RU2773195C2 - Method for producing an open-cell polymer material - Google Patents

Abstract

FIELD: polymers.

SUBSTANCE: invention relates to the chemistry and technology of polymers, in particular, to the technology for producing open-cell polymer materials, usable in the production of films, filters, membranes, sorbents, and other gas- and liquid-permeable and heat-insulating products; accumulator battery separators, matrices for producing nanocomposites, polymer-polymer mixtures, etc. The problem herein is solved by the method for producing an open-cell polymer material including the stages of preparing a polymer solution, adding a template, removing the solvent, shaping the material, and removing the template. A polymer, wherein high-density polyethylene is used as a polymer, a solvent, wherein toluene is used as a solvent, and a template, wherein paraffin is used as a template, are therein mixed at a mass ratio of polyethylene:toluene equal to 1:29 and polyethylene:paraffin equal to 1:2-58, at a temperature of 70 to 110°C, stirring intensively at 400 to 600 rpm until a homogeneous solution is formed, heated to a temperature of 110°C, and toluene is distilled to a temperature of the solution of 95°C, then the material is shaped by casting in layers with a thickness of 4 to 40 mm into moulds until solidification for 2.5 to 3 minutes at a temperature of 40 to 43°C, the polymer material is extracted from the moulds, the residual toluene is removed by natural drying or evacuation, then paraffin is removed by extraction with methylene chloride, wherein for a material with a mass ratio of polyethylene:paraffin of 1:2 to 10, paraffin is removed by extraction with methylene chloride for 10 to 12 hours, and for a material with a mass ratio of polyethylene:paraffin greater than 1:10, paraffin is removed by extraction with methylene chloride for 15 to 17 hours, then the residual methylene chloride is removed by natural drying or evacuation.

EFFECT: reduced labour intensity of manufacture, simplicity of instrumentation, and production of a material with a given porosity; macroporous with possible mesoporosity (according to the IUPAC classification), both with cells of 100 to 300 nm in size and groups of cavities less than 70 nm with the presence of polyethylene filaments (SEM-based), with high values of edge angles relative to water, permeable for non-polar organic compounds and partially water-permeable.

1 cl, 4 tbl, 7 dwg, 10 ex

Description

The invention relates to the chemistry and technology of polymers, in particular the technology of obtaining polymeric materials with open pores, which can be used in the production of films, filters, membranes, sorbents and other gas- and liquid-permeable, as well as heat-insulating products; battery separators, matrices for obtaining nanocomposites, polymer-polymer mixtures, etc.

