CN114892404B - Method for improving surface wettability of ultra-high molecular weight polyethylene fiber - Google Patents

Abstract

The invention discloses a method for improving the surface wettability of an ultra-high molecular weight polyethylene fiber in the technical field of fiber surface modification, and aims to solve the problems that single modification methods for UHMWPE fiber have respective defects and the like in the prior art. The invention improves the ultra-high molecular weight polyethylene fiber through the low-temperature plasma-polypyrrole grafting synergy, overcomes the defect of adopting a single surface modification method, and is beneficial to long-term preservation of fiber surface activity.

Description

A method for improving surface wettability of ultra-high molecular weight polyethylene fibers

technical field

The invention relates to a method for improving the surface wettability of ultra-high molecular weight polyethylene fibers, and belongs to the technical field of fiber surface modification.

Background technique

Ultra-high molecular weight polyethylene (UHMWPE) fibers have the advantages of low density, high strength, impact resistance, and corrosion resistance. played an important role in other fields. However, due to the smooth surface and lack of polar groups of UHMWPE fibers without surface treatment, it is relatively inert and difficult to form a good interface with the resin matrix, which seriously restricts the overall performance of UHMWPE fiber reinforced composites. Therefore, it is necessary to The wettability between UHMWPE fiber and resin matrix is improved by surface treatment, thereby improving the interfacial bonding strength.

At present, there are many methods for fiber surface modification, which are mainly divided into chemical methods and physical methods. Among them, the chemical method mainly includes strong acid oxidation method, grafting method, coupling agent modification, etc. Although it can effectively improve the surface activity of the fiber, it will cause great damage to the fiber body and is not an environmentally friendly technology; while the irradiation method, After physical methods such as radiation treatment, the surface activity of fibers generally decays quickly, which will also damage the performance of the fiber body to a certain extent, and the requirements for safety protection in the working environment are relatively high.

By ionizing the fiber under different atmospheres, the plasma treatment can not only clean and etch the fiber surface, increase the surface roughness, but also change the chemical structure of the fiber surface and introduce new free radicals, so as to improve the fiber-matrix Adhesive force, enhance the effect of interfacial shear strength, and the process is simple, clean and environmentally friendly, it is a better choice for fiber surface modification technology. However, after plasma modification, the surface activity of UHMWPE fiber has a short storage time, and it often decreases to the level before modification within a few hours, and the fiber body strength will be damaged to a certain extent.

Polypyrrole (PPy) is a common conductive polymer, which belongs to the heterocyclic conjugated conductive polymer material. It has the advantages of light weight, good stability, simple preparation process, economical and environmental protection, and is widely used in supercapacitors, Electrode materials, conductive polymer composites, etc. If PPy can be grafted on the surface of UHMWPE fiber, it is expected not only to endow it with excellent surface wetting properties, but also to help preserve the surface activity of the fiber for a longer period of time, and improve the comprehensive properties of the fiber material such as mechanical, electrical conductivity and thermal properties. UHMWPE fibers have poor surface activity, and it is difficult to directly achieve effective grafting of PPy.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, to provide a method for improving the surface wettability of ultra-high molecular weight polyethylene fibers, through low-temperature plasma-polypyrrole grafting to synergistically improve ultra-high molecular weight polyethylene fibers, overcoming the need for a single The drawback of the surface modification method is that it contributes to the long-term preservation of the fiber surface activity.

In order to achieve the above object, the present invention is achieved by adopting the following technical solutions: a method for improving the surface wettability of ultra-high molecular weight polyethylene fibers, comprising the following steps:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers, the air pressure is 500-3000Pa, the power is 100-350W, and the treatment time is 5-10min;

S2. Put the treated ultra-high molecular weight polyethylene fibers into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, stir for 30 to 60 minutes, and then take it out;

S3. Place the ultra-high molecular weight polyethylene fiber obtained in step S2 in an aqueous pyrrole solution, stir for 10 to 30 minutes, then place it in an ice bath, then slowly and evenly drop into the ammonium persulfate solution, and continue to stir for 10 to 30 minutes;

S4. Soak the ultra-high molecular weight polyethylene fiber sample obtained in step S3 in deionized water for 2-6 hours, then take it out and dry it to obtain UHMWPE fiber with improved surface wettability.

Further, the atmosphere used in the plasma treatment in step S1 is a mixed gas of oxygen and nitrogen, wherein the volume ratio of oxygen is 40-60 Vol%.

Further, the reaction electrodes for the plasma treatment are a pair of cylindrical electrodes, and the distance between the plates of the cylindrical electrodes is 20-50 mm.

Further, the pH range of the mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride in step S2 is 8.0-10.5, the stirring method adopts magnetic stirring, and the magnetic sub-rotation speed range of the magnetic stirring is 300-500rpm.

