Composite materials formation for orthopaedic implants

One of most up-to-date problems of orthopaedy is the development of new materials for replacement of osseous tissue and cartilage defects. Electron beam (EB) processing of polymer composites with bioactive ceramics has been used for manufacture of artificial materials for orthopaedic implants. Exp...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Вопросы атомной науки и техники
Datum:2004
Hauptverfasser: Avilov, A.M., Deryuga, V.A., Popov, G.F., Popova, N.G., Rudychev, V.G., Shkilev, A.L.
Format: Artikel
Sprache:English
Veröffentlicht: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2004
Schlagworte:
Online Zugang:https://nasplib.isofts.kiev.ua/handle/123456789/79067
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Zitieren:Composite materials formation or orthopaedic implants / A.M. Avilov, V.A. Deryuga, G.F. Popov, N.G. Popova, V.G. Rudychev, A.L. Shkilev // Вопросы атомной науки и техники. — 2004. — № 1. — С. 181-183. — Бібліогр.: 3 назв. — англ.

Institution

Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-79067
record_format dspace
spelling Avilov, A.M.
Deryuga, V.A.
Popov, G.F.
Popova, N.G.
Rudychev, V.G.
Shkilev, A.L.
2015-03-25T20:20:26Z
2015-03-25T20:20:26Z
2004
Composite materials formation or orthopaedic implants / A.M. Avilov, V.A. Deryuga, G.F. Popov, N.G. Popova, V.G. Rudychev, A.L. Shkilev // Вопросы атомной науки и техники. — 2004. — № 1. — С. 181-183. — Бібліогр.: 3 назв. — англ.
1562-6016
PACS: 29.17.+w
https://nasplib.isofts.kiev.ua/handle/123456789/79067
One of most up-to-date problems of orthopaedy is the development of new materials for replacement of osseous tissue and cartilage defects. Electron beam (EB) processing of polymer composites with bioactive ceramics has been used for manufacture of artificial materials for orthopaedic implants. Experimental approaches and problems of EB processing of composites based on ultra-high-molecular weight polyethylene (UHMWPE) are discussed.
Однією з актуальних задач в ортопедії є пошук і розробка нових штучних матеріалів для заміщення кісткової тканини і хряща. Обробка полімерних композиційних матеріалів з біоактивною керамікою електронними пучками використовувалась для виготовлення штучних матеріалів ортопедичного призначення. Приводяться експериментальні досягнення і проблеми радіаційної технології отримання композитів на основі надвисокомолекулярного поліетилену.
Одной из актуальных задач в ортопедии является поиск и разработка новых материалов для замены костной ткани и хряща. Обработка полимерных композиционных материалов с биоактивной керамикой электронными пучками использовалась для изготовления искусственных материалов для ортопедических имплантатов. Обсуждаются экспериментальные достижения и проблемы радиационной технологии обработки композитов на основе сверхвысокомолекулярного полиэтилена.
The work was supported by the STCU, Kyiv, project #957. The authors wishes to express gratitude to Prof. N.Dedukh, Prof.V.Radchenko, and Dr. S.Malushkina, SJPI, for conducting of the full cycle testing of new composite materials on biocompatibility.
en
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
Вопросы атомной науки и техники
Применение ускоренных пучков
Composite materials formation for orthopaedic implants
Розробка композиційних матеріалів для ортопедичних імплантатів
Разработка композиционных материалов для ортопедических имплантатов
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Composite materials formation for orthopaedic implants
spellingShingle Composite materials formation for orthopaedic implants
Avilov, A.M.
Deryuga, V.A.
Popov, G.F.
Popova, N.G.
Rudychev, V.G.
Shkilev, A.L.
Применение ускоренных пучков
title_short Composite materials formation for orthopaedic implants
title_full Composite materials formation for orthopaedic implants
title_fullStr Composite materials formation for orthopaedic implants
title_full_unstemmed Composite materials formation for orthopaedic implants
title_sort composite materials formation for orthopaedic implants
author Avilov, A.M.
