Fibers, methods for their preparation and use in the manufacture of reinforced elements

Abstract

Fibers with crystallization seeds attached to its surface, method of making such composite fibers by surface treatment of fibers followed by either treating such fibers with premade crystallization seeds or by precipitation and direct crystallization of seeds onto pretreated fibers. Controlling and tuning the properties of inorganic binder compositions with fiber-bound crystallization seeds and thereby generating inorganic binder compositions with tailor-made characteristics.

Claims

1. A plurality of individual fiber bodies having attached to the surface of such individual fiber bodies crystallization seeds wherein the crystallization seeds are attached to the individual fiber bodies via linker moieties, wherein the crystallization seeds are attached to the individual fiber bodies via covalently bound linker moieties in the presence of comb polymer, wherein the linker moieties are selected from one or more functional groups containing an amine, amide, phosphate or phosphonate functionality, and wherein the crystallization seeds are selected from calcium silicate hydrate, ettringite, or calcium sulfate dihydrate.

2. The plurality of individual fiber bodies of claim 1, wherein the size of the crystallization seeds is between 1 nm 10 ?m.

3. The plurality of individual fiber bodies of claim 1, wherein the fiber bodies are selected from at least one of cellulose-based fiber, mineral-based fiber, carbon, metal-based fiber, or synthetic polymer-based fiber.

4. The plurality of individual fiber bodies of claim 1, wherein the fiber bodies are selected from polyvinylalcohol, polypropylene, cellulose, glass or mixtures thereof.

5. A method for the preparation of the plurality of individual fiber bodies of claim 1, wherein the individual fiber body surface is modified and contacting crystallization seeds with said modified individual fiber bodies.

6. The method of claim 5 wherein the individual fiber body surface is modified by treatment with a reagent creating one or more linker moieties on the fiber surface.

7. A method for the preparation of the plurality of individual fiber bodies according to claim 5, wherein (a) fibers are treated with a solution obtained by combining individually prepared solutions of a water-soluble calcium compound (Solution I) and a water-soluble silicate or sulfate compound (Solution II), optionally separately to a solution of a water-soluble comb polymer (Solution III) or (b) individually prepared Solution I and Solution II are added optionally separately to fibers suspended in Solution III.

8. A method comprising utilizing the plurality of individual fiber bodies of claim 1 for reinforcement of inorganic binder compositions.

9. A method for enhancement of bonding between fibers and an inorganic binder composition characterized by utilizing the plurality of individual fiber bodies according to claim 1.

10. An inorganic binder composition, comprising, hydraulic, latent hydraulic or non-hydraulic binders and the plurality of individual fiber bodies of claim 1.

11. The inorganic binder composition of claim 10 wherein, in said plurality of individual fiber bodies, said individual fiber bodies are separated from each other.

12. The inorganic binder composition of claim 10, wherein said plurality of individual fiber bodies are selected from polyvinylalcohol, polypropylene, cellulose or glass.

13. The inorganic binder composition of claim 10, wherein said composition is a cementitious material.

14. The inorganic binder composition of claim 10, further comprising a plasticizer, water reducer, air entrainer, air detrainer, corrosion inhibitor, set accelerator, set retarder, shrinkage reducing admixture, fly ash, silica fume, or a mixture thereof.

15. A structure reinforced with the plurality of individual fiber bodies of claim 1.

16. The structure according to claim 15, being made of a material selected from a non-hydraulic, plaster material or hydraulic, cementitious material, mortar or concrete.

17. The structure according to claim 16, being made of concrete.

18. A crack-resistant, high tensile strength shaped article comprising the inorganic binder composition concrete material as defined by claim 10.

19. The plurality of individual fiber bodies of claim 1, wherein the linker moieties are selected from one or more amphiphilic molecule containing amine, ammonium, amide, nitrate, sulfate, sulfonate, sulfonamide, carboxylate, silanol, phosphate, phosphinate or phosphonate groups.

20. The plurality of individual fiber bodies of claim 1, wherein the size of the crystallization seeds is between 5 nm 1.5 ?m.

21. The plurality of individual fiber bodies of claim 1, wherein the size of the crystallization seeds is between 10 nm-300 nm.

22. The plurality of individual fiber bodies of claim 1, wherein the size of the crystallization seeds is between 10 nm and 100 nm.