Further, in step S3, the concentration of the pyrrole aqueous solution is 10-30 wt%, and the concentration of the ammonium persulfate solution is 15-40 wt%.

Further, the stirring methods in step S3 all adopt magnetic stirring, and the magnetic sub-rotation speed range of the magnetic stirring is 500-800 rpm.

Further, the drying temperature in step S4 is 60-80° C., and the drying time is 1-6 hours.

Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

The present invention first etches the surface of ultra-high molecular weight polyethylene fiber and introduces active groups through plasma treatment, which improves the surface wetting performance of the fiber and the resin matrix, and improves the load transfer capability at the fiber/matrix interface, thereby improving Mechanical properties of ultra-high molecular weight polyethylene fiber-reinforced composites.

Then dopamine was introduced as a carrier, and polypyrrole was grafted onto the surface of UHMWPE fibers in batches. The grafted polypyrrole polymerized in situ at the microscopic cracks and defects of the fiber to form a bridging effect, which to a certain extent reinforced the damage of the UHMWPE fiber body caused by plasma treatment, so the polypyrrole after plasma treatment A more stable group and a protective film layer are formed on the surface of the ultra-high molecular weight polyethylene fiber, which is conducive to the long-term preservation of the surface activity of the modified fiber.

Description of drawings

Fig. 1 is a schematic process flow diagram of a method for improving the surface wettability of ultra-high molecular weight polyethylene fibers in an embodiment of the present invention;

Fig. 2 is a SEM scanning electron microscope schematic diagram of the morphology of ultra-high molecular weight polyethylene fibers before and after surface treatment of the method for improving the surface wettability of ultra-high molecular weight polyethylene fibers in an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

Example 1:

As shown in Figure 1, a method for improving the surface wettability of ultra-high molecular weight polyethylene fibers provided by the embodiment of the present invention includes the following steps:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers. The treatment atmosphere of plasma treatment is a mixed gas of oxygen and nitrogen, wherein the gas volume ratio of oxygen and nitrogen is 5:5, and the reaction electrodes are a pair of cylindrical electrodes. The plate spacing is 30mm, the air pressure is 500Pa, the power is 350W, and the processing time is 5min;

S2. Put the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, the pH value of the mixed aqueous solution is 9.0, and take it out after stirring for 30 minutes;

S3. Place the ultra-high molecular weight polyethylene fiber obtained in step S2 in an aqueous solution of pyrrole with a concentration of 10 wt%, stir it for 20 min, then place it in an ice bath, then slowly and evenly drop it into an ammonium persulfate solution with a concentration of 15 wt%, and continue stirring for 20 min;

S4. Soak the ultra-high molecular weight polyethylene fiber sample obtained in step S3 in deionized water for 2 hours, take it out, and dry it at 60° C. for 1 hour to obtain ultra-high molecular weight polyethylene fiber with improved surface wettability.

Example 2:

The method for improving the surface wettability of ultra-high molecular weight polyethylene fibers of the present embodiment comprises the following steps:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers. The treatment atmosphere of plasma treatment is a mixed gas of oxygen and nitrogen, wherein the gas volume ratio of oxygen and nitrogen is 8:2, and the reaction electrode position is a pair of cylindrical electrodes. The distance between the plates is 40mm, the air pressure is 1000Pa, the power is 350W, and the processing time is 5min;

S2. Put the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, the pH value of the mixed aqueous solution is 10.5, and take it out after stirring for 30 minutes;

S3. Place the ultra-high molecular weight polyethylene fiber obtained in step S2 in an aqueous solution of pyrrole with a concentration of 20 wt%, stir for 20 min, then place it in an ice bath, then slowly and evenly drop in an ammonium persulfate solution with a concentration of 20 wt%, and continue stirring for 20 min;

S4. Soak the ultra-high molecular weight polyethylene fiber sample obtained in step S3 in deionized water for 2 hours, take it out, and dry it at 60° C. for 1 hour to obtain ultra-high molecular weight polyethylene fiber with improved surface wettability.

Example 3:

The method for improving the surface wettability of ultra-high molecular weight polyethylene fibers of the present embodiment comprises the following steps:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers. The treatment atmosphere of plasma treatment is pure nitrogen, the reaction electrode position is a pair of cylindrical electrodes, the distance between the plates is 50mm, the air pressure is 2000Pa, the power is 350W, and the treatment time is 5min;

S2. Put the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, the pH value of the mixed aqueous solution is 8.0, and take it out after stirring for 30 minutes;

S3. Place the ultra-high molecular weight polyethylene fiber obtained in step S2 in an aqueous solution of pyrrole with a concentration of 30 wt%, stir it for 20 min, then place it in an ice bath, then slowly and evenly drop it into an ammonium persulfate solution with a concentration of 30 wt%, and continue stirring for 20 min;

S4. Soak the ultra-high molecular weight polyethylene fiber sample obtained in step S3 in deionized water for 2 hours, take it out, and dry it at 60° C. for 1 hour to obtain ultra-high molecular weight polyethylene fiber with improved surface wettability.

