Method of preparation of cardo polyetherketone (PEK-C) structural foam material

Abstract

A method of preparation of a cardo polyetherketone structural foam material, including the following steps: 1) performing a mould pressing on a cardo polyetherketone resin by a high-temperature vulcanizing machine to prepare a foaming billet; 2) placing the foaming billet in a foaming cavity of a mould-pressing machine, performing a penetration and a swelling by introducing a supercritical fluid to achieve diffusion equilibrium, forming a polymer-supercritical fluid homogeneous solution, and 3) making the polymer-supercritical fluid homogeneous solution supersaturated through a sudden release of the inner pressure of the system, thereby inducing nucleation and foaming, and finally forming a structural foam having a closed pore structure with a uniform pore size and an adjustable pore density. The production process of the present invention is clean, environmentally friendly, and has relatively high efficiency. The obtained structural foam has good mechanical properties.

Claims

1. A method of preparation of a cardo polyetherketone structural foam material, comprising the following steps: 1) performing a mould pressing on a cardo polyetherketone resin by a high-temperature vulcanizing machine to prepare a billet having a thickness of 3-10 mm, wherein in step 1), multiple surface pressures ranging from 0.1 MPa to 3 MPa are applied before the mould pressing is performed; 2) placing the billet in a cavity of a preheated mould-pressing machine, and introducing a supercritical fluid for a penetration and a swelling; and 3) inducing a nucleation and a foaming by controlling a pressure change to form the cardo polyetherketone structural foam material having a closed pore structure.

2. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, the cardo polyetherketone resin in the step 1) is an amorphous structure having a structure of formula (1): ##STR00002## wherein, 1≤t≤5; X, n are positive integers, and y is a non-negative integer; and the cardo polyetherketone resin loses 5% by weight at a temperature of equal to or higher than 400° C., and loses 10% by weight at a temperature of equal to or higher than 500° C.

3. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, a viscosity of the cardo polyetherketone resin in the step 1) ranges from 0.4 dl/g to 1.2 dl/g.

4. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, a viscosity of the cardo polyetherketone resin in the step 1) ranges from 0.6 dl/g to 0.9 dl/g.

5. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, the cardo polyetherketone resin in the step 1) has a glass transition temperature ranging from 208° C. to 230° C.

6. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, a process of the mould pressing in the step 1) comprises: preheating at a temperature of 200-230° C., and compacting and discharging gas under a first surface pressure of 0.1-2 MPa for 10 min; slowly increasing the temperature from 230° C. to 280° C. within a heating time of 20 min, with a second surface pressure of 2-3 MPa during the heating time; then, performing the mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 MPa and a moulding time of 30-45 min; and finally, cooling and releasing from the mould to obtain the billet having the thickness of 3-10 mm.

7. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, a temperature inside the cavity of the mould-pressing machine in the step 2) is 230-265° C., the supercritical fluid is supercritical CO.sub.2, a pressure of the supercritical fluid is 7.5-15 MPa, and a duration of the swelling and penetration is 30-180 min.

8. The method of preparation of the cardo polyetherketone structural foam material of claim 1, wherein, the pressure change in the step 3) ranges up to 15 MPa, and a pressure change rate is 75-150 MPa/s.

9. The method of preparation of the cardo polyetherketone structural foam material of claim 2, wherein, a viscosity of the cardo polyetherketone resin in the step 1) ranges from 0.4 dl/g to 1.2 dl/g.

10. The method of preparation of the cardo polyetherketone structural foam material of claim 2, wherein, a viscosity of the cardo polyetherketone resin in the step 1) ranges from 0.6 dl/g to 0.9 dl/g.

11. The method of preparation of the cardo polyetherketone structural foam material of claim 2, wherein, the cardo polyetherketone resin in the step 1) has a glass transition temperature ranging from 208° C. to 230° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a scanning electron micrograph of a cut surface of a sample according to embodiment 1; It can be seen from the scanning electron micrograph that the cell size ranges from 20 μm to 50 μm, and the cell density ranges from 10.sup.8 cells/cm.sup.3 to 10.sup.12 cells/cm.sup.3; and

(2) FIG. 2 is a scanning electron micrograph of a cut surface of a sample according to embodiment 3; It can be seen from the scanning electron micrograph that the cell size ranges from 80 μm to 120 μm, and the cell density ranges from 10.sup.6 cells/cm.sup.3 to 10.sup.8 cells/cm.sup.3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) In order to make the objective, the technical solution and the advantages of the present invention clearer and more definite, the present invention is further described in detail in combination with specific embodiments. It should be understood that these descriptions are illustrative, rather than limiting the scope of the present invention.

Embodiment 1

(4) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.87 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C state was in a powder state with a size of less than 80 mesh, and was subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(5) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and mould-pressing time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(6) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×10 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 265° C. A pressure of the supercritical fluid was controlled to be 15 MPa, and the time of the swelling and penetration was 3 h.

(7) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 120-150 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 420×420×45 mm) was obtained. The density of the foamed plate was measured to be 65 kg/m.sup.3, and the foamed material was expanded by about 20 times compared with the raw material.

