High-performance polyoxymethylene fiber for concrete and method for preparing the same

Abstract

The application provides high-performance polyformaldehyde fibers for concrete and a preparation method thereof, and belongs to the field of polymer material processing and relates to the technical field, and has the characteristics that polyformaldehyde is blended with polyamide which is better compatible with the polyformaldehyde, polyformaldehyde / polyamide composite fibers are prepared, then high-adhesion polydopamine is used as a bridging molecule, graphene nanosheets are grafted on the surface of the polyformaldehyde-based composite fibers, the interface action with the concrete is enhanced, a strong mechanical interlocking action between the interfaces is formed, and the compressive strength of the polyformaldehyde fiber reinforced concrete is improved by using the high enhancement characteristics of the graphene.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer material processing and relates to a kind of high-performance polyformaldehyde fibers for concrete and a preparation method thereof. BACKGROUND

[0002] Polyformaldehyde (POM) fiber is a kind of high-performance organic synthetic fiber with excellent comprehensive performance, which has high strength and high modulus characteristics, excellent resistance to friction and wear, excellent resistance to chemicals, excellent resistance to cracking and low water absorption. Its molecular structure contains a large number of ether bonds, which has good compatibility with inorganic materials and high bonding strength, and can be widely used for toughening and crack resistance of cement-based materials.

[0003] Liu Lu et al., Journal of Wuhan Textile University, 2013, 26(3): 35-38, studied the flexural performance of polyformaldehyde fiber reinforced concrete, and showed that the reinforcing effect of polyformaldehyde fiber with a length of 6 mm was better, and the flexural performance was best when the volume content was 0.6 kg / m3. Zhang Lihui et al., Concrete and Cement Products, 2018, 1: 58-62, used a certain amount of polyformaldehyde fiber with a length of 12 mm, a diameter of 27.6 m, a tensile strength of 576 MPa, and an elastic modulus of 5.70 GPa, and cement to effectively improve the plastic anti-cracking ability of mortar, the splitting tensile strength and durability of concrete. A large number of studies have shown that although polyformaldehyde fiber has good dispersibility in concrete, its flexural, tensile and crack resistance are significantly improved, but the compressive strength of concrete is reduced. SUMMARY

[0004] The present application provides a kind of high-performance polyformaldehyde fibers for concrete and a preparation method thereof, which is characterized by: polyformaldehyde is blended with polyamide which has good compatibility with it, polyformaldehyde / polyamide composite fiber is prepared, and then graphene nanosheet is grafted on the surface of polyformaldehyde-based composite fiber using high-adhesion polydopamine as a bridging molecule to enhance the interfacial interaction with concrete, forming a strong mechanical interlocking effect between the interfaces. At the same time, the compressive strength of polyformaldehyde fiber reinforced concrete is improved by taking advantage of the high reinforcement characteristics of graphene.

[0005] The purpose of the present application is achieved by the following technical measures, wherein the raw material fraction is by weight unless otherwise specified:

[0006] A kind of high-performance polyformaldehyde fibers for concrete and a preparation method thereof, including polyformaldehyde / polyamide composite fiber and graphene grafted polyformaldehyde / polyamide composite fiber.

[0007] Further, the polyformaldehyde / polyamide composite fiber includes the following components: polyformaldehyde 80-120 parts, antioxidant 0.05-5 parts, and polyamide 0.5-10 parts.

[0008] Further, the graphene grafted polyformaldehyde / polyamide composite fiber comprises the following components: 10-100 parts of dopamine hydrochloride, 0.5-10 parts of ultrasonic graphene oxide, 100-1000 ml of deionized water, and 5-100 ml of ethylenediamine.

[0009] A high-performance polyformaldehyde fiber for concrete and a preparation method thereof, comprising the following steps:

[0010] S1: preparing a polyformaldehyde / polyamide blend;

[0011] S2: preparing a polyformaldehyde / polyamide composite primary fiber;

[0012] S3: preparing a polyformaldehyde / polyamide composite fiber;

[0013] S4: preparing a polyformaldehyde / polyamide composite fiber grafted with polydopamine;

[0014] S5: preparing amino-functionalized graphene;

[0015] S6: preparing a graphene grafted polyformaldehyde / polyamide composite fiber.

[0016] Further, 80-100 parts of polyformaldehyde, 0.05-5 parts of an antioxidant, and 0.5-10 parts of polyamide are uniformly mixed in a high-speed mixer, and then melt-kneaded by a twin-screw extruder, extruded and granulated, with a screw rotation speed of 150-400 r / min and a barrel temperature of 150-220°C, to obtain a polyformaldehyde / polyamide blend.

