CN111171507B - Special-shaped polyvinyl alcohol fiber reinforced composite material and preparation method thereof - Google Patents
Special-shaped polyvinyl alcohol fiber reinforced composite material and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
- C08J5/06—Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/08—Melt spinning methods
- D01D5/088—Cooling filaments, threads or the like, leaving the spinnerettes
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/253—Formation of filaments, threads, or the like with a non-circular cross section; Spinnerette packs therefor
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/14—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated alcohols, e.g. polyvinyl alcohol, or of their acetals or ketals
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- C08J2361/00—Characterised by the use of condensation polymers of aldehydes or ketones; Derivatives of such polymers
- C08J2361/04—Condensation polymers of aldehydes or ketones with phenols only
- C08J2361/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2361/00—Characterised by the use of condensation polymers of aldehydes or ketones; Derivatives of such polymers
- C08J2361/04—Condensation polymers of aldehydes or ketones with phenols only
- C08J2361/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
- C08J2361/08—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols with monohydric phenols
- C08J2361/10—Phenol-formaldehyde condensates
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2429/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
- C08J2429/02—Homopolymers or copolymers of unsaturated alcohols
- C08J2429/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2461/00—Characterised by the use of condensation polymers of aldehydes or ketones; Derivatives of such polymers
- C08J2461/04—Condensation polymers of aldehydes or ketones with phenols only
- C08J2461/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
- C08J2461/08—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols with monohydric phenols
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Abstract
The invention discloses a special-shaped polyvinyl alcohol fiber reinforced composite material and a preparation method thereof, belonging to the technical field of fiber reinforced materials. Which comprises the following steps: is prepared from short-cut special-shaped polyvinyl alcohol fiber reinforced phenolic resin or special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin. The special-shaped polyvinyl alcohol fiber adopted by the invention has high strength, large special-shaped degree and good special-shaped retention degree, and can improve the performance of the special-shaped fiber reinforced composite material.
Description
Technical Field
The invention relates to the technical field of fiber reinforced materials, in particular to a special-shaped polyvinyl alcohol fiber reinforced composite material and a preparation method thereof.
Background
The fiber reinforced composite material has the advantages of high strength, light weight, shock absorption, fatigue resistance, chemical corrosion resistance and the like, so the fiber reinforced composite material is widely applied to various fields, such as: mechanical manufacturing, electronic packaging, aerospace, and the like.
The profiled fiber not only has excellent mechanical property, but also has larger specific surface area, can increase the binding force between the fiber and a matrix when used as a composite material for reinforcement, improves the interface bonding strength, and the irregular topological structure of the profiled fiber can also increase the mechanical engaging force between the profiled fiber and a base material, increases the geometrical steric effect, can better transfer stress and energy, and enables the composite material to have more excellent performance.
The polyvinyl alcohol (PVA) fiber has the characteristics of high strength, high modulus, acid and alkali resistance and good weather resistance, and the polyhydroxy strong polar structure has good chemical compatibility and higher interface bonding strength with the composite material, so that the PVA fiber is an ideal fiber for reinforcing and reinforcing the composite material. However, the polyhydroxy strong hydrogen bond characteristic of PVA enables the PVA to have high crystallinity, the melting point of the PVA is very close to the decomposition temperature, and no thermoplastic processing window exists, so that the PVA fiber is prepared by solution spinning. At present, the main processing methods of the PVA fiber comprise wet spinning, boron cross-linking spinning, dry spinning, gel spinning and the like, and the solution method has low controllability of the cross section of the fiber due to osmotic pressure, so that the preparation of the special-shaped polyvinyl alcohol fiber with the controllable cross section is difficult, the reinforcing effect of the special-shaped polyvinyl alcohol fiber on the composite material is limited, and the high performance requirement of the fiber reinforced composite material cannot be met.
Disclosure of Invention
The invention aims to provide a profiled polyvinyl alcohol fiber reinforced composite material and a preparation method thereof, and aims to solve the problems that the conventional profiled polyvinyl alcohol fiber with controllable cross section is difficult to prepare, so that the reinforcing effect of the conventional polyvinyl alcohol fiber on the composite material is limited, and the high requirement of the fiber reinforced composite material on the performance cannot be met.
The technical scheme for solving the technical problems is as follows:
a preparation method of a special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: is prepared from short-cut special-shaped polyvinyl alcohol fiber reinforced phenolic resin or special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin.
