CC BY
17
ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
AZERBAIJAN CHEMICAL JOURNAL № 3 2022
51
UDC 678.01: 541.68
INFLUENCE OF CONCENTRATION AND DISPERSION OF HOUSEHOLD
WASTE THERMOASH ON THE PHYSICAL-MECHANICAL PROPERTIES
OF COMPOSITES BASED ON POLYPROPYLENE
1 12 1 N.T.Kakhramanov, A.A.Hasanova, Y.N.Kahramanli, Kh.V.Allahverdiyeva,
3V.S.Osipchik, 1F.A.Mustafayeva, 1G.Sh.Gasimova
institute of Polymer Materials, NAS of Azerbaijan 2Azerbaijan State Oil and Industry University D.Mendeleev University of Chemical Technology, Russia
najaf1946@rambler.ru
Received 17.01.2022 Accepted 22.02.2022
The paper presents the results of studying the influence of the concentration of thermoash from household waste on the main physical-mechanical properties of composites based on polypropylene. Properties such as ultimate tensile stress, tensile yield strength, flexural strength, elongation at break, heat resistance and melt flow index were studied. We used thermoash of various dispersity: 75-110 nm, 300-500 nm, 12002000 nm. The results of studying the regularity of changes in properties depending on the concentration and fineness of thermoash showed the advantage of nanocomposites. The loading of a compatibilizer into the composition of composites contributed to a significant improvement in strength characteristics.
Keywords: tensile yield strength, ultimate tensile stress, elongation at break, heat resistance, ultimate flexural strength, thermoash.
doi.org/10.32737/0005-2531-2022-3-51-56 Introduction
With the expansion of the fields of application of industrial polymeric materials in various fields of mechanical engineering, shipbuilding, aircraft building, military and space technology, etc. the problem of improving their quality and operational characteristics arose more and more acutely [1, 2]. Various approaches have been taken to modify their structure and properties by loading mineral and polymeric fillers, plasticizers, stabilizers, lubricating agents, mixing polymer with polymer, chemical cross-linking, etc. [3, 4]. It is quite obvious that for the synthesis of polymeric materials with desired properties for various technical areas, it does not always seem appropriate and effective. Therefore, a purposeful change in the properties of polymers is given to large-tonnage polymers already directly in the process of their processing. This raises not only the problem of obtaining a polymer material of the desired quality, but also the problem of reducing its cost. In this regard, the use of production waste as a modifier of industrial polymers has always been in the focus of attention of specialists in the
field of processing and application of composite materials [5-7].
Therefore, in this work, we made an attempt, using the example of polypropylene, to consider the effect of the concentration and dispersion of household waste thermoash on the main physical-mechanical properties of composites obtained on its basis. Thermoash was obtained at a waste processing plant in the Balakhani district of Baku city [8]. The problem under consideration becomes even more relevant if na-nosized particles of thermoash are used as a filler. This problem is relatively new and little studied.
For this purpose, in this work, the main attention is paid to studying the complex of physical-mechanical and technological characteristics of nanocomposite materials based on polypropylene and thermoash from household waste.
Experimental part
Industrial samples of polypropylene (PP) and household waste thermoash (TA) were used as the object of research.
PP is characterized by the following properties - ultimate tensile stress 33.0 MPa, ultimate flexural strength is 35.0 MPa, elonga-
tion at break is 130%, heat resistance according to Vicat is 160 V, melt flow index is 4.6 g/10min., melting point is 1690C, density is 903 kg/m3, crystallinity is 65%.
As filler, we used TA obtained at 12000C in a thermal furnace of the Balakhani waste processing plant in Baku city [8].
Compatibilizer (PPMA) - Exxelor PO1020 maleic anhydride (MA) functionalized polypropylene for loading into the composition of filled PP composites. The degree of grafting of MA in the composition of PP is 5.6 wt %, MFI is 8.6 g/10 min.
The particle size of the thermoash was determined using an STA PT1600 Linseiz device (Germany), it was 75-110 nm, 300-500 nm, 1200-2000 nm. Of the obtained 3 grind-ings, nanoparticles were samples of thermoash, having dimensions of 75-110 nm. Thermoash nanoparticles were obtained on an A-11 analytical instrument at a rotor speed of 30000 rpm.
