CN108456401B

CN108456401B - Pipeline composite material and preparation method thereof

Info

Publication number: CN108456401B
Application number: CN201810410229.0A
Authority: CN
Inventors: 魏晶; 何新平
Original assignee: Beijing Zhonghuan Xinhui Technology Co ltd
Current assignee: Beijing Zhonghuan Xinhui Technology Co ltd
Priority date: 2018-05-02
Filing date: 2018-05-02
Publication date: 2021-04-23
Anticipated expiration: 2038-05-02
Also published as: CN108456401A

Abstract

A pipeline composite material comprises modified bamboo fiber and epoxy resin; based on the weight of the composite material, the content of the modified bamboo fiber is 5-20 wt%; the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo fibers in subcritical water; (2) reacting the pretreated bamboo fibers obtained in the step (1) with alkali liquor and a surfactant; (3) then reacting with alkylene oxide, mixing with meta-aluminate aqueous solution, soaking, adjusting pH value to neutrality, stirring, aging, filtering and drying. The method has simple process, is environment-friendly and safe, and the composite material pipe prepared by the method has high strength and high toughness, and is widely applicable to the fields of chemical industry, agricultural production and the like.

Description

Pipeline composite material and preparation method thereof

Technical Field

The invention belongs to the field of pipeline production, and particularly relates to a pipeline composite material and a preparation method thereof.

Background

The non-metal composite material pipeline has the advantages of corrosion resistance, smooth inner surface, low energy consumption for transportation and the like, is widely applied to industries such as petroleum, chemical industry, papermaking, urban water supply and the like, and the market acceptance and the demand of the composite material pipeline are gradually expanded along with the rapid development of economy in China. But the nonmetal composite material pipeline has the defects of insufficient toughness, high temperature resistance and the like, so the method has very important practical significance for the research of nonmetal composite pipeline materials.

Materials consisting of two or more bodies with different tissue phases are combined into composite materials in materials science. High strength, high modulus brittle materials are typically dispersed into low strength, low modulus ductile materials, such as glass fibers, carbon fibers, etc. compounded into resin materials, ceramics, etc. The composite material can overcome the weakness of a single material, integrates the advantages of two or more materials, and has the working principle that high-strength fibers are used as stressed base materials, and shearing force between the fibers is transmitted through a matrix. Meanwhile, the fibers are easy to be pressed and bent, and the matrix can play a role in preventing the fibers from being bent to a certain degree. Fiber composite materials have been widely used in various aspects of industrial production, and among numerous composite materials, bamboo fiber composite materials are a composite material which is researched more and have wide application. The bamboo fiber composite resin is a composite material which takes bamboo fiber as a reinforcing material and resin as a matrix material.

The bamboo fiber is a fiber derived from bamboo plants, the bamboo plants grow rapidly, the resources are rich, the development and utilization values are high, and the bamboo fiber has the advantages of high strength, good toughness, large rigidity and easy longitudinal separation. The bamboo fiber surface contains hemicellulose, lignin, pectin, esters and other substances besides cellulose, the cellulose mainly forms a skeleton structure of fiber cell walls, and the hemicellulose, the lignin and the pectin are filled in gaps of the lignin fibers and serve as adhesives. In the bamboo fiber, hemicellulose and lignin form a complex network structure through covalent bonds, and the cellulose is embedded in the complex network structure. Cellulose has high crystallinity, and a large number of hydroxyl groups with high reactivity are enclosed in a crystallization area, so that the cellulose has low reactivity, and the surface polarity difference of matrix materials such as group fibers, resin and the like is large, so that the bamboo fiber used as a composite material generally needs to be subjected to surface modification treatment.

The common surface treatment method of the bamboo fiber is an alkali washing method, the alkali liquor can obviously expand the cellulose, the active specific surface area is increased, and the reaction activity is enhanced. The ultrasonic treatment liquid is also used as a common treatment method, and can enhance the action effect of the alkali liquor. The oxidation pretreatment is also a common modification method, the oxidation treatment can degrade lignin in a large amount, but hardly influences cellulose and hemicellulose, so that the content of the cellulose is obviously improved, and common oxidants mainly comprise oxygen, ozone, hydrogen peroxide and the like.

Epoxy resin is an organic material with good physical and chemical stability and mechanical properties, and is widely applied to pipeline materials, but due to the defects of large internal stress and poor toughness and thermal stability, the epoxy resin can be added with other components to form a composite material for use.