Further, in a preferred embodiment of the present invention, the preparation of the phenolic resin reinforced by the chopped polyvinyl alcohol fibers comprises the following steps:
(1) ultrasonically cleaning the short-cut special-shaped polyvinyl alcohol fibers, and drying at the temperature of 40-120 ℃;
(2) soaking the dried chopped special-shaped polyvinyl alcohol fibers in a dispersing agent solution for 10-25 h, cleaning and drying;
wherein the dispersant solution comprises a methyl cellulose solution, a hydroxypropyl methyl cellulose solution or a sodium polyacrylate solution, and the weight percentage concentration of the dispersant is 0.1-0.7%; the weight percentage concentration of the dispersant is the proportion of the dispersant in the dispersant solution.
(3) Adding the dried chopped special-shaped polyvinyl alcohol fibers into absolute ethyl alcohol to prepare 0.05-0.25 g/mL solution, adding 40-60g of phenolic resin powder into every 100mL solution, and stirring and mixing uniformly to prepare a premix;
wherein the phenolic resin comprises one or more of phenol formaldehyde resin, cresol formaldehyde resin, xylenol formaldehyde resin or p-tert-butylphenol formaldehyde resin;
(4) standing the premix at room temperature for 3-6 h, defoaming, and drying at the temperature of 30-50 ℃;
(5) and keeping the dried premix at 100-120 ℃ for 5-10 min under the pressure of 3-8 MPa, keeping the temperature at 120-150 ℃ for 20-40 min, and cooling to room temperature for compression molding.
Further, in a preferred embodiment of the present invention, the preparation of the phenolic resin reinforced by the profiled polyvinyl alcohol fiber cloth comprises the following steps:
(1) the profiled polyvinyl alcohol fiber strips are crossed and woven into profiled polyvinyl alcohol fiber cloth;
(2) gum dipping: laying the special-shaped polyvinyl alcohol fiber cloth according to 2-5 layers, and dipping the special-shaped polyvinyl alcohol fiber cloth in a phenolic resin dipping solution for 15-30 min under the pre-tension of 1000-3000 kPa to prepare a fiber cloth mixed material;
(3) pre-curing: vacuum drying the fiber cloth mixed material;
(4) laminating: carrying out laminating molding on the fiber cloth mixed material on a fluidized bed;
(5) and (3) curing: and drying, cooling and demolding the laminated section to obtain the special-shaped polyvinyl alcohol fiber reinforced composite material.
Further, in a preferred embodiment of the present invention, in the preparation of the profiled polyvinyl alcohol fiber cloth reinforced phenolic resin:
the thickness of the profiled fiber cloth in the step (1) is 0.05-1 mm; in the step (2), formaldehyde and phenol are adopted in a molar ratio of 1.15:1-2:1, and a basic catalyst is used for catalyzing in a reaction kettle to prepare the phenolic resin impregnation liquid with the solid content of 13-16%, wherein the basic catalyst comprises one or more of ammonia water, hexamethylenetetramine, alkali metal or sodium carbonate;
the drying conditions in the step (3) are as follows: keeping the temperature at 20-40 ℃ for 3-6 h under the vacuum degree of 10-90 kPa, and then heating to 50-80 ℃ and keeping the temperature for 30-60 min;
the condition of the laminating in the step (4) is as follows: the temperature is 150-180 ℃, and the pressure is 8-12 MPa;
drying conditions in the step (5): the temperature is 130-140 ℃; the time is 3-6 h.
Further, in a preferred embodiment of the present invention, the cross-sectional shape of the profiled polyvinyl alcohol fibers is one or more of triangular, quadralobal, trilobal or wavy, the fineness of the profiled polyvinyl alcohol fibers is 60 to 150dtex, and the strength of the profiled polyvinyl alcohol fibers is 6 to 12 cN/dtex.
Further, in a preferred embodiment of the present invention, the step of preparing the profiled polyvinyl alcohol fibers comprises:
carrying out melt spinning on modified polyvinyl alcohol powder on extrusion-spinning equipment, carrying out melt extrusion, filtering and metering, then spraying out from a spinneret plate containing profiled spinneret micropores, and carrying out side-blowing cooling on melt trickle to obtain profiled polyvinyl alcohol nascent fibers;
and (ii) carrying out multistage drawing, wet heat drawing or dry heat drawing and heat setting on the profiled polyvinyl alcohol nascent fiber to obtain the melt-spun profiled polyvinyl alcohol fiber. The profile degree of the prepared profiled polyvinyl alcohol fiber is 50-90%, and the variation amplitude of the profile degree is less than or equal to 10%; the strength is greater than or equal to 6 cN/dtex.