Composites based on PP and thermoash were obtained by mixing on roller at a temperature of 1900C. After melting the PP on the rollers for 8 min., the thermoash was loaded in parts. Plates 2 mm thick were pressed on the basis of the obtained polymer composite at a temperature of 1900C. The exposure time under a pressure of 90 MPa was carried out in the process of cooling from 190 to 500C.
The melting temperature was determined on a Q-1500d derivatograph, and the heat resistance was determined by the Vicat method on an HDT-Vicat device, which is characterized by high measurement accuracy. The relative error of the experiment is 3-5%.
Ultimate tensile stress, tensile yield strength, and elongation at break of the nano-composites were determined from the results of analytical data (from 5 measurements) in accordance with GOST 11262-80.
When measuring the ultimate bending strength in accordance with GOST-4648-2014, the speed of the movable traverse was 50 mm/min. The 80x10x4 - sized samples obtained by pressing were used. Analytical data were determined from 5 measurements. The scatter of readings was no more than 5 rel %.
The MFI of polymeric materials was determined on a MELT FLOW TESTER, CEAST MF50 capillary rheometer (INSTRON, Italy) at a temperature of 190°C and a load of 5 kg. The relative error of the experiment is 5%.
Results and discussion
In the process of studying the physical-mechanical properties of composites based on polypropylene and thermosol, first of all, we proceeded from the fact that the developed materials have low cost, sufficiently high strength characteristics, heat resistance and satisfactory melt flow for processing by traditional methods - extrusion and injection molding. To achieve this goal, dispersed particles of thermosols of various degrees of grinding were used. This approach to the study of the properties of composite materials makes it possible to conduct research in a wide range of ratios of the mixture components and to obtain a fairly complete picture of the processes occurring in it.
It should also be taken into account that PP is a non-polar polymer and, therefore, it is not necessary to speak of good wettability or compatibility with a polar filler (TA). In this regard, we used a commercially available graft copolymer PP with maleic anhydride (PPMA) as a compatibilizer. It was important to identify the main criteria influencing the formation of the supramolecular structure and strength characteristics. To this end, it seemed interesting to first consider the effect of the concentration and fineness of the filler on the properties of composite materials without a compatibilizer.
So, for example, Table 1 shows the results of studies on the effect of the concentration and dispersion of the filler on the physical-mechanical properties of composites. Analyzing the data presented in this Table, it can be established that, regardless of the dispersion of TA, with an increase in its concentration, an ambiguous change in the properties of composite materials is observed. According to the data obtained, relatively high values of physical and mechanical properties are possessed by nano-composites, in which the particle size of TA varies within 75-110 nm. At the same time, nanocomposites with 1.0 wt% content of nano-
particles have the maximum value of ultimate tensile stress. A further increase in the concentration of TA is accompanied by a regular decrease in the tensile yield strength, ultimate tensile stress, and elongation at break. Typically, as the filler particle size increases from 75-110 nm to 300-500 nm, there is a slight decrease in the magnitude of the ultimate tensile stress, tensile yield strength, ultimate flexural strength, and elongation at break of the composites. In the case when the particle size of TA is 12002000 nm, the values of the strength parameters and elongation at break of the composites are even lower.
There is reason to believe that the size of the filler particles has a significant impact on the process of formation of the supramolecular structure and, as a consequence, on the change in physical-mechanical characteristics. If, in uniaxial tension, the maximum value of strength characteristics is achieved at 1.0 wt % TA content, then when evaluating the ultimate bending strength, composites with 20 wt % filler content have the maximum value.
It is known that even in the melt of a poly-
mer composite, homogeneous and heterogeneous nucleation centers are formed. According to the fluctuation theory, the formation of homogeneous nucleation centers or primary structural formations in the melt begins as a result of the mutual orientation of polypropylene macro-chains relative to each other. Filler particles have the ability to form heterogeneous nuclea-tion centers, which become crystallization centers during cooling [9, 10]. Simultaneous growth of crystal structures on homogeneous and heterogeneous crystallization centers contributes to the formation of a finely spherulite supramolecular structure, which, as is known, leads to an improvement in the strength properties of composite materials. In the presence of a filler, orientation processes also occur on the surface of solid particles. In this case, the smaller the size of the filler particles, the more developed surface they have for the orientation of macrochains.