23. The plurality of individual fiber bodies of claim 3, wherein the fiber bodies are selected from at least one of cotton, viscose, hemp, jute, sisal, abaca, bamboo, cellulose, regenerated cellulose, glass, mineral wool, basalt, oxide ceramic, steel, polyamide, polyester, polyvinylalcohol, aramide, polyethylene, polypropylene, polyoxymethylene, poly(vinylidene fluoride), poly(methylpentene), poly(ethylene-chlorotrifluoroethylene), poly(vinylfluoride), poly(ethyleneoxide), poly(ethyleneterephthalate), poly(butylenterephthalate) or polybutene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Heat flow curve for control fiber F1 and modified fiber F1-Seed1. Cumulated heat of hydration (HoH) is a measure of the activity of the seeds on the fiber (A=PVA Fiber; B=PVA Fiber modified by 3-(Aminopropyl)triethoxysilane; C=CSH-Seeds on PVA Fiber modified by 3-(Aminopropyl)triethoxysilane; y-axis=Normalized Heat Flow [mW/g (cement)]; x-axis=Time [h])

(2) FIG. 2: Scanning electron microscopy (SEM) micrograph of the CSH seed particle on a modified polypropylene fiber

(3) FIG. 3: Notched Coupon Test setup (left) and test specimen geometry (right)

(4) FIG. 4: Notched Coupon Test results of polypropylene fibers (A: PP fiber reference (coextruded with fumed silica); B: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (1 wt % with respect to the fiber content); C: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (2 wt % with respect to the fiber content); D: CSH modified PP fiber (coextruded with fumed silica); x-axis: crack opening [?m], y-axis: load [N])

(5) FIG. 5: Notched Coupon Test results of polypropylene fibers with (E) and without (F) ettringite precipitate; x-axis: crack opening [?m], y-axis: load [N])

(6) FIG. 6: SEM micrograph of the CSH seed particle on a modified polyvinylalcohol fiber

(7) FIG. 7: SEM micrograph of the gypsum calcium disulfate seed particle on a modified poyvinylalcohol fiber

(8) Table 1: Heat of hydration values (HoH) are represented as integrals of different heat flow measurements (see examples F1-F8) up to 6 h (HoH-6h) and 10 h (HoH-10h) (see FIG. 1). The modification of the fiber surface with different anchor groups or linkers influences the heat of hydration in most cases in a negative way. The CSH modification shows a shift of the heat flow measurements towards earlier hydration times in comparison with the reference system.

(9) Table 2: Summary of application tests. The F.sub.Max,2 increased after CSH modification. Also a significant improvement in the crack opening at this load can be recognized. (A: PP fiber reference (coextruded with fumed silica); B: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (1 wt % with respect to the fiber content); C: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (2 wt % with respect to the fiber content); D: CSH modified PP fiber (coextruded with fumed silica)

(10) TABLE-US-00002 TABLE 1 modified fiber with different modified fiber Route for unmodified fiber linker moieties with stabilizer Example Fiber Seeding HoH-6h (J/g) HoH-10H (J/g) HoH-6h (J/g) HoH-10H (J/g) HoH-6h (J/g) HoH-10H (J/g) F1 PVA Route 1 17.2 46.2 17.2 46.5 25.8 61.0 F2 PP Route 1 19.5 51.1 18.3 48.9 21.3 53.8 F3 PP Route 1 19.5 51.1 17.4 47.0 21.5 54.0 F4 PP Route 1 16.3 44.1 16.0 44.1 20.6 52.1 F5 Basalt Route 1 15.2 42.1 13.7 38.4 15.5 52.4 F6 cellulose Route 2 14.6 40.8 9.7 21.6 16.9 45.1 F7 cellulose Route 2 14.6 40.8 12.6 36.0 15.6 42.6 F8 cellulose Route 2 14.6 40.8 13.8 40.1 16.0 44.0

(11) TABLE-US-00003 TABLE 2 Fiber F.sub.Max, 2 ?.sub.Max, 2 W.sub.Max, 2 A 564 422 284 D 861 760 261 B 531 420 259 C 581 363 214

(12) Surface Modification and Treatment of Fibers

EXAMPLES

Example F1

(13) 4 L Ethanol, 8 g 3-aminopropyltriethoxysilane and 10 mL conc. ammonium hydroxide solution were put in a reaction vessel and stirred. 80 g polyvinylalcohol fiber were suspended in this as prepared mixture. After storing for 5 h at room temperature the fibers were separated from the liquid, washed and dried at 70? C. for 16 h.

