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Section 6. Materials Science
Ziyamukhamedova Umida Alijanovna, professor, of a Tashkent State technical University Bakirov Lutfillo Yuldoshaliyevich, Scientific researcher, of a Tashkent State technical University Miradullaeva Gavkhar Bakpulatovna, Scientific researcher, of a Tashkent State technical University
Bektemirov Begali Shukhrat ugli, Master of a Tashkent State technical University E-mail: [email protected]
SOME SCIENTIFIC AND TECHNOLOGICAL PRINCIPLES OF DEVELOPMENT OF COMPOSITE POLYMER MATERIALS AND COATINGS OF THEM FORCOTTON MACHINE
Abstract: The article presents the results of experimental researches of influence of technological factors on the mechanical and performance properties heterogeneity polymeric materials using standard methods and devices. Examined and shows the changes of deformation properties and intergovernmental heterogeneity plasticization of polymeric materials from the content and type of filler, as well as the technological compatibility of their use. This borders the amount of use of fillers based on the explanation of the obtained experimental data.
Keyword: heterocomposite polymer materials (GKPM), roughness, glass transition temperature, plasticizer, filler, epoxy composition.
One of the most important mechanical properties the range of 3-5 microns. And the roughness of the run-
of heterocomposite polymer materials heterogeneity in surfaces significantly depends on the above factors. It
(HCPM) are modules of elasticity and hardness, which depends on the friction of regime and physio-mechanical
depends on the adhesive and mechanical components' properties of HCPM when RZincreases from10 to 25
force of friction interaction. It is also important to pro- microns; the highest growth of RZ is observed at a low
vide a high uniformity of the micro hardness and suffi- content of the filler, due to the high uniformed micro-
cient electrical and thermal conductivity of the material. hardness of the HCPM at the expense of the uneven dis-
Typically, these properties HCPM are achieved with a tribution of the filler particles in the composite. Thus, it is
very high content of fillers [1-3]. noted that the increase of RZ contributes to the increase
We carried out experiments to identify the influence of the friction coefficient (f) cotton with the surface of
of technological factors on the mechanical and opera- polymeric materials [2]. (Fig. 1) shows that the increase
tional properties HCPM using the standard method and of the filler's content up to 20-43 of the masses.h. leads
devices [4, 5]. The results of the study showed that initial to more uniform distribution of the particles and to in-
roughness HCPM practically does not depend on the crease the mechanical (hardness) properties HCPM
content and filler dispersion, and the value of RZ is in and, consequently, decrease of RZ and f. The increase of
f, and RZ at high filler content (30 mass.h and above for graphite; 35 mass.h. and above cement and kaolin) is associated with a decrease of the mechanical properties of epoxy composite at the expense of the deterioration of the technological characteristics HCPM forming.
The results of the study revealed, on the one hand, the inadvisability of creating HCPM with less solid content of the fillers than 20-30 mass.h., on the other
hand - there was a limit to the technological compatibility of the filler with a binder which deteriorates not only the adaptability of obtaining HCPM, but significantly reduced their mechanical properties. It should be noted that technological compatibility and contrast the "critical amount of content" depends not only on the amount of filler, but also on its nature and properties.
Figure 1. The effect of filler content on the roughness of surface HCPM. 1 - graphite; 2 - concrete; 3 - kaolin
a) b)
Figure 2. The influence of thefluoroplastic content and polyethylene on temperature glass transition (Tg) and strength (AN) HPCM on the basis of ED-16
One of the most versatile and effective methods of evaluating the technological compatibility of the fillers and binders, in our opinion, is the glass transition temperature, determined by thermomechanical scales [6]. Since, ceteris paribus HCPM mechanical properties, especially hardness and elastic modulus, proportional to the temperature of their glass transition. However, it should be noted that the term "glass transition tempera-
ture" for HCPM in the literature is not met. Since the glass transition temperature determines the deformation properties of the material and connected with the mobility segments of macromolecules, then its value can be judged on confirmation changes in the interfacial layer of polymer-filler compatibility.
From the results of researchthe various contents influence of fillers on the glass transition temperature
HCPM on the basis of ED-16 (Fig. 2) it can be seen that with increasing content of organic fillers (fluoroplastic and polyethylene) in the polymer composition decreases the glass transition temperature. For example, the introduction of these fillers in an amount of 30 mass.h. reduces the temperature-glass transition till 15-18 ° C. This is apparently due to the fact that the inactive filler Teflon and polyethylene in epoxy compositions do not act chemically and form a mesh structure.
Increasing the amount of these fillers till 20-40 masses.h. reduces the TC of the polymer composition is straightforward, which is due to the spatial attenuation of the epoxy cross-linking and the difficulty ofstructure formationfull process.
When developing HPCM, mechanical engineering is traditionally used, for example, asbestos, cement and kaolin are the active mineral fillers, and are widely used to improve the mechanical properties of various polymer compositions.
From (Fig. 3) it can be seen that at low content of asbestos (up to 10 masses.h.) significantly increasing the glass transition temperature, and subsequent grades there has been some reduction in it. Similar, but less effective increase is observed with the introduction of the cement. With the introduction of kaolin (up to 20 masses.h.) there is a slight increase in the glass transition temperature and subsequent values (up to 30-40 mass.h.) observed natural decline. Despite the almost identical chemical composition of asbestos, cement and kaolin, there are significantly different effects during the filling. In one case, the effect of interstructural filling and the other with the effect of interstructural plasticization [6]. The physical structure of fillers becomes clear. Asbestos, because of its fibrous nature, increases the strength HCPM, and kaolin, due to the layered structure plays the role of plasticizer. An intermediate position is cement with explicit interphase structural effect causing a high glass transition temperature and thus the strength properties HCPM.
a)
20 30 40 With, masses.hour Cement —Kaolin
b)
Figure 3. The influence of asbestos, cement and kaolin content in the temperature glass transition (Tg) and strength (AN) HCPM on the basis of ED-16
There is a concept of realization of the effect of interstructural plasticizing fillers, of lamellar structure [2, 6], which is clearly seen when comparing the glass transition temperature HCPM filled with granular graphite and lamellar (scaly) structure.
