Polymer Complex

Abstract

The present disclosure relates to a polymer complex containing microcellulose fibers comprising nanofibrils and fine particles: and a polymer matrix comprising a polyester resin. According to the present disclosure, there is provided a polymer complex capable of exhibiting excellent mechanical properties while being environmentally friendly by including cellulose fibers as a reinforcing material.

Claims

1. A polymer complex comprising microcellulose fibers and a polymer matrix, wherein the microcellulose fibers comprise nanofibrils and fine particles, and the polymer matrix comprises a polyester resin.

2. The polymer complex of claim 1, wherein the nanofibrils are bonded to a surface of the microcellulose fibers, and the fine particles are bonded to the nanofibrils or bonded to a surface or inside of the microcellulose fibers.

3. The polymer complex of claim 1, wherein the fine particles comprise one or more metal particles selected from the group consisting of copper, zinc, calcium, aluminum, iron, silver, platinum, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, vanadium, molybdenum, magnesium, strontium, titanium, zirconium, hafnium, and gallium, or silicon oxide particles.

4. The polymer complex of claim 1, wherein the fine particles are included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the microcellulose fibers.

5. The polymer complex of claim 1, wherein the fine particles comprise spherical fine particles having a diameter of 0.01 μm to 10 μm, columnar particles having a diameter of 0.01 μm to 10 μm on one axis and a diameter of 0.02 μm to 30 μm on another axis, or a mixture thereof.

6. The polymer complex of claim 1, wherein the microcellulose fibers have a minor axis diameter of 1 μm to 30 μm, and the nanofibrils have a minor axis diameter of 10 nm to 400 nm.

7. The polymer complex of claim 1, wherein the polymer matrix is an aliphatic-aromatic copolyester resin.

8. The polymer complex of claim 1, wherein the polymer matrix comprises at least one selected from the group consisting of poly(ethylene adipate-co-terephthalate), poly(butylene adipate-co-terephthalate), poly(ethylene succinate-co-terephthalate), poly(butylene succinate-co-terephthalate), poly(ethylene adipate-co-succinate-co-terephthalate), and poly(butylene adipate-co-succinate-co-terephthalate).

9. The polymer complex of claim 1, wherein the polymer complex contains 60 to 95 wt % of the polymer matrix; and 5 to 40 wt % of the microcellulose fibers.

10. The polymer complex of claim 1, further comprising a compatibilizer.

11. The polymer complex of claim 1, which has a yield strength measured according to ASTM D638-5 of 8 MPa to 30 MPa.

12. The polymer complex of claim 1, which has a tensile strength measured according to ASTM D638-5 of 15 MPa to 30 MPa.

13. The polymer complex of claim 1, which has an elastic modulus measured according to ASTM D638-5 of 120 MPa to 800 MPa.

14. The polymer complex of claim 9, wherein the compatibilizer is a modified polyolefin.

15. The polymer complex of claim 14, wherein the modified polyolefin is polypropylene or polyethylene in which 0.1 to 10 wt % thereof is grafted with maleic anhydride.

16. The polymer complex of claim 9, wherein the compatibilizer is contained in the polymer complex in an amount of 0.1 to 15 wt %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG. 1A is an enlarged schematic view of microcellulose fibers, and FIG. 1B is an enlarged schematic view of microcellulose fibers including nanofibrils and fine particles.

[0078] FIG. 2 is a scanning electron microscope (SEM) image of pulp fibers used in Example 1.

[0079] FIG. 3 is a SEM image of microcellulose fibers including nanofibrils and fine particles obtained in Example 1.

[0080] FIG. 4 is a SEM image of microcellulose fibers including nanofibrils and fine particles obtained in Example 2.

[0081] FIG. 5A shows a comparison of SEM images of fibrillated microcellulose fibers according to Example 1, and FIG. 5B shows a comparison of SEM images of miniaturized cellulose complexed with fine particles according to Comparative Example 4.

[0082] FIG. 6A is a comparison of SEM images of FIG. 5A taken at a higher magnification, and FIG. 6B is a comparison of SEM images of FIG. 5B taken at a higher magnification.

[0083] FIG. 7 shows specifications of a dog-bone-shaped specimen (or a dumbbell-shaped specimen) for measuring tensile strength according to Type V of ASTM D638 (unit: mm).

DESCRIPTION OF SYMBOLS

[0084] 100, 100′: microcellulose fiber [0085] 11: nanofibril [0086] 20: fine particle

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0087] Hereinafter, the function and effect of the present invention will be described in more detail through specific examples. However, these examples are for illustrative purposes only, and the invention is not intended to be limited by these examples.