, H. Usuda // Polymer. - 2016. - Vol. 99. - P. 515-524], сшивание полимерных порошков [авторское свидетельство СССР 1666476, МПК C08J 9/24, C08L 23/06, 1991 г.], использование фазового разделения, индуцированного действием нерастворителя и/или его паров [Superwetting polypropylene aerogel supported form-stable phase change materials with extremely high organics loading and enhanced thermal conductivity / H. Hong, Y. Pan, H. Sun, Z. Zhu // Solar Energy Materials and Solar Cells. - 2018. - Vol. 174. - P. 307-313., Additive-free poly(vinylidene fluoride) aerogel for oil/water separation and rapid oil adsorption / X. Chen, Y. N. Liang, X. Tang, W. Shen, X. Hu // Chemical Engineering Journal. - 2017. - Vol. 308. - P. 18-26], химически индуцированного фазового разделения, в котором при непосредственном разделении происходит реакция полимеризации [Facile Synthesis of Marshmallow-like Macroporous Gels Usable under Harsh Conditions for the Separation of Oil and Water / G. Hayase, K. Kanamori, M. Fukuchi, H. Kaji // Angewandte Chemie. - 2013. - Vol. 52. - P. 1-5., Handbook of Porous Solids / Edited by F. Schuth, K. S.W. Sing, and J. Weitkarnp. - WILEY-VCH Verlag GmbH, 2002. - 1964 - 2013], совмещение вышеуказанных способов [Gu, S. Open cell aerogel foams with hierarchical pore structures / S. Gu, S.C. Jana // Polymer. - 2017. - Vol. 127. - P. 1-9].General approaches to the synthesis of porous polymeric materials are known [Advanced sorbents for oil-spill cleanup: recent advances and future perspectives / J. Ge, H.-Y. Zhao, H.-W. Zhu, J. Huang // Advanced Materials. - 2016. - Vol. 28. - P. 10459-10490., Saleem, J. Oil sorbents from plastic wastes and polymers: A review / J. Saleem, MA Riaz, G. McKay // Journal of Hazardous Materials. - 2018. - Vol. 341. - P. 424-437., Handbook of Porous Solids / Edited by F. Schuth, KSW Sing, and J. Weitkarnp. - WILEY-VCH Verlag GmbH, 2002. - P. 1964-2013., Gu, S. Open cell aerogel foams with hierarchical pore structures / S. Gu, SC Jana // Polymer. - 2017. - Vol. 127. - P. 1-9]: the use of blowing agents of various nature [Fundamentals of plastics processing technology: Textbook for universities / S.V. Vlasov, L.B. Kandyrin, V.N. Kuleznev et al. - M.: Mir, 2006. - 600 p.], molding on hard and soft templates [Hou, Q. Preparation of interconnected highly porous polymeric structures by a replication and freeze-drying process / Q. Hou, DW Grijpma, J. Feijen // J. Biomed Mater Res. B.Appl. biomater. - 2003. - Vol. 67. - P. 732-740], cold drawing in the presence of liquid media that cause swelling of the polymer [US patent No. 3426754, IPC A61F 13/02 and others, 1969 and US patent No. 3839516, IPC B29C 44/00 and etc., 1974], thermally induced phase separation [Wang, G. Facile synthesis of flexible macroporous polypropylene sponges for separation of oil and water / G. Wang, H. Uyama// Scientific Reports. - 2016. - Vol. 6. - P. 21265-21269., Preparation and characterization of ECTFE hollow fiber membranes via thermally induced phase separation / H. Karkhanechi, S. Rajabzadeh,

, H. Usuda // Polymer. - 2016. - Vol. 99. - P. 515-524], cross-linking of polymer powders [USSR author's certificate 1666476, IPC C08J 9/24, C08L 23/06, 1991], the use of phase separation induced by the action of a non-solvent and / or its vapors [Superwetting polypropylene aerogel supported form-stable phase change materials with extremely high organics loading and enhanced thermal conductivity / H. Hong, Y. Pan, H. Sun, Z. Zhu // Solar Energy Materials and Solar Cells. - 2018. - Vol. 174. - P. 307-313., Additive-free poly(vinylidene fluoride) aerogel for oil/water separation and rapid oil adsorption / X. Chen, YN Liang, X. Tang, W. Shen, X. Hu // Chemical Engineering Journal. - 2017. - Vol. 308. - P. 18-26], chemically induced phase separation, in which a polymerization reaction occurs during direct separation [Facile Synthesis of Marshmallow-like Macroporous Gels Usable under Harsh Conditions for the Separation of Oil and Water / G. Hayase, K. Kanamori, M. Fukuchi, H. Kaji // Angewandte Chemie. - 2013. - Vol. 52. - P. 1-5., Handbook of Porous Solids / Edited by F. Schuth, KSW Sing, and J. Weitkarnp. - WILEY-VCH Verlag GmbH, 2002. - 1964 - 2013], a combination of the above methods [Gu, S. Open cell aerogel foams with hierarchical pore structures / S. Gu, SC Jana // Polymer. - 2017. - Vol. 127. - P. 1-9].

Only a few of them have been proposed or implemented for the most large-tonnage, cheap and widespread polyolefins - polyethylene and polypropylene, and open-pore structures suitable for use as membranes and filters are described in single works.