Example F2

(14) 1.5 g Phosphonated polypropylene, prepared from triethylphosphit and chlorinated polypropylene followed by acidic hydrolysis, was dissolved in 500 mL methyl-tertbutyl ether. Then 25 g polypropylene (PP) fibers were added and stored for 5 h in the mixture at room temperature before the fibers were separated from the liquid, washed and dried at 70? C. for 16 h.

Example F3

(15) 20 g PP fibers were suspended in 1.4 L chloroform, 15 g n-bromo succinimide and 2.0 g dibenzoyl peroxide were added and the mixture was heated to 60? C. to maintain a gentle reflux. After 1 h the mixture was cooled down to room temperature for 2.5 h. The fibers where then separated from the liquid compounds, washed with methyl-tertbutyl ether and dried at room temperature.

(16) Then, the fibers were mixed with 500 mL diethylene triamine and heated for 5 h at 90? C. Afterwards, the fibers were washed with methyl-tertbutyl ether and dried at room temperature.

Example F4

(17) 20 g PP fibers were suspended in a solution of polyvinylamine-polypropylene copolymer (VP PR 8358 X; BASF) in 600 g water and heated to 60? C. for 8 h. The mixture was then allowed to cool down to room temperature slowly. The fibers were separated, washed with water and dried at 60? C.

Example F5

(18) 4 L Ethanol, 8 g 3-aminopropyltriethoxysilane and 10 mL conc. ammonium hydroxide solution were put in a reaction vessel and mixed. 25 g basalt fiber were suspended in this mixture. After storing for 5 h at room temperature the fibers were separated from the liquid, washed with ethanol and dried at 70? C. for 16 h.

Example F6

(19) 700 mL THF and 5 g ammonium polyphosphate were put in a reaction vessel and stirred. 42.5 g viscose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling THF the fibers were separated from the liquid, washed and dried at 70? C. for 16 h.

Example F7

(20) 1.5 L acetone, 4.5 g 1,4-butanosultone and 4.5 g sodium hydroxide were put in a reaction vessel and stirred. 45 g viscose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling acetone the fibers were separated from the liquid, washed and dried at 70? C. for 16h.

Example F8

(21) 1.5 L isopropanol, 5.8 g sodium chloroacetate and 2-1 g sodium hydroxide were put in a reaction vessel and stirred. 30 g cellulose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling isopropanol the fibers were separated from the liquid, washed and dried at 70? C. for 16h.

Example F9

(22) 96 g tetrahydrofurane, 0.5 g sulforylchloride and 5 g polyvinylalcohol fiber was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water and dried for 1 h at 60? C.

Example F10

(23) 150 g cyclohexane, 1 g aminoacetaldehyde dimethylacetale and 0.2 g methansulfonic acid mixed together, 10 g polyvinylalcohol fibers were added. The mixture was heated in a Dean-Stark apparatus (water separator) for 3 h and 120 mL cyclohexane containing small amounts of methanol-byproduct was distilled off and same amount of cyclohexane was freshly added to the fibers continuously. Then the fibers were filtered and washed with water, saturated sodium carbonate solution, again washed with water and dried at 60? C. for 16 h.

Example F11

(24) 96 g tetrahydrofurane, 0.5 g phosphorous oxychloride and 5 g polyvinylalcohol fiber was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water and dried at 60? C. for 1 h.

Example F12

(25) 100 g tetrahydrofurane, 0.25 g sulforylchloride and 5 g cellulose fiber (Lyocell) was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water three times each and dried for 16h at 60? C.

Example F 13

(26) 5 g of glass fiber were dispersed in 100 mL ethanol. Then, 0.5 mL of aminopropyltriethoxysilane were added together with 0.1 microliter of 33 wt % ammonia solution. The Mixture was stirred for 16h at room temperature. Then the fibers were filtered off and dried at 40? C. for 16 h.

(27) Attachment of Seed Particles to Fibers

(28) The modification of fibers may be carried out in two different ways: 1. synthesis of seeding material separately, followed by storage of fibers in suspension containing seeding material, or 2. direct synthesis of seeding material in suspension containing modified fibers.

Example SP1

Production of Modified Fibers after Route 1

(29) As seeding material polymer stabilized CSH was produced after following procedure:

(30) Polymer 1: MVA? 2500 (BASF):

(31) Polymer 1 is a comb shaped polymer based on the monomers maleic acid, acrylic acid and vinyl-O-butyl polyethyleneglycol-5800. The molar ratio acrylic acid/maleic acid is 7. Mw=40.000 g/mol determined by gel permeation chromatography (GPC). The solid content is 45.1 weight-% (wt %). The charge density is 930 ?eq/g polymer.

