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22 AZERBAIJAN CHEMICAL JOURNAL No 4 2020 ISSN 2522-1841 ((
ISSN 0005-2531 (I
UDC 678.01:620:17
PHYSICOMECHANICAL PROPERTIES OF NANOCOMPOSITES BASED ON COPOLYMERS OF ETHYLENE WITH a-OLEFINS AND CLINOPTILOLITE
N.T.Kakhramanov, I.V.Bayramova, V.S.Osipchik*, A.D.Ismayilzade**, S.R.Abdalova,
I.A.Ismayilov, U.V.Namazli
Institute of Polymer Materials of Azerbaijan National Academy of Sciences *D.I. Mendeleev University of Chemical Technology of Russia ** Institute of Geology and Geophysics of Azerbaijan National Academy of Sciences
najaf1946@rambler.ru
Received 06.05.2020 Accepted 03.08.2020
The results of studying the effect of clinoptilolite concentration on the properties of nanocomposites based on of ethylene with butylene and of ethylene with hexene copolymer are presented. The effect of clinoptilolite particle size on ultimate tensile stress, elongation at break, flexural modulus, heat resistance, and melt flow index of composites was studied. It is shown that nanocomposites based on ethylene copolymers are characterized by higher values of physicomechanical properties. The additional use of ingredients such as alizarin and calcium stearate contributes to a significant improvement in the complex of properties of nanocomposites based on ethylene copolymers and clinoptilolite.
Keywords: ultimate tensile stress, elongation at break, heat resistance, flexural modulus, composite, copolymer.
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doi.org/10.32737/0005-2531-2020-4-22-27
Introduction
In recent years, polyolefin-based polymer materials are finding wider application in various fields of technology. Being demand of poly-olefins in the production of structural materials and products based on them is due, first of all, to the unique combination of their physicomecha-nical and technological properties, which opening promising direction for expanding the areas of practical use [1-4]. In this regard, the most interesting are polyethylene of various types and its copolymers of ethylene with a-olefins. By varying the composition and ratio of the catalytic systems, it seems possible to carry out industrial synthesis of copolymers of ethylene with butylene, pentene, hexene and octene, which in their operational and technological characteristics are superior to high density polyethylene (HDPE). All these copolymers of ethylene with a-olefins in their structural parameters are combined under the general name linear low density polyethylene (LLDPE). In this regard, would like to note that in the literature there are limited studies aimed at studying the effect of various mineral fillers, in particular nanoparticles, on the main physico-mechanical characteristics of ethylene copoly-
mers. The use of natural mineral nanoscale fillers in the mixture of the copolymers is a breakthrough in the direction of creating high-quality materials of a new generation. However, the lack of a sufficient number of publications in this field does not allow the researchs in this direction into a unite holistic theory to be systematized [5, 6].
In this regard, it seemed interesting to carry out mechanochemical synthesis and a systematic approach to the study of polymer nano-composite materials based on copolymers of ethylene and natural mineral filler.
Experimental part
As the object of study, a copolymer of ethylene with butylene (CEB) and a copolymer of ethylene with hexene (CEH) were used.
SEH RE6438R is characterized by the
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following properties: density - 0.932 g/cm , ultimate tensile stress 37.4 MPa, elongation at break 810%, flexural modulus 712 MPa, melting point - 1270C, Vicat softening point -1150C, melt flow index (MFI) - 5.12 g/10 min, the degree of crystallinity - 75%.
CEB RE4133Q is characterized by the following properties: ultimate tensile stress - 27.1 MPa, elongation at break - 880%, flexural modulus - 532 MPa, MFI - 4.6 g/10 min, melting point - 1280C, Vicat softening point - 1160C.
Clinoptilolite (CTL) of the Aydag deposit of Azerbaijan, the typical oxide of with formula is (Na2K2)OAl2O3-10SiO2-8H2O, and the probable crystalline one, is Ca45Al9SiO24O72. In accordance with the agreement on mutually beneficial cooperation, finely dispersed clinoptilolite was presented by the Institute of Geology and Geophysics of the National Academy of Sciences of Azerbaijan by academician A.D.Ismayilzade.
Calcium stearate (CS) (molecular formula C36H70Ca04) is a lubricating-stabilizing additive at the processing of PVC, polyolefins, polyamide, polystyrene, and in the production of pipe and cable thermoplastics. Calcium stearate is used as a plasticizer, stabilizer, and surfactant.
