Ways of preparing a partially crystalline polycarbonate powder are provided that include dissolving an amorphous polycarbonate in a polar aprotic solvent to form a first solution of solubilized polycarbonate at a first temperature. The first solution is then cooled to a second temperature, the second temperature being lower than the first temperature, where a portion of the solubilized polycarbonate precipitates from the first solution to form a second solution including the partially crystalline polycarbonate powder. Certain partially crystalline polycarbonate powders resulting from such methods are particularly useful in additive manufacturing processes, including powder bed fusion processes.

In accordance with one or more embodiments of the present disclosure, a process includes introducing a mixture comprising polypropylene carbonate (PPC) polyol, carbon dioxide, propylene oxide, and at least one dibasic ester to a quenching vessel to separate the PPC polyol from the carbon dioxide and the propylene oxide; introducing additional dibasic ester to the separation vessel, thereby separating the carbon dioxide from the propylene oxide and the dibasic ester such that a mixture of propylene oxide and the dibasic ester is formed; and introducing the mixture of propylene oxide and the dibasic ester to a recovery vessel, wherein the propylene oxide is separated from the dibasic ester in the recovery vessel.

In accordance with one or more embodiments of the present disclosure, a process includes introducing a mixture comprising polypropylene carbonate (PPC) polyol, carbon dioxide, propylene oxide, and at least one dibasic ester to a quenching vessel to separate the PPC polyol from the carbon dioxide and the propylene oxide; introducing additional dibasic ester to the separation vessel, thereby separating the carbon dioxide from the propylene oxide and the dibasic ester such that a mixture of propylene oxide and the dibasic ester is formed; and introducing the mixture of propylene oxide and the dibasic ester to a recovery vessel, wherein the propylene oxide is separated from the dibasic ester in the recovery vessel.

Disclosed herein are embodiments of a method for making recyclable polymers and a method for decomposing the polymers back to the monomers which can then be reused. The polymer are stable to aqueous and/or acid conditions and may have a formula II ##STR00001## The method to decompose the polymer back to the monomers may comprise heating the polymer in a protic organic solvent.

In an embodiment, a polycarbonate polymerization process comprises interfacially polymerizing a carbonate compound and dihydroxy compound in the presence of an interfacial catalyst to form a polycarbonate and adding a viscosity reducing agent and a transesterification catalyst to polycarbonate upstream of a first filter to form an adjusted polycarbonate. The first filter can be replaced with a replacement filter and the adjusted polycarbonate can be introduced to the replacement filter. The flow can be diverted to a replacement filter. The process further comprises reducing the addition rate of the viscosity reducing agent and the transesterification catalyst until the addition rate is 0 mol/hr.

The present invention relates to a production method of polyalkylene carbonate particles capable of precipitating and separating resin particles from a polyalkylene carbonate suspension obtained through polymerization of an epoxide and carbon dioxide. According to the present invention, the production method is capable of obtaining a polyalkylene carbonate resin having excellent workability with a high yield and a low energy cost while reducing a scale of a facility, a processing time, and a wastewater amount, as compared to conventional methods such as a flash separation method.

Disclosed herein are embodiments of a method for making recyclable polymers and a method for decomposing the polymers back to the monomers which can then be reused. The polymer are stable to aqueous and/or acid conditions and may have a formula II

##STR00001##

The method to decompose the polymer back to the monomers may comprise heating the polymer in a protic organic solvent.

Ways of preparing a partially crystalline polycarbonate powder are provided that include dissolving an amorphous polycarbonate in a polar aprotic solvent to form a first solution of solubilized polycarbonate at a first temperature. The first solution is then cooled to a second temperature, the second temperature being lower than the first temperature, where a portion of the solubilized polycarbonate precipitates from the first solution to form a second solution including the partially crystalline polycarbonate powder. Certain partially crystalline polycarbonate powders resulting from such methods are particularly useful in additive manufacturing processes, including powder bed fusion processes.

Ways of preparing a partially crystalline polycarbonate powder are provided that include dissolving an amorphous polycarbonate in a polar aprotic solvent to form a first solution of solubilized polycarbonate at a first temperature. The first solution is then cooled to a second temperature, the second temperature being lower than the first temperature, where a portion of the solubilized polycarbonate precipitates from the first solution to form a second solution including the partially crystalline polycarbonate powder. Certain partially crystalline polycarbonate powders resulting from such methods are particularly useful in additive manufacturing processes, including powder bed fusion processes.

A method of continuously producing a polyol includes: (i) feeding a solid catalyst into a continuous stirred tank reactor (CSTR); (ii) contacting a reaction mixture comprising one or more epoxides and carbon dioxide with the solid catalyst and a chain transfer agent comprising a plurality of sites capable of initiating copolymerization of epoxides and carbon dioxide in the CSTR; (iii) allowing polymerization reaction to proceed until a desired molecular weight polyol has formed; and (iv) terminating the polymerization reaction.