It is this feature of nanoparticles that makes it possible to assert a high probability of adhesive contact between macrochains and a solid surface [11, 12].
Table 1. Influence of the concentration and particle size of thermoash on the main physical-mechanical properties of
composite materials based on PP
No The composition of composites based on PP + thermoash (TA) Thermoash particle size, nm Tensile yield strength, MPa Ultimate tensile stress, MPa Elongation at break, % Ultimate flexural strength, MPa
1 PP — 32.3 33.0 130 35.0
2 99PP+1TA 35.8 34.7 105 36.2
3 95PP+5TA 34.4 32.2 85 37.1
4 90PP+10TA 32.7 30.3 55 38.6
5 80PP+20TA 75-110 29.2 28.5 15 39.3
6 70PP+30TA 26.7 26.7 10 38.4
7 60PP+40TA 25.1 25.1 - 37.2
8 99PP+1TA 34.9 33.3 90 36.5
9 95PP+5TA 33.6 31.1 75 37.2
10 90PP+10TA 300-500 31.5 29.1 45 38.0
11 80PP+20TA 27.7 27.7 10 38.8
12 70PP+30TA 26.0 26.0 - 37.1
13 60PP+40TA 24.5 24.5 - 36.5
14 99PP+1TA 32.4 30.5 80 36.0
15 95PP+5TA 31.5 29.3 60 36.8
16 90PP+10TA 1200-2000 29.0 28.2 35 37.7
17 80PP+20TA 26.5 26.5 - 37.4
18 70PP+30TA 24.8 24.8 - 36.7
19 60PP+40TA 22.2 22.2 - 36.0
It is quite obvious that under conditions of intense mixing of the polymer matrix with the filler, the viscosity of the medium and the shear stress created can simultaneously promote the sorption and desorption of macrochains on the surface of nanoparticles until dynamic equilibrium is established. Based on this position, it can be argued that with an increase in the size of the filler particles, the probability of orientation processes decreases, which in a certain way affects the decrease in the number of heterogeneous nu-cleation centers. As a result, during the crystallization of the composite, relatively larger spheru-litic formations with characteristic defects in the crystal structure are formed. Actually, based on this assumption, it will be possible to interpret the main reasons for the deterioration in the strength characteristics of composites filled with particles with a size of 300 nm and above.
According to the data given in Table 1, with a sharp decrease in the elongation at break of the composites, the difference in the values of the tensile yield strength and the ultimate tensile stress decreases. At an elongation at break of 10% or less, the values of these strength indicators are practically comparable. This circumstance is due to the fact that at high filler concentrations in the range of 20-40 wt %, the samples become brittle and lose their ability to plastic deformation.
At the same time, attention should also be paid to the fact that even at high concentrations of TA, samples of nanocomposites retain the fluidity of the melt necessary for their processing by extrusion or injection molding. However, even at 30-40 wt % TA content, composite samples do not lose their ability to melt flow. For example, an increase in the concentration of TA nanoparticles in the range of 1.0, 5.0, 10, 20, 30, and 40% wt. the MFI of the samples changes in the following sequence: 4.9, 6.4, 5.8, 3.6, 2.5 and 1.1 g/10min. For PP samples filled with TA with a particle size of 300-500 nm, the MFI value of the composites changes as follows: 4.7, 5.7, 5.2, 3.0, 1.8, 0.6 g/10 min. For composites filled with TA with a particle size of 1200-2000 nm, the MFI value changes in the following sequence: 4.6, 5.1, 3.2, 1.7, 0.5, and 0 g/10 min. The preservation of the MFR of composites
even at high concentrations of TA indicates that, along with such combustion products as oxides of a number of metals, the composition of TA contains graphite, which has a lubricating effect that positively affects the preservation of melt fluidity. There is reason to believe that in the process of thermoash formation, along with various metal oxides, technical carbon and graphite are formed. The latter has a lubricating effect and therefore helps to maintain the fluidity of the melt at a relatively high level. However, with an increase in the size of the TA particles, the fluidity of the melt becomes relatively lower. It is characteristic that the heat resistance of composites in the considered concentration range changes by 2-30C, i.e. from 160 to 1630C at 30-40 wt % TA content.