Deryuga, V.A.
Popov, G.F.
Popova, N.G.
Rudychev, V.G.
Shkilev, A.L.
author_facet Avilov, A.M.
Deryuga, V.A.
Popov, G.F.
Popova, N.G.
Rudychev, V.G.
Shkilev, A.L.
topic Применение ускоренных пучков
topic_facet Применение ускоренных пучков
publishDate 2004
language English
container_title Вопросы атомной науки и техники
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
format Article
title_alt Розробка композиційних матеріалів для ортопедичних імплантатів
Разработка композиционных материалов для ортопедических имплантатов
description One of most up-to-date problems of orthopaedy is the development of new materials for replacement of osseous tissue and cartilage defects. Electron beam (EB) processing of polymer composites with bioactive ceramics has been used for manufacture of artificial materials for orthopaedic implants. Experimental approaches and problems of EB processing of composites based on ultra-high-molecular weight polyethylene (UHMWPE) are discussed. Однією з актуальних задач в ортопедії є пошук і розробка нових штучних матеріалів для заміщення кісткової тканини і хряща. Обробка полімерних композиційних матеріалів з біоактивною керамікою електронними пучками використовувалась для виготовлення штучних матеріалів ортопедичного призначення. Приводяться експериментальні досягнення і проблеми радіаційної технології отримання композитів на основі надвисокомолекулярного поліетилену. Одной из актуальных задач в ортопедии является поиск и разработка новых материалов для замены костной ткани и хряща. Обработка полимерных композиционных материалов с биоактивной керамикой электронными пучками использовалась для изготовления искусственных материалов для ортопедических имплантатов. Обсуждаются экспериментальные достижения и проблемы радиационной технологии обработки композитов на основе сверхвысокомолекулярного полиэтилена.
issn 1562-6016
url https://nasplib.isofts.kiev.ua/handle/123456789/79067
citation_txt Composite materials formation or orthopaedic implants / A.M. Avilov, V.A. Deryuga, G.F. Popov, N.G. Popova, V.G. Rudychev, A.L. Shkilev // Вопросы атомной науки и техники. — 2004. — № 1. — С. 181-183. — Бібліогр.: 3 назв. — англ.
work_keys_str_mv AT avilovam compositematerialsformationfororthopaedicimplants
AT deryugava compositematerialsformationfororthopaedicimplants
AT popovgf compositematerialsformationfororthopaedicimplants
AT popovang compositematerialsformationfororthopaedicimplants
AT rudychevvg compositematerialsformationfororthopaedicimplants
AT shkileval compositematerialsformationfororthopaedicimplants
AT avilovam rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT deryugava rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT popovgf rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT popovang rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT rudychevvg rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT shkileval rozrobkakompozicíinihmateríalívdlâortopedičnihímplantatív
AT avilovam razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
AT deryugava razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
AT popovgf razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
AT popovang razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
AT rudychevvg razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
AT shkileval razrabotkakompozicionnyhmaterialovdlâortopedičeskihimplantatov
first_indexed 2025-11-26T00:09:48Z
last_indexed 2025-11-26T00:09:48Z
_version_ 1850594220437405696
fulltext COMPOSITE MATERIALS FORMATION FOR ORTHOPAEDIC IMPLANTS A.M. Avilov, V.A. Deryuga, G.F. Popov, N.G. Popova, V.G. Rudychev, A.L. Shkilev Kharkov National University, P.O. Box 60, 61052, Kharkov, Ukraine; E-mail: popov@univer.kharkov.ua One of most up-to-date problems of orthopaedy is the development of new materials for replacement of osseous tissue and cartilage defects. Electron beam (EB) processing of polymer composites with bioactive ceramics has been used for manufacture of artificial materials for orthopaedic implants. Experimental approaches and problems of EB processing of composites based on ultra-high-molecular weight polyethylene (UHMWPE) are discussed. PACS: 29.17.