The glass transition temperature HCPM, graphite-filled leaf shaped, somewhat less even than that of the unfilled epoxy composite. With the introduction of the aluminum powder, powders of copper and iron TC increases (Fig.4 and Fig.5). This is because the introduction in the polymeric composition of the active metallic
fillers leads to a reorientation of unrelated and have sufficient mobility of polymer chains, with formation of more structured (compared to empty) polymer structure. At sufficiently high concentrations of the metal fraction in direct contact increases, consequently, decreases the mobility and speed of polymer order. The highest TC is observed when filling the iron powder.
Active surface of iron dispersed at low concentrations contributes to the orientation and ordering of the polymer along with grafting to macromolecules, and the high content prevailing chemical interaction
with a decrease in the mobility of full-length chains at the interface of the binder active filler, which leads to a gradual increase in the glass transition temperature of the composition. In the polymerization of epoxy resin
in the presence of fillers such as iron, copper and aluminum there is a transfer of electrons to the surface metal atoms the polymer molecule with the formation of active particles of the ion-radical [1-3].
a) b)
Figure 4. The influence ofgraphite content (lamellar and granular), aluminum dust on the Vehicle (glass transition temperature) and AN (strength b) HCPM on the basis of ED-16
Such a compound formed of the polymer with solid surfaces is possible only in case of stable chemicalforma-tion bonding of the disperse inorganic substances with the carbon atoms of the polymer chain. As can be seen from the above, the formation of strong linkages of the polymer with the filler can occur simultaneously with a substantial improvement of physio-mechanical properties, characterized by a change in the glass transition temperature HCPM [2, 3].
It should be noted that when creating HCPM with high strength characteristics are the most effective fillers of fibrous type having a reinforcing effect. Significantly increases the wear resistance of the PCM when filled with glass fiber, available high glass transition temperature, according to our research, also points to the effectiveness of fillers reinforcing nature.
a)
b)
Figure 5. The influence of copper and iron powder content on the Vehicle (glass transition temperature) and AN (strength b) HCPM on the basis of ED-16
However, as noted above, rigid fibrous fillers (asbestos and fiberglass) lead to a substantial increase of the mechanical damage of cotton.
From Fig.6 shows that the highest glass transition temperature is observed with the introduction of short cotton fibers are purified from the wax layer. Intermediate positionhas chopped cotton stalks and cotton fibers with the wax (pectin) layer, and the lowest glass transition temperature - HCPM filled polyamide fiber.
On the basis of these results, as well as the structural characteristics and surface state of the fillers can be assumed that between the reinforcing cellulose fiber TCi —»—Fiberglass
355 —■—Polyamide fiber
Cotton fiber Cotton stems
355
345
335
325
315
and epoxy resin possible chemical interaction with the formation of ether bonds. Hydroxyl groups of cellulose are capable of forming a chemical bond with the epoxy group in the emergence of three-dimensional reticulated structure. This chemical structure also limits the flexibility of the polymer chains and the sliding of the macro-molecules. It is easy to see when comparing the glass transition temperature HCPM on the basis of epoxy, filled with cotton fiber with different surface. Pectin layer on the surface of the cotton fiber plays the role of the interfacial plasticization of the macromolecules of the polymer, resulting in a somewhat reduced TC HCPM.
15
25
C, parts by weight.
a) b)
Figure 6. The influence of glass fiber content, polyamide fiber, cotton fibers and stalks of the cotton plant on the glass transition temperature (TC) and strength (AN) HCPM on the basis of ED-16
A slight decrease in TC with the introduction of polyamide fibers connect with the structure of polymeric filler, high mobility of macromolecules of polyamide due to the side hydroxyl and amide groups [3]. In addition, a high glass transition temperature epoxy CPM filled with chopped stalks of cotton, and activated the surface of cotton fibers can be explained by diffusion processes in the interfacial layer when the reinforcing filler is in the oriented state and has the micro pores of the filler. As the filling of voids of the reinforcing filler epoxy resin is effective hardening in the interface layer, the filler -binder. Observed phenomenon is analogous to the interfacial structure, reduces mobility of macromolecules and increases the rigidity of HCPM.
Thus, it can be noted that the glass transition temperature HCPM is the most universal characteristics to assess the strength and thermomechanical properties of polymers; it can be used to assess technological compatibility of the binder and filler, simultaneously estimating the uniformity of the microhardness of the surface HCPM depending on the type and content of filler.
It should be emphasized that the influence of fillers portage-necessary nature on the mechanical properties HCPM stronger than that of dispersed fillers due to the high uneven distribution of fillers in the amount of HCPM. In addition, the introduction of fibrous fillers significantly worsens the adaptability of obtaining HCPM due to increasing the viscosity of the compositions.
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2. Lipatov Yu. S. Physical Chemistry of Filled Polymers.- M: Chemistry,- 1977.- 304 p.
3. Nilsen L. Mechanical properties of polymers and polymer composites.- M: Chemistry, - 1978.- 310 p. 4. FAP 00782 Disk Tribometer /Dzhumabaev, A. B. etc. / / RA AIS No. 122012.- P. 79-80.
4. O'zDSt 2822-2014 / - 29 p.
5. Dzhumabaev A. B. Friction and damage ofthe cotton // NII. The Agency "Uzstandard".- Tashkent,- 2011.- 275 p.