It seemed interesting to study the influence of the compatibilizer on the main physical-mechanical properties of composites based on PP + TA, the results of which are shown in Table 2. Analyzing the data presented in this table, it can be established that the loading of PPMA into the composition of composites contributes to a significant improvement in their properties. To interpret the observed regularities in the change in properties, it would be correct to consider possible changes in the formation of the structure of composites in the presence of PPMA. There is reason to believe that the improvement of the compatibility of mixed components in the presence of PPMA becomes possible due to the peculiarities of the behavior of its macrochains during the formation of the crystal structure of the composites. First, PPMA is a graft copolymer, characterized in that male-ic anhydride (MA) is located in the side chain of PP as a single grafted monomer. Second, the segments of the PPMA macrochain segments that do not contain polar monomeric units, as well as the PP macrochains, can participate in the formation of crystalline formations of the composite.
There is reason to believe that the segments of the PPMA macrochain containing MA monomeric units in their structure are displaced together with TA particles into the interspheru-litic amorphous region during the growth of crystalline formations.
Table 2. Influence of the concentration and particle size of TA, as well as the compatibilizer (PPMA) on the main phy-
sical-mechanical properties of composite materials based on PP
The composition of compo- Thermoash Tensile yield Ultimate Elongation Ultimate flexural
No sites based on PP + thermoash particle size, strength, tensile stress, at break, strength,
(TA) nm MPa MPa % MPa
1 98PP+2PPMA - 30.2 31.6 140 34.6
2 97PP +1TA+2PPMA 37.6 35.5 125 37.2
3 93PP+5TA+2PPMA 37.8 35.2 95 38.6
4 88PP+10TA+2PPMA 35.7 33.3 75 39.7
5 78PP+20TA+2PPMA 75-110 32.2 30.7 35 40.0
6 68PP+30TA+2PPMA 29.1 28.6 20 39.4
7 58PP+40TA+2PPMA 26.5 26.5 10 38.5
8 97PP+1TA+2PPMA 36.5 34.7 105 37.0
9 93PP+5TA+2PPMA 36.0 34.1 95 38.4
10 88PP+10TA+2PPMA 300-500 34.8 32.0 65 39.0
11 78PP+20TA+2PPMA 31.9 29.7 20 39.2
12 68PP+30TA+2PPMA 27.5 27.5 10 38.3
13 58PP+40TA+2PPMA 25.4 25.4 - 37.8
14 97PP+1TA+2PPMA 35.2 32.0 90 37.0
15 93PP+5TA+2PPMA 33.3 30.7 70 38.1
16 88PP+10TA+2PPMA 1200-2000 31.8 29.2 45 38.3
17 78PP+20TA+2PPMA 28.5 27.8 25 38.2
18 68PP+30TA+2PPMA 25.9 25.9 10 37.4
19 58PP+40TA+2PPMA 23.6 23.6 - 37.0
The MA groups and TA particles bound to the macrochain, accumulating in the interspheru-lite region, increase the polarity of the amorphous space and improve the compatibility and miscibility of the polymer-filler binary system. This circumstance contributes to a significant increase in all strength characteristics of composite materials. It is obvious that, as TA particles accumulate in the amorphous region of the polymer matrix, they form certain steric hindrances for the mobility of the PP chains responsible for the deformation characteristics of the composite. And, the higher the concentration of TA in this area, the lower the elongation at break of the composites becomes. Finally, at 40 wt % filler concentration in the composition of the polymer matrix, the through chains almost completely lose their mobility, are blocked by TA particles until brittle fracture. From a comparative analysis of the data given in tables 1 and 2, it can be seen that the loading of PPMA contributes to a significant improvement in the deformation characteristics of composite materials, which is in good agreement with our ideas on the mechanism of action of the compatibilizer in the in-terspherulitic amorphous space.
