxide). The polymers are elastomeric and non-crystalline at temperatures well below room temperature. They can be blended with crystalline acetal polymers to produce blends that have improved impact properties.

Crosslinked elastomeric acetal polymers

Crosslinked elastomeric acetal polymers are made by the copolymerization of 1,3-dioxolane with a smaller amount of one or more bifunctional monomers. The two functional groups of the bifunctional monomer react under the same cationic polymerization conditions as the 1,3-dioxolane. The elastomeric acetal polymer does not crystallize even when the temperature is as low as -50.degree. C. The elastomeric acetal polymer is particularly useful for blending with crystalline acetal polymers to yield a composition with improved impact resistance.

Elastomeric crosslinked poly(1,3-dioxlane)

Non-crystalline elastomeric acetal polymers are disclosed which have ethylenic unsaturation in the polymer backbone. The polymers are synthesized by the ring-opening polymerization of 1,3-dioxolane, 1,3-dioxepane, and the cyclic formal of an ethylenically unsaturated diol having at least 4 adjacent carbon atoms in its main chain. The preferred cyclic formal is 4,7-dihydro-1,3-dioxepin. Because of the ethylenic unsaturation, the elastomeric acetal polymers can be vulcanized or cured with multifunctional vinyl monomers to produce elastomers with improved properties, such as better elasticity, decreased thermoplasticity and decreased solubility. The elastomeric acetals in any of their embodiments are particularly useful for blending with crystalline acetal polymers to improve the impact resistance of the crystalline acetal polymers.

Vulcanizable non-crystalline acetal elastomers

Copolymers of 1,3-dioxolane and 1,3-dioxepane in the form of non-crystalline high molecular weight elastomers having low glass transition temperatures (Tg) are disclosed. Such copolymers are formed by polymerizing from about 40 to about 60 mol percent of 1,3-dioxolane and correspondingly from about 60 to about 40 mol percent of 1,3-dioxepane under substantially anhydrous conditions in the presence of a cationic polymerization catalyst, e.g., a strong Bronsted acid such as trifluoromethanesulfonic acid. Blends of such non-crystalline copolymers with crystalline oxymethylene polymers are also disclosed.

Non-crystalline acetal copolymer elastomers

There are provided new articles comprising elements having surfaces bonded together with a bonding resin which is an elastomeric copolymer of about 15 to 45 mol %, preferably about 25 to 35 mol % trioxane, about 55 to 85 mol %, preferably about 65 to 75 mol % of 1,3-dioxolane, said mol percents based on the total of trioxane and 1,3-dioxolane, and about 0.005 to 0.15 wt. %, preferably about 0.05 to 0.12 wt. % of 1,4-butanediol diglycidyl ether or butadiene diepoxide as a bifunctional monomer, based on the total weight of copolymer. Preferably, at least one of said surfaces, and more preferably at least two of said surfaces bonded to each other are of a crystalline acetal polymer comprising at least 85 mol % of polymerized oxymethylene units.

Articles utilizing acetal copolymer bonding resins

Low Tg copolymers of trioxane and 1,3-dioxolane which have a dioxolane content greater than 65 mol percent and less than about 75 mol percent and an IV of from about 1.0 to about 2.3, and which are non-crystalline at room temperature or above, are disclosed. These polymers, when blended with crystalline oxymethylene polymers, improve the latter's impact properties. They can also be used as adhesives for crystalline oxymethylene polymers.

Low Tg non-crystalline acetal copolymers

Ultraviolet curable terpolymers of trioxane, from at least 65 weight percent to about 75 weight percent of 1,3-dioxolane and from about 2 weight percent to about 20 weight percent of a monoethylenically unsaturated aliphatic diol formal having at least 4 carbon atoms in its main chain, e.g., 4,7-dehydro- 1,3-dioxepin, which are non-crystalline at room temperature or above are disclosed. These terpolymers, when admixed with a multifunctional crosslinking monomer, e.g., a multifunctional acrylate such as 1,6-hexanediol diacrylate, and a photosensitizer, e.g., a benzoin compound such as benzoin isobutyl ether, can be cured to an insoluble, non-tacky, rubbery state using UV radiation. The thus-cured polymeric materials form useful crosslinked films, and when cryogenically ground to a suitable small particle size can be blended with conventionally prepared crystalline oxymethylene homo-, co- and terpolymers to improve the latters' impact properties.

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Stanhope, NJ, United States of America

William M Pleban