RU2792879C1 - Polymer composite material for structural purposes based on ultra-high molecular weight polyethylene reinforced with basalt fabric - Google Patents

Abstract

FIELD: polymer materials.

SUBSTANCE: invention be used for the manufacture of parts in friction units, machines and other mechanisms that operate under conditions of abrasive wear in aggressive environments. A polymer composite material based on ultra-high molecular weight polyethylene (UHMWPE) 99.5 wt.% with the addition of 0.5 wt.% N-Cyclohexylbenzothiazole-2-sulfenamide is proposed, including basalt fabric as a reinforcing element, which is laid in a polymer matrix in two layers, between which an additional UHMWPE layer is formed.

EFFECT: increase in the strength, wear resistance and reliability of friction units, as well as a decrease in the intensity of mass wear of a structural material based on UHMWPE and basalt fabric.

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Description

The invention relates to the field of polymer materials science and can be used as a high-modulus, wear-resistant composite material based on ultra-high molecular weight polyethylene (UHMWPE) for the manufacture of structural products used in contact with an abrasive surface in aggressive environments: oil, oils, lubricants, fuel as a lining material used, in particular, for lining mining and processing equipment.

When developing polymeric materials for structural and functional purposes, a number of requirements are imposed on operational properties: resistance to aggressive media, high elastic and strength properties, resistance to deformation, wear resistance, good thermal properties and other characteristics. In this regard, the tasks are set for the selection of components that have a complex effect on the polymer matrix and lead to an improvement in properties.

Known structural polymer composite based on UHMWPE with a molecular weight of 4×10 ⁶ g/mol, a copolymer of high density ethylene with grafted vinyl trimethoxysilane (HDPE-g-VTMS) or a copolymer of high density ethylene with grafted maleic anhydride (HDPE-g-SMA) in in the form of ground granulate with a particle size of 160-250 microns, reinforced with carbon fibers, having a diameter of 7.5-15.0 microns and a length of 75-200 microns (see RU No. 2674019, class C08J 5/16, C08L 23/06, C08L 51/06, C08K 3/04, C08K 7/06, published 12/04/2018). The material is intended for the production of antifriction products in friction units in mechanical engineering and medicine using additive technologies.

The disadvantages of the known material are unsatisfactory strength, low modulus of elasticity, high cost.

A hybrid composite based on fibrous fillers of UHMWPE, basalt fabric, glass fiber fabric and hollow glass microspheres is known (see E.A. Belyaeva, A.F. Kosolapov, S.V. Shatsky, V.S. Osipchik, A. A. Nabiulina / Hybrid composites based on fibrous fillers from ultra-high molecular weight polyethylene and glass fillers // Advances in chemistry and chemical technology. - 2015. - V.24. - No. 10.). According to the known invention, the laying of the layers is carried out in turn: a layer of UHMWPE fabric, a layer of basalt or glass fabric. The material is intended for obtaining antifriction products in friction units in mechanical engineering.

The disadvantages of the known material are the high cost and complexity of manufacturing technology.

The closest in technical essence to the claimed material is a composition based on UHMWPE with a molecular weight of 2.7×10 ⁶ g/mol and an inorganic filler, which is used as basalt fibers in an amount of 5.0-20.0 wt. % (see WO 2015/002568, class C08K 7/04, C08L 23/06, published 01/08/2015). Moreover, the length of the crushed fibers corresponded to 30-90 microns, and the diameter was 8-10 microns. The material is intended for the manufacture of wear-resistant products used for lining mining and processing equipment.

The disadvantages of the material are low strength, complex manufacturing process.

The task to be solved by the claimed solution is to develop a structural and wear-resistant composite material for the manufacture of parts in friction units, machines and other mechanisms operating under abrasive wear in aggressive environments.

The technical effect obtained when solving the problem is expressed in increasing the strength, wear resistance and reliability of units, reducing the intensity of mass wear of the material.

To solve the problem, the polymer composite material based on UHMWPE as a reinforcing element contains a basalt fabric laid in a polymer matrix between layers of UHMWPE, while UHMWPE additionally contains sulfenamide C as a modifier in the following ratio of components, wt.%: UHMWPE - 99.5 ; sulfenamide C - 0.5. In addition, the reinforcing basalt fabric is laid in a polymer matrix in two layers, between which an additional layer of UHMWPE is formed.