The modified polyvinyl alcohol powder is physically or chemically modified polyvinyl alcohol powder;
wherein, the step of physically modifying the polyvinyl alcohol powder comprises the following steps: compounding polyvinyl alcohol powder with auxiliary additives of polar micromolecules and low molecular weight, or compounding polyvinyl alcohol powder with high molecular compounds; polar small molecules include water or glycerol; the low molecular weight auxiliary additive comprises amide, polyoxyethylene with the molecular weight of less than 100 ten thousand or polyethylene glycol with the molecular weight of less than 20000; the polymer compound includes: starch, lignin, collagen, polyamide or polylactide;
the method for chemically modifying the polyvinyl alcohol powder comprises the following steps: copolymerizing vinyl monomer on the molecular chain of polyvinyl alcohol, or grafting acrylamide, n-butyl boric acid or phenyl boric acid on the molecular chain of polyvinyl alcohol.
Further, in a preferred embodiment of the present invention, the cross-section of the profiled spinneret micro-holes in step (i) is triangular, trilobal, quadralobal or flat wave, and the profile degree of the profiled spinneret micro-holes is 50-90%.
Further, in a preferred embodiment of the present invention, the spinning temperature in the step (i) is 130 to 180 ℃; the spinning shear rate is 2000-15000 s～1(ii) a The spinning shear viscosity is 100-300 Pa.s; the spinning pressure is 10-30 MPa; the volume flow of the spinning is 70-300 mm3S; the stretch ratio of the spinning nozzle is 1-4 times; the temperature of the cross air blow is 10-70 ℃.
Further, in a preferred embodiment of the present invention, the step (ii) includes the following steps: carrying out 1-3-stage stretching, wet-heat stretching or dry-heat stretching on the profiled polyvinyl alcohol nascent fiber at the temperature of 150-230 ℃, wherein the total stretching multiple is 10-20 times; and then carrying out heat setting at the temperature of 200-240 ℃, wherein the heat setting time is 0.5-5 min.
A profiled polyvinyl alcohol fiber reinforced composite material is prepared by the preparation method of the profiled polyvinyl alcohol fiber reinforced composite material.
The invention has the following beneficial effects:
1. the special-shaped polyvinyl alcohol fiber adopted by the invention has high strength, large special-shaped degree and good special-shaped retention degree, has larger specific surface area compared with a round fiber, increases the interface binding power of the fiber and a polymer matrix, and can improve the performance of the special-shaped fiber reinforced composite material.
2. The invention realizes the stable and continuous melt spinning of the polyvinyl alcohol fiber and can obtain the nascent fiber with a triangular, trilobal, quadralobal or flat wave section. The melt-spun profiled polyvinyl alcohol fiber which can be used for reinforcing and toughening composite materials is successfully prepared through subsequent hot stretching and hot setting processes, and has high strength, large profile degree and good profile retention degree.
3. The invention aims at the fact that the modified polyvinyl alcohol powder is spun at the temperature of 130-180 ℃, because the modified polyvinyl alcohol powder is a pseudoplastic fluid and has obvious shear thinning behavior at the same temperature, the modified polyvinyl alcohol powder is subjected to melt spinning at the temperature, the change range of the shear degree of the melt is small, the melt is in a stable flowing state, and the spinnability of the modified polyvinyl alcohol powder can be effectively improved.
4. The profiled fiber after multistage drawing still keeps a perfect profiled section, the profile degree of the section is controllable, the profiled polyvinyl alcohol fiber is always in a drawing and tightening state at high temperature in the subsequent hot drawing process, the forced orientation movement of a polyvinyl alcohol molecular chain is more than the random thermal movement of a high molecular chain segment, therefore, the section of the fiber shrinks synchronously under the surface tension, the rounding trend is small, and the characteristic shape of the profiled polyvinyl alcohol fiber is hardly influenced in the treatment process after the primary fiber is hot drawn.
5. The invention realizes that the short-cut special-shaped polyvinyl alcohol fiber is well dispersed in the phenolic resin to form a unique three-dimensional topological network structure, and simultaneously, a two-dimensional film network structure can be formed in the phenolic resin through the special-shaped polyvinyl alcohol fiber cloth, thereby avoiding the agglomeration and uneven dispersion of the fiber in the phenolic resin and improving the strength of the phenolic resin.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic cross-sectional view of a spinneret plate according to the present invention;
FIG. 2 is a schematic view of the structural distribution of shaped spinning micro-holes of a spinneret plate according to the present invention;
fig. 3 is a schematic cross-sectional view of the shaped orifices of the spinneret of the present invention.