+w 1. INTRODUCTION Now there are no artificial materials that completely satisfy all demands of medicine. The mechanical prop- erties of human osseous tissue are very different from those of inert metal alloys currently used in artificial joints. This large mismatch in mechanical properties causes bone resorption or loss around the implant, as well as loosening of the artificial joint stem in the medullar cavity. Ultra high-molecular weight polyethy- lene (UHMWPE) used as a substitute for gristle is also rigid, it is not of sufficient wear-resistance, it has little adhesion to bone cement, that causes both decreasing of a service life of the product and increasing of number of surgical operations. All previously mentioned puts a task for searching of new materials for replacement of natural osseous and gristle tissues. Polymeric composites with bioactive ce- ramics are considered as the most appropriate candi- dates to this role. Our investigations deals with research and engineering studies of the use of EB processing of artificial materials based on UHMWPE for construction elements of orthopedic implants. There are several competitive radiation-chemical processes, which realize simultaneously in the polymer composite under electron irradiation. Such processes are the crosslinking of macromolecules and creation of spa- tial structure in polymeric matrix of composite, the radi- ation grafting of macromolecules to material of filler, the destruction of macromolecules, the appearance of long-lived free radicals, etc. Every of these processes modifies selectively the different physical, mechanical, and operation characteristics of irradiated composites. The formation of conditions for preferential realization of specific radiation-chemical processes permits pur- posefully regulating the composite characteristics. This work presents investigation results of influ- ence of EB regimes irradiation, surrounding envi- ronment, post-radiation treatments of UHMWPE on variation of physical, mechanical, and operation characteristics of the finished product of UHMW- PE. 2. EB PROCESSING OF UHMWPE The production technique of material for elastic ele- ments of prostheses to be simultaneously the elements of friction couples was elaborated. Cylinder and plate samples were made by hot molding or by shaping under pressure of UHMWPE powder (Tomsk, Russia) with molecular weight distribution 2.5-4.7 million grams/mole. The samples were made of conventional UHMWPE and of UHMWPE reinforced by carbon, glass fiber, cord, and textile. The EB irradiation of UHMWPE samples was car- ried out by pulsed electron accelerator with energy range from 4 to 7 MeV, beam power up to 5 kW, in the absorbed dose rate from 100 to 1200 Gy/s, and absorbed dose within the range from 1 to 300 kGy [1]. EB pro- cessing of UHMWPE was performed in vacuum, in medium of the air or an inert gas. The absorbed dose distribution of electron beam into irradiated samples was measured by dosimetric film. An equalization of electron depth dose distribution into one - and double- sided irradiated compounds was conducted with help of simulation tools ModeRTL [2]. To provide the dose dis- tribution with enhanced uniformity ~ 5 to 10% special semitransparent filters for beam electrons were designed and made [3]. Under electron beam irradiation of UHMWPE basi- cally two competitive radiation-chemical processes in- fluence on properties of the finished product of UHMWPE: crosslinking and generation of long-term free radicals in bulk of UHMWPE. The radiation-in- duced crosslinking creates a 3-D network (gel phase) in the structure of UHMWPE that lead to significant changing its properties. The free radicals interact with oxygen, which diffus- es into the composite volume from the surrounding air. This process causes the scission of macromolecules of UHMWPE and the decrease its molecular weight. As a result, the wear of composite is increased. The wear products cause the inflammatory reactions and lysis of osseous tissue in the bone-joint boundary. To minimize free radicals, we have investigated the process of artificial ageing of UHMWPE-based com- posites treated by pulsed electron beams. As result, an EB treatment of hot samples in the temperature range 100…160 0C with subsequent annealing leads to mini- mum value free radicals at end product. Crosslink density was determined by placing irradi- ated samples in hot xylene and measuring of gel phase as well as by the use of Fourier Transform Infrared Spectroscopy (FTIR) technique. Crosslink density was measured by a spectrophotometer as the ratio of trans- vinylene peak area at 965 cm-1 to the irradiation stable peak area at 2020 cm-1. The control of concentration of ___________________________________________________________ PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 1. Series: Nuclear Physics Investigations (42), p.181-183. 