Embodiment 2

(8) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.68 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C resin was in a powder state with a size of less than 80 mesh, and subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(9) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and mould-pressing time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(10) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×6 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 255° C. A pressure of the supercritical fluid was controlled to be 10 MPa, and the time of the swelling and penetration was 2.5 h.

(11) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 100-120 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 380×380×28 mm) was obtained. The density of the foamed plate was measured to be 75 kg/m.sup.3, and the foamed material was expanded by about 17 times compared with the raw material.

Embodiment 3

(12) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.61 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C resin was in a powder state with a size of less than 80 mesh, and subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(13) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and moulding time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(14) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×3 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 265° C. A pressure of the supercritical fluid was controlled to be 7.5 MPa, and the time of the swelling and penetration was 0.5 h.

(15) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 75-100 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 365×365×8 mm) was obtained. The density of the foamed plate was measured to be 150 kg/m.sup.3, and the foamed material was expanded by about 9 times compared with the raw material.

(16) The performance test was performed on the foamed materials prepared in embodiment 1 and embodiment 3. The results are shown in Table 1.

(17) TABLE-US-00001 TABLE 1 Properties of Foamed Materials Prepared in Embodiment 1 and Embodiment 3 Test Retention Retention Test item condition Unit Embodiment 1 rate Embodiment 3 rate Density Room kg/m.sup.3 65.6 99.8% 163 99.6% temperature 180° C. 65.5 162 Compression Room MPa 0.572 59.1% 1.93 59.1% strength temperature 180° C. 0.338 1.14 Compression Room MPa 30.6 83.0% 103 84.7% modulus temperature 180° C. 25.4 87.2

Embodiment 4

(18) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.97 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C resin was in a powder state with a size of less than 80 mesh, and subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(19) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and moulding time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(20) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×10 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 230° C. A pressure of the supercritical fluid was controlled to be 15 MPa, and the time of the swelling and penetration was 3 h.

(21) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 75-120 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 355×355×38 mm) was obtained. The density of the foamed plate was measured to be 110 kg/m.sup.3, and the foamed material was expanded by about 12 times compared with the raw material.

Embodiment 5

(22) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.87 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C resin was in a powder state with a size of less than 80 mesh, and subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(23) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and moulding time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(24) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×6 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 265° C. A pressure of the supercritical fluid was controlled to be 12 MPa, and the time of the swelling and penetration was 2 h.

(25) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 120-150 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 385×385×29 mm) was obtained. The density of the foamed plate was measured to be 70 kg/m.sup.3, and the foamed material was expanded by about 18 times compared with the raw material.

Embodiment 6

(26) First, a cardo polyetherketone (PEK-C) resin from Changchun Institute of Applied Chemistry is used. A viscosity of the PEK-C resin is 0.61 dl/g (0.5% CHCl.sub.3, 25° C.), and the PEK-C resin is an amorphous structure, and has a glass transition temperature ranging from 208° C. to 230° C. The PEK-C resin was in a powder state with a size of less than 80 mesh, and subjected to a mould pressing by a high-temperature vulcanizing machine to form a foaming billet.

(27) The mould-pressing process includes: 1) preheating at a temperature of 200-230° C., and compacting and discharging gas under a surface pressure of 0.1-2 MPa for 10 min; 2) slowly increasing the temperature from 230° C. to 280° C. within the heating time of 20 min, and maintaining the surface pressure of 2-3 Mpa; 3) then performing a mould pressing at 280-295° C. with a mould-pressing pressure of 4.5-6 Mpa and moulding time of 30-45 min; and 4) finally, cooling and releasing the mould to obtain a billet having a thickness of 3-10 mm.

(28) Then, the pre-prepared PEK-C foaming billet plate (having a size of 200×200×6 mm) was placed in a foaming cavity of a mould-pressing machine, the oxygen in the foaming cavity was replaced by the high-pressure CO.sub.2 gas. The mould-pressing machine was configured at a constant temperature of 265° C. A pressure of the supercritical fluid was controlled to be 15 MPa, and the time of the swelling and penetration was 3 h.

(29) Finally, after reaching equilibrium, the pressure was relieved to 0 at a pressure relief rate of 100-120 MPa/s, and the swollen PEK-C billet plate forms a nucleus uniformly. Then, the mould-pressing machine was quickly opened, the gas nucleuses continued to grow, and a PEK-C structural foam plate material (having a size of 360×360×26 mm) was obtained. The density of the foamed plate was measured to be 90 kg/m.sup.3, and the foamed material was expanded by about 14 times compared with the raw material.

(30) The PEK-C structural foam of the present invention has the characteristics of light weight and high strength, and can be directly applied to the fields of aerospace, transportation, ship, etc. The PEK-C structural foam can be cut into various specifications of plates as a core layer of the sandwich structure material, and can further be cut into sheet materials for secondary moulding to meet the needs of different application fields.

(31) The foam prepared by the present invention is a typical structural foam. The mechanical property of the foam prepared by the present invention is higher than that of the polyvinyl chloride (PVC) structural foam, and is close to that of the polymethacrylimide (PMI) foam. Especially, the mechanical property can be maintained at the level of MPa at a high temperature. The foam prepared by the present invention is an excellent high-temperature structural foam.

(32) Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications may be made to the embodiments of the present invention without departing from the spirit and scope of the present invention.