Detailed Description
The principles and features of the present invention are described below in conjunction with the embodiments and the accompanying drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Referring to fig. 1 and 2, the profile spinneret adopted in the present invention includes: the spinneret plate body 1, the both ends of spinneret plate body 1 are seted up correspondingly and are spouted guide hole 2 and a plurality of dysmorphism and spout a micropore 3, spout the center that guide hole 2 and dysmorphism spout a micropore 3 and set up with coaxial. A straight hole flow guide section 4 is arranged in the spinneret plate body 1, the pipe diameter of the straight hole flow guide section 4 is 2mm, the straight hole flow guide section 4 enables the spinneret guide holes 2 to be communicated with special-shaped spinneret micropores 3, the special-shaped spinneret micropores 3 are uniformly distributed on the spinneret plate body 1 in an annular mode by taking the center of the spinneret plate body 1 as a concentric circle, and the number of the special-shaped spinneret micropores 3 can be 16 holes, 24 holes or 30 holes. Wherein, 16 holes are uniformly distributed single rings, and the diameter of each single ring is 32 mm; the 24 holes are respectively divided into an 8-hole inner ring and a 16-hole outer ring, the diameter of the inner ring is 20mm, and the diameter of the outer ring is 32 mm; the 30 holes are respectively divided into a 10-hole inner ring and a 20-hole outer ring, the diameter of the inner ring is 10mm, and the diameter of the outer ring is 32 mm.
Referring to fig. 3, the cross section of the special-shaped spinning micro-holes 3 is triangular, trilobal, quadralobal or flat wave, when the cross section is triangular and the triangle is equilateral, the special-shaped spinning micro-holes are triangular spinning micro-holes with a special-shape degree of 50%; when the cross section is a trilobal type or a quadralobal type, the shape of the trilobal type or the quadralobal type is adjustable, and the blades are uniformly arranged, the special-shaped spinning micropores are trilobal type or quadralobal type spinning micropores, and the special-shaped degree is 50-80 percent; when the section is flat wave shape, the flat wave shape is in a shape like a straight line, and the upper end face and the lower end face of the flat wave shape are provided with semicircular arc repeating units with the same size and number, the special-shaped spinning micropores are flat wave-shaped spinning micropores, and the special-shaped degree is 80-90%.
The spinneret plate containing the anisotropic spinneret micropores is processed according to the specification, and the processing technology of the spinneret plate belongs to the prior art. The invention also comprises an extrusion-spinning device, and a discharge port of the extrusion-spinning device is provided with the spinneret plate containing the anisotropic spinneret micropores.
In the spinning process, the equivalent diameter Dh of the profiled spinning micropores of the spinneret plate, the shear rate gamma of the modified polyvinyl alcohol powder melt and the volume flow Q of the modified polyvinyl alcohol powder melt controlled by the metering pump satisfy the following relations:
in the formula: gamma is the melt shear rate of the modified polyvinyl alcohol powder with the unit of s～1(ii) a Q represents the volume flow of the modified polyvinyl alcohol powder melt and the unit is mm3/s，DhThe equivalent diameter of the irregular hole is expressed in mm; q represents the cross-sectional area of the spinning nozzle in mm2(ii) a s represents the perimeter of the spinning pores in mm; lambda represents a shape factor related to the cross section of the spinning micro-hole, and is a constant and ranges from 6 to 8, wherein the trilobe is 6.5, and the tetraloba is 6.63.
Example 1:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the chopped special-shaped polyvinyl alcohol fiber reinforced phenolic resin comprises the following steps:
(1) pretreatment: cleaning the short-cut special-shaped polyvinyl alcohol fibers with acetone in ultrasonic waves for 10min, and then drying in an oven at the temperature of 40 ℃ until the acetone is completely volatilized;
(2) soaking the dried chopped special-shaped polyvinyl alcohol fiber in a methyl cellulose solution with the weight percentage concentration of 0.1% for 10 hours, cleaning with distilled water and then drying;
(3) adding the dried chopped special-shaped polyvinyl alcohol fibers into absolute ethyl alcohol to prepare a 0.05g/mL solution, adding 60g of phenolic resin powder into every 100mL of the solution, and stirring and mixing uniformly to prepare a premix; wherein the phenolic resin comprises phenol formaldehyde resin;
(4) standing the premix at room temperature for 3h, defoaming, and drying at 30 ℃;
(5) keeping the dried premix at 100 deg.C for 5min under 3MPa, keeping at 120 deg.C for 20min, cooling to room temperature, and molding.
Wherein, in the preparation of the profiled polyvinyl alcohol fiber, the profiled spinning micropores of the spinneret plate adopt a four-leaf type, and the profile degree is 50%.
The preparation of the special-shaped polyvinyl alcohol fiber comprises the following steps:
(1) carrying out melt spinning on chemically modified polyvinyl alcohol powder on extrusion-spinning equipment, carrying out melt extrusion, filtering and metering, then spraying out from special-shaped spinning micropores, and carrying out side-blowing cooling on melt trickle to obtain special-shaped polyvinyl alcohol nascent fibers; wherein, the step of chemically modifying the polyvinyl alcohol powder comprises the following steps: vinyl monomers are copolymerized in the molecular chain of polyvinyl alcohol.