181 free radicals in the irradiated samples in the course of artificial aging was performed by the value of the oxida- tion index (OI). OI was determined as the ratio of car- bonyl peak area at 1717 cm-1 to the radiation stable peak area at 1370 cm-1. Typical infrared absorption spectrums for UHMW- PE specimen with thickness of 200 μm which was EB-irradiated in an air (Curve 2) (absorbed dose 100 kGy) and for unirradiated specimen (Curve1) are shown in Fig.1. Fig.1. Infrared absorption spectrum for UHMWPE ir- radiated by EB in an air (2) and unirradiated (1) The following physical, mechanical and operation characteristics for conventional and crosslinked UHMWPE were tested versus absorbed EB dose and dose rate: elastic modulus, ultimate tensile strength (σ), elongation at break (ε), micro-hardness (H), and wear rate. Elastic modulus, ultimate tensile strength and elon- gation at rupture were measured on tensile-testing ma- chines and by acoustic methods. Two different type of hip joint simulators were used for in vitro investigation of the wear rate for the crosslinked UHMWPE specimens. The first one a pin- on-disk hip simulator was used as the test device for the accelerated wear rate examining. The dependence of the wear rate of the composite on the sliding distance was investigated. The investigations were carried out as for dry friction, as in the presence of a lubricant i.e., dis- tilled water, physiological solution or bovine serum. The measurements of wear of the composite were per- formed by gravimetric method after every 1000 m of the sliding distance. The second one a friction couple type of hip simula- tor was used for long-term examination of the wear rate for UHMWPE specimens. A friction couple consisting of a spherical insert of UHMWPE based composite with counterface of a highly polished sphere of stainless steel with diameter 32 mm was immersed in physiological solution or bovine serum as lubricants. Insert imitates acetabulum, and a polished sphere of stainless steel imi- tates the head and the neck of the hip joint. Wear rate of the inserts was examined at their cyclic loading up to 100 kg in the range of 5·105…3·106 cycles by gravimet- ric technique. The influence of absorbed dose on variation of phys- ical, mechanical and operation characteristics of UHMWPE irradiated by pulsed EB with electron energy 6 MeV are shown in Fig.2 and 3. Heated to temperature 120 0C the UHMWPE specimens were irradiated in ar- gon environment. After irradiation the specimens were annealed at temperature 140 0C under vacuum for 4 hours. Characteristics testing of radiation-modified UHMWPE specimens was performed at temperature 25 0C. Fig.2. Effect of an absorbed dose on the ultimate tensile strength (1), micro-hardness (2), and elongation (3) of UHMWPE Fig.3. Effect of an absorbed dose on the gravimetric wear rate of UHMWPE As a result of investigations it was shown, that the minimum of oxidation index into irradiated UHMWPE specimens is observed at a maximal dose rate and re- spectively at minimal irradiation time. For example, ir- radiation of UHMWPE wit EB in air results in increas- ing of the dose rate from 100 Gy/s to 1.2 kGy/s leading to decreasing of the oxidation index and, respectively, of the number of free radicals in 6 times. The minimum gravimetric wear rate of about 2 mg/(million cycles) and minimum of free radicals was observed in the crosslinked UHMWPE, which was irradiated by the electron dose higher than 90 kGy at specimen tempera- ture of 120 to 1500C in vacuum or in inert gas with sub- sequent thermal annealing. 