[0017] Further, the antioxidant is any one of tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester (i.e., Irganox 1010), N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine (i.e., Irganox 1098), b-(4-hydroxy-3,5-di-tert-butylphenyl)propionate octadecanol (i.e., Irganox 1076), triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylbenzyl)propionate (i.e., Irganox 245), and 2,6-di-tert-butyl-4-methylphenol (i.e., BHT (264)).

[0018] Further, the polyamide is any one of nylon 6, nylon 610, nylon 1010, nylon 12, and nylon 11.

[0019] Further, the polyformaldehyde / polyamide blend is spun in a melt spinning machine at a spinning temperature of 180-230°C and a winding speed of 100-1000 m / min to obtain a polyformaldehyde / polyamide composite primary fiber.

[0020] Further, the polyformaldehyde / polyamide composite primary fiber is heat-drawn and set by a heat-drawing setting device, the heat-drawing temperature is 120-150 DEG C, the heat-drawing multiple is 5-10 times, the heat-setting temperature is 140-150 DEG C, and the heat-setting time is 1-10 min, and finally the polyformaldehyde / polyamide composite fiber is obtained.

[0021] Further, 10-100 parts of dopamine hydrochloride is weighed first, and a 0.5-20 wt% aqueous solution is prepared, 100 parts of the polyformaldehyde / polyamide composite fiber is placed in the solution, and the pH value of the solution is adjusted to 8.5 by adding Tris, and the solution is mechanically stirred at room temperature for 5-20 h, and the free dopamine is removed by washing with deionized water for multiple times, and the polyformaldehyde / polyamide composite fiber grafted with polydopamine is obtained.

[0022] Further, 0.5-10 parts of graphene oxide is ultrasonically dispersed in 100-1000 ml of deionized water, and 5-100 ml of ethylenediamine is added, and ultrasonic reaction is carried out for 0.5-5 h, and thus the aminated graphene is obtained.

[0023] Further, the S6 comprises: adding HCl to adjust the pH value of the solution to 8.5, placing the polyformaldehyde / polyamide composite fiber grafted with polydopamine in the aminated graphene solution, stirring and reacting for 2-10 h, removing the free aminated graphene by washing with deionized water for multiple times, and obtaining the graphene grafted polyformaldehyde / polyamide composite fiber after drying.

[0024] Compared with the prior art, the polyformaldehyde / polyamide composite fiber grafted with graphene has the following beneficial effects:

[0025] In the scheme, the polyformaldehyde and the polyamide have good compatibility, and the polydopamine having a structure similar to the mussel adhesion protein has high adhesion, so the polydopamine molecules are bonded to the surface of the composite fiber by the Schiff base reaction between the amino group of the polyamide component of the composite fiber and the phenolic hydroxyl group on the polydopamine molecules, and then the aminated graphene is grafted to the surface of the composite fiber by taking the polydopamine as a bridging molecule, so as to enhance the interfacial action with the concrete, form a riveting structure and strong mechanical engagement between the interfaces, and improve the compressive strength of the polyformaldehyde fiber reinforced concrete by using the high reinforcement characteristics of the graphene; on the other hand, the active groups such as the phenolic hydroxyl group and the amino group on the polydopamine molecules are beneficial to enhancing the interfacial chemical action between the composite fiber and the concrete, and the introduction of the polydopamine and the graphene is beneficial to improving the thermal stability and the light stability of the polyformaldehyde fiber. DETAILED DESCRIPTION

[0026] The application will be described in detail below by examples. It is necessary to point out here that the examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application. Those skilled in the art can make some non-essential improvements and adjustments to the application according to the content of the application.

[0027] Example 1

[0028] A high-performance polyformaldehyde fiber for concrete and a preparation method thereof, comprising two steps of polyformaldehyde / polyamide composite fiber preparation and graphene grafted polyformaldehyde / polyamide composite fiber preparation;

[0029] First, 100 parts of polyformaldehyde, 0.3 parts of pentaerythritol tetrakis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate and 1 part of nylon 12 are uniformly mixed in a high-speed mixer, and then melt-kneaded, extruded and granulated by a twin-screw extruder, with a screw rotation speed of 200 r / min and a barrel temperature of 150-220℃, to obtain a polyformaldehyde / nylon 12 blend;

[0030] Subsequently, the polyformaldehyde / nylon 12 blend is spun in a melt spinning machine at a spinning temperature of 200℃ and a winding speed of 200 m / min; then the as-spun fiber is heat stretched and set by a heat stretching setting equipment, with a heat stretching temperature of 140-150℃, a heat stretching multiple of 4 times, a heat setting temperature of 150℃ and a heat setting time of 2 min, to obtain a polyformaldehyde / nylon 12 composite fiber;