Wherein the spinning temperature is 165 ℃; the spinning shear rate is 10000s～1(ii) a The spinning shear viscosity is 300 Pa.s; the spinning pressure is 25 MPa; the volume flow of the spinning is 300mm3S; the stretch ratio of the spinneret is 2 times; the cross-blow temperature was 50 ℃. The equivalent diameter of the special-shaped spinneret micropores of the spinneret plate is 0.6 mm.
(2) Carrying out 1-stage stretching on the profiled polyvinyl alcohol nascent fiber at the temperature of 200 ℃, wherein the total stretching multiple is 15 times; and then carrying out heat setting at the temperature of 220 ℃ for 3min to obtain the melt-spun profiled polyvinyl alcohol fiber.
The melt-spun profiled polyvinyl alcohol fiber obtained in this example had a profile degree of 47%, a reduced profile degree of 3%, a strength of 7cN/dtex, a length of 6mm and a fineness of 60 dtex.
The bending strength of the special-shaped fiber reinforced phenolic resin obtained by the method is 90MPa, and the notch impact strength is 3.5KJ/m2。
Example 2:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the chopped special-shaped polyvinyl alcohol fiber reinforced phenolic resin comprises the following steps:
(1) pretreatment: cleaning the short-cut special-shaped polyvinyl alcohol fibers with acetone in ultrasonic waves for 30min, and then drying the fibers in a drying oven at the temperature of 80 ℃ until the acetone is completely volatilized;
(2) soaking the dried chopped special-shaped polyvinyl alcohol fibers in 0.3 weight percent hydroxypropyl methyl cellulose solution for 18 hours, cleaning with distilled water and drying;
(3) adding the dried chopped special-shaped polyvinyl alcohol fibers into absolute ethyl alcohol to prepare a solution of 0.15g/mL, adding 50g of phenolic resin powder into every 100mL of the solution, and stirring and mixing uniformly to prepare a premix; wherein the phenolic resin comprises cresol formaldehyde resin and xylenol formaldehyde resin, and the mass ratio of the cresol formaldehyde resin to the xylenol formaldehyde resin is 1: 1;
(4) standing the premix at room temperature for 5h, defoaming, and drying at 40 ℃;
(5) keeping the dried premix at 110 deg.C for 8min under 5MPa, keeping at 135 deg.C for 30min, cooling to room temperature, and molding.
Wherein, in the preparation of the profiled polyvinyl alcohol fiber, the profiled spinneret micropores of the spinneret plate adopt a flat wave shape, and the profile degree is 90%.
The preparation of the special-shaped polyvinyl alcohol fiber comprises the following steps:
carrying out melt spinning on chemically modified polyvinyl alcohol powder on extrusion-spinning equipment, carrying out melt extrusion, filtration and metering, then spraying out from special-shaped spinning micropores, and carrying out air blowing cooling on a melt trickle side to prepare special-shaped polyvinyl alcohol nascent fibers; wherein, the step of chemically modifying the polyvinyl alcohol powder comprises the following steps: the molecular chain of the polyvinyl alcohol is grafted with n-butyl boric acid.
Wherein the spinning temperature is 180 ℃; the spinning shear rate is 6000s-1(ii) a The spinning shear viscosity is 200 Pa.s; the spinning pressure is 30 MPa; the volume flow of the spinning is 250mm3S; the stretch ratio of the spinneret was 4 times; the temperature of the cross-air was 70 ℃. The equivalent diameter of the special-shaped spinneret micropores of the spinneret plate is 0.4 mm.
(ii) 3-stage stretching the profiled polyvinyl alcohol nascent fiber at 230 ℃, wherein the total stretching multiple is 20 times; and then carrying out heat setting at the temperature of 240 ℃ for 5min to obtain the special-shaped polyvinyl alcohol fiber. The profile degree of the prepared profiled polyvinyl alcohol fiber is 82%, the profile degree is reduced by 8%, the strength is 8cN/dtex, the length is 8mm, and the titer is 130 dtex.
The bending strength of the profiled fiber reinforced phenolic resin obtained by the method is 110MPa, and the notch impact strength is 4.2KJ/m2。
Example 3:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the chopped special-shaped polyvinyl alcohol fiber reinforced phenolic resin comprises the following steps:
(1) pretreatment: cleaning the short-cut special-shaped polyvinyl alcohol fibers with acetone in ultrasonic waves for 60min, and then drying the fibers in a drying oven at the temperature of 120 ℃ until the acetone is completely volatilized;
(2) soaking the dried chopped special-shaped polyvinyl alcohol fibers in 0.7 wt% sodium polyacrylate solution for 25h, cleaning with distilled water, and drying;
(3) adding the dried chopped special-shaped polyvinyl alcohol fibers into absolute ethyl alcohol to prepare a 0.25g/mL solution, adding 40g of phenolic resin powder into every 100mL of the solution, and stirring and mixing uniformly to prepare a premix;
wherein the phenolic resin comprises cresol formaldehyde resin, xylenol formaldehyde resin and p-tert-butylphenol formaldehyde resin, and the mass ratio of the cresol formaldehyde resin to the xylenol formaldehyde resin is 1:1: 1;
(4) standing the premix at room temperature for 6h, defoaming, and drying at 50 ℃;
(5) keeping the dried premix at 120 deg.C for 10min under 8MPa, keeping at 150 deg.C for 40min, cooling to room temperature, and molding.