3. GRAFTING OF MMA ON UHMWPE In restorative surgery of joints many artificial im- plants are fixed to living bone by bone cement. The ba- sis of composition of bone cement is polymethyl- methacrylate (PMMA) or other acrylic polymers. Im- plants from UHMWPE have weak adhesion to bone ce- ment. For increasing adhesion of UHMWPE to bone ce- ment, the investigation of radiation grafting of MMA monomer on surface of UHMWPE were performed. The radiation-induced graft copolymerization of MMA was carried out on the surface of UHMWPE plates to be preliminarily irradiated by 6 MeV EB in the air with subsequent heating in contact with solution of 182 MMA monomer in methanol. This is so-called the graft copolymerization on the base of the post-effect. In this case, the copolymerization in a boundary layer on UHMWPE surface occurs under heating due to free rad- icals. These ones are generated in the course of decom- position of peroxides and hydroperoxides appearing un- der irradiation. To prevent homopolymerization of MMA monomer, saline Fe2SO4 • 7 H2O was added in the MMA solution. The values of degree of the MMA radiation grafting at a surface of UHMWPE samples were obtained exper- imentally in the range from 1 to 50 mg/cm2. EB treat- ment of UHMWPE samples was conducted within the range of absorbed dose from 1 to 40 kGy. Free radicals were extracted from UHMWPE plates after radiation grafting by artificial aging of heated samples in oxyge- nous environment. UHMWPE and PMMA samples were connected to- gether by bone cement "PALACOS R", GmbH Germany containing 90% of PMMA. The tensile bonding strength between bone cement and UHMWPE samples with radia- tion-induced grafted MMA increased up to 80 times in comparison with the samples without radiation grafting. Realizations of the principal possibility of a crosslinking of a thin UHMWPE layer and a graft copolymerization of MMA on the bearing surface of UHMWPE specimens by an irradiation of the thin sur- face layer with a thickness ~15…40 μm by low energy electrons were shown experimentally. Electrons with the energy in the range 150-200 keV were generated by the X-ray pulsed apparatus MIRA-2D with the electron tube IMAE-150E. Electron beam current parameters were the following: pulse duration of 15 ns, pulse repe- tition rate of 10 Hz, number of electrons per pulse of about 5.1012. Such an irradiation mode avoids modifica- tion of physical and mechanical properties of the bulk material and essentially reduces a time of post-irradia- tion treatment of UHMWPE specimens. One of the features of new composites is the inclu- sion in their structure of biologically active ceramics in the form of powder or granules. The bioceramics is in- troduced into a composite as the constituent over all volume or in the form of coatings. Calcium phosphate compounds - hydroxyapatite (HA) and tricalcium phos- phate (TCP) were used as bioceramics. HA and TCP are the basic inorganic components of the hard tissues of an organism. HA and TCP show excellent biocompatibility and are well integrated with bone tissues due to interac- tions at the interface and growing of new tissues into its pore structure. The inclusion of bioceramics into the structure of composites leads to effective osteointegra- tion of composite material with living bone and creation of firm biomechanical interface. All new composite materials were examined on bio- compatibility, cytotoxicity and carcinogenicity. For these purposes, an express method of cultivation of cel- lular culture was used. The osteointegration of сompos- ite materials with living tissue, the process of bone tis- sue formation at the surface and into composite materi- als were investigated on rats and rabbits. 4. CONCLUSION EB processing was used for radiation modification and manufacture of artificial materials based on UHMWPE for construction elements of orthopaedic im- plants. It was shown that a formation of conditions for preferential realization of specific radiation-chemical processes under EB processing of UHMWPE based composites permits programmable to regulate their physical, mechanical, and operation characteristics. In vitro examination using the hip joint simulator of wear rate of UHMWPE was carried out. The minimum gravi- metric wear rate about 2 mg/(million cycles) and mini- mum of free radicals was observed in the crosslinked UHMWPE, which was irradiated by the electron dose higher than 90 kGy. EB-induced grafting of MMA at the surface of UHMWPE samples significantly increase its adhesion to bone cement. 