Poncirus et al respectively use the refining coupling agent A-174 for treatment, acetylation coating treatment and potassium permanganate grafting treatment to modify banana fiber, and then use the modified banana fiber as filler to prepare the epoxy resin-based composite material. Researches find that the banana fiber can obviously improve the tensile strength, the bending strength and the compressive strength of the epoxy resin, and compared with unmodified banana fiber, the mechanical property of the composite material can be further improved by 3 modification treatments. The Liangchun swarm is prepared from raw materials of silane coupling agent KH-550 modified bamboo fiber and epoxy resin E-44. The result shows that the bamboo fiber can improve the impact strength and the tensile strength of the epoxy resin, and the mechanical property of the composite material is best when the content of the bamboo fiber is 20 percent. The method comprises the steps of modifying bamboo fibers by using a 2% NaOH solution and a KH-560 coupling agent respectively, and preparing the epoxy resin composite material by using the bamboo fibers and the modified bamboo fibers as fillers respectively by the Jojoba and the like of the southwest university of transportation. Researches show that when the content of the bamboo fiber is 20%, the tensile strength, the elongation at break and the impact strength of the composite material are obviously improved compared with those of pure epoxy resin, and the tensile strength and the elongation at break of the composite material can be further improved by the two modifications.

In the prior art, the bamboo fiber composite resin material mainly focuses on modifying the surface of bamboo fiber, so that the difference of the interface between the surface of the bamboo fiber and resin is minimized, and the mechanical property of the bamboo fiber composite material is improved.

Disclosure of Invention

On the basis of the prior art, the invention further improves the interface difference between the bamboo fiber and the resin, so that more chemical bonds are formed between the bamboo fiber and the resin material, and the mechanical property of the composite material is further improved. Specifically, the method partially hydrolyzes the cellulose in the bamboo fiber through subcritical treatment, controls the degree of hydrolysis reaction by controlling the ratio of the bamboo fiber to water and the hydrolysis time, increases the space between cellulose molecules on the premise of ensuring that the microstructure of the bamboo fiber is not damaged, facilitates the diffusion and the entry of foreign molecules, improves the compatibility of the bamboo fiber and a polyester material, and further improves the mechanical property of the obtained composite material.

The invention provides a pipeline composite material, which comprises modified bamboo fiber and epoxy resin; based on the weight of the composite material, the content of the modified bamboo fiber is 5-20 wt%; the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo fibers in subcritical water; (2) reacting the pretreated bamboo fibers obtained in the step (1) with alkali liquor and a surfactant; (3) then reacting with alkylene oxide, mixing with meta-aluminate aqueous solution, soaking, adjusting pH value to neutrality, stirring, aging, filtering and drying.

The temperature of the pretreatment in the step (1) is 300-370 ℃, the pressure is 15-22MPa, preferably 350-370 ℃, and the pressure is 20-22 MPa; the pretreatment time is 10-100 seconds, preferably 20-50 seconds; the mass ratio of the bamboo fibers to the water in the step (1) is 1:5-20, preferably 1: 5-10.

In the step (2), the alkali liquor is an aqueous solution of sodium hydroxide, potassium hydroxide or ammonia water, the pH value of the alkali liquor is 12-14, and the treatment time is 6-12 h. The surfactant in the step (2) is a nonionic surfactant, preferably a polyoxyethylene ether series.

The alkylene oxide in the step (3) is one of ethylene oxide and propylene oxide; the mass ratio of the bamboo fiber to the alkylene oxide is 1:10-20, and the reaction time is 1-6 h.

And (4) uniformly mixing the metaaluminate solution neutralized in the step (4), soaking for 10-36h, adjusting the pH value to 6-6.5, stirring and aging for 24-72h, filtering, and drying at the temperature of 110-120 ℃.

In a preferred embodiment, in the pretreatment step in step (1), ammonia water with a concentration of 0.1-1wt% may also be added, and the pretreatment time is 10-20 seconds.

The preparation method of the composite material comprises the following steps: mixing the diluent, the epoxy resin and the modified bamboo fiber according to the ratio of 0.1-0.5:1:0.01-0.15, heating to 80-150 ℃, adding the curing agent, and uniformly stirring to obtain the composite material.