In the preparation method of the profiled polyvinyl alcohol fiber, the profiled spinning micropores of the spinneret plate adopt a trilobal shape, and the profile degree is 75%.
The preparation of the special-shaped polyvinyl alcohol fiber comprises the following steps:
carrying out melt spinning on physically modified polyvinyl alcohol powder on extrusion-spinning equipment, carrying out melt extrusion, filtration and metering, then spraying out from special-shaped spinning micropores, and carrying out air blowing cooling on a melt trickle side to prepare special-shaped polyvinyl alcohol nascent fibers; wherein, the step of physically modifying the polyvinyl alcohol powder comprises the following steps: mixing and compounding glycerol, starch and polyvinyl alcohol according to the mass ratio of 10:30:60 to obtain modified polyvinyl alcohol powder.
Wherein the spinning temperature is 175 ℃; the spinning shear rate is 2000s-1(ii) a The spinning shear viscosity is 150 Pa.s; the spinning pressure is 20 MPa; the volume flow of the spinning is 100mm3S; the stretch ratio of the spinneret is 2 times; the cross-blow temperature was 30 ℃. The equivalent diameter of the special-shaped spinneret micropores of the spinneret plate is 0.35 mm. (ii) carrying out dry heat stretching on the profiled polyvinyl alcohol nascent fiber at the temperature of 175 ℃, wherein the total stretching multiple is 15 times; and then carrying out heat setting at the temperature of 220 ℃ for 2min to obtain the special-shaped polyvinyl alcohol fiber. The profile degree of the prepared profiled polyvinyl alcohol fiber is 65%, the profile degree is reduced by 10%, the strength is 6cN/dtex, and the titer is 150 dtex.
The bending strength of the profiled fiber reinforced phenolic resin obtained by the method is 135MPa, and the notch impact strength is 5.3KJ/m2
Example 4:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin comprises the following steps:
(1) the profiled polyvinyl alcohol fiber strips are crossed and woven into profiled polyvinyl alcohol fiber cloth; wherein the thickness of the profiled fiber cloth is 1 mm;
(2) gum dipping: laying the special-shaped polyvinyl alcohol fiber cloth according to 2 layers, and dipping the special-shaped polyvinyl alcohol fiber cloth in phenolic resin dipping solution for 15min under the pre-tension of 1000kPa to prepare a fiber cloth mixed material; the phenolic resin impregnation liquid is prepared by catalyzing formaldehyde and phenol in a molar ratio of 1.15:1 in a reaction kettle by using ammonia water as a catalyst, and the solid content of the phenolic resin impregnation liquid is 13%;
(3) pre-curing: carrying out vacuum drying on the fiber cloth mixed material, wherein the drying conditions are as follows: keeping the temperature at 20 ℃ for 3h under the vacuum degree of 10kPa, heating to 50 ℃ and keeping the temperature for 30 min;
(4) laminating: laminating the dried fiber cloth mixed material on a vulcanizing bed under the conditions that the temperature is 150 ℃ and the pressure is 8 MPa;
(5) and (3) curing: and drying the laminated section at the temperature of 130 ℃ for 3h, cooling and demolding to obtain the special-shaped polyvinyl alcohol fiber reinforced composite material.
The method of making the shaped polyvinyl alcohol fibers of example 4 was identical to the method of making the shaped polyvinyl alcohol fibers of example 1.
The bending strength of the special-shaped polyvinyl alcohol fiber reinforced phenolic resin obtained by the method is 90MPa, and the notch impact strength is 3.5KJ/m2。
Example 5:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin comprises the following steps:
(1) the profiled polyvinyl alcohol fiber strips are crossed and woven into profiled polyvinyl alcohol fiber cloth; wherein, the thickness of the profiled fiber cloth in the step (1) is 0.05 mm;
(2) gum dipping: laying the special-shaped polyvinyl alcohol fiber cloth according to 3 layers, and dipping the special-shaped polyvinyl alcohol fiber cloth in phenolic resin dipping solution for 25min under the pre-tension of 2000kPa to prepare a fiber cloth mixed material; the phenolic resin impregnation liquid is prepared by catalyzing formaldehyde and phenol in a molar ratio of 1.5:1 in a reaction kettle by using hexamethylenetetramine as a catalyst, and the solid content of the phenolic resin impregnation liquid is 15%;
(3) pre-curing: carrying out vacuum drying on the fiber cloth mixed material, wherein the drying conditions are as follows: keeping the temperature at 30 ℃ for 4h under the vacuum degree of 50kPa, heating to 60 ℃ and keeping the temperature for 40 min;
(4) laminating: laminating the dried fiber cloth mixed material on a vulcanizing bed under the conditions that the temperature is 160 ℃ and the pressure is 10 MPa;
(5) and (3) curing: and drying the laminated section at the temperature of 135 ℃ for 4h, cooling and demolding to obtain the special-shaped polyvinyl alcohol fiber reinforced composite material.
