Chain scission to make improved polymers for 3D printing
An end capped condensation polymer may be formed by heating a condensation polymer in the presence of an end capping compound to form cleaved condensation polymer reacting at least a portion of the cleaved condensation polymer with the end capping compound to form the end capped condensation polymer. The end capped condensation polymers may be used to form additive manufactured articles having high solids loading and improved processing due to improved rheological behavior.
1 . A method of forming an end capped condensation polymer comprising:
(i) heating a linear or branched polyamide polymer having a melt flow of at most 5 grams/10 min (2.16 kg @235° C.) in the presence of at least one end capping compound, wherein each end capping compound has a functionality of 1 to form a cleaved condensation polymer, and
(ii) reacting at least a portion of the cleaved condensation polymer with the end capping compound to form the end capped condensation polymer, wherein the end capped condensation polymer has a melt flow rate of 10 to 200 grams/10 min (2.16 kg @ 235° C.) and is at least 5 times greater than the melt flow of the linear or branched polyamide.
2 . The method of claim 1 , wherein the at least one end capping compound is selected from the group consisting of an epoxide, carboxylic acid, alcohol, anhydride, amine, isocyanate, aziridine, oxazoline, phosphite ester, and combinations thereof.
3 . The method of claim 2 , wherein the at least one end capping compound is an anhydride or carboxylic acid.
4 . The method of claim 3 , wherein the at least one end capping compound is the anhydride.
5 . The method of claim 4 , wherein the polyamide is a 6/66/12 co-polyamide.
6 . The method of claim 1 , wherein the end capped condensation polymer has a higher polydispersity than the linear or branched polyamide such that a ratio of the polydispersity of the end capped condensation polymer to the polydispersity of the linear or branched polyamide is at least 1.2.
7 . The method of claim 6 , wherein the end capped condensation polymer has a melt flow rate of at least 30 grams/10 min (2.16 kg @ 235° C.).
8 . The method of claim 7 , wherein the end capped condensation polymer has a melt flow rate of at least 50 grams/10 min (2.16 kg @ 235° C.).
9 . The method of claim 8 , wherein the end capped condensation polymer has a melt flow rate of at least 75 grams/10 min (2.16 kg @ 235° C.).
10 . The method of claim 1 , further comprising adding a filler to the end capped condensation polymer wherein the filler is added in an amount of 20% to 90% by weight based on the combined weight of the end capped condensation polymer and filler.
11 . The method of claim 1 , wherein the end capped condensation polymer has a melt flow rate that is at least 10 times greater than the melt flow of the linear or branched polyamide.
12 . The method of claim 1 further comprising shearing the condensation polymer during heating.
13 . The method of claim 12 , wherein the heating is performed in a screw extruder.
14 . The method of claim 1 further comprising removing water during at least a portion of the method.
15 . The method of claim 14 , wherein water is removed by performing the method under a reduced pressure.
16 . The method of claim 1 , wherein the at least one end capping compound is selected from the group consisting of tetrabromophthalic anhydride, hexahydrophthalic anhydride, 1,8-naphthalic anhydride, phthalic anhydride, and combinations thereof.
17 . The method of claim 1 , wherein the at least one end-capping compound is present in an amount of 0.01% to 5% by weight of the condensation polymer and end capping compound.
18 . A method of forming an article comprised of fusing layers of the end capped condensation polymer made by the method of claim 1 , the layers being sequentially deposited and fused by directed application of heating via an additive manufacturing method.
19 . The method of claim 18 , wherein the additive manufacturing method is SLS or FFF and the end capped condensation polymer has a filler in an amount of at least 50% to 90% by weight of the polymer and filler.
20 . The method of claim 1 , further comprising adding a filler to the end capped condensation polymer wherein the filler is added in an amount of 20% to 40% by weight based on the combined weight of the end capped condensation polymer and filler.