A method of recovering polymer from a three-dimensional printed object can include dissolving a polyamide polymer of a three-dimensional printed object in a polyamide-dissolving solvent to generate dissolved polyamide polymer from the three-dimensional object, where the three-dimensional printed object can include a particulate fusing compound and from about 90 wt % to about 99.9 wt % of the polyamide polymer; separating the particulate fusing compound from the polyamide-dissolving solvent and the dissolved polyamide polymer; and evaporating the polyamide-dissolving solvent from the dissolved polyamide polymer.

A secondary shredder can include a rotor assembly that employs a modular rotor design. Each rotor of the rotor assembly can include a number of blades that are symmetrical around a horizontal and a vertical axis. Each rotor can include a number of radial extensions forming gaps into which the blades insert. The blades can be secured within the gaps by wedges that apply an inward force against the blades when the wedges are secured into the gaps. The radial extensions and blades can include keyways into which keys insert to prevent the blades from escaping the gaps. The secondary shredder may also include a stationary knife assembly that includes multiple stationary knives that are positioned on the same side of the rotor assembly.

An extruder and molding assembly comprising an extruder positioned upstream from a mold, the mold having a mold cavity and a separate pressurization member fluidly connected to the mold cavity wherein the extruder is operable at a first pressure to fill at least a majority of the mold cavity and the pressurization member is operable to fill a remainder of the mold cavity.

An apparatus for recycling synthetic thermoplastic waste material combining heretofore multiple stage processing steps in a single stage shredder grinder pulverizer device. The apparatus has multiple interchangeable material processing blade sets on respective effacing engageable rotating and fixed blade mounts within a cooled material infeed and blade containment enclosure with multiple vacuum outlet ports and communicating vacuum ducts to draw off and transport processed material therefrom for separation and classification, as required. Each replaceable interchangeable processing blade set includes registerable shredding and grinding blades and annular pulverizing blade sets on fixed and movable mediums for progressive processing of waste material into uniform recyclable material.

There are provided recycled polystyrene polymers having a melt flow index of less than about 25 g/10 min. There are provided processes for recycling polystyrene waste. The processes can comprise dissolving said polystyrene waste in p-cymene under conditions to obtain a polystyrene/p-cymene mixture, adding the polystyrene/p-cymene mixture to a hydrocarbon polystyrene non-solvent under conditions to obtain precipitated polystyrene and washing the precipitated polystyrene with additional portions of hydrocarbon polystyrene non-solvent under conditions to obtain twice-washed polystyrene. The twice-washed polystyrene can optionally be dried and formed into polystyrene pellets. There is also provided recycled polystyrene obtained from such processes for recycling polystyrene waste.

A process for recovery and devulcanization of vulcanized rubber is provided. The process takes place in a plant including a mill for grinding vulcanized rubber into particles, a twin-screw extruder provided with a device for forced feeding of vulcanized rubber particles and a thermostatting device, a single-screw extruder arranged downstream of the twin-screw extruder and equipped with a thermostatting device, a filter for devulcanized rubber and an extrusion die shaped like a slot, from the which devulcanized rubber comes out in the form of a strip or sheet, and a cooling device for the devulcanized rubber strip or sheet. The twin-screw extruder operates at a temperature between 35 and 450° C., with a rotation speed of the screws between 15 and 600 rpm, and a torque density between 11 and 18 Nm/cm.sup.3, so that the shear rate remains constant for the entire longitudinal extension of the twin-screw extruder.

A method for grinding plastic waste includes mixing 30 to 80 wt % of plastic waste and 20 to 70 wt % of a woodchip by a mixer after equalizing the size of a diameter or a side thereof so as to be 5 mm or less, and grinding a mixture thereof into a fine powder with a particle size of 1 mm or less by a grinding device including a rotor rotating at a high speed.

A process for the extraction of one or more colour pigments from waste plastic in which a waste plastic feedstock is mixed with a solvent in a reactor having a shearing mechanism and the solvent is separated out and recycled in the process. The shearing mechanism provides high shear, high contact mixing so as to move the pigment to the surface of the plastic for contact with the solvent to give efficient colour pigment removal. Embodiments of reactors with shearing mechanisms are described. Environmentally friendly solvents are also described. The process gives highly sought after natural recyclate at a commercial scale.

A method of manufacturing a part, includes: obtaining recycled fibers; mixing the recycled fibers with a thermoplastic to obtain a fiber-reinforced intermediate; and manufacturing the part with the fiber-reinforced intermediate. The recycled fibers may come from a grinding operation of recycled composite parts. A feedstock may be manufactured using recycled fibers. The feedstock may then be used in subsequent manufacturing.

Provided herein is a method of recycling additively manufactured articles or recovered coating material that comprises a crosslinked polymer formed from a single-cure resin comprising a reactive blocked prepolymer, into a regenerated resin useful for additive manufacturing. Recyclable light-polymerizable resins, methods of making recyclable objects from such resins, and methods for sustainable manufacturing are also provided.