The method of making the shaped polyvinyl alcohol fibers of example 5 was identical to the method of making the shaped polyvinyl alcohol fibers of example 2.
The bending strength of the profiled fiber reinforced phenolic resin obtained by the method is 125MPa, and the notch impact strength is 4.3KJ/m2。
Example 6:
the preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material comprises the following steps: the preparation method of the special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin comprises the following steps:
(1) the profiled polyvinyl alcohol fiber strips are crossed and woven into profiled polyvinyl alcohol fiber cloth; wherein, the thickness of the profiled fiber cloth in the step (1) is 0.1 mm; (ii) a
(2) Gum dipping: laying the special-shaped polyvinyl alcohol fiber cloth according to 5 layers, and dipping the special-shaped polyvinyl alcohol fiber cloth in a phenolic resin dipping solution for 30min under the pre-tension of 3000kPa to prepare a fiber cloth mixed material; the phenolic resin impregnation liquid is prepared by catalyzing formaldehyde and phenol in a molar ratio of 2:1 in a reaction kettle by using sodium carbonate as a catalyst, and the solid content is 16%;
(3) pre-curing: carrying out vacuum drying on the fiber cloth mixed material, wherein the drying conditions are as follows: keeping the temperature at 40 ℃ for 6h under the vacuum degree of 90kPa, and then heating to 80 ℃ and keeping the temperature for 60 min;
(4) laminating: laminating the dried fiber cloth mixed material on a vulcanizing bed under the conditions that the temperature is 180 ℃ and the pressure is 12 MPa;
(5) and (3) curing: and drying the laminated section at 140 ℃ for 6h, cooling and demoulding to obtain the special-shaped polyvinyl alcohol fiber reinforced composite material.
The method of making the shaped polyvinyl alcohol fibers in this example 6 was identical to the method of making the shaped polyvinyl alcohol fibers in example 3.
The bending strength of the profiled fiber reinforced phenolic resin obtained by the method is 138MPa, and the notch impact strength is 4.9KJ/m2
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. The preparation method of the special-shaped polyvinyl alcohol fiber reinforced composite material is characterized by comprising the following steps: is prepared by short-cut special-shaped polyvinyl alcohol fiber reinforced phenolic resin or special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin;
wherein the preparation steps of the profiled polyvinyl alcohol fiber comprise:
carrying out melt spinning on modified polyvinyl alcohol powder on extrusion-spinning equipment, carrying out melt extrusion, filtering and metering, then spraying out from a spinneret plate containing profiled spinneret micropores, and carrying out side-blowing cooling on melt trickle to obtain profiled polyvinyl alcohol nascent fibers;
(ii) carrying out multi-stage drawing, wet heat drawing or dry heat drawing and heat setting on the profiled polyvinyl alcohol nascent fiber to prepare melt-spun profiled polyvinyl alcohol fiber;
the preparation method of the special-shaped polyvinyl alcohol fiber cloth reinforced phenolic resin comprises the following steps:
(1) the profiled polyvinyl alcohol fiber strips are crossed and woven into profiled polyvinyl alcohol fiber cloth;
(2) gum dipping: laying the special-shaped polyvinyl alcohol fiber cloth according to 2-5 layers, and dipping the special-shaped polyvinyl alcohol fiber cloth in a phenolic resin dipping solution for 15-30 min under the pre-tension of 1000-3000 kPa to prepare a fiber cloth mixed material;
(3) pre-curing: vacuum drying the fiber cloth mixed material;
(4) laminating: carrying out laminating molding on the fiber cloth mixed material on a fluidized bed;
(5) and (3) curing: and drying, cooling and demolding the laminated section to obtain the special-shaped polyvinyl alcohol fiber reinforced composite material.