Alizarin (AZ) - Ci4H8O4 - 1,2-dihydroxy-anthraquinone, dye with a molecular mass of 240.2, melting point - 2890C. The structural formula of alizarin is as follows:
CTL nanoparticles were prepared in an A-11 analytical mill at a maximum speed of 30000 rpm. With increasing grinding time the size of the filler particles decreased noticeably.
The size of CTL nanoparticles was determined using an STA PT1600 Linseiz device (Germany); it was 20-110, 300-840, 10002300, 2700-4000 nm. From the obtained 4 grindings, the nanoparticles were CTL samples, which had size of 20-110 nm.
Nanocomposites based on ethylene co-polymers and CTL were obtained by mixing them on rollers at 1700C. After melting the co-polymer on the rollers CTL for 8 min administered in parts. On the basis of the obtained polymer composite, 2 mm thick plates were pressed at a 1900C, the exposure time under pressure was 30 min. Under a pressure of 90
MPa, the temperature of the pressed plate was reduced to 900C.
Ultimate tensile stress and elongation at break of nanocomposites were determined according to the results of analytical data (from 10 measurements) in accordance with GOST 1126280, flexural modulus - according to GOST 955081. The relative error of the experiment is 5%.
MFI of polymer materials were determined on the MELT FLOW TESTER, CEAST MF50 capillary rheometer (INSTRON, Italy) at 1900C and a load of 5 kg. The relative error of the experiment is 5%.
Results and discussion
In this paper, we consider the main phys-icomechanical properties of nanocomposites depending on the concentration and dispersion of CTL particles in the mixture of CEB and CEH compositions. It was important to determine the optimal concentration of nano- and dispersed particles CTL, as well as various structure-forming reagents, at which the highest strength, thermophysical and technological properties of the composites are achieved. Taking into account that insufficient attention was paid to the studied objects in the literature, it was considered necessary to dwell in more detail on an integrated approach to assessing the structural features and properties of composites based on them.
Table 1 presents the main physicomecha-nical properties of nanocomposites based on CEB, CEH, and CTL. Analysing the data presented in this table, the experimental data can be established that, regardless of the type of polymer matrix, the highest values of the ultimate tensile stress are achieved in nanocomposites with 5.0 mass% CTL content.
According to the data in Table 1, with an increase in the concentration of nanoparticles in the mixture of the copolymers, a monotonic increase in heat resistance and flexural modulus is observed. The increase in heat resistance can be interpreted by the fact that the supramolecular structure of nanocomposites is strengthened as a result of the formation of fine-spherulite crystalline formations.
Table 1. Effect of CTL concentration on the physicomechanical properties of nanocomposites based on CEB and CEH
№ Composition formulation, mass % Ultimate tensile stress, MPa Elongation at break, % Flexural modulus, MPa Vicat softening point, °C MFI, g/10min
1 CEH 37.4 810 712 115 5.1
2 CEB 27.1 880 532 116 4.6
3 CEB+1.0 CTL 29.5 870 556 116 5.2
4 CEB+5.0 CTL 31.4 215 612 118 6.4
5 CEB+10 CTL 29.6 135 725 121 7.9
6 CEB+20 CTL 25.4 55 789 122 6.7
7 CEH+1.0 CTL 39.7 850 720 116 5.5
8 CEH+5.0 CTL 42.0 220 744 122 6.7
9 CEH+10 CTL 37.1 120 785 124 7.3
10 CEH+20 CTL 32.8 30 837 125 7.0
The appearance of such a supramolecular organization in the structure is due to the fact that in nanocomposites, along with homogeneous nucleation centers, heterogeneous centers with the participation of nanoparticles are formed. The formation of crystalline structures simultaneously on two nucleation centers leads to a spontaneous increase in the number of fine spherulite formations [7-10]. Part of the nanoparticles is displaced into the intersferolite region, creating certain difficulties for the thermos fluctuation decay of the supramolecular structure, that ultimately leads to an increase in the heat resistance of nanocomposites. When assessing the flexural modulus, a slightly different picture is observed, consisting in a continuous increase in the value of this indicator with an increase in the CTL concentration. The sharpest decrease in elongation at break begins at 5.0 mass% filler content. This circumstance is important, since it once again confirms the idea that for CTL nanoparticles the maximum effect in the strength characteristics of SEB and SEH is achieved at its concentration of no more than 5.0 mass%.
