Electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules and their preparation method

Abstract

Electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules include raw materials, in parts by weight, comprising 15-55 parts of petroleum resin, 5-10 parts of paraffin, 5-10 parts of polyethylene wax, 3-10 parts of magnetic iron powder and 20-67 parts of diisocyanate. The diisocyanate microcapsules use the diisocyanate as a core material, and the petroleum resin/paraffin/polyethylene wax/magnetic iron powder mixture as the shell of the capsule. When micro cracks occur in the concrete, the crack propagation can break partial of the microcapsule inside, the diisocyanate inside the microcapsules flows out and diffuses into the crack and is subjected to a solidifying reaction with water in the concrete, so that the crack is repaired in time; and for the microcapsules that are not broken by cracks, external electromagnetic field can be applied to melt the shell to release the diisocyanate inside, thereby diffusing into cracks and solidify with water to repair them.

Claims

1. Electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules, comprising: raw materials, in parts by weight, comprising 15-55 parts of petroleum resin, 5-10 parts of paraffin, 5-10 parts of polyethylene wax, 3-10 parts of magnetic iron powder and 20-67 parts of diisocyanate, wherein the paraffin has a melting point of 50-70° C.

2. The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules according to claim 1, wherein the petroleum resin is a C5 resin or a C9 resin.

3. The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules according to claim 1, wherein the polyethylene wax has a melting point of 100-110° C.

4. The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules according to claim 1, wherein the magnetic iron powder is pure iron powder, carbonyl iron powder or iron oxide powder, and has a fineness of 200-2000-mesh.

5. The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules according to claim 1, wherein the diisocyanate is hexamethylene diisocyanate, 1,5-naphthalene diisocyanate or isophorone diisocyanate.

6. A preparation method of electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules, comprising the steps of: (a) providing raw materials, in parts by weight, comprising 15-55 parts of petroleum resin, 5-10 parts of paraffin, 5-10 parts of polyethylene wax, 3-10 parts of magnetic iron powder and 20-67 parts of diisocyanate, wherein the paraffin has a melting point of 50-70° C.; (b) heating the petroleum resin to 130-140° C., adding the paraffin under stirring, mixing the paraffin and the petroleum resin uniformly, adding the polyethylene wax and stirring continuously to mix the polyethylene wax and the paraffin/petroleum resin uniformly, adding the magnetic iron powder, continuing to perform stirring to mix the magnetic iron powder and the petroleum resin/paraffin/polyethylene wax uniformly, finally adding the diisocyanate, and carrying out stirring for 2-4 h while controlling the temperature at 100-110° C.; (c) stopping heating, increasing the stirring speed, adding the perfluorotributylamine solution, and lowering the temperature of the mixture to obtain a petroleum resin/paraffin/polyethylene wax/magnetic iron powder coated diisocyanate microcapsule suspension; and (d) carrying out ultrasonic dispersion treatment on the suspension, separating out the microcapsules by filtration, and carrying out drying treatment to obtain the electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules.

7. The preparation method according to claim 6, wherein the stirring speed in the step (b) is 300-500 rpm, and the stirring speed in the step (c) is 1000-1200 rpm.

8. The preparation method according to claim 6, wherein in the step (b), the petroleum resin is heated to 130-140° C. and stirred for 20-40 min, the paraffin is added, stirring is continued to be performed for 10-20 min, the polyethylene wax is added, stirring is continued to be performed for 10-20 min, the magnetic iron powder is added, and stirring is continued to be performed for 10-20 min.

9. The preparation method according to claim 6, wherein the ultrasonic dispersion treatment process in the step (d) is carried out at an ultrasonic frequency of 40 kHz for 30 min.

10. The preparation method according to claim 6, wherein the drying treatment in the step (d) is carried out at a temperature of 40-50° C. for 24 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A and 1B shows respectively crack changes before and after electromagnetic induction of cement concrete doped with the diisocyanate microcapsules according to Embodiment 1.