So, in the patent of the Russian Federation No. 2224773 [MPK C08J 9/04, B29C 67/20 et al., 2004] a technology is provided for obtaining foamed polyolefins with open cells (pores), which can be used as sound insulation. The formation of a porous structure is ensured by the use of foaming agents directly in the processing process. The disadvantage of technologies using blowing agents is the presence of closed and open pores.

Most likely, the material obtained by the technology reflected in the patent of the Russian Federation No. 2194719 [MPK C08F 6/12, 2002] is porous, although there is no direct indication of this fact in the text of the patent. In this work, polyolefins were used, the patent is devoted to a method for isolating polyolefins from solutions.

Known methods for producing nanoporous polymers, including polyolefins, by the method of uniaxial or biaxial drawing in a physically active medium [RF patent No. 2676765, IPC B29C 55/04, B29C 55/12, 2019; RF patent No. 2308375, IPC B29C 55/06, C08J 9/28, 2007; and etc]. The disadvantage of these methods is the complexity of the drawing technology and the regulation of the porosity of products.

A known method of obtaining porous polymeric materials of various sizes by a common set of methods based on the physical separation of the polymer-solvent mixture. The solvent is a mixture of substances of different dissolving power in relation to the soluble polymer. So, the simplest system consists of the following components: a polymer, a “good” solvent, and a “bad” solvent. The general principle of operation of this group of methods is based on the formation of a homogeneous system under certain conditions (this condition is necessary and sufficient) and the subsequent violation of homogeneity with the formation of phase boundaries: liquid-solid, liquid-liquid to increase the nucleation of the precipitated polymer. The principle of physical separation can be implemented in the following versions: thermally induced [Wang, G. Facile synthesis of flexible macroporous polypropylene sponges for separation of oil and water / G. Wang, H. Uyama// Scientific Reports. - 2016. - Vol. 6. - P. 21265-21269], chemically induced [Facile Synthesis of Marshmallow-like Macroporous Gels Usable under Harsh Conditions for the Separation of Oil and Water / G. Hayase, K. Kanamori, M. Fukuchi, H. Kaji // Angewandte Chemie. - 2013. - Vol. 52. - P. 1-5], induced by the non-solvent and/or its vapors [Additive-free poly(vinylidene fluoride) aerogel for oil/water separation and rapid oil adsorption / X. Chen, Y. N. Liang, X. Tang, W. Shen, X. Hu // Chemical Engineering Journal. - 2017. - Vol. 308. - P. 18-26]. A common disadvantage is the mandatory use of freeze drying when extracting one of the solvents, which limits the process by the following factors: time, complexity of the process, productivity by weight of the finished product, restrictions on the solvents used.

A known method of forming a porous structure by sintering powders of polyethylene, irradiated and non-irradiated with ionizing radiation, followed by compaction and sintering [USSR author's certificate 1666476, IPC C08J 9/24, C08L 23/06, 1991]. In the description of the invention, there are only some technical data of the obtained membranes (tensile strength, air permeability, air pressure loss, air bubble size) necessary to conclude that the material meets the requirements for porous plates for fine-bubble aeration in aerotanks. Density, porosity, and pore size data are not given.

Thus, there are few known methods for the manufacture of open-cell materials based on polyolefins, in particular polyethylenes.

As the closest analogue, a method for producing a porous material is adopted, applicable to various polymers: modified polyvinyl alcohol, sodium alginate, carboxymethylcellulose, dextran polymers, phosphocellulose, etc. [RF patent No. 2035476, IPC C08J 9/00, 1995]. The porous material is obtained by preparing an aqueous solution of a polymer salt, followed by its freezing and removal of the aqueous solvent. Removal of the aqueous solvent is carried out without defrosting the frozen starting components, after which the polymer is treated with an acid or salt solution in an organic solvent, which is a non-solvent of the polymer, followed by removal of the treatment solution. The method is characterized in that the aqueous solvent is removed by freeze drying or cryoextraction.