2. The method of claim 1, wherein the preparation of the phenolic resin reinforced by the chopped polyvinyl alcohol fiber profile comprises the following steps:
(1) ultrasonically cleaning the short-cut special-shaped polyvinyl alcohol fibers, and drying at the temperature of 40-120 ℃;
(2) soaking the dried chopped special-shaped polyvinyl alcohol fibers in a dispersing agent solution for 10-25 h, cleaning and drying;
wherein the dispersant solution comprises a methyl cellulose solution, a hydroxypropyl methyl cellulose solution or a sodium polyacrylate solution, and the weight percentage concentration of the dispersant is 0.1-0.7%;
(3) adding the dried chopped special-shaped polyvinyl alcohol fibers into absolute ethyl alcohol to prepare a solution of 0.05-0.25 g/mL, adding 40-60g of phenolic resin powder into every 100mL of the solution, and stirring and mixing uniformly to prepare a premix;
wherein the phenolic resin comprises one or more of phenol formaldehyde resin, cresol formaldehyde resin, xylenol formaldehyde resin or p-tert-butylphenol formaldehyde resin;
(4) standing the premix at room temperature for 3-6 h, defoaming, and drying at the temperature of 30-50 ℃;
(5) and keeping the dried premix at 100-120 ℃ for 5-10 min under the pressure of 3-8 MPa, keeping the temperature at 120-150 ℃ for 20-40 min, and cooling to room temperature for compression molding.
3. The method of claim 1, wherein the phenolic resin is reinforced by the profiled polyvinyl alcohol fiber cloth, and the method comprises the following steps:
the thickness of the profiled fiber cloth in the step (1) is 0.05-1 mm; in the step (2), formaldehyde and phenol are adopted as the phenolic resin impregnation liquid in a molar ratio of 1.15:1-2:1, and a basic catalyst is used for catalyzing in a reaction kettle to prepare the phenolic resin impregnation liquid with the solid content of 13-16%, wherein the basic catalyst comprises one or more of ammonia water, hexamethylenetetramine, alkali metal or sodium carbonate;
the drying conditions in the step (3) are as follows: keeping the temperature at 20-40 ℃ for 3-6 h under the vacuum degree of 10-90 kPa, and then heating to 50-80 ℃ and keeping the temperature for 30-60 min;
the condition of the laminating in the step (4) is as follows: the temperature is 150-180 ℃, and the pressure is 8-12 MPa;
drying conditions in the step (5): the temperature is 130-140 ℃; the time is 3-6 h.
4. The method for preparing the profiled polyvinyl alcohol fiber-reinforced composite material according to any one of claims 1 to 3,
the cross section of the special-shaped polyvinyl alcohol fiber is in one or more of a triangular shape, a four-leaf shape, a three-leaf shape or a wave shape, the titer of the special-shaped polyvinyl alcohol fiber is 60-150 dtex, and the strength of the special-shaped polyvinyl alcohol fiber is 6-12 cN/dtex.
5. The method for preparing the profiled polyvinyl alcohol fiber reinforced composite material according to claim 1, wherein the cross section of the profiled spinneret micro-holes in the step (i) is triangular, trilobal, quadralobal or flat wave, and the profile degree of the profiled spinneret micro-holes is 50-90%.
6. The method for preparing the profiled polyvinyl alcohol fiber reinforced composite material according to claim 5, wherein the spinning temperature in the step (i) is 130-180 ℃; the spinning shear rate is 2000-15000 s～1(ii) a The spinning shear viscosity is 100-300 Pa.s; the spinning pressure is 10-30 MPa; the volume flow of the spinning is 70-300 mm3S; stretch ratio of spinning nozzle1-4 times; the temperature of the cross air blow is 10-70 ℃.
7. The method of claim 5, wherein the step (ii) comprises the following steps: carrying out 1-3-stage stretching, wet-heat stretching or dry-heat stretching on the profiled polyvinyl alcohol nascent fiber at the temperature of 150-230 ℃, wherein the total stretching multiple is 10-20 times; and then carrying out heat setting at the temperature of 200-240 ℃, wherein the heat setting time is 0.5-5 min.
8. A profiled polyvinyl alcohol fiber reinforced composite material, which is prepared by the preparation method of the profiled polyvinyl alcohol fiber reinforced composite material of any one of claims 1 to 7.
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| CN101286565A (en) * | 2008-05-23 | 2008-10-15 | 黄志达 | Production method of electrode material of high performance carbon fibre for fuel cell |
| CN202509170U (en) * | 2012-03-22 | 2012-10-31 | 上海罗洋新材料科技有限公司 | Trilobal PVA (Polyvinyl Acetate) fiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101286565A (en) * | 2008-05-23 | 2008-10-15 | 黄志达 | Production method of electrode material of high performance carbon fibre for fuel cell |
| CN202509170U (en) * | 2012-03-22 | 2012-10-31 | 上海罗洋新材料科技有限公司 | Trilobal PVA (Polyvinyl Acetate) fiber |
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