Comparative analysis of the features of the claimed solution with known features indicates the compliance of the claimed solution with the criterion of "novelty".

The set of features of the invention provides a solution to the stated technical problem, namely, improving the strength properties and increasing the wear resistance of the polymer composite, expanding the range of polymer composite materials for structural purposes based on UHMWPE.

To increase the strength of the polymeric material based on UHMWPE, it is proposed to use basalt fabric included in the composite as a reinforcing element in the polymer matrix. The choice of the reinforcing layer was made on the basis of the results of studies on the reinforcing properties of basalt fabric in epoxy resin (see I.G. Lukachevskaya, M.P. Lebedev, A.K. Kychkin / Study of the effect of fillers on the properties of polymer composite materials using textolites as an example / / Scientific notes of the Komsomolsk-on-Amur State Technical University. - 2019. - V. 1. - No. 4). It was found that the introduction of basalt fabric leads to an increase in the strength of the composite material based on epoxy resin up to 503 MPa. An increase in the wear resistance of composite materials was achieved by introducing the filler sulfenamide C into the polymer matrix. The addition of certain organic fillers to the polymer matrix based on UHMWPE increases the abrasion resistance (see A.A. Dyakonov, S.N. Danilova, A.P. Vasiliev, A. A. Okhlopkova, S.A. Sleptsova, A.A. Vasilyeva / Study of the effect of sulfur, diphenylguanidine and 2-mercaptobenzthiazole on the physical and mechanical properties and structure of ultra-high molecular weight polyethylene // Perspective materials. - 2020. - No. 1).

During the operation of thermoplastic polymeric materials, the problem of irreversible changes in the linear dimensions of products arises due to insufficient resistance to shear deformations. UHMWPE belongs to the class of thermoplastics, during the operation of which strong changes in linear dimensions in combination with wear resistance are also undesirable.

For the manufacture of composites used ultra-high molecular weight polyethylene UHMWPE brand Ticona GUR-4022 (Celanese, China), with a molecular weight of 5.0×10 ⁶ g/mol, with an average particle size of 145 μm and a density of 0.93 g/cm ³ . As a reinforcing layer, basalt fabric was used, which is widely used to protect hot surfaces, as well as thermal insulation and for the manufacture of fire-retardant clothing, shells for heat-insulating materials, etc. It is also known to use basalt fabric in the production of composite materials as a reinforcing base for a binder. Advantages of basalt fabric: high heat resistance, incombustibility, continuous use temperature up to 700°С; basalt is an environmentally friendly material of natural origin, is durable, has high chemical resistance, wind resistance, is resistant to microorganisms and mold.

In order to impart increased wear resistance to UHMWPE, the modifying additive sulfenamide Ts (N-Cyclohexylbenzothiazosulfenamide-2) was additionally introduced into the polymer matrix, which is also used as slow-acting vulcanization accelerators in rubber products (see SU No. 190557, class C08L 7/00, C08K 5/20, C08K 5/47, published 12/29/1966).

For experimental work, two compositions of the polymer material were used (see Table 1), where the ratios of sulfenamide C and UHMWPE powder are given. At the same time, the experimental samples were formed in the following order of laying the layers of basalt fabric in the polymer matrix of UHMWPE modified with sulfenamide C (see figure): a) basalt fabric inside the polymer matrix, b) basalt fabric over the polymer matrix, c) 2 layers of basalt fabric in a polymer matrix separated by a polymer, d) 2 layers of basalt tissue in contact with each other.

The manufacture of composites from UHMWPE containing sulfenamide C was carried out by hot pressing according to standard technology, namely, by pressing at a temperature of 175 ± 2°C, a pressure of 10 ± 0.1 MPa and holding under a pressure of 20 ± 0.1 min, followed by cooling to 80°C.