The disadvantage of this method is the limitation in applicability only to water-soluble polymers.

The task to be solved by the claimed invention is the development of a simple and convenient method for producing high-density macroporous polyethylenes with an open pore structure and with a given porosity.

The technical result, which is achieved when solving the problem, is expressed in reducing the complexity of manufacturing, ease of instrumentation and obtaining material:

- with a given porosity;

- macroporous with possible mesoporosity (according to IUPAC classification) with pore sizes of both 100-300 nm and groups of cavities less than 70 nm with the presence of polyethylene threads (based on SEM);

- with high contact angles with respect to water;

- permeable to non-polar organic compounds;

- limited permeability to water.

The problem is solved by the fact that the method of obtaining an open-pore polymer material, including the preparation of a polymer solution, the addition of a template, the removal of a solvent, the formation of a material, the removal of a template, is characterized in that a polymer is mixed, which is used as high-density polyethylene, a solvent, as which use toluene, and the template, which is used as paraffin, in a ratio of polyethylene : toluene, equal to 1:29 and polyethylene: paraffin, equal to 1:2-58, at a temperature of at least 70 ° C and a mixing intensity of 400-600 rpm min until a homogeneous solution is formed, which is heated to a temperature of 110°C and toluene is distilled off to a solution temperature of 95°C, then the material is molded and toluene residues are removed from it, then paraffin is removed by extraction with methylene chloride, and then drying is carried out from methylene chloride residues .

In addition, the material is molded by casting in layers 4-40 mm thick.

In addition, the solidification of the material occurs at a temperature of 40-43°C.

In addition, toluene residues are removed from the material by natural drying.

In addition, toluene residues are removed from the material by vacuum.

In addition, the paraffin from the material with a ratio of polyethylene : paraffin 1:2-10 is removed by extraction with methylene chloride for 10-12 hours.

In addition, paraffin from a material with a ratio of polyethylene : paraffin greater than 1:10 is removed by extraction with methylene chloride for 15-17 hours.

In addition, residual methylene chloride is removed from the material by natural drying.

In addition, residual methylene chloride from the material is removed by vacuum.

A comparative analysis of the set of essential features of the proposed technical solution and the set of essential features of the prototype and analogues indicates its compliance with the criterion of "novelty".

In this case, the distinctive features of the claims solve the following functional tasks.

The attribute "high-density polyethylene is used as [polymer]" describes the type of raw material used - a large-tonnage, cheap and widespread polyolefin with a wide range of performance properties.

The feature "toluene is used as [solvent]" describes the type of solvent for the polymer, which must meet the following requirements:

- completely dissolve the polymer at elevated temperatures;

- stop the dissolution and lead to precipitation of the polymer and template at temperatures in the ranges close to or reaching normal values (25°C);

The feature “paraffin is used as [template]” describes the type of template that acts as a structurant and heat fixer of the solution structure, which meets the following requirements:

- the possibility of obtaining homogeneous mixtures with a solvent under certain conditions;

- lower dissolving power in relation to the polymer compared to the solvent;

- solid state of aggregation under normal conditions;

- availability and chemical resistance.

The sign "in the ratio of polyethylene : toluene, equal to 1:29" describes the ratio of components by weight, which is determined based on the dissolving power and process conditions.

The sign "in the ratio of polyethylene : paraffin, equal to 1:2-58" describes the ratio of components by weight and allows you to set the porosity of the resulting material within no more than 1:10.

Setting the mass ratio of toluene : paraffin (or exceeding the ratio of polyethylene : paraffin more than 1:10) allows you to create materials with high porosity, but increased contraction and brittleness of the resulting material.

The features “polymer, solvent and template are mixed at a temperature of at least 70 ° C and a mixing intensity of 400-600 rpm until a homogeneous solution is formed” describe the technology for preparing a solution, while the minimum temperature is 70 ° C and the mixing intensity is 400-600 rpm provide dissolution in toluene of both polyethylene and paraffin.

