Method for manufacturing objects by selective sintering
The application relates to methods for manufacturing an object from a powder by selective sintering. More particularly, the methods described herein involve the step of selecting a polymer wherein the density of the crystalline phase of said polymer is equal to or lower than the density of the amorphous phase of said polymer.
1. A method for manufacturing an object by selective sintering of a powder, said method comprising:
selecting at least one semi-crystalline polymer, wherein a density of a crystalline phase of said at least one semi-crystalline polymer is equal to or lower than a density of an amorphous phase of said at least one semi-crystalline polymer upon crystallization; and
manufacturing said object from a powder by selective sintering, wherein said powder comprises said at least one semi-crystalline polymer.
2. The method according to claim 1 , wherein the selective sintering is at least one of selective laser sintering or an additive manufacturing process.
3. The method according to claim 2 , wherein a change in density upon crystallization of said at least one semi-crystalline polymer compensates for at least part of a change in specific volume or density of said at least one semi-crystalline polymer upon cooling.
4. The method according to claim 2 , wherein selecting the at least one semi-crystalline polymer comprises:
identifying a change in specific volume or density of one or more polymers upon crystallization; and
selecting the at least one semi-crystalline polymer from the one or more polymers based on the identifying the change in specific volume or density.
5. The method according to claim 2 , wherein said at least one semi-crystalline polymer is a polymer selected from a list consisting of syndiotactic polystyrene, poly(4-methyl-1-pentene), and syndiotactic poly(p-methylstyrene).
6. The method according to claim 2 , wherein said powder comprises at least 30 w % of said at least one semi-crystalline polymer.
7. The method according to claim 2 , wherein a degree of crystallinity of said at least one semi-crystalline polymer is between 50 and 80%.
8. The method according to claim 2 , wherein said powder is a composite powder.
9. The method of claim 2 , wherein the density of the crystalline phase is lower than the density of the amorphous phase of the at least one semi-crystalline polymer.
10. The method according to claim 9 , wherein said at least one semi-crystalline polymer is a polymer selected from a list consisting of syndiotactic polystyrene, poly(4-methyl-1-pentene), and syndiotactic poly(p-methylstyrene).
11. The method according to claim 9 , wherein said powder comprises at least 30 w % of said at least one semi-crystalline polymer.
12. The method according to claim 9 , wherein a degree of crystallinity of said at least one semi-crystalline polymer is between 50 and 80%.
13. The use of a powder in the manufacture of a 3D object by means of selective sintering of said powder, wherein at least 30 w % of said powder is a semi-crystalline polymer wherein a density of a crystalline phase is lower than a density of an amorphous phase of the semi-crystalline polymer.
14. The use according to claim 13 , wherein the means of selective sintering is at least one of selective laser sintering or an additive manufacturing process.
15. The use according to claim 14 , wherein said semi-crystalline polymer comprises a polymer selected from a list consisting of syndiotactic polystyrene, poly(4-methyl-1-pentene), and syndiotactic poly(p-methylstyrene).