Example 4:

The method for improving the surface wettability of ultra-high molecular weight polyethylene fibers of the present embodiment comprises the following steps:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers. The treatment atmosphere of plasma treatment is pure oxygen, the reaction electrode position is a pair of cylindrical electrodes, the distance between the plates is 50mm, the air pressure is 3000Pa, the power is 350W, and the treatment time is 5min;

S2. Put the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, the pH value of the mixed aqueous solution is 10.5, and take it out after stirring for 30 minutes;

S3. Place the ultra-high molecular weight polyethylene fiber obtained in step S2 in an aqueous solution of pyrrole with a concentration of 30 wt%, stir it for 20 min, then place it in an ice bath, then slowly and evenly drop it into an ammonium persulfate solution with a concentration of 40 wt%, and continue stirring for 20 min;

S4. Soak the ultra-high molecular weight polyethylene fiber sample obtained in step S3 in deionized water for 2 hours, take it out, and dry it at 60° C. for 1 hour to obtain ultra-high molecular weight polyethylene fiber with improved surface wettability.

Comparative example 1:

Soak the UHMWPE fiber in deionized water for 2 hours, take it out, and dry it at 60°C for 1 hour.

Comparative example 2:

S1. Perform plasma treatment on ultra-high molecular weight polyethylene fibers. The treatment atmosphere of plasma treatment is a mixed gas of oxygen and nitrogen, wherein the gas volume ratio of oxygen and nitrogen is 5:5, and the reaction electrode position is a pair of cylindrical electrodes. The distance between the plates is 30mm, the air pressure is 500Pa, the power is 350W, and the processing time is 5min;

S2. Soak the obtained UHMWPE fiber sample in deionized water for 2 hours, take it out, and dry it at 60° C. for 1 hour.

Comparative example 3:

S1. Put the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of trishydroxyaminomethane and dopamine hydrochloride, the pH value of the mixed aqueous solution is 9.0, and take it out after stirring for 30 minutes;

S2. Place the ultra-high molecular weight polyethylene fiber obtained in step S1 in an aqueous solution of pyrrole with a concentration of 10 wt%, stir it for 20 min, then place it in an ice bath, then slowly and evenly drop it into an ammonium persulfate solution with a concentration of 15 wt%, and continue stirring for 20 min;

S3. Soak the UHMWPE fiber sample obtained in step S2 for 2 hours in deionized water, take it out, and dry it at 60° C. for 1 hour.

The properties of the ultra-high molecular weight polyethylene fibers obtained in the examples of the present invention and the comparative examples will be analyzed below in conjunction with the accompanying drawings and tables.

First, the morphology of UHMWPE fibers before and after treatment was compared.

Comparison results: From the SEM scanning image in Figure 2, it can be seen that there is damage to the UHMWPE fiber body that has not been synergistically improved by low-temperature plasma-polypyrrole grafting, which leads to a faster decay of fiber surface activity.

In contrast, after the ultra-high molecular weight polyethylene fiber is synergistically improved by low-temperature plasma-polypyrrole grafting, the grafted polypyrrole polymerizes in-situ at the microscopic cracks and defects of the fiber to form a bridging effect, which strengthens the plasma to a certain extent. Pyrrole formed a more stable group and a protective film layer on the surface of the ultra-high molecular weight polyethylene fiber after plasma treatment, which contributed to the surface activity of the modified fiber. long-term preservation.

Secondly, the interfacial shear strength (IFSS), monofilament strength retention rate and contact angle of the ultra-high molecular weight polyethylene fiber and epoxy resin obtained in Examples 1-4 and Comparative Examples 1-3 were analyzed respectively.

The interfacial shear strength (IFSS) was measured by the microsphere debonding method as follows:

S1. Fix the ultra-high molecular weight polyethylene fiber monofilament on the fixture frame with double-sided tape;

S2. Dip a small amount of prepared resin-curing agent system (mass ratio: 100:30) with a fine needle and apply it evenly on the surface of the monofilament to form resin droplets;

S3. Curing and molding according to the curing process parameters of the composite material to obtain a microsphere debonding test sample;

S4. The microsphere debonding test sample is tested on a pull-out tester (YG163 from Wenzhou Jigao Testing Instrument Co., Ltd.) at a loading speed of 0.2mm/min.

The monofilament strength retention rate is measured by FAVIMAT+ fiber tester, in accordance with the standard GB/T 31290-2014, and the tensile rate is 2.0mm/min.