The features "[homogeneous solution] is heated to a temperature of 110°C and toluene is distilled off to a solution temperature of 95°C" describe the process of removing part of the solvent from the solution.

The temperature of 110°C is due to the boiling point of toluene, after distillation of the main part of the solvent while maintaining the heat flux introduced into the system, the temperature naturally decreases to 95°C.

Thus, the temperature of 95°C indicates the end of the distillation process and the separation of most of the solvent, and is also the molding temperature of the material.

The sign “material is formed” and the signs of the first and second dependent claims describe the process and regime characteristics of forming the material, and also describe the temperature at which polyethylene solidifies in a solution containing polyethylene, paraffin and toluene residues, as a result, the structure of this solution is fixed with the formation of interconnected pores and the formation of a developed inner surface capable of sorbing and passing condensed non-polar organic compounds and their mixtures.

The feature “remove toluene residues from [material]”, as well as the features of the third and fourth dependent claims describe the process and regime characteristics of removing toluene residues.

The feature “paraffin is removed by extraction with methylene chloride, and then drying is carried out from methylene chloride residues”, as well as the signs of the dependent claims from the fifth to the eighth describe the process and regime characteristics of the removal of paraffin and methylene chloride residues from the material.

Moreover, the solvent used to remove paraffin must meet the following requirements:

- have a low boiling point, which is at least 10°C below the softening point of the polymer;

- have a significant dissolving power in relation to the template;

- be inert with respect to the polymer at the boiling point.

In FIG. 1 shows the structure of the sample according to example 1 at 20 µm.

In FIG. 2 shows the structure of the sample according to example 2 at 2 µm.

In FIG. 3 shows the structure of the sample according to example 3 at 20 µm.

In FIG. 4 shows the structure of the sample according to example 4 at 10 µm.

In FIG. 5 shows the structure of the sample according to example 5 at 10 µm.

In FIG. 6 shows linear isotherms of adsorption and desorption for the sample according to example 1.

In FIG. 7. Shows linear isotherms of adsorption and desorption for the sample according to example 2.

The following are used as raw materials:

- low pressure polyethylene in the form of powder, granules, etc. - according to GOST 16338-85 or TU of the corresponding manufacturer;

- toluene - in accordance with GOST 5789-78;

- hard paraffin - according to GOST 23683-89.

The inventive method is carried out in several stages according to standard methods on known equipment.

1. High-density polyethylene, toluene and finely chopped paraffin are mixed in a given ratio at a temperature of 70-110 ° C and intensive stirring 400-600 rpm, resulting in 50-55 minutes (average value, upward changes are possible) a homogeneous solution is formed - 2 options are possible here:

- connect all components at once;

- high-density polyethylene is added to toluene, heated with stirring, and after dissolution, paraffin is added without stopping heating and stirring.

It is possible to change the process conditions, which are set based on the need for complete dissolution of the polymer, the template and the achievement of complete homogeneity of the solution.

2. The resulting homogeneous solution is brought to a temperature of 110°C and the toluene is distilled off to the point where the temperature of the solution is 95°C, as a result, free toluene is completely evaporated, while dropping into the receiving flask practically stops.

The process of removing part of the toluene from the solution is controlled by changing the temperature, since after distillation of the main part of the toluene, while maintaining the value of the heat flux supplied to the system, the temperature of the solution naturally decreases from 110°C (boiling point of toluene) to the molding temperature (95°C) .

In this case, it should be taken into account that the more toluene remains, the more pronounced the contraction of the material after molding during solidification, however, the presence of solvent residues makes it possible to obtain additional porosity by the mechanism of thermally induced phase separation with a decrease in the temperature of the solution after the removal of toluene, in particular, already in the form of finished products containing the polymer and the template distributed in it, to room size.