Example 1

[0088] 1) Preparation of Microcellulose Fibers Including Nanofibrils and Fine Particles

[0089] Softwood kraft pulp fibers (cellulose fibers) were prepared as cellulose raw materials. Then, the shape of the pulp was observed using a scanning electron microscope (SEM image of FIG. 2).

[0090] 20 g of the above pulp fibers were added to an aqueous solution in which 20 g of zinc acetate was dissolved in 1000 g of distilled water, and stirred at 500 rpm for 2 hours to prepare a mixture. In this mixture, zinc acetate was attached to the swollen pulp fibers through hydrogen bonding or ionic bonding.

[0091] 3.6 g of sodium hydroxide (NaOH) was added to the mixture at room temperature, and stirred at 500 rpm for 2 hours to grow fine particles on the pulp fibers. As shown in FIG. 3, FIG. 5A and FIG. 6A, it was confirmed using a scanning electron microscope that fibrillation occurred in the pulp fiber portion on which particles (ZnO) were grown.

[0092] By the above method, microcellulose fibers including nanofibrils and fine particles were obtained.

[0093] 2) Preparation of Polymer Complex

[0094] 5 wt % of microcellulose fibers including nanofibrils and fine particles, and 95 wt % of poly(butylene adipate-co-terephthalate) were added to a batch mixer, and mixed at 170° C. for 20 minutes to prepare a master batch in the form of pellets. As the poly(butylene adipate-co-terephthalate), Solpol 1000N (MFI 3 g/10 min, density 1.26 g/ml) manufactured by SOLTECH was used.

[0095] The master batch was put into a twin-screw extruder to perform a compounding process, and then extruded. The polymer complex thus obtained was put back into an injection machine and injected, and a dog-bone-shaped specimen according to Type V of ASTM D638 (see FIG. 7) was prepared.

Example 2

[0096] 1) Preparation of Microcellulose Fibers Including Nanofibrils and Fine Particles

[0097] 20 g of the same pulp fibers as in Example 1 were added to 1 L of a 0.05 M aqueous solution in which 9.08 g (0.05 mol) of copper acetate was dissolved in distilled water, and stirred at 500 rpm for 2 hours to prepare a mixture. In this mixture, copper acetate was attached to the swollen pulp fibers through hydrogen bonding or ionic bonding.

[0098] 0.05 mol of benzene-1,3,5-tricarboxylate (BTC) was added to the mixture at room temperature, and stirred at 500 rpm for 2 hours to grow fine particles on the pulp fibers. As shown in FIG. 4, it was confirmed using a scanning electron microscope that fibrillation occurred in the pulp fiber portion on which particles (HKUST-1: Cu-BTC) were grown.

[0099] By the above method, microcellulose fibers including nanofibrils and fine particles were obtained.

[0100] 2) Preparation of Polymer Complex

[0101] 5 wt % of microcellulose fibers including nanofibrils and fine particles, and 95 wt % of poly(butylene adipate-co-terephthalate) were added to a batch mixer, and mixed at 170° C. for 20 minutes to prepare a master batch in the form of pellets. As the poly(butylene adipate-co-terephthalate), Solpol 1000N (MFI 3 g/10 min, density 1.26 g/ml) manufactured by SOLTECH was used.

[0102] The master batch was put into a twin-screw extruder to perform a compounding process, and then extruded. The polymer complex thus obtained was put back into an injection machine and injected, and a dog-bone-shaped specimen according to Type V of ASTM D638 (see FIG. 7) was prepared.

Example 3

[0103] A polymer complex and a specimen were prepared in the same manner as in Example 1, except that the content ratio of the microcellulose fibers including nanofibrils and fine particles, and the poly(butylene adipate-co-terephthalate) was changed to 20:80 (wt %).

Example 4

[0104] A polymer complex and a specimen were prepared in the same manner as in Example 1, except that the content ratio of the microcellulose fibers including nanofibrils and fine particles, and the poly(butylene adipate-co-terephthalate) was changed to 30:70 (wt %).

Comparative Example 1

[0105] A specimen was prepared in the same manner as in Example 1 using poly(butylene adipate-co-terephthalate), except that the microcellulose fibers including nanofibrils and fine particles were not added. The specimen is a neat polymer specimen.

Comparative Example 2

[0106] 1) Preparation of Miniaturized Cellulose Fibers Including Fine Particles

[0107] The same softwood kraft pulp fibers as in Example 1 were prepared as cellulose raw materials. A surface of the pulp fibers was oxidized using 2,2,6,6-tetramethylpiperidinyl-1-oxyradical (TEMPO) as a catalyst to obtain oxidized pulp.