(2) FIGS. 2A and 2B shows respectively crack changes before and after electromagnetic induction of cement concrete doped with the diisocyanate microcapsules according to Embodiment 2.

DETAILED DESCRIPTION

(3) In order to better understand the present invention, the contents of the present invention will be further clarified below with reference to the embodiments, but the contents of the present invention are not limited to the following embodiments.

Embodiment 1

(4) The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules are prepared by the following method:

(5) (1) weighing the following raw materials in parts by weight: 25 parts of C9 petroleum resin, 5 parts of paraffin (having a melting point of 68-70° C.), 5 parts of polyethylene wax (having a melting point of 100-103° C.), 5 parts of 2000-mesh iron oxide powder (Fe.sub.3O.sub.4) and 60 parts of hexamethylene diisocyanate;

(6) (2) adding 25 parts of petroleum resin into a three-necked flask with a heating mantle, heating the petroleum resin to 130-140° C., and stirring it at a speed of 300-500 rpm for 30 min;

(7) (3) adding 5 parts of paraffin into the three-necked flask, maintaining the temperature at 130-140° C., and stirring the mixture at a speed of 300-500 rpm for 15 min to mix the paraffin with the petroleum resin uniformly;

(8) (4) adding 5 parts of polyethylene wax into the three-necked flask, maintaining the temperature at 130-140° C., and stirring the mixture at a speed of 300-500 rpm for 15 min to mix the polyethylene wax with the petroleum resin/paraffin uniformly;

(9) (5) adding 5 parts of iron oxide powder (Fe.sub.3O.sub.4) into the three-necked flask, maintaining the temperature at 130-140° C., and stirring the mixture at a speed of 300-500 rpm for 15 min to mix the iron oxide powder with the petroleum resin/paraffin/polyethylene wax uniformly;

(10) (6) adding 60 parts of hexamethylene diisocyanate into the three-necked flask, maintaining the temperature at 100-110° C., and stirring the mixture at a speed of 300-500 rpm for 3 h;

(11) (7) removing the heating mantle, increasing the stirring speed to 1000-1200 rpm, adding 500 parts of perfluorotributylamine solution into the three-necked flask, and rapidly lowering the temperature of the mixture to obtain a petroleum resin/paraffin/polyethylene wax/iron oxide powder mixture coated hexamethylene diisocyanate microcapsule suspension;

(12) (8) carrying out ultrasonic dispersion treatment on the suspension at an ultrasonic frequency of 40 kHz for 30 min, carrying out filtering, and drying the separated microcapsule in a drying oven of 50° C. for 24 h to obtain the electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules.

(13) The average particle size and shell thickness of the microcapsules prepared in this embodiment are tested, and the encapsulation efficiency and the core/shell mass ratio of the capsule are tested and calculated. The results are shown in Table 1. The results in Table 1 show that the microcapsules prepared in this embodiment have a small average particle size, a thin shell thickness, a high encapsulation efficiency and a high core/shell mass ratio.

(14) TABLE-US-00001 TABLE 1 Microcapsules prepared in Embodiment 1 Average Shell Encapsulation Particle Size Thickness Efficiency Core/shell (μm) (μm) (%) Mass Ratio 100 1.2 79.41 1.95

(15) Electromagnetic induction self-healing test of cement concrete doped with the diisocyanate microcapsules prepared in Embodiment 1:

(16) (1) Preparation molding and curing of self-healing concrete: the microcapsules prepared above are added to concrete (the doping amount is 8% by mass of the cement) to prepare self-healing concrete; the prepared concrete is poured into a mold of 500 mm×100 mm×50 mm, vibrated and smoothed, placed for 24 hours and demolded; and the concrete specimens are transferred to a curing room for 28 days, then taken out and placed at room temperature for 7 days.

(17) (2) Prefabrication of a crack: using a three-point bending test method (i.e., the test specimen is placed on two support points with a certain distance, and a downward load is applied to the test specimen on the midpoint of the two support points), a microcrack is generated on the surface of the test specimen, the test specimen is immediately taken down and the initial crack width is measured.