The contact angle was measured at room temperature with a contact angle meter (Suzhou Mingyu Technology Co., Ltd.) and calculated according to the following formula:

θ/2＝tan ^-1 (2h/w)

Among them, h is the height of the droplet on the fiber surface, w is the width of the droplet on the fiber surface, and θ is the contact angle.

test results:

The fiber IFSS strength of table 1 each embodiment and comparative example and the monofilament strength retention rate before and after surface treatment

As shown in Table 1, comparing the embodiment with the control example, the ultrahigh molecular polyethylene fiber IFSS strength and monofilament strength retention rate of the examples 1-4 after plasma treatment and surface post-treatment are obviously higher than the control example 1 -3 (Since the fibers in Comparative Example 1 were not surface-treated, the retention rate of monofilament strength was not compared). Comparing Comparative Examples 1-3, it can be seen that the IFSS intensity of the ultra-high molecular polyethylene fiber of Comparative Example 1 without plasma treatment and surface post-treatment is the lowest, and the ultra-high molecular polyethylene fiber IFSS of Comparative Example 2 treated with plasma The vinyl fiber IFSS strength and monofilament strength retention rate are lower than those of Control Example 3 after surface post-treatment.

And, as shown in Example 1, the interfacial shear strength (IFSS) of UHMWPE fiber and epoxy resin after modification is increased by 357%, while the fiber bulk strength is only slightly reduced by about 5% compared with before modification.

The contact angle measured value of table 2 each embodiment and comparative example

It can be seen from Table 2 that the contact angle of UHMWPE fibers synergistically improved by low-temperature plasma-polypyrrole grafting is much smaller than that of UHMWPE fibers without surface treatment or with only a single surface treatment, proving that The surface wetting properties of ultra-high molecular weight polyethylene fibers and resin matrix synergistically improved by low-temperature plasma-polypyrrole grafting are superior.

In summary, the UHMWPE fiber synergistically improved by low-temperature plasma-polypyrrole grafting not only causes less damage to the fiber itself, but also greatly improves the surface wetting properties of the fiber and the resin matrix, improving the The load transfer capability at the fiber/matrix interface improves the mechanical properties of UHMWPE fiber reinforced composites.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made. It should also be regarded as the protection scope of the present invention.

Claims (5)

1. A method for improving the surface wettability of ultra-high molecular weight polyethylene fiber is characterized in that: the method comprises the following steps:

s1, performing plasma treatment on ultra-high molecular weight polyethylene fibers, wherein the air pressure is 500-3000 Pa, the power is 100-350W, and the treatment time is 5-10 min;

s2, placing the treated ultra-high molecular weight polyethylene fiber into a mixed aqueous solution of the trihydroxy aminomethane and the dopamine hydrochloride, stirring for 30-60 min, and taking out, wherein the pH range of the mixed aqueous solution of the trihydroxy aminomethane and the dopamine hydrochloride is 8.0-10.5, the stirring method adopts magnetic stirring, and the magnetic stirring has a magneton rotating speed range of 300-500 rpm;

s3, placing the ultra-high molecular weight polyethylene fiber obtained in the step S2 into an aqueous pyrrole solution, stirring for 10-30 min, then carrying out ice bath, slowly and uniformly dripping an ammonium persulfate solution, and continuously stirring for 10-30 min, wherein the concentration of the aqueous pyrrole solution is 10-30 wt%, and the concentration of the ammonium persulfate solution is 15-40 wt%;

s4, soaking the ultrahigh molecular weight polyethylene fiber sample obtained in the step S3 in deionized water for 2-6 hours, taking out and drying to obtain the ultrahigh molecular weight polyethylene fiber with improved surface infiltration performance.

2. The method for improving the surface wettability of the ultra-high molecular weight polyethylene fiber according to claim 1, wherein the method comprises the following steps: the atmosphere used for the plasma treatment in step S1 is a mixed gas of oxygen and nitrogen, wherein the oxygen volume ratio is 40 to 60Vol%.

3. The method for improving the surface wettability of the ultra-high molecular weight polyethylene fiber according to claim 2, wherein the method comprises the following steps: the reaction electrodes for plasma treatment are a pair of cylindrical electrodes, and the distance between the polar plates of the cylindrical electrodes is 20-50 mm.

4. The method for improving the surface wettability of the ultra-high molecular weight polyethylene fiber according to claim 1, wherein the method comprises the following steps: and (3) the stirring methods in the step (S3) are all magnetic stirring, wherein the rotating speed range of a magnetic seed for the magnetic stirring is 500-800 rpm.

5. The method for improving the surface wettability of the ultra-high molecular weight polyethylene fiber according to claim 1, wherein the method comprises the following steps: and in the step S4, the drying temperature is 60-80 ℃ and the drying time is 1-6 h.

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