(32) Polymer 2: Polyarylether

(33) The comb polymer Polymer 2 is produced by polycondensation of phenol-polyethyleneglycol 5000 and phenoxyethanolphosphate. The molecular weight is 23.000 g/mol as determined by GPC. The solid content is 35 wt %. The charge density is 745 ?eq/g polymer.

(34) 40.3 g Calciumacetate (100%) was dissolved in 231 g H.sub.2O resulting in solution 1. Solution 2 was obtained by dissolving 47.2 g Na-metasilicate-pentahydrate in 133.2 g H.sub.2O.

(35) In a reactor solution 3 was obtained by mixing 65.4 g of Polymer 1 (polymer suspension with 45.1 wt % solid content), 22.8 g of Polymer 2 (polymer suspension with 35 wt % solid content) and 460 g water. Within 50 minutes solution 1 and solution 2 were slowly added to solution 3 in the reactor. The suspension was stirred constantly at 400 rpm.

(36) After production of the suspension containing CSH seed particles stabilized by polymers 1.5 g of fiber (non-modified or modified with different functionalities) were stored in 250 g of the CSH seed particle suspension (solid content ?11 wt %). The beaker was sealed with a film. Storage time was varied between 1 hour and 24 hours. After storage fibers were separated from the suspension by filtration and washed 2 times with 50 ml of 0.005 n Ca(OH).sub.2-solution. Finally fibers were dried at 60? C. in a drying oven.

(37) Production of Modified Fibers after Route 2:

(38) The synthesis of CSH seed particles as described in Route 1 was done in a comparable way with the exception that the modified fiber was present in solution 3 during the synthesis of the CSH seed particle suspension. 1.5 g of fibers were added to solution 3.

(39) Additionally, the synthesis of the CSH seed particle suspension was done without usage of comb polymer as stabilizers. In this case the solution 3 contains only 180.5 g water. After synthesis of the CSH seed particles fibers were separated from the suspension by filtration and washed 2 times with 50 ml of 0.005 n Ca(OH).sub.2-solution each. Finally fibers were dried at 60? C. in a drying oven.

(40) Results

(41) The effects of the CSH seed particles were studied by isothermal heat flow calorimetry. For the investigation 1.5 wt % of the fibers by weight of cement were mixed with cement with a water/cement ratio of 0.4. The measurements were performed at 20? C. The measurements were done with the original fiber as control and with the modified fiber and with added CSH seed particles.

(42) FIG. 1 and table 1 present and summarize the results for the heat flow calorimetry comparing control vs. seed particle modified fibers.

Example SP2

Production of Modified Fibers after Route 2

(43) 5 g of polypropylene Masterfibers? 100 (BASF) coextruded with ?1 wt % of amorphous fumed silica (diameter: 40 ?m; length: 12.7 mm) were deposited in 600 mL 0.005 m Ca(OH).sub.2 solution for 2 hours. The treated fiber was filtered and redispersed in 965.72 g water and 129.96 g MVA? 2500 (BASF). 543, 41 g of solution 1 (120.12 g calcium acetate dissolved in 695.00 g water) and 360.96 g of solution 2 (141.84 g Na.sub.2SiO.sub.3*5 H.sub.2O+399.60 g water) were, in the course of 100 minutes slowly added to solution 1.

(44) After synthesis of CSH seed particles fibers were separated from the suspension by filtration and washed 2 times with 200 mL ethanol. Finally fibers were dried at 60? C. in a drying oven. The increase in weight caused by CSH crystallization on the fibers was round 1 wt %. Scanning electron microscopy (SEM) verified that CSH seed particles were attached to the fiber surface (FIG. 2).

Comparative Example

(45) For the preparation of ettringite coated fiber (E) 30 g polypropylene fibers (30 micrometer diameter; 12.7 mm length) were deposited in 30 mL water, initially stirred for 30 min at 200 rpm, followed by the addition of 5.4 g Ca(OH).sub.2 and further stirring of the suspension for another 20 min. For ettringite precipitation a solution of 8.1 g Al.sub.2(SO.sub.4).sub.3*18 H.sub.2O was dissolved in 60 g water and added to the fiber-suspension and stirred at 150 rpm for 30 min. The resulting suspension was filtered through a paper-filter and the wet fibers dried under ambient conditions.