(18) (3) Electromagnetically-induced self-healing: the electromagnetic heating equipment has a power of 7.5 kW, a voltage of 650 V, a frequency of 123 kHz and an induction heating coil size of 100 mm×200 mm, the induction heating coil is placed 2 cm above the crack on the surface of the concrete test specimen, the surface temperature of the induction heating zone of the concrete slab is tested by an infrared thermometer during the heating, and the heating is stopped when the temperature rises to 120° C.

(19) Changes of crack width: initial cracks of different widths are selected and the crack widths are separately measured at 1 h, 3 h and 5 h after electromagnetic induction. The test results are shown in Table 2. The results in Table 2 show that the electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules prepared in Embodiment 1 can rapidly repair concrete cracks of different widths, a crack of 0.16 mm can be repaired in 1 h, and a crack of 0.39 mm can be repaired in 5 h. The crack changes before and after electromagnetic induction of cement concrete doped with the diisocyanate microcapsules according to Embodiment 1 are shown in FIGS. 1A and 1B, respectively.

(20) TABLE-US-00002 TABLE 2 Changes of crack width of concrete doped with the microcapsules prepared in Embodiment 1 under electromagnetic induction action Crack width tested at different Initial crack before times after electromagnetic induction electromagnetic induction 1 h 3 h 5 h 0.16 mm 0.00 mm 0.00 mm 0.00 mm 0.25 mm 0.11 mm 0.00 mm 0.00 mm 0.39 mm 0.26 mm 0.11 mm 0.00 mm

Embodiment 2

(21) The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules are prepared using the following raw materials in parts by weight: 31 parts of C5 petroleum resin, 6.5 parts of paraffin (with a melting point of 64-66° C.), 6 parts of polyethylene wax (with a melting point of 106-110° C.), 3.5 parts of 1500-mesh carbonyl iron powder and 53 parts of 1,5-naphthene diisocyanate. The preparation method is the same as that in Embodiment 1.

(22) The average particle size and shell thickness of the microcapsules prepared in this embodiment are tested, and the encapsulation efficiency and the core/shell mass ratio are tested and calculated. The results are shown in Table 3 Similar to Embodiment 1, the microcapsules prepared in this embodiment have a small average particle size, a thin shell thickness, a high encapsulation efficiency and a high core/shell mass ratio.

(23) TABLE-US-00003 TABLE 3 Microcapsule prepared in Embodiment 2 Average Shell Encapsulation Particle Size Thickness Efficiency Core/Shell (μm) (μm) (%) Mass Ratio 120 1.45 75.28 1.84

(24) Electromagnetic induction self-healing of cement concrete doped with the diisocyanate microcapsules prepared in Embodiment 2:

(25) (1) the microcapsules prepared above are added to concrete (the doping amount is 10% by mass of the cement) to prepare self-healing concrete; the preparation molding and curing of the self-healing concrete and the prefabrication of the crack are the same as those in Embodiment 1;

(26) (2) electromagnetically-induced self-healing: the electromagnetically-induced self-healing process is the same as that in Embodiment 1, and the surface temperature of the concrete specimen in the induction heating zone is controlled at 130° C.

(27) Initial cracks of different widths are selected and the crack widths are separately measured at 1 h, 3 h and 5 h after electromagnetic induction. The test results are shown in Table 4. The results in Table 4 show that the electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules prepared in Embodiment 2 can rapidly repair concrete cracks of different widths, and the crack of 0.34 mm is basically repaired within 3 h. The crack changes before and after electromagnetic induction of cement concrete doped with the diisocyanate microcapsules according to Embodiment 2 are shown in FIGS. 1A and 1B, respectively.