3. The material is formed, for which the remaining thick solution containing polyethylene, paraffin and toluene residues is cast in layers of 4-40 mm thick into prepared molds (molds) or onto a flat surface and left until complete solidification, which occurs within 2.5- 3 min at 40-43°C.

Beforehand, it is necessary to place a transition surface in the molds (for example, aluminum foil), which must completely repeat the geometric shape of the mold and be inert to the effects of temperature (up to 110-120°C) and solution components, to prevent mold adhesion to the material.

In the claimed technical solution, in the case of premature solidification of the solution, molding is possible by machining the surface of the material to give the necessary geometric shape of the product. Reheating is unacceptable due to the violation of the porous structure.

4. Next, the polymeric material is removed from the molds (and transitional surfaces), if necessary, to obtain granules, the plates are cut into particles of the required size and the remaining toluene is removed by natural drying or vacuum.

5. The paraffin is removed, for which the material containing the polymer and the template, in a sheath made of non-woven polypropylene material, is placed in a Soxhlet apparatus and extracted with methylene chloride under the specified operating characteristics.

The process must be carried out in the absence of external mechanical influences, including mixing, vibration, etc., since the integrity of the final product may be violated. It is recommended to use a retaining mesh to avoid loss of integrity and to minimize the formation of material with dimensions less than 3 mm.

The completeness of the extraction is checked gravimetrically, based on the known ratio of polyethylene : paraffin.

6. Remove residual methylene chloride by natural drying or vacuum drying until the template solvent has completely evaporated.

The authors used polyethylene brand HD7000F Innoplus by PTT Global Chemical (made in Thailand) and prepared a homogeneous solution using a reflux condenser.

The ratio of components is shown in table 1.

In examples with a ratio of polyethylene : paraffin of not more than 1:10, a note was added about a low concentration of paraffin (MK).

In examples with a ratio of polyethylene:paraffin greater than 1:10, the ratio of toluene:paraffin is additionally given.

Table 1

The ratio of the components of the polymer material

Example Weight of polyethylene, g Weight of paraffin, g Volume of separated toluene, ml Polyethylene : paraffin ratio Ratio toluene : paraffin one 3 86.85 78 1:29 1:1 2 3 43.14 75 1:14.5 1:0.5 3 3 173.83 80 1:58 1:2 4 (MK) 3 30.02 82 1:10 - 5 (MK) 3 15.08 90 1:5 - 6 (MK) 3 6.07 92 1:2 - 7 (MK) 6 12.03 89 1:2 - 8 (MK) 6 18.12 92 1:3 - 9 (MK) 6 30.10 88 1:5 - 10 (MK) 6 42.10 84 1:7 -

The regime characteristics of obtaining a polymeric material are given in table 2.

table 2

Regime characteristics of obtaining polymeric material

Example Mixing temperature of polyethylene, toluene and paraffin, °C Mixing intensity, rpm Cast layer thickness, mm Pour point of material, °C Duration of extraction with methylene chloride, hours one 70 600 twenty 42 16 2 75 550 thirty 42.5 fifteen 3 80 600 40 43 17 4 (MK) 85 450 fifteen 41 eleven 5 (MK) 90 500 ten 41.5 10.5 6 (MK) 93 400 four 40 ten 7 (MK) 95 420 6 40 11.5 8 (MK) 100 450 25 42 ten 9 (MK) 105 530 32 42.5 eleven 10 (MK) 110 580 35 43 12

Next, the obtained samples were examined.

1. To determine the structure, scanning electron microscopy of individual samples was performed using a Carl Zeiss CrossBeam 1540XB microscope.

As seen in FIG. 1-5, with an increase in the ratio of polyethylene : paraffin, the number of elongated depressions with a size of 4-6 microns, pores, voids and protrusions of the material increases. In addition, the number and distribution of pore clusters in the range of 2 µm or less increases. The number of polymer threads also increases. In general, this material is characterized by a developed surface with significant depressions in the form of "gorges" and several large depressions. The presence of irregularities at the seams of PE fibers and the presence of a region with very small pores suggests the presence of mesopores in these regions with sizes less than 50 nm.

