E.i. Dupont De Nemours and Company

Rita S McMinn

Donnan E Priester

George R Chapman, Jr

Richard A Morgan

Charles W Stewart, Sr

Robert E Tarney

Lewis E Crenshaw

William Howard Tuminello

Mark Elliot Wagman

Daniel Gregory Tynan

Chi-Kai Shih

William L Phillips

John G Van Alsten

A staged feeding process for preparing a composition by mixing at least a first polymer and a second, dissimilar polymer forms a final composition comprising a uniform, small-particle dispersion of the first polymer in a matrix of the second polymer. Preferably, the first polymer has a melt viscosity greater than the second polymer. The process comprises the steps of feeding the first polymer in a first feed stage and feeding all of the second polymer as a melt at least two feed stages to mix the first and second polymers. Alternatively, the process may comprise feeding the first polymer in a first feed stage and feeding all of the second polymer in at least two feed stages subsequent to the first feed stage. In either case, this mixing initiates a chemical reaction between the first and second polymers.

Staged feeding process for mixing polymers

Copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) having high HFP content and end-of-melting temperature, T.sub.m (end), as low as 200.degree. C. are disclosed. Exceptional performance as a processing aid in polyolefins results from having T.sub.m (end) of the TFE/HFP copolymer close to the processing temperature of the polyolefin. These TFE/HFP copolymers are soluble in fluorinated cyclic solvents. Copolymer/solvent systems copolymer at significant concentrations in selected solvents are fluid and stable at room temperature.

Low-melting tetrafluoroethylene copolymer and its uses

Low-melting tetrafluorethylene copolymer and its uses

Process of melt extruding through an extrusion die whose surface is coated with one or more metal oxides, M.sub.x O.sub.y, wherein M is a metal selected from the group consisting of Ti, Zr, Cr, Fe, Ni, Pd, Pt, Cu, Ag, Au, Al and Si, and x and y are selected to satisfy the valencies of M, a difficultly-melt-processible polymer containing 0.002-2 parts by weight, based on the weight of the polymer, of at least one melt-processible fluorocarbon polymer processing aid having a fluorine to carbon ratio of at least 1:2 and having metal oxide-reactive sites capable of reacting with or physically associating with the metal oxide of the die surface.

Process for melt extrusion of polymers

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Newark, DE, United States of America

Rita S McMinn