Microcellular extrusion/blow molding process and aricle made thereby

An article comprising:

• an extruded, microcellular parison suitable for blow molding.

A system for microcellular blow molding, comprising:

• extrusion apparatus including an extruder having an inlet designed to receive a precursor of polymeric microcellular material, constructed and arranged to provide a single-phase, non-nucleated solution of polymeric material and blowing agent, and a blow molding forming die fluidly connected to the extruder and having an outlet designed to release a parison of microcellular material, the apparatus including an enclosed passageway connecting the extruder inlet with the die outlet, the passageway including a nucleating pathway having length and cross-sectional dimensions selected to create in a single-phase, non-nucleated solution of blowing agent and fluid polymeric material a pressure drop at a rate sufficient to cause microcellular nucleation;
• and
• a blow mold positionable to receive a parison of microcellular material from the die outlet.

A method comprising:

• extruding microcellular polymeric foam extrudate from an extruder die while varying the thickness of the extrudate.

A method comprising:

• providing a polymeric foam parison;
• and
• subjecting the parison to blow molding conditions of at least about 15 psi thereby expanding at least a portion of the parison by at least about 50% in circumference and forming a blow-molded article, while maintaining a relatively unchanged density by increasing the density of the parison by no more than about 20% in going from the parison to the blow-molded article.

A method comprising:

• providing an extruded polymeric microcellular foam parison;
• and
• subjecting the parison to blow molding conditions.

A method comprising:

• providing a polymeric microcellular foam parison;
• and
• without heating the parison subjecting the parison to blow molding conditions.

A method comprising:

• extruding a polymeric foam extrudate from a extruder die in a machine direction while varying the temperature of the extrudate exiting the die thereby forming an extrudate having a first portion and a second portion spaced from the first-portion in the machine direction, the first portion and the second portion differing in material density by a factor of at least about 1.1.

A device comprising:

• a polymer forming die including an inlet at an upstream end thereof constructed and arranged to receive a single-phase, homogeneous solution of polymeric fluid and blowing agent that is a gas under ambient conditions, an outlet at a downstream end thereof, defining a die gap, for releasing foamed polymeric material, and a fluid pathway connecting the inlet with the outlet, the fluid pathway including a nucleating pathway, the die constructed and arranged to vary the width of the die gap during extrusion while maintaining a constant nucleating pathway gap.