Conclusion
Thus, based on the foregoing, it can be concluded that with an increase in the size of the TA particles, a decrease in the tensile yield strength, ultimate tensile stress, flexural strength, and elongation at break is observed.
The loading of PPMA into the composition of the composite promotes an increase in all strength indicators and elongation at break of composite materials.
The heat resistance of composites increases at relatively high concentrations of TA in the composition of PP. At the same time, the MFI of composites is maintained at a satisfactory level, which is necessary for their processing by extrusion and injection molding.
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МЭГ^ЭТ TULLANTILARININ 'ВДВ KULU"NUN MiQDARININ VЭ DiSPERSLiYiNiN POLiPROPiLEN ЭSASINDA OLAN KOMPOZiTLЭRlN Fiziкl-MEXANiкl XASSЭLЭRlNЭ TЭSiRl
N.T.Qэhrэmanov, A.Э.Hэsэnova, Y.N.Qэhrэmanh, X.V.Allahverdiyeva, V.S.Osip9ik,
F.Э.Mustafayeva, G.§.Qaslmova
Mэqalэdэ mэi§эt tullantllaпnln МШ ки1и"пип miqdaпnln polipropilen эsasll kompozitlэrin Э8а8 1кШ-техатИ ха88э1эг1пэ tэsirinin бyrэnilmэsinin nэticэlэri tэqdim о1ипиг. Dartllmada mбhkэmlik hэddi, dartllma axlclllq hэddi, эyi1mэyэ qar§l davamhhq hэddi, nisbi uzanma, isti1iyэ davamhhq vэ эrintinin axlclllq gбstэricisi к^ xиsusiyyэt1эr tэdqiq olunmu§dur. Mиxtэ1if dispers1iyэ malik "&Ь МШ^ЭП istifadэ о1ипти§йш: 75-110 nm, 300-500 nm, 12002000 nm. 'ТОЬ Ш^Шп miqdarmdan vэ dispers1iyindэn aslll olaraq xassэ1эrin dэyi§mэ qanunauygunlugunun tэdqiqinin nэticэ1эri nanokompozit1эrin ^Ш^^иМ gбstэrmi§dir. Kompozit1эrin tэrkibinэ kompatibi1izatorun daxi1 edi1mэsi mбhkэmlik gбstэrici1эrinnin эhэmiyyэt1i dэrэcэdэ yax§lla§masma kбmэk
Адаг sбzlэr: dartllmada ахш1щ hэddi, dartllmada mдhkэmlik НэёЛ, пг^'Ы тапша, davamhhq, эуИшэуэ qar§l
davamЫщ hэddi, "dib МШ "
ВЛИЯНИЕ КОНЦЕНТРАЦИИ И ДИСПЕРСНОСТИ ТЕРМОЗОЛЫ БЫТОВЫХ ОТХОДОВ НА ФИЗИКО-МЕХАНИЧЕСКИЕ СВОЙСТВА КОМПОЗИТОВ НА ОСНОВЕ ПОЛИПРОПИЛЕНА
Н.Т.Кахраманов, А.А.Гасанова, Ю.Н.Кахраманлы, Х.В.Аллахвердиева, В.С.Осипчик, Ф.А.Мустафаева, Г.Ш.Гасымова
В работе приводятся результаты исследования влияния концентрации термозолы бытовых отходов на основные физико-механические свойства композитов на основе полипропилена. Исследовали такие свойства, как разрушающее напряжение, предел текучести при растяжении, предел прочности на изгиб, относительное удлинение, теплостойкость и показатель текучести расплава. Использовали термозолу различной дисперсности: 75-110 нм, 300-500 нм, 1200-2000 нм. Результаты исследования закономерности изменения свойств в зависимости от концентрации и дисперсности ТЗ показали преимущество нанокомпозитов. Введение компатибилизатора в состав композитов способствовало существенному улучшению прочностных показателей.
Ключевые слова: предел текучести при растяжении, разрушающее напряжение, относительное удлинение, теплостойкость, предел прочности на изгиб, термозола.