(28) TABLE-US-00004 TABLE 4 Changes of crack width of concrete doped with the microcapsules prepared in Embodiment 2 under electromagnetic induction action Crack width tested at different Initial crack before times after electromagnetic induction electromagnetic induction 1 h 3 h 5 h 0.12 mm 0.00 mm 0.00 mm 0.00 mm 0.24 mm 0.12 mm 0.00 mm 0.00 mm 0.34 mm 0.19 mm 0.05 mm 0.00 mm

Embodiment 3

(29) The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules are prepared from the following raw materials in parts by weight: 42 parts of C9 petroleum resin, 8 parts of paraffin (with a melting point of 64-66° C.), 8 parts of polyethylene wax (with a melting point of 103-106° C.), 8 parts of 200-mesh high-purity iron powder and 34 parts of isophorone diisocyanate. The preparation method is the same as that in Embodiment 1.

(30) The average particle size and shell thickness of the microcapsules prepared in this embodiment are tested, and the encapsulation efficiency and the core/shell mass ratio are tested and calculated. The results are shown in Table 5 Similar to Embodiment 1, the microcapsules prepared in this embodiment have a small average particle size, a thin shell thickness, a high encapsulation efficiency and a high core/shell mass ratio.

(31) TABLE-US-00005 TABLE 5 Microcapsules prepared in Embodiment 3 Average Shell Encapsulation Particle Size Thickness Efficiency Core/Shell (μm) (μm) (%) Mass Ratio 150 1.82 70.41 1.72

(32) Electromagnetic induction self-healing test of cement concrete doped with the diisocyanate microcapsules prepared in Embodiment 3:

(33) (1) the microcapsules prepared in this embodiment are added to concrete (the doping amount is 10% by mass of the cement) to prepare self-healing concrete; the preparation molding and curing of the self-healing concrete and the prefabrication of the crack are the same as those in Embodiment 1;

(34) (2) electromagnetically-induced self-healing: the electromagnetically-induced self-healing process is the same as that in Embodiment 1, and the surface temperature of the concrete specimen in the induction heating zone is controlled at 140° C.

(35) Initial cracks of different widths are selected and the crack widths are separately measured at 1 h, 3 h and 5 h after electromagnetic induction. The test results are shown in Table 6. The results in Table 6 show that the electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules prepared in Embodiment 3 can rapidly repair concrete cracks of different widths, and the crack of 0.32 mm can be repaired within 5 h.

(36) TABLE-US-00006 TABLE 6 Changes of crack width of concrete doped with the microcapsules prepared in Embodiment 3 under electromagnetic induction action Crack width tested at different Initial crack before times after electromagnetic induction electromagnetic induction 1 h 3 h 5 h 0.13 mm 0.00 mm 0.00 mm 0.00 mm 0.22 mm 0.12 mm 0.00 mm 0.00 mm 0.32 mm 0.21 mm 0.11 mm 0.00 mm

Embodiment 4

(37) The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules are prepared from the following raw materials in parts by weight: 50 parts of C9 petroleum resin, 10 parts of paraffin (with a melting point of 78-80° C.), 10 parts of polyethylene wax (with a melting point of 103-106° C.), 10 parts of 500-mesh high-purity iron powder and 20 parts of hexamethylene diisocyanate. The preparation method is the same as that in Embodiment 1.

(38) The microcapsules prepared in this embodiment are added to concrete (the doping amount is 8% by mass of the cement) to prepare electromagnetically-induced self-healing concrete.

Embodiment 5

(39) The electromagnetically-induced cement concrete crack self-healing diisocyanate microcapsules are prepared from the following raw materials in parts by weight: 21 parts of C5 petroleum resin, 6 parts of paraffin (with a melting point of 50-52° C.), 8 parts of polyethylene wax (with a melting point of 100-103° C.), 5 parts of 2000-mesh iron oxide powder (γ-Fe.sub.2O.sub.3) and 60 parts of hexamethylene diisocyanate. The preparation method is the same as that in Embodiment 1.

(40) The microcapsules prepared in this embodiment are added to concrete (the doping amount is 12% by mass of the cement) to prepare electromagnetically-induced self-healing concrete.

(41) It is apparent that the above-described embodiments are merely examples for clear description, and are not intended to limit the implementations. Other variations or variations of the various forms may be made by those skilled in the art on the basis of the above description. There is no need and no way to exhaust all of the implementations. Obvious changes or variations resulting therefrom are still within the scope of protection of the present invention.