The diluent is one of acetone or dimethyl carbonate; the curing agent is ethylenediamine; the addition amount of the curing agent is 5-15wt% of the mass of the epoxy resin.

According to the invention, impurities such as lignin, colloid and esters in the bamboo fiber are removed through subcritical water pretreatment, so that gaps among cellulose molecules are increased, and the improvement agent can penetrate into the bamboo fiber; in the surface modification process of the bamboo fiber, alkylene oxide is added to react with hydroxyl in the bamboo fiber to generate a large amount of carboxyl, which is beneficial to more compact combination of cellulose and a modifier, thereby further improving the compatibility of the bamboo fiber and resin; in the selection of the modifier, the conventional silicon modifier is not used, and the aluminum modifier is adopted, so that the bamboo fiber has better compatibility with the modified bamboo fiber.

The invention has the beneficial technical effects that: further improves the void structure and the composition of the bamboo fiber, increases the porous structure in the cellulose, removes lignin and other impurities as much as possible, improves the content of the cellulose, and further improves the mechanical processing strength of the modified resin composite material. The method has simple process, is environment-friendly and safe, and the composite material pipe prepared by the method has high strength and high toughness, and is widely applicable to the fields of chemical industry, agricultural production and the like.

Detailed Description

Example 1

A pipe composite comprising 5wt% modified bamboo fibre; the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo cellulose in subcritical water for 20 seconds at 370 ℃ and 21MPa, wherein the mass ratio of the bamboo fiber to the water is 1: 10; (2) treating the pretreated bamboo fibers obtained in the step (1) with sodium hydroxide alkali liquor with the pH value of 13 for 6 hours, and adding 0.05wt% of OP-10 into the alkali liquor; (3) adding propylene oxide according to the mass ratio of 1:10, reacting for 1h, (4) soaking in a meta-aluminate aqueous solution for 24h, adjusting the pH value to 6-6.5, stirring and aging for 48h, filtering, and drying at 110 ℃ for 10 h.

Example 2

A pipe composite comprising 10wt% modified bamboo fibres; the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo cellulose in subcritical water for 20 seconds at 370 ℃ and 21MPa, wherein the mass ratio of the bamboo fiber to the water is 1: 10; (2) treating the pretreated bamboo fibers obtained in the step (1) with sodium hydroxide alkali liquor with the pH value of 13 for 6 hours, and adding 0.05wt% of OP-10 into the alkali liquor; (3) adding propylene oxide according to the mass ratio of 1:10, reacting for 1h, (4) soaking in a meta-aluminate aqueous solution for 24h, adjusting the pH value to 6-6.5, stirring and aging for 48h, filtering, and drying at 110 ℃ for 10 h.

Example 3

A pipe composite comprising 15wt% modified bamboo fibre; the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo cellulose in subcritical water for 20 seconds at 370 ℃ and 21MPa, wherein the mass ratio of the bamboo fiber to the water is 1: 10; (2) treating the pretreated bamboo fibers obtained in the step (1) with sodium hydroxide alkali liquor with the pH value of 13 for 6 hours, and adding 0.05wt% of OP-10 into the alkali liquor; (3) adding propylene oxide according to the mass ratio of 1:10, reacting for 1h, (4) soaking in a meta-aluminate aqueous solution for 24h, adjusting the pH value to 6-6.5, stirring and aging for 48h, filtering, and drying at 110 ℃ for 10 h.

Comparative example 1

A pipe composite comprising 15wt% unmodified raw bamboo fibres.

Comparative example 2

A pipe composite comprising 15wt% modified bamboo fibre; subcritical water treatment is not adopted in the preparation process of the modified bamboo fiber. The other steps were the same as in example 3.

Comparative example 3

A pipe composite comprising 15wt% modified bamboo fibre; and in the step (4) of preparing the modified bamboo fiber, water glass is adopted for modification. The other steps were the same as in example 3.

Comparative example 4

A pipe composite comprising 15wt% modified bamboo fibre; the preparation method of the modified bamboo fiber adopts alkali liquor treatment and silicon oxide hybridization in the prior art. The specific preparation process of the modified bamboo fiber comprises the following steps: (1) adding 20wt% sodium hydroxide lye into the raw bamboo fibers for treating for 3 hours, carrying out auxiliary treatment by using ultrasonic waves, cleaning, filtering, and drying at 105 ℃ for 12 hours; (2) soaking activated bamboo fiber in ethyl orthosilicate ethanol-water solution for 24 hr, adjusting pH to weak acidity, aging in water bath for 36 hr, filtering, and drying at 105 deg.C for 12 hr.

