A method of increasing bubble stability of a needful high molecular weight bimodal high-density polyethylene resin in need thereof, the method comprising subjecting the needful high molecular weight bimodal high-density polyethylene resin to a determined amount of oxygen tailoring of the resin so as to independently increase both the resin's melt storage modulus G (at G=3000 pascals) and complex viscosity ratio SH1000, and thereby make an oxygen-tailored high molecular weight bimodal high-density polyethylene resin having a targeted increase in bubble stability. The method uses a tailoring effective amount of molecular oxygen (O.sub.2) to achieve the desired oxygen tailoring. The method uses these advanced rheological properties from dynamic mechanical spectroscopy, but analyzes the data in a different way that is more sensitive to changes in resin composition and properties, and yet achieves a resin regime having a targeted increase in bubble stability.

Apparatus for injection of fluid into an extruder is provided, including a static mixer section with a pipe assembly coupled with the static mixer outlet and leading to the extruder barrel; the pipe assembly outlet and barrel injection opening have diameters less than the maximum internal diameter of the static mixer casing. The invention greatly simplifies the fluid injection apparatus used with extruders, while giving more efficient absorption of thermal energy with a minimum of environmental contamination, and the ability to inject multiple streams into the extruder.

Apparatus for injection of fluid into an extruder is provided, including a static mixer section with a pipe assembly coupled with the static mixer outlet and leading to the extruder barrel; the pipe assembly outlet and barrel injection opening have diameters less than the maximum internal diameter of the static mixer casing. The invention greatly simplifies the fluid injection apparatus used with extruders, while giving more efficient absorption of thermal energy with a minimum of environmental contamination, and the ability to inject multiple streams into the extruder.

Apparatus (20) for injection of fluid into extrusion system components such as a preconditioner (24) or extruder (100) is provided, preferably as a composite assembly including a fluid injection valve (52) and an interconnected static mixer section (54). Alternately, use may be made of the fluid injection valve (52) or static mixer section (54) alone. The invention greatly simplifies the fluid injection apparatus used in extrusion systems, while giving more efficient absorption of thermal energy with a minimum of environmental contamination, and the ability to inject multiple streams into the extrusion systems.

An extruder (100) for comestible material comprises a tubular barrel (104) and one or more elongated, axially rotatable, helically flighted screws (120, 122) within the barrel (104), where the barrel (104) has a delivery opening (114a). The extruder barrel (104) is equipped with an assembly (22) for delivery of fluid to the interior thereof, including a static mixing section (54) operable to blend the steam and water to create a blended mixture; the blended mixture is delivered to the barrel opening (114a) by means of a conveying assembly (84, 86) having a pipe assembly (86) with an outlet in communication with the barrel opening (114a); the pipe assembly (86) and opening (114a) have diameters less than maximum internal diameter of the static mixer casing (72).

A method for extruding a comestible material comprises the steps of passing comestible material into an extruder (100) with rotation of the extruder screw(s) (120, 122) and delivery of fluid comprising steam and water into an opening (114a) of the extruder barrel (104). The fluid delivery step comprises separately directing individual quantities of steam and water into the casing (72) of a static mixing section (54), and blending the steam and water to create a blended mixture, and then delivering the blended mixture into the barrel (114a). The blended mixture is delivered to the barrel opening (114a) by means of a conveying assembly (84, 86) having a pipe assembly (86) with an outlet in communication with the barrel opening (114a); the pipe assembly (86) and opening (114a) have diameters less than maximum internal diameter of the static mixer casing (72).

Apparatus (20) for injection of fluid into extrusion system components such as a preconditioner (24) or extruder (100) is provided, preferably as a composite assembly including a fluid injection valve (52) and an interconnected static mixer section (54). Alternately, use may be made of the fluid injection valve (52) or static mixer section (54) alone. The invention greatly simplifies the fluid injection apparatus used in extrusion systems, while giving more efficient absorption of thermal energy with a minimum of environmental contamination, and the ability to inject multiple streams into the extrusion systems.

A method for extruding a comestible material comprises the steps of passing comestible material into an extruder (100) with rotation of the extruder screw(s) (120, 122) and delivery of fluid comprising steam and water into an opening (114a) of the extruder barrel (104). The fluid delivery step comprises separately directing individual quantities of steam and water into the casing (72) of a static mixing section (54), and blending the steam and water to create a blended mixture, and then delivering the blended mixture into the barrel (114a). The blended mixture is delivered to the barrel opening (114a) by a conveying assembly (84, 86) having a pipe assembly (86) with an outlet in communication with the barrel opening (114a); the pipe assembly (86) and opening (114a) have diameters less than maximum internal diameter of the static mixer casing (72).

An extruder (100) for comestible material comprises a tubular barrel (104) and one or more elongated, axially rotatable, helically flighted screws (120, 122) within the barrel (104), where the barrel (104) has a delivery opening (114a). The extruder barrel (104) is equipped with an assembly (22) for delivery of fluid to the interior thereof, including a static mixing section (54) operable to blend steam and water to create a blended mixture; the blended mixture is delivered to the barrel opening (114a) by of a conveying assembly (84, 86) having a pipe assembly (86) with an outlet in communication with the barrel opening (114a); the pipe assembly (86) and opening (114a) have diameters less than maximum internal diameter of the static mixer casing (72).

Methods of preconditioning comestible materials such as foods or feeds include the step of separately injecting steam and water into a static mixer in order to create a blend, which is then injected into the materials within a preconditioner barrel. The methods yield increased cook values in the preconditioned materials, with a reduction in evolved steam from the preconditioner.