In the first sample, a layer of basalt fabric was laid on top of the first layer of modified UHMWPE powder and then covered with a second layer (see Fig. a); in the second sample, a layer of basalt fabric was placed on top of the modified UHMWPE powder poured into the mold (see Fig. b); in the third sample, the first basalt fabric layer was laid on top of the modified UHMWPE powder, then the basalt fabric was covered with modified UHMWPE powder, then the second layer of basalt fabric was laid and then filled with modified UHMWPE powder (see Fig. c); in the fourth sample, two basalt layers were laid on top of the poured modified UHMWPE powder and then covered with powder-modified UHMWPE (see Fig. d).

The physical and mechanical properties of the composites were studied on an AGS-J tensile testing machine (Shimadzu, Japan) according to GOST 11262–2017 at a moving gripper speed of 50 mm/min. Tensile modulus was determined according to GOST 9550-2014. Wear resistance was determined on a UMT-3 tribometer (CETR, USA) at a specific load of 1.9 MPa and a sliding speed of 0.5 m/s according to the “finger-disk” friction scheme for 3 hours. The friction coefficient was determined according to GOST 11629. The number of parallel tests for each series of samples was 6.

Table 2 shows the physico-mechanical and tribological properties of polymers based on UHMWPE modified with sulfenamide C, where δ is the tensile strength, MPa; ε - elongation at break, %; E _p - tensile modulus, MPa; I - mass wear rate, mg/h;

Table 2 shows that the greatest increase in strength properties and wear resistance is observed in a composite containing 0.5 wt.% sulfenamide C. Thus, composition 1 has a tensile strength higher by 23%, elongation at break is higher by 18%, and the intensity of the mass wear rate is 6 times lower compared to the original UHMWPE.

Table 3 shows the values of the physical and mechanical characteristics of the claimed composition based on a polymer matrix UHMWPE with sulfenamide C (composition 1), reinforced with basalt fabric, and a comparison with the original UHMWPE and the prototype, where δ is the tensile strength, MPa; ε - elongation at break, %; E _p - tensile modulus, MPa.

Table 3 shows that polymer compositions with a schematic laying of the reinforcing basalt fabric of options a and b have the greatest strength (see image). The introduction of basalt fabric into a polymer matrix leads to a significant increase in strength and a decrease in relative elongation, which gives the material high-modulus properties. To increase wear resistance, polymer composites are made on the basis of UHMWPE powder modified with 0.5 wt.% sulfenamide C, which leads to a 6-fold increase in abrasion resistance.

Thus, the composition consists of a UHMWPE polymer matrix, sulfenamide Ts and a reinforcing layer of basalt fabric, laid in one or two layers. The developed polymer compositions are characterized by high strength, high resistance to deformation and wear resistance. The use of basalt fabric as a reinforcing material makes it possible to obtain polymer composite materials with increased strength properties and resistance to deformation without complicating technological operations.

Table 1
The composition of the modified polymeric material based on UHMWPE and sulfenamide C Sample Ingredients, wt.% UHMWPE Sulfenamide C Composition 1 99.5 0.5 Composition 2 99.0 1.0

table 2
Properties of the Modified UHMWPE Composite Sample σ _rm , MPa ε _rr , % Е _r , MPa I, mg/h Initial UHMWPE 34 311 420 0.12 Composition 1 42 369 589 0.02 Composition 2 38 347 499 0.14

Table 3
Properties of polymer composites Indicators Sample Prototype Ref. UHMWPE Composition 1 Var. A Var. b Var. V Var. G δ, MPa 34 42 62.6 28.2 68.5 43 43 ε, % 311 369 6 251 7 8 270 Е _r , MPa 420 589 - - - - 1085 I, mg/h 0.12 0.02 0.02 0.02 0.02 0.02 -

Claims (3)

1. A polymer composite material for the manufacture of parts in friction units, machines and other mechanisms operating under abrasive wear conditions in aggressive environments, based on ultra-high molecular weight polyethylene (UHMWPE), including a reinforcing element, characterized in that it contains basalt fabric as a reinforcing element, laid in a polymer matrix between layers of UHMWPE, while UHMWPE additionally contains sulfenamide C as a modifier in the following ratio, wt.%: UHMWPE 99.5 sulfenamide C 0.5 2. A polymer composite material according to claim 1, characterized in that the reinforcing basalt fabric is laid in a polymer matrix in two layers, between which an additional layer of UHMWPE is formed.

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