Hoechst Celanese Corporation

Michael R Ahern

Charles B Hilton

Bennett C Ward

Carrie A Feeney

Thomas M Kenesson

Edward M De La Garza

B Frank Wood

Lakshaman Mahinda Walpita

James L Ragan

Kan J Tsai

Thomas L Grantland

Gregory M Adams

Ida L Jones

A polymeric composition which has a dielectric constant K' greater than 4 at 20.degree. C. which varies little with temperature is made from a polymer or mixture of polymers and a ceramic or a mixture of ceramics, where the polymer or mixture of polymers has a dielectric constant K' in the range of about 1.5 to about 3.5 and a temperature coefficient of dielectric constant TCK' that is negative and is between 0 and about -300 ppm/degree C.; and the ceramic includes a first ceramic, which may be one ceramic or a mixture of ceramics, each having a dielectric constant in the range of about 15 to about 200 and a TCK' that is positive and is between zero and about 3000 ppm/degree C.; and an optional second ceramic, which may be one ceramic or a mixture of ceramics, each having a dielectric constant in the range from about 3 up to about 15 and a TCK' that is positive and is between zero and about 300 ppm/degree C.

Polymeric compositions having a temperature-stable dielectric constant

Processes for recovering 4,4'-dimethyl bibenzoate (DMBB) from byproduct streams of dimethyl terephthalate (DMT) production are disclosed. The byproduct streams are treated to produce an overhead stream which includes DMBB. In one aspect of the invention, the overhead product stream is added to an organic solvent under conditions sufficient to rapidly form a suspension of crystallized DMBB. In another aspect of the invention, the overhead is dissolved in an appropriate organic solvent and cooled to form a suspension of DMBB crystals in the solvent. A portion of the suspension is removed, and the remaining portion of the suspension centrifuged to recover DMBB crystals. In still another aspect of the invention, the overhead stream is treated with an organic solvent to form a slurry of DMBB crystals, and the resultant slurry thermally treated to increase the concentration of DMBB crystals therein while also solubilizing any organic contaminants.

Processes for cystallizing 4, 4'-dimethyl bibenzoate (DMBB) recovered

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Bayonne, NJ, United States of America

Michael R Ahern