[0031] Then, 20 parts of dopamine hydrochloride are weighed, and a 5wt% aqueous solution is prepared; 100 parts of the polyformaldehyde / nylon 12 composite fiber is placed in the solution, and the pH value of the solution is adjusted to 8.5 by adding tris (hydroxymethyl) aminomethane (Tris); the mixture is mechanically stirred at room temperature for 10 h, and then washed with deionized water multiple times, to obtain a polyformaldehyde / nylon 12 composite fiber grafted with polydopamine;

[0032] 2 parts of graphene oxide are ultrasonically dispersed in 500 ml of deionized water, 20 mL of ethylenediamine is added, and ultrasonic reaction is carried out for 1 h, to obtain aminated graphene; the pH value of the solution is adjusted to 8.5 by adding HCl, and the polyformaldehyde / nylon 12 composite fiber grafted with polydopamine is placed in the solution and stirred for 5 h; the mixture is washed with deionized water multiple times, and then dried to obtain a graphene grafted polyformaldehyde / polyamide composite fiber.

[0033] Example 2

[0034] Firstly, 90 parts of polyformaldehyde, 0.4 parts of N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine and 2 parts of nylon 11 are mixed in a high-speed mixer, and then melt-kneaded by a twin-screw extruder, extruded and granulated, with a screw rotation speed of 200 r / min and a barrel temperature of 170-200℃, to obtain a polyformaldehyde / nylon 11 blend;

[0035] Subsequently, the polyformaldehyde / nylon 11 blend is spun in a melt spinning machine at a spinning temperature of 200℃ and a winding speed of 200 m / min; then the as-spun fiber is heat-drawn and set by a heat-drawing setting device, with a heat-drawing temperature of 140-150℃, a heat-drawing multiple of 4, a heat-setting temperature of 150℃ and a heat-setting time of 2 min, to obtain a polyformaldehyde / nylon 11 composite fiber;

[0036] Then, 30 parts of dopamine hydrochloride is weighed, and a 6wt% aqueous solution is prepared; 90 parts of the polyformaldehyde / nylon 11 composite fiber is placed in the solution, and the pH value of the solution is adjusted to 8.5 by adding Tris (tris(hydroxymethyl)aminomethane); the solution is mechanically stirred at room temperature for 10 h, and then washed with deionized water multiple times, to obtain a polyformaldehyde / nylon 11 composite fiber grafted with polydopamine;

[0037] 3 parts of graphene oxide is ultrasonically dispersed in 600 ml of deionized water, and 30 mL of ethylenediamine is added, and ultrasonic reaction is carried out for 1 h, to obtain aminated graphene; the pH value of the solution is adjusted to 8.5 by adding HCl, and the polyformaldehyde / nylon 11 composite fiber grafted with polydopamine is placed in the solution, and stirred for 5 h; the solution is washed with deionized water multiple times, and dried to obtain a graphene grafted polyformaldehyde / polyamide composite fiber.

[0038] Example 3:

[0039] Firstly, 110 parts of polyformaldehyde, 0.6 parts of 2,6-di-tert-butyl-4-methylphenol and 3 parts of nylon 6 are mixed in a high-speed mixer, and then melt-kneaded by a twin-screw extruder, extruded and granulated, with a screw rotation speed of 200 r / min and a barrel temperature of 170-200℃, to obtain a polyformaldehyde / nylon 6 blend;

[0040] Subsequently, the polyformaldehyde / nylon 6 blend is spun in a melt spinning machine at a spinning temperature of 200℃ and a winding speed of 200 m / min; then the as-spun fiber is heat-drawn and set by a heat-drawing setting device, with a heat-drawing temperature of 140-150℃, a heat-drawing multiple of 4, a heat-setting temperature of 150℃ and a heat-setting time of 2 min, to obtain a polyformaldehyde / nylon 6 composite fiber;

[0041] Again take 40 parts of dopamine hydrochloride, prepare a 6wt% aqueous solution, put 110 parts of polyformaldehyde / nylon 6 composite fiber into the solution, add Tris to adjust the pH value of the solution to 8.5, mechanically stir for 10h at room temperature, wash with deionized water for several times, and obtain polyformaldehyde / nylon 11 composite fiber grafted with polydopamine;

[0042] Ultrasonic dispersion of 4 parts of graphene oxide in 800ml deionized water, add 60mL ethylenediamine, ultrasonic reaction for 1h, thus obtain aminated graphene; add HCl to adjust the pH value of the solution to 8.5, put the polyformaldehyde / nylon 6 composite fiber grafted with polydopamine into the solution, stir for 5h, wash with deionized water for several times, and obtain graphene grafted polyformaldehyde / polyamide composite fiber after drying.

