Thermoplastic composition made from a polyamide polymer obtained from a prepolymer and a chain extender and manufacturing method

1. A composition, comprising at least one polyamide polymer derived from at least one reactive polyamide prepolymer comprising at least one chain extender (PA 1 -All 1 -PA 1 ), said polyamide polymer being prepared at a temperature T 1 greater than or equal to the temperature T m or T g of said polymer, determined respectively according to standards ISO 11357-3 and ISO 11357-2, and having an average molecular weight Mn 1 , as determined by size exclusion chromatography,

wherein said composition has a melt viscosity which can be modulated according to the temperature to which said composition is subjected,

said temperature being included from T 2 to T 3 , T 2 and T 3 being greater than T 1 ,

and said melt viscosity η′ 2 or η′ 3 observed respectively at the temperature T 2 or T 3 being less than the melt viscosity η 2 or η 3 of said polyamide polymer, free of chain extender and having the same average molecular weight Mn 1 (PA 1 ) observed at the same temperature T 2 or T 3 ,

and with:

said composition comprising or consisting of one or more polyamides, including random or block copolyamides which are polymers and which comprise different amide units of formula A/(B) r /(C) s , selected as follows:

A is a repeating amide unit chosen from lactams or an amino acid of C 6 -C 14 , an amide unit X.Y in which X represents at least one diamine, said diamine being chosen from a linear or branched aliphatic diamine, a cycloaliphatic diamine and an aromatic diamine or a mixture thereof, and Y represents at least one dicarboxylic acid, said diacid being chosen from:

an aliphatic diacid, a cycloaliphatic diacid and an aromatic diacid,

said diamine and said diacid comprising from 4 to 36 carbon atoms;

B and C are repeating amide units different than A, optionally present depending on the value of r and s, r=0 or 1, s=0 or 1, said amides units B and C being chosen from the same constituents as for A, on the condition that when r and s=1, then B and C are different,

the sum of the units A+B+C being equal to 100% by weight, and

said composition comprising or consisting of a polyamide polymer resulting from the polymerization of the reaction product of:

a1) at least one prepolymer of said thermoplastic polyamide polymer, bearing n reactive end functions X 1 , chosen from NH 2 and —CO 2 H with n being 1 to 3, with

a2) at least one chain extender Y 1 -A′-Y 1 , with A′ being a hydrocarbon-based biradical of non-polymeric structure, bearing 2 identical end reactive functions Y 1 , reactive by polyaddition with at least one function X of said prepolymer a1),

Y 1 is chosen from: oxazine, oxazoline, oxazolinone, oxazinone,

imidazoline, epoxy, maleimide, and cyclic anhydride, and said composition being free of reinforcing fibers and also of polymeric chain extender,

wherein:

A is present in a molar content ranging from 55% to 95%, chosen from x.T units, wherein x is a linear aliphatic C 4 to C 18 diamine, and wherein T is terephthalic acid, and

B is present in a molar content ranging from 5% to 45%, depending on the Tm of the polyamide based on unit A, and B is chosen from an aliphatic repeating unit obtained from a lactam or an amino acid,

and C is an optional amide unit different than A and B.

2. The composition of claim 1 , wherein the ratio of melt viscosity η′ 3 /η 3 observed at a temperature T 3 is lower than the ratio of melt viscosity η′ 2 /η 2 observed at a temperature T 2 , T 3 ≥T 2 +10° C.

3. The composition of claim 1 , wherein the ratio of melt viscosity η′ 3 /η 3 observed at a temperature T 3 is higher than the ratio of melt viscosity η′ 2 /η 2 observed at a temperature T 2 , T 3 ≤T 2 −10° C.

4. The composition of claim 1 , wherein C is present in a molar content ranging up to 30% relative to the total molar content of the polyamide polymer.

5. The composition of claim 1 , wherein A is present with a molar content ranging from 55% to 80%, relative to all of the units of said polymer.

6. The composition of claim 1 , wherein A and B are selected as follows:

when A is 6T, B is selected from: 9T, 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%,

when A is 9T, B is selected from: 6T, 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 30% to 45%,

when A is 10T, B is selected from: 6T, 9T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 25% to 45%,

when A is 11T, B is selected from: 6T, 9T, 10T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%, and

when A is 12T, B is selected from: 6T, 9T, 10T, 11T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%.

7. The composition of claim 6 , wherein A is 6T and B is selected from: 9T, 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%.

8. The composition of claim 6 , wherein A is 9T and B is selected from: 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 30% to 45%.

9. The composition of claim 6 , wherein A is 10T and B is selected from: 9T, 11T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 25% to 45%.

10. The composition of claim 6 , wherein A is 11T and B is selected from: 9T, 10T, 12T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%.

11. The composition of claim 6 , wherein A is 12T and B is selected from: 10T, 11T, 13T, 14T, 15T, 16T, 17T and 18T, MPMD.T and MXD.T, with a molar content of B ranging from 20% to 45%.

12. The composition of claim 1 , wherein said reactive polyamide prepolymer has a number-average molecular weight Mn ranging from 500 to 10,000.

13. The composition of claim 1 , wherein said reactive polyamide polymer has an average molecular weight which can be modulated according to the temperature to which said polyamide polymer is subjected.

14. The composition of claim 1 , wherein said chain extender Y 1 -A′-Y 1 is 1,3-phenylene-bis(2-oxazoline) or 1,4-phenylene-bis(2-oxazoline).