[0108] 1 g of the oxidized pulp was dispersed in 99 g of distilled water and miniaturized (defibrated) with a mixer for 30 minutes to obtain an aqueous dispersion of miniaturized cellulose at a concentration of 1%.

[0109] A zinc acetate aqueous solution was prepared by dissolving 20 g of zinc acetate in 1000 g of distilled water. 3.6 g of sodium hydroxide (NaOH) was dissolved in 10 ml of distilled water to prepare a sodium hydroxide solution.

[0110] While stirring 100 g of the aqueous dispersion of miniaturized cellulose at 15° C., 50 ml of the zinc acetate aqueous solution and 10 ml of the sodium hydroxide solution were added thereto, followed by stirring at 500 rpm for 2 hours to prepare a complex of zinc oxide (ZnO) particles and miniaturized cellulose.

[0111] As shown in FIG. 5B and FIG. 6B, it was confirmed using a scanning electron microscope that the complex of zinc oxide particles and miniaturized cellulose according to Comparative Example 4 had strong bonding strength and aggregation between the miniaturized celluloses, so that nanofibers were aggregated and the dispersion degree of particles was low.

[0112] 2) Preparation of Polymer Complex

[0113] A polymer complex and a specimen was prepared in the same manner as in Example 1, except that a complex of zinc oxide (ZnO) particles and miniaturized cellulose was used instead of the microcellulose fibers including nanofibrils and fine particles.

Test Examples

[0114] The physical properties of the specimens prepared in Examples and Comparative Examples were evaluated by the following method, and the results are shown in Table 1 below.

[0115] 1) Minor Axis Diameter of Fiber

[0116] The minor axis diameter of the microcellulose fibers (the shortest diameter in the cross section of fiber) prepared in Examples was measured using a scanning electron microscope.

[0117] Specifically, in the case of microcellulose fibers, the minor axis diameters of 10 microfibers per each sample were measured and displayed in a range excluding the maximum and minimum values. In the case of nanofibrils, the minor axis diameters of nanofibrils per each sample were measured, and displayed in a range excluding the maximum and minimum values.

[0118] In addition, in Comparative Example 2, the pulp fibers were miniaturized (defibrated), and then complexed with particles unlike Examples. The minor axis diameter of nanofibrils of Comparative Example 2 in Table 1 below means the minor axis diameter of the miniaturized cellulose after complexing with particles.

[0119] 2) Tensile Test

[0120] The following specimen (FIG. 7) was prepared according to the standard of specimen Type V of ASTM D638. The specimen was left for 24 hours in a constant temperature and humidity room adjusted to a temperature of 23° C. and a relative humidity of 50%, and then subjected to a tensile test.

[0121] The yield strength, tensile strength and elastic modulus of the specimen was measured according to ASTM D638 using a universal testing machine (UTM) manufactured by Instron. In accordance with ASTM D638, a gap between the grips holding the specimen at both ends was set to 25.4 mm, and the test was performed at a constant tensile rate with a crosshead speed of 5 mm/min.

TABLE-US-00001 TABLE 1 Minor axis diameter Size of fine Yield Tensile Elastic Microcellulose Nanofibrils particles strength strength modulus fibers (μm) (nm) (μm) (MPa) (GPa) (MPa) Example 1 1~10 50~100 0.1~1 10.4 16.5 150 Example 2 1~10 50~100  0.05~0.1 10.2 16.5 150 Example 3 1~10 50~100 0.1~1 13.9 17.5 220 Example 4 1~10 50~100 0.1~1 24.6 24.6 780 Comparative None None None 8.5 22.2 90 Example 1 Comparative None 10~100 0.1~1 9.8 14.0 125 Example 2

[0122] Referring to Table 1, it was confirmed that the specimens of Examples could exhibit equivalent or higher mechanical properties compared to the specimens of Comparative Examples. In particular, Examples exhibited a behavior in which the yield strength and the tensile strength become similar as the content ratio of the microcellulose fibers increases. This behavior is caused by an increase in elastic deformation and a decrease in plastic deformation. That is, as the content ratio of the microcellulose fibers increases, ductility decreases and hardening proceeds, so that they can be used as a hard eco-friendly material.

[0123] In the cellulose fibers prepared in Comparative Example 2, although the particles were grown on the miniaturized cellulose, re-aggregation of the miniaturized cellulose and the particles occurred excessively when complexed with the polymer matrix. The specimen of Comparative Example 2, which showed low dispersibility due to the re-aggregation, exhibited relatively poor mechanical properties.