[0043] Through experiments, the tensile strength and elongation at break of the polyformaldehyde / nylon 12 composite fiber prepared by the scheme can reach 8.0 cN·dtex-1 and 20% respectively when the hot stretching multiple is 4 times, and the polyformaldehyde fiber prepared by the scheme effectively enhances the compressive strength of the cement-based material.

[0044] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the described embodiments, and the described embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-performance polyoxymethylene fiber for concrete, characterized in that, Including polyoxymethylene / polyamide composite fibers and graphene-grafted polyoxymethylene / polyamide composite fibers; Polyoxymethylene / polyamide composite fiber comprises the following components: 80-120 parts polyoxymethylene, 0.05-5 parts antioxidant, and 0.5-10 parts polyamide; The graphene-grafted polyoxymethylene / polyamide composite fiber comprises the following components: 10-100 parts dopamine hydrochloride, 0.5-10 parts graphene oxide, 100-1000 ml deionized water, and 5-100 mL ethylenediamine; High-performance polyoxymethylene fibers are obtained by the following preparation method, which includes the following steps: S1: Preparation of polyoxymethylene / polyamide blends; S2: Preparation of polyoxymethylene / polyamide composite nascent fibers; S3: Preparation of polyoxymethylene / polyamide composite fibers; S4: Preparation of polyoxymethylene / polyamide composite fibers grafted with polydopamine; S5: Preparation of amino-based graphene; S6: Preparation of graphene-grafted polyoxymethylene / polyamide composite fibers.

2. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 1, characterized in that, The preparation method includes the following steps: S1: Preparation of polyoxymethylene / polyamide blends; S2: Preparation of polyoxymethylene / polyamide composite nascent fibers; S3: Preparation of polyoxymethylene / polyamide composite fibers; S4: Preparation of polyoxymethylene / polyamide composite fibers grafted with polydopamine; S5: Preparation of amino-based graphene; S6: Preparation of graphene-grafted polyoxymethylene / polyamide composite fibers.

3. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S1 includes: adding 80-100 parts of polyoxymethylene, 0.05-5 parts of antioxidant, and 0.5-10 parts of polyamide to a high-speed mixer and mixing them evenly, then using a twin-screw extruder for melt mixing, extrusion granulation, with a screw speed of 150-400 r / min and a barrel temperature of 150-220℃, to obtain a polyoxymethylene / polyamide blend.

4. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S2 includes: The polyoxymethylene / polyamide blend is spun in a melt spinning machine at a spinning temperature of 180-230℃ and a winding speed of 100-1000m / min to obtain polyoxymethylene / polyamide composite nascent fibers.

5. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S3 includes: using a heat stretching and setting device to heat stretch and set the polyoxymethylene / polyamide composite nascent fiber, wherein the heat stretching temperature is 120-150℃, the heat stretching ratio is 5-10 times, the heat setting temperature is 140-150℃, and the heat setting time is 1-10 min, and finally polyoxymethylene / polyamide composite fiber is obtained.

6. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S4 includes: First, weigh 10-100 parts of dopamine hydrochloride and prepare an aqueous solution with a concentration of 0.5-20 wt%. Place 100 parts of the polyoxymethylene / polyamide composite fiber into this solution, add tris(hydroxymethyl)aminomethane (Tris) to adjust the pH of the solution to 8.5, and mechanically stir at room temperature for 5-20 hours. Wash repeatedly with deionized water to remove free dopamine and obtain polyoxymethylene / polyamide composite fiber grafted with polydopamine.

7. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S5 includes: ultrasonically dispersing 0.5-10 parts of graphene oxide in 100-1000 ml of deionized water, adding 5-100 mL of ethylenediamine, and ultrasonically reacting for 0.5-5 h to obtain amino-based graphene.

8. The method for preparing high-performance polyoxymethylene fiber for concrete according to claim 2, characterized in that, S6 includes: adding HCl to adjust the pH of the solution to 8.5, placing the polyoxymethylene / polyamide composite fiber grafted with polydopamine in an aminated graphene solution, stirring and reacting for 2-10 hours, washing repeatedly with deionized water to remove free aminated graphene, and drying to obtain graphene-grafted polyoxymethylene / polyamide composite fiber.