RU2474594C2 - Polymer nanocomposites and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: carbon nanofiller - carbon nanofibres or globular nanocarbon - is added to a polymer nanocomposite based on bisphenol A polyhydroxy ether, with the following ratio of components: bisphenol A polyhydroxy ether - 99.975-99.5%, nanofiller - 0.025-0.5%. When producing the nanocomposites, the carbon nanofiller is pre-activated sulphuric acid solution with concentration of 20-60% while heating at temperature of 70-100°C for 45-60 minutes. The treated carbon nanofiller is added the polymer in situ.

EFFECT: invention enables to obtain polymer nanocomposites based on bisphenol A polyhydroxy ether and activated carbon nanofiller with high output and reduced viscosity with improved hardness and resistance to aggressive media.

2 cl, 1 tbl, 6 dwg, 3 ex

Description

The invention relates to polymer composite nanomaterials that can be used in various fields of technology as thermoplastic coatings with high hardness.

Known methods for producing polymer nanocomposites by polymerization processes [S.N. Chvalun, L.A. Novokshonova, A.P. Korobko, P.N. Brevnov. - Polymer-silicate nanocomposites: physicochemical aspects of synthesis by in situ polymerization. - Grew up. Chem. Well, vol. LII, No. 5, pp. 52-57]. The production of condensation-type polymers is complicated by the processes either in solution or by interfacial method. Under these conditions, i.e. in an environment of organic solvents or mixtures thereof, carbon nanoparticles have poor wettability, as a result of which they coalesce, float to the surface, or settle, forming a phase separate from the polymer, not distributed evenly in it, which leads to polymer materials with poor characteristics.

A known method of producing polymer nanocomposites on epoxy and polyester matrices containing carbon nanotubes [Tarasov VA, Stepanishchev N.A. The creation of nanocomposites based on the introduction of carbon nanotubes into epoxy and polyester binders. - Materials of the All-Russian Scientific and Practical Internet Conference with international participation "High Technologies in Mechanical Engineering", Samara, November 17-20, 2010]. However, this method was developed and studied for resins - epoxy and polyester, which are then cured, i.e. the reaction is carried out in bulk. For a uniform distribution of fillers in a binder, ultrasonic processing of the material is used.

Closest to the technical nature of the proposed method is to obtain a composite material based on the polyhydroxy ester of bisphenol A and graphite [Beeva D.A., Mikitaev A.K., Beev A.A., Abaev A.M. Synthesis of composite materials based on polyhydroxy ethers. - "The successes of modern science." - No. 1, 2005 - p.20-21]. Compositions were obtained in which high-crystalline flake graphite of the GL-1 brand was introduced into the polymer as a filler during the synthesis of polyhydroxyether. Graphite was used in its raw form and in oxidized form. A disadvantage of the known solution is that oxidation led to functionalization, i.e. the formation on the surface of graphite of carboxyl, carbonyl and other groups. This led to covalent interaction with monomers and chain termination, a decrease in the reduced viscosity of the polymer and its molecular weight. The resulting graphite particles were not nanoscale.

An object of the present invention is to provide high molecular weight thermoplastic polyhydroxy esters uniformly filled with carbon nanofibers (CNFs) or other carbon nanofillers (GNC globular nanocarbon) with a holistic structure.

The stated objective is achieved by introducing a carbon nanofiller: carbon nanofibers or globular nanocarbon into a polymer nanocomposite based on the bisphenol A polyhydroxy ester A in the following ratio of components: bisphenol A polyhydroxy ester 99.975-99.5 wt.%, Nanofiller 0.025-0.5 wt.%.

The method consists in the fact that precipitation polycondensation of the polyhydroxy ester of bisphenol A is carried out, characterized in that the carbon nanofillers are pre-activated with a solution of sulfuric acid with a concentration of 20-60% when heated at temperatures of 70-100 ° C for 45-60 minutes. In this case, the surface of the filler is activated by protonation of the double bonds of the graphene structure. The obtained protonated structure of carbon nanofillers plays the role of a matrix that adsorbs and carries negatively charged particles of the phenoxide anion formed in an aqueous alkaline medium from bisphenol A. One of the monomers for polycondensation, namely bisphenol A, is immobilized by ion interaction with a positively charged matrix, the second monomer - epichlorohydrin, gets more free access to the second reaction functional group of bisphenol. The result is: a decrease in the proportion of chain termination reactions and an acceleration of the chemical reaction; more uniform distribution of the carbon filler in the polymer.

The resulting nanocomposite polymer containing 0.025-0.5% carbon fillers, is a fibrous material of white, light gray color, forming almost colorless transparent films. Polyhydroxyether with carbon fibers has a high density, improved values of hardness, resistance to aggressive environments.

