Process to make a composite of controllable porosity

A coextrusion process for the preparation of a composite having a first component comprising a first thermoplastic and a second component comprising a second thermoplastic and a natural cellulosic wood fiber, wherein the first and second thermoplastics are selected from the group consisting of polyvinyl chloride, polyolefins, polystyrenes, polyacrylics and polyesters which comprises the steps of:

• mixing the natural cellulosic wood fiber and the second thermoplastic with a porosity aid which is selected from the group consisting of a paraffin and a hydrocarbon wax blend having a melting point of 200.degree. F. or lower, and
• an oxidized polyolefin fusion enhancer which forms a homogeneous melt of the natural cellulosic fiber and the second thermoplastic and modifies the effect of the porosity aid which deters fusion, yet retains porosity in the composite and forms a mixture of the second component;
• extruding the mixture of the second component and the first thermoplastic of the first component through a dual extrusion die of an extruder to form the composite;
• and
• shaping the composite to a desired profile.

A process for the preparation of a porous natural cellulosic wood fiber and polyvinyl chloride composite comprising:

• mixing the natural cellulosic wood fiber and the polyvinyl chloride with
• a porosity aid which is selected from the group consisting of a paraffin and a hydrocarbon wax blend having a melting point of 200.degree. F. or lower, said porosity aid added in an amount of from about 0.01% to 5% by weight;
• and
• an oxidized polyethylene fusion enhaneer which forms a homogeneous melt of the natural cellulosic wood fiber and the polyvinyl chloride and modifies the effect of the porosity aid which deters fusion, yet retains porosity in the composite and forms a mixture, said fusion enhancer added in an mount of from about 0.01% to 2% by weight;
• extruding the mixture through an extrusion die of an extruder as the composite;
• and
• shaping the composite to a desired profile.

A coextrusion process for the preparation of a composite having a first component comprising polyvinyl chloride and a second component comprising polyvinyl chloride and a natural cellulosic wood fiber, which comprises the steps of:

• mixing the natural cellulosic wood fiber and the polyvinyl chloride of the second component with
• a porosity aid which is selected from the group consisting of a paraffin and a hydrocarbon wax blend having a melting point of 200.degree. F. or lower, said porosity aid added in an amount of from about 0.01% to 5% by weight;
• and
• an oxidized polyethylene fusion enhancer which forms a homogeneous melt of the natural cellulosic fiber and the polyvinyl chloride and modifies the effect of the porosity aid which deters fusion, yet retains porosity in the composite and forms a mixture of the second component, said fusion enhancer added in an mount of from about 0.01% to 2% by weight;
• extruding the mixture of the second component and the first component through a dual extrusion die of an extruder to form the composite;
• and
• shaping the composite to a desired profile.