5. ACKNOWLEDGMENTS The work was supported by the STCU, Kyiv, project #957. The authors wishes to express gratitude to Prof. N.Dedukh, Prof.V.Radchenko, and Dr. S.Malushkina, SJPI, for conducting of the full cycle testing of new composite materials on biocompatibility. REFERENCES 1. A. Avilov, V. Deryuga, S. Korenev, G. Popov: Abstract book of EBT’00 Conf., Varna, Bulgaria, 2000, p. 86-87. 2. V.T. Lazurik, V.M. Lazurik, G. Popov, Yu. Rogov // Proceed. of EBT’03 Conf. Varna, Bulgaria, 2003, p.616-622. 3. A. Lisitsky, S. Pismenesky, G. Popov, V. Rudy- chev // Radiation Physics and Chemistry. 2002, Is- sue 3-6, v. 63, p. 591-594. РАЗРАБОТКА КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ ДЛЯ ОРТОПЕДИЧЕСКИХ ИМПЛАНТАТОВ О.М. Авилов, В.О. Дерюга, Г.Ф. Попов, Н.Г. Попова, В.Г. Рудычев, А.Л. Шкилев Одной из актуальных задач в ортопедии является поиск и разработка новых материалов для замены кост- ной ткани и хряща. Обработка полимерных композиционных материалов с биоактивной керамикой элек- тронными пучками использовалась для изготовления искусственных материалов для ортопедических им- плантатов. Обсуждаются экспериментальные достижения и проблемы радиационной технологии обработки композитов на основе сверхвысокомолекулярного полиэтилена. РОЗРОБКА КОМПОЗИЦІЙНИХ МАТЕРІАЛІВ ДЛЯ ОРТОПЕДИЧНИХ ІМПЛАНТАТІВ О.М. Авілов, В.О. Дерюга, Г.Ф. Попов, Н.Г. Попова, В.Г. Рудичев, А.Л. Шкілев ___________________________________________________________ PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 1. Series: Nuclear Physics Investigations (42), p.181-183. 183 Однією з актуальних задач в ортопедії є пошук і розробка нових штучних матеріалів для заміщення кісткової тканини і хряща. Обробка полімерних композиційних матеріалів з біоактивною керамікою електронними пучками використовувалась для виготовлення штучних матеріалів ортопедичного призначення. Приводяться експериментальні досягнення і проблеми радіаційної технології отримання композитів на основі надвисокомолекулярного поліетилену. 184 1. introduction Now there are no artificial materials that completely satisfy all demands of medicine. The mechanical properties of human osseous tissue are very different from those of inert metal alloys currently used in artificial joints. This large mismatch in mechanical properties causes bone resorption or loss around the implant, as well as loosening of the artificial joint stem in the medullar cavity. Ultra high-molecular weight polyethylene (UHMWPE) used as a substitute for gristle is also rigid, it is not of sufficient wear-resistance, it has little adhesion to bone cement, that causes both decreasing of a service life of the product and increasing of number of surgical operations. 2. EB PROCESSING OF UHMWPE 3. GRAFTING OF MMA ON UHMWPE 4. CONCLUSION 5. ACKNOWLEDGMENTS The work was supported by the STCU, Kyiv, project #957. The authors wishes to express gratitude to Prof. N.Dedukh, Prof.V.Radchenko, and Dr. S.Malushkina, SJPI, for conducting of the full cycle testing of new composite materials on biocompatibility. References Разработка композиционных материалов для ортопедических имплантатов О.М. Авилов, В.О. Дерюга, Г.Ф. Попов, Н.Г. Попова, В.Г. Рудычев, А.Л. Шкилев Одной из актуальных задач в ортопедии является поиск и разработка новых материалов для замены костной ткани и хряща. Обработка полимерных композиционных материалов с биоактивной керамикой электронными пучками использовалась для изготовления искусственных материалов для ортопедических имплантатов. Обсуждаются экспериментальные достижения и проблемы радиационной технологии обработки композитов на основе сверхвысокомолекулярного полиэтилена. Розробка композиційних матеріалів для ортопедичних імплантатів О.М. Авілов, В.О. Дерюга, Г.Ф. Попов, Н.Г. Попова, В.Г. Рудичев, А.Л. Шкілев Однією з актуальних задач в ортопедії є пошук і розробка нових штучних матеріалів для заміщення кісткової тканини і хряща. Обробка полімерних композиційних матеріалів з біоактивною керамікою електронними пучками використовувалась для виготовлення штучних матеріалів ортопедичного призначення. Приводяться експериментальні досягнення і проблеми радіаційної технології отримання композитів на основі надвисокомолекулярного поліетилену.