The Dow Chemical Company

Chad A Strait

Gerald M Lancaster

Ricky L Tabor

Hoang T Pham

Richard O Kirk

Morgan Mark Hughes

Michael E Rowland

A method of improving the oxidative thermal stability of ethylene polymers is disclosed. The method comprises removing residual unreacted monomer(s), solvent and thermally unstable species from the molten polymer. The resulting polymer is characterized by having an oxidative exotherm of not more than about 50 percent of the original polymer, as measured by differential scanning calorimetry.

Method of improving the oxidative thermal stability of ethylene polymers

An extruder screw having a plurality of plasticating sections sufficient for plasticating polymeric materials of different bulk density.

Single screw method and apparatus

Single screw extruder method and apparatus

Ethylene polymers grafted with dicarboxylic acid functionality have synergistically improved adhesive properties and acquire heatability employing RF electromagnetic radiation when blended with a carbon monoxide-containing ethylene polymer. The dicarboxylic acid grafted and carbon monoxide-containing ethylene polymers and blends thereof are particularly useful as adhesive layers in laminate structures where RF heat sealing methods can be employed.

Adhesive, RF heatable grafted polymers and blends

Maleic anhydride can be satisfactorily grafted to polymers at low pressures by feeding the polymer through a multiple screw extruder and injecting the maleic anhydride and a free radical initiator into the extruder. The maleic anhydride and initiator can be pre-mixed in a solvent solution. The solvent and unreacted maleic anhydride can be removed by low pressure devolatilization. The graft copolymer has a yellowness index as measured by ASTM D-1925-70 less than about 10.0 and as measured by ASTM E-313-73 less than about 11.0. Further, between 0.75 and 2.0 weight percent of the graft copolymer comprises maleic anhydride. The graft copolymer can further be blended with an olefinic polymer to yield adhesive thermoplastics suitable for use as food packaging multilayer coextruded films.

Meleic anhydride graft copolymers having low yellowness index and films

Maleic anhydride graft copolymers having low yellowness index and films

Maleic anhydride can be satisfactorily grafted to polymers at low pressures by feeding the polymer through a co-rotating, twin-screw extruder and injecting the maleic anhydride and a free radical initiator into the extruder. The maleic anhydride and initiator can be pre-mixed in a solvent solution. The solvent and unreacted maleic anhydride can be removed by low pressure devolatilization.

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Lake Jackson, TX, United States of America

Chad A Strait