Example 1. The activation of the nanofiller (CNF or GNC) is carried out as follows. In a round-bottom flask (volume 100-250 ml), 10-15 g of carbon material, 50-70 ml of 35% sulfuric acid are placed under reflux and heated for 45-60 minutes at a temperature of 70-80 ° C. At the end of the process, the mixture is diluted with 2 times the volume of distilled water, filtered and washed with water until a negative reaction to sulfate ions (1% solution of BaCl ₂ ). Activated nanocarbon is dried first in air, then in an oven at a temperature of 100-120 ° C to constant weight.

To obtain a polymer composite in a three-necked cylindrical flask with a volume of 150-200 ml, equipped with an electric stirrer and a reflux condenser, 12.5 ml of distilled water, 12.5 ml of isopropyl alcohol (grade hc), 2.8536 g (0.0125 moles) are placed bisphenol A, 0.52 g (0.029 moles) of dry sodium hydroxide, 0.001775 g (0.05% of the calculated polymer yield) of a carbon nanofiller — CNF or GNC in activated form. While stirring, slowly raise the temperature to 65 ° C, 0.98 ml (0.0125 moles) of epichlorohydrin are quickly added to the resulting homogeneous medium, which is considered the beginning of the reaction. During the reaction, with an increase in the molecular weight of the polymer, it precipitates out of solution in the form of a plastic mass, in the pores of which the polycondensation reaction continues. After 2-4 hours, the polymer is removed from the flask, washed with distilled water, dissolved in dioxane-1,4. Then, the polymer composite in the form of a solution is precipitated into water, washed to a negative reaction to chloride ions, first dried in air, then in an oven at a temperature of 80-90 ° C to constant weight. The reduced viscosity of the obtained polymer composites is 0.35-1.2 dl / g (0.5% solution in chloroform). Yield 94%.

Example 2. According to example 1, but the amount of carbon nanofiller is 0.025%, i.e. 0.0008875 g. The obtained polymer has a reduced viscosity of 0.54 dl / g (0.5% solution in chloroform). Yield 92%.

Example 3. According to example 1, but the amount of carbon nanofiller is 0.1%, i.e. 0.00355 g. The resulting polymer has a viscosity of 0.45 dl / g (0.5% solution in chloroform). Yield 87%.

Example 4. According to example 1, but the amount of carbon nanofiller is 0.5%, i.e. 0.01775 g. The obtained polymer has a reduced viscosity of 0.42 dl / g (0.5% solution in chloroform). Yield 87%.

Comparative characteristics of the synthesized composites are given in the table.

The properties PGE PGE-UNV * (0.05%) PGE-GNC * (0.05%) Density, g / cm ³ 1.19 1.22 1.15 The reduced viscosity, dl / g 0.6-0.8 0.6-1.23 0.4-0.53 The degree of swelling in water 0.24 0.49 2.03 for 20 days at 20 ° C,% Hydrolytic resistance (weight loss),% for 30 days at 20 ° C - sodium chloride, 10% 4.2 2,3 7.3 - potassium hydroxide, 40% 2,8 0.34 5.5 - hydrochloric acid, 10% 5.2 2,4 2,4 Dielectric loss tangent, 20 ° С · 10 ³ 17 9 19 Shore hardness, (scale D) 77/75 92/90 83/81 * - activated

Figure 1 shows the electronic micrographs of films of unfilled polyhydroxyether:

a - an increase of 100 times;

b - an increase of 200 times;

in - an increase of 500 times.

Figure 2 shows electronic micrographs of a polyhydroxyether filled with GNC inactive:

a - an increase of 100 times;

b - an increase of 200 times;

in - an increase of 500 times.

Figure 3 shows electronic micrographs of a polyhydroxyether filled with GNC activated:

a - an increase of 100 times;

b - an increase of 200 times;

in - an increase of 500 times.

Figure 4 shows the electronic micrographs of a polyhydroxyether filled with activated carbon:

a - an increase of 100 times;

b - an increase of 200 times;

in - an increase of 500 times.

Figure 5 shows electronic micrographs of a polyhydroxyether filled with an unactivated CNF:

a - an increase of 100 times;

b - an increase of 200 times;

c - 500 times increase

The technical result of the invention is to obtain polymer nanocomposites based on the bisphenol A polyhydroxy ester and activated carbon nanofillers with a high yield and reduced viscosity during in situ synthesis, characterized by improved values of hardness and resistance to aggressive environments. The synthesized polyhydroxy esters are readily soluble in polar organic solvents and have film-forming properties.

Claims (2)

1. The method of producing polymer nanocomposites based on the polyhydroxy ester of bisphenol A by precipitation polycondensation, characterized in that the carbon nanofillers introduced into the polymer in situ are subjected to preliminary activation with a solution of sulfuric acid at a concentration of 20-60% when heated to 70-100 ° C for 45- 60 min 2. Polymer nanocomposites obtained by the method according to claim 1, containing carbon nanofillers - carbon nanofibers or globular nanocarbon, with the following component ratios, wt.%:
polyhydroxyether 99.975-99.5 nanofiller 0.025-0.5

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