Reduced porosity 3d printed composites

A method of additively manufacturing reduced porosity composites, the method comprising the steps of:

• providing an additive manufacturing printer comprising a feed hopper, the feed hopper comprising:
• a first hopper wall defining a feed inlet and a chamber opening;
• a second hopper wall contacting an outlet end of the first hopper wall and defining a feed outlet;
• a vacuum lid contacting a feed end of the first hopper wall;
• a first valve disposed proximate the feed inlet in a closed position;
• a second valve disposed proximate the chamber opening in an open position;
• and
• a vacuum pump;
• wherein the first hopper wall and the vacuum lid define a first chamber disposed proximate to a second chamber defined by the first hopper wall and the second hopper wall;
• and
• wherein the first chamber and the second chamber are in selective fluid communication via the chamber opening;
• applying a rough vacuum to the first chamber and the second chamber using the vacuum pump;
• feeding feedstock into the feed hopper of the additive manufacturing printer;
• opening the first valve and closing the second valve, thereby pulling feedstock into the first chamber from a feedstock source;
• closing the first valve and opening the second valve, thereby allowing feedstock from the first chamber to enter the second chamber and maintain a rough vacuum in the second chamber;
• allowing the feedstock to exit the feed hopper via the feed outlet;
• heating the feedstock to give a heated printing material;
• and
• extruding the heated printing material out of the additive manufacturing printer.