Comparative example 5

A resin material to which no bamboo fiber is added.

The composites obtained in examples 1 to 3 and comparative examples 1 to 4 were subjected to mechanical property tests, and the results are shown in the following table:

	tensile Strength (MPa)	Flexural Strength (MPa)	Impact Strength (KJ/m)²)
				Example 1	51	116	4.3
Example 2	73	157	5.9
				Example 3	86	195	7.0
Comparative example 1	45	92	3.9
				Comparative example 2	55	108	4.1
Comparative example 3	71	141	5.6
				Comparative example 4	65	123	4.8
Comparative example 5	40	65	2.7

The raw bamboo fiber in the invention refers to the stripped bamboo fiber without any modification treatment.

From the results of the performance tests of the examples of the present invention and the comparative examples, it can be seen that the mechanical properties of the composite material are significantly increased as the content of the bamboo fibers in the composite material is increased, but the improvement of the mechanical properties becomes insignificant when the content of the bamboo fibers exceeds 15%, and when the content exceeds 20wt%, the mechanical properties of the composite material are rather decreased. By adopting the subcritical water treatment method to pretreat the bamboo fibers, the pore structure of the bamboo fibers can be obviously improved, and the bonding tightness of the modifier and the bamboo fibers is increased, so that the mechanical properties of the composite material are improved.

Claims

1. A pipeline composite material comprises modified bamboo fiber and epoxy resin; based on the weight of the composite material, the content of the modified bamboo fiber is 5-20 wt%;

the preparation method of the modified bamboo fiber comprises the following steps: (1) pretreating bamboo fibers in subcritical water; (2) reacting the pretreated bamboo fibers obtained in the step (1) with alkali liquor and a surfactant; (3) then reacting with alkylene oxide, and (4) mixing with metaaluminate aqueous solution uniformly, dipping, adjusting pH value to be neutral, stirring and aging, filtering and drying; the pretreatment temperature is 300-370 ℃, the pressure is 15-22MPa, and the mass ratio of the bamboo fiber to the water is 1: 5-20; the pretreatment time is 10-100 seconds; the surfactant in the step (2) is nonionic surfactant polyoxyethylene ether; the alkylene oxide in the step (3) is one of ethylene oxide and propylene oxide; the mass ratio of the bamboo fiber to the alkylene oxide is 1:10-20, and the reaction time is 1-6 h;

the preparation method comprises the following steps: mixing a diluent, epoxy resin and modified bamboo fiber according to a ratio of 0.1-0.5:1:0.01-0.15, heating to 80-150 ℃, adding a curing agent, and uniformly stirring to obtain the composite material;

2. The composite material according to claim 1, wherein the temperature of the pretreatment in step (1) is 350-370 ℃ and the pressure is 20-22 MPa; the pretreatment time is 20-50 seconds; the mass ratio of the bamboo fibers to the water in the step (1) is 1: 5-10.

3. The composite material of claim 1, wherein in the step (2), the alkali solution is an aqueous solution of sodium hydroxide, potassium hydroxide or ammonia water, the pH value of the alkali solution is 12-14, and the treatment time is 6-12 h.

4. The composite material as claimed in claim 1, wherein the metaaluminate aqueous solution is mixed uniformly in the step (4), the pH value is adjusted to 6-6.5 after the soaking for 10-36h, the stirring and aging are carried out for 24-72h, the filtration is carried out, and the drying is carried out at 110-120 ℃.

5. The composite material according to claim 1, wherein in the pretreatment step in the step (1), aqueous ammonia is further added at a concentration of 0.1 to 1wt% for a pretreatment time of 10 to 20 seconds.

6. A process for the preparation of a composite material according to any one of claims 1 to 5, comprising the steps of: mixing the diluent, the epoxy resin and the modified bamboo fiber according to the ratio of 0.1-0.5:1:0.01-0.15, heating to 80-150 ℃, adding the curing agent, and uniformly stirring to obtain the composite material.

7. The method of claim 6, wherein the diluent is one of acetone or dimethyl carbonate; the curing agent is ethylenediamine; the addition amount of the curing agent is 5-15wt% of the mass of the epoxy resin.