Another important point is that in the nanocomposites under consideration, the MFI also increases with an increase in the CTL concentration. Only at 20 mass % content there is a slight decrease in the MFI, while remaining above the melt flow of the initial ethylene copolymers SEB and SEH. As noted earlier, this is due to the fact that, like other natural minerals, CTL contains nanoclay, which is characterized by a layered structure [11, 12]. In the process of thermomechanical mixing on a roll or extruder, the copolymer macrochains are intercalated into the interlayer space of nanoparticles, which, in
the process of decay into even smaller parts, release surfactant organic liquids or glycerine, which improve the fluidity of nanocomposites.
An important circumstance is the issues associated with improving the compatibility of the mixed components of the mixture by using various ingredients. In this case, CS and AZ were used as ingredients. The need for their joint use was due to the manifestation of synergism in the direction of increasing strength indicators. Table 2 summarizes the results of experimental studies on the effect of these ingredients on some properties of CTL nanocomposites based on SEB and SEH. From a comparative analysis of the data presented in Tables 1 and 2, it can be established that the introduction of these ingredients contributes to a significant improvement in the ultimate tensile stress, elongation at break and MFI of nanocomposites based on SEB and SEH. An increase in the MFI of nanocomposites clearly indicates that AZ exhibits a structure-forming effect, and SC exhibits the role of an external lubricant agent. A significant increase in ultimate tensile stress and an improvement in elongation at break can be interpreted as a synergistic effect with the simultaneous use of AZ and CS. And, indeed, as can be seen from Table 2, on studying the separate effect of these ingredients, such a significant increase in the ultimate tensile stress, elongation at break, and MFR were not found. In this case, such a noticeable improvement in properties in the presence of AZ and CS is interpreted by the fact that these particles, in addition to the structure-forming effect, have the ability to improve the technological compatibility of the mixed components of the mixture.
It was of interest to establish the effect of CTL particle size on the properties of composites based on SEB and SEH (Table 3). This fact presents rathe the actual sicance, since most plastic processing enterprises use the fillers mainly with a particle size of 1000-3000 nm. Table 3 presents the results of a study of the influence of CTL particle size on the main physicomechanical parameters. Analyzing the experimental data given in this table, it can be noted that, regardless of the CTL concentration in the copolymers under consideration, with a increase in the particle size of the CTL from 300 to 4000 nm, a regular decrease in the physicomechanical characteristics occurs.
The interpretation of the obtained results consists in the fact that, in contrast to nanoparticles, coarsely dispersed CTL particles are less susceptible to the formation of heterogeneous nucleation centers. The latter circumstance, ultimately, contributes to the fact that certain difficulties are created in the formation of a fine-spherical supramolecular structure. In this case, the probability of an increase in defectness in crystalline structures in the presence of comparatively great dispersed particles of the fillers is not excluded. As a result, in comparison with nanocomposites, there is a slight decrease in the ultimate tensile stress, elongation at break, flexural modulus, and MFR of composites.
Table 2 Composition and physicomechanical properties of polymer nanocomposites based on CEB and CEH, CTL, AZ and CS
№ Mixture compositions, Ultimate tensile Elongation at break, MFI,
mass% stress, MPa % g/10min
1 93 CEB+5 CTL+1.0 AZ+1.0 CC 32.9 880 7.8
2 88 CEB+10 CTL+1.0 AZ+1.0 CC 31.0 195 10.8
3 78 CEB+20 CTL+1.0 AZ+1.0 CC 29.8 160 9.2
4 93 CEH+5 CTL+1.0 AZ+1.0 CC 44.6 650 11.4
5 88 CEH+10 CTL +1.0AZ+1.0 CC 39.3 325 12.4
6 78 CEH+20 CTL+1.0 AZ+1.0 CC 35.3 95 9.0
7 80 CEH+10 CTL+AZ 29.4 155 8.7
8 80 CEH+10 CTL+CC 28.8 190 8.0
№ Composition formulation, mass % Ultimate tensile stress, MPa Elongation at break, % Flexural modulus, MPa MFI, g/10min
CEB+5.0 mass %
1 300-800 nm 29.2 185 595 6.5
2 1000-2300 nm 29.0 160 581 6.1
3 2700-4000 nm 28.1 115 572 5.2
CEB +10 mass %
1 300-800 nm 30.4 105 701 7.6
2 1000-2300 nm 29.5 85 688 6.7
3 2700-4000 nm 28.1 65 673 5.0
CEH+5.0 mass %
1 300-800 nm 38.2 190 734 6.1
2 1000-2300 nm 37.7 155 725 5.4
3 2700-4000 nm 36.5 120 702 4.7
CEH+10mass %
1 300-800 nm 39.8 85 766 6.8
2 1000-2300 nm 38.1 55 752 6.0
3 2700-4000 nm 37.7 35 735 5.2
Table 3. Effect of CTL concentration and particle size on the physicomechanical properties of composites based on SEB and SEH
Conclusion
1. It has been established that, at the same filler concentration, the CEB+CTL and CEH+ CTL nanocomposites (particle size 20-110 nm) in comparison with its dispersion-filled composites (particle size 300-4000 nm) are characterized by relatively high stress-strain properties and melt flow.