(46) The Notched-Coupon-Test is used as mechanical test method to demonstrate fiber adhesion and pull-out behavior of fiber in cementitious binder systems. The test specimens, prisms with specific dimensions (see FIG. 3) were prepared with mortar containing control fibers and seed particle modified fibers. 10 test specimens have been prepared for each individual fiber composition tested. The fiber dosage was 1 vol % if nothing else is explicitly mentioned. The prepared specimen are stripped after one day and stored under water at 20? C. for another 27 days to provide a total hydration time of 28 days. The prisms are then polished and a notch of only 0.5 mm is introduced. The test specimens were then tested in the tensile test apparatus. Within the measurement, the test prism is pulled apart and the notch simulates a single crack. The results of the measurements are diagrams showing the load (N) at a specific crack opening (?m). 5-10 specimens have been tested for each system.

(47) Preparation of Microfiber/Mortar Composites for Testing:

(48) 430 g Portland cement, 880 g fly ash, 150 g quartz sand (0-0.3 mm), 150 g quartz flour, 300 g water and 4.3 g superplastiziser (Melflux? 2641; BASF) as well as 0.5 g stabilizer are mixed. followed by the addition of the respective fibers. The mortar quality is tested optically for the existence of lumps or if the fibers are screwed around the mixer. A subsequent slump tests shows the flow behavior of the fiber filled mortar paste and finishes the workability test. The prepared composite blocks all have shown good to acceptable behavior in the workability test.

(49) Results of the Application Tests:

(50) The CSH modified polypropylene fiber (coextruded with amorphous fumed silica) showed an increase in F.sub.Max,2, ?.sub.Max,2 and W.sub.Max,2 in comparison to the unmodified fiber (FIG. 4 and Table 2). The increase of the F.sub.Max,2, ?.sub.Max,2 and W.sub.Max,2 values was due to the CSH seed particles on the fiber surface, since the application test with the pristine polypropylene fibers (coextruded with fumed silica) and additional CSH powder (1 wt % referring to the fiber content) did not show any improvement. Moreover an increase of the CSH powder content to 2 wt % also did not result in any benefit. Ettringite coated fibers (E) performed even worse when compared to unmodified fiber (FIG. 5)

Example SP3

Production of Modified Fibers after Route 2

(51) 2.5 g of polyvinylalcohol fibers modified with phosphate anchor groups (F 11 (diameter: 13 ?m; length: 6 mm) were dispersed in 482.94 g water and 64.98 g MVA? 2500 (BASF). 271.7 g of solution 1 (70.9 g Calciumacetat dissolved in 199.81 g water) and 180.6 g of solution 2 (60.1 g Na.sub.2SiO.sub.3*5 H.sub.2O+347.5 g water) were slowly dosed into solution 1 in a period of 50 minutes.

(52) After synthesis of CSH seed particle fibers were separated from the suspension by filtration. Afterwards fibers were washed for 2 times with 100 mL ethanol. Finally fibers were dried at 60? C. in a drying oven. The increase in weight caused by CSH crystallization on the fibers was round 3 wt %. SEM micrograph (FIG. 6) also verifies that CSH seeds were attached to the fiber surface.

Example SP4

Calcium Sulfate Dehydrate Seed Particles on the Surface of a Polyvinylalcohol (PVA) Fiber Modified with Sulfate Anchor Groups (F9)

(53) 2.5 g of the fibers (modified with phosphate groups) were dispersed in 200 mL of a 0.1 m MgSO.sub.4 solution and in 200 mL of a 0.1 m CaCl2 solution. 300 g of a 0.15 molar MgSO.sub.4 solution and 300 g of a CaCl2 solution were dosed in parallel to the fiber in 45 minutes. After the addition of 100 g of the 0.15 molar solutions 0.46 g Melflux? 2650 L (BASF; SC=32.5 wt %) are added. After a further addition of 100 g of the 0.15 molar solutions accessory 0.40 g Melflux? 2650 L (BASF; SC=32.5 wt %) were dosed to the reaction.

(54) After synthesis of gypsum seeds on the PVA fibers they were separated from the suspension by filtration. Afterwards fibers were washed for 2 times with 100 mL ethanol. Finally fibers were dried at 40? C. in a drying oven. SEM micrograph FIG. 7 shows gypsum seeds on the fiber surface.