2. The specific surface area, porosity and pore volume were studied on the Autosorb Quantachrome® ASiQwin™ apparatus by N2 adsorption at 77.3 K.

Sample preparation was carried out at a temperature of 30°C. The results are shown in table 3.

Table 3

Indicators of specific surface area, porosity and pore volume

Example Specific surface area, m ² /g Pore volume, cm ³ /g Pore size, nm one 14.10 0.08207 3.784 2 12.12 0.08720 4.085

As can be seen from Table 3, at a higher ratio of polyethylene : paraffin, the specific surface area is slightly higher, but the volume and size of the pores are smaller. The values are practically equivalent with a large difference in the ratios, which allows us to assume that for the remaining ratios, the parameter values will be identical. In general, the same surface is mesoporous and macroporous.

3. The linear adsorption and desorption isotherms shown in FIG. 6 and 7.

As you can see in the graphs, they are identical to each other with a slight difference in values. According to the classification of the type of Langmuir isotherm curves, the studied porous PE is characterized by a macroporous structure, which is consistent with the SEM data. The saturation line sets in rather early (around ⁴ cm3/g); however, with an increase in relative pressure, despite no desorption, saturation continues to reach adsorbate multilayers.

4. Conducted a study of the contact angle with respect to water (Θ) by the method of "captive bubble" with subsequent measurement on the goniometer. The measurements were carried out at two points for a series of samples of the same concentration.

Measurements were also made for products with free solidification without surface treatment and accelerated solidification caused by additional cooling at the stage of molding the product. Repeated measurements were carried out after a short period of time - 35 min.

Before the measurement, the surface was machined with a scalpel until a flat area was reached. The data obtained are presented in table 4.

Table 4

Contact angle values with respect to water

Example Θ, degrees Θ repeated, degrees one 154 128 2 157 125 3 152 132 four 153 136 5, 9 152 138 6, 7 132.3 124 7 (free setting) 58.6 - 7 (accelerated setting) 81 - eight 150 137 8 (unprepared surface) 144 - ten 151 140 10 (unprepared surface) 148 -

Based on the data in Table 4, an increase in the contact angle index is observed during surface treatment. However, with an increase in the ratio of PE : paraffin, no significant increase in the contact angle was found, and the main values are in the range of 150-158°. The decrease in values during repeated measurements in the same areas is due to the retention of water microdrops on irregularities, in pores, voids until the material is completely dry. In addition, a noticeable influence of molding conditions has been established, under which, in the absence of a form, the formed surface is not rough, which leads to a significant decrease in the contact angle.

Claims (1)

A method for producing an open-pore polymeric material, including preparing a polymer solution, adding a template, removing a solvent, shaping a material, removing a template, characterized in that a polymer is mixed, which is high-density polyethylene, a solvent, which is toluene, and a template , which is used as paraffin, at a mass ratio of polyethylene:toluene, equal to 1:29, and polyethylene:paraffin, equal to 1:2-58, at a temperature of 70-110 ° C and vigorous stirring at 400-600 rpm until the formation homogeneous solution, which is heated to a temperature of 110 ° C and the toluene is distilled off to a solution temperature of 95 ° C, then the material is molded by casting in layers 4-40 mm thick into molds until solidification for 2.5-3 minutes at a temperature of 40-43 ° C, the polymeric material is removed from the molds, the toluene residues are removed by natural drying or vacuum, then the paraffin is removed by extraction with methylene chloride, while m paraffin from a material with a mass ratio of polyethylene:paraffin 1:2-10 is removed by extraction with methylene chloride for 10-12 hours, and paraffin from a material with a mass ratio of polyethylene:paraffin more than 1:10 is removed by extraction with methylene chloride for 15 -17 hours, then remove the remains of methylene chloride by natural drying or vacuum.

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