2. It was shown that, regardless of the particle size, with an increase in the concentration of CTL, an increase in the heat resistance of composite materials is observed.
3. The reinforcement mechanism of nanocom-posites is considered taking into account the processes occurring in the interfacial region.
4. The additional use of ingredients such as alizarin, calcium stearate may significantly affect the improvement of physicomecha-nical properties of nanocomposites.
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ETiLENiN a-OLEFiNLOR iLO BiRGOPOLiMERLORi VO KLiNOPTiLOLiT OSASINDA NANOKOMPOZiTLORiN FiZiKi-MEXANiKi XASSOLORi
N.T.Qahramanov, i.V.Bayramova, V.S.Osipchik, A.D.ismayilzada, S.R.Abdalova,
i.A.ismayilov, U.V.Namazli
Tadqiqat i§inda klinoptilolitin miqdannin etilen-butilen va etilen-heksen birgapolimerlari asasinda nanokompozitlarin xassalarina tasiri üzra tadqiqatlann naticalari taqdim olunmu§dur. Klinoptilolit hissaciklarinin ölgüsünün kompozitlarin dartilmada möhkamlik haddina, nisbi uzanmasina,ayilmada elasiklik moduluna va arintisinin axiciliq göstaricisina tasiri öyranilmi§dir. Göstarilmi§dir ki, etilen birgapolimerlari asasinda nanokompozitlar dha yüksak fiziki-mexaniki xassalar ila xarakteriza olunurlar. Alizarin va sink stearat kimi inqridiyentlarin alava istifada olunmasi etilen birgapolimerlari va klinoptilolit asasinda nanokompozitlarin xassalar kompleksinin nazara garpacaq daracada yax§ila§masina sabab olur.
Agar sözlar: dartilmada möhkamlik haddi, nisbi uzanma, istiliyadavamliliq, ayilmada elasiklik modulu, kompozit, birgapolimer.
ФИЗИКО-МЕХАНИЧЕСКИЕ СВОЙСТВА НАНОКОМПОЗИТОВ НА ОСНОВЕ СОПОЛИМЕРОВ ЭТИЛЕНА С а-ОЛЕФИНАМИ И КЛИНОПТИЛОЛИТА
Н.Т.Кахраманов, И.В.Байрачова, В.С.Осипчик, А.Д.Исмайылзаде, С.Р.Абдалова,
И.А.Исмайлов, У.В.Намазлы
В работе приводятся результаты исследования влияния концентрации клиноптилолита на свойства нанокомпо-зитов на основе сополимера этилена с бутиленом и сополимера этилена с гексеном. Изучено влияние размера частиц клиноптилолита на разрушающее напряжение, относительное удлинение, модуль упругости на изгиб, теплостойкость и показатель текучести расплава композитов. Показано, что нанокомпозиты на основе этиленовых сополимеров характеризуются более высокими значениями физико-механических свойств. Дополнительное использование таких ингредиентов, как ализарин и стеарат кальция способствует заметному улучшению комплекса свойств нанокомпозитов на основе этиленовых сополимеров и клиноптилолита.
Ключевые слова: разрушающее напряжение, относительное удлинение, теплостойкость, модуль упругости на изгиб, композит, сополимер.
