CC BY
97
DOI: 10.17277/amt.2018.01 .pp.047-051
The Structure Formation and Evaluation of the Properties of Polymermatric Composites Based on Sub-Microdimensional Fillers
T.P. Ustinova*, L.G. Panova, Yu.A. Kadykova, N.L. Levkina
Engels Technological Institute (Branch), Gagarin Saratov State Technical University, 17, Pl. Svobody, Engels, Saratov region, 413100, Russia
* Corresponding author: Tel.: +7 (8453) 56 86 18. E-mail: [email protected]
Abstract
The effect of submicrocore fillers on the processes of structure formation, structural features and operational properties of filled composites based on thermoplastic and thermo-reactive matrices was studied. It was found that the introduction of the investigated fillers creates conditions for the growth of linear macromolecules of epoxy binders, providing an increase in the deformation properties of the composite based on it. The consequence of the modification of polyamide 6 is an increase in the degree of crystallinity of the polymer, which contributes to an increase in the physico-mechanical characteristics of the modified polymer.
Keywords
Polymer matrix composites; epoxy binder; polyamide 6; submicrometer fillers; potassium polititanate; dispersed basalt; combination of components; kinetics of curing; parameters of supramolecular structure; performance properties.
Polymer-matrix composites based on dispersed-fibrous fillers refer to promising materials widely used in various industries. Currently, the main trend is the development of composite materials for specific applications with a given set of operational properties [1-3], as well as alternative science-intensive technologies for their production [4-7].
In recent years functional fillers, including nano-and submicro-dimensional [8, 9] ones have been developed for the directed regulation of the structure of polymer matrix composite materials (PMCM) and giving new functional properties to them. In this regard, it becomes urgent to study the features of creating polymer matrix composites based on ingredients of the new generation.
To assess the effect of the above fillers on the structure formation processes and the operational properties of PMCM, both traditional methods of combining the components and methods of polycondensation and polymerization filling were used.
The obtained experimental data (Fig. 1) indicate that the active influence of submicron-size fillers -potassium tetrathionate (PT) and dispersed basalt is
© T.P. Ustinova, L.G. Panova, Yu.A. Kadykova, N.L. Levkina, 2018
manifested when they are introduced into the thermoset epoxy binder, which is confirmed by the conducted kinetic studies. And this influence is determined by the chemical nature of the filler (Table 1).
Time, min
Fig. 1. Kinetic parameters of curing epoxy compositions, hardened 15 parts by weight Polyethylenepolyamines:
1 - 70epoxy-20+30trichloroethylphosphate +
+ lpotassium tetrathionate;
2 - 70 epoxy-20+30trichloroethylphosphate +
+ 5potassium tetrathionate;
3 - 70 epoxy-20+30trichloroethylphosphate +
+ 50potassium tetrathionate
Table 1
Kinetics of curing epoxy compositions
Composition of the material, cured 15 parts by weight of Polyethylenepolyamines Gelation time, Tgel, min Curing time, Tcur, min Max. curing temperature, T °C 1 max ^
70epoxy-20 + 30trichloroethylphosphate 36 50 130
70epoxy-20 + 30trichloroethylphosphate+ lpotassium tetrathionate 26 95 73
70epoxy-20 + 30trichloroethylphosphate+ 5potassium tetrathionate 27 95 76
70epoxy-20 + 30trichloroethylphosphate + 50potassium tetrathionate 25 60 45
70epoxy-20 + 30trichloroethylphosphate + lbasalt 33 70 120
770epoxy-20 + 30trichloroethylphosphate + 5basalt 54 70 110
70epoxy-20 + 30trichloroethylphosphate + 50basalt 44 82 85
Table 2
Properties of epoxy compositions cured with Polyethylenepolyamines
Breaking Impact Brinell Wear Oxygen
Composition, pbw bending strength, hardness, by weight index,
stress, MPa kJ/m2 MPa in friction, g % vol.
70epoxy-20 lb 17
70epoxy-20 + 30trichloroethylphosphate 50
70epoxy-20 + 30trichloroethylphosphate + 35
+ 1 potassium tetrathionate
3 110
7 77
10 105
0.0048 19
0.0115 24
0.0002 28
Filling the epoxy matrix with basalt leads to an increase in the viability of the formulations, since the gelation time increases from 36 (without filler) to 44-54 min in the composition. At the same time, the curing time is increased from 70 minutes (without filler) to 82 minutes; the maximum curing temperature is significantly reduced from 130 °C to 110-85 °C, which, on the whole, improves the technological properties of the resulting composition.
The introduction of potassium tetrathitanate in the epoxy matrix modified with trichloroethylphosphate reduces the gelation time from 36 to 27-25 min and a maximum curing temperature from 130 to 73, 76 and 45 °C, respectively. However, the curing time is increased from 50 to 60-95 min, which may indicate an increase in the possibility of forming a linear chain of the macromolecule. A consequence of this is an increase in the physical-mechanical properties of the resulting composites.
The study of the influence of small additives of potassium tetrathionate on the physical-mechanical properties of epoxide-based composites modified with trichloroethylphosphate (Table 2) showed an increase in resistance to bending, impact, increase in hardness and decrease in frictional wear. At the same time, an
additional increase in the oxygen index (from 24 to 28 % vol.) makes it possible to classify the resulting composite as a non-combustible material.
The analysis of the physical-mechanical properties of epoxide compositions filled with basalt also confirms the effectiveness of introducing a submicrometer filler (Table 3). In this case, the addition of 50 parts by weight of basalt provides an increase in impact strength (by 60 %), material hardness (by 94 %), breaking bending stress (by 171 %) and heat resistance of PCM (by 66-92 °C) compared to an unfilled epoxy matrix.
The introduction of submicro-fillers in the thermoplastic matrix is Effective, it allows for the correction of the properties of the produced PMCM.
The modification of the polyamide matrix by introducing the potassium tetrathionate at the stage of polymer synthesis or by combining it with polyamide-6 granulate confirms the significant effect of the modifier on the structure formation processes that occur during matrix formation (Fig. 2).
As it follows from the IRS data, regardless of the method of introducing the filler, the intensity of the absorption bands characteristic of amide, amino and carboxy groups (3065-3300, 1640 and 1545 cm-1,
1030-900 cm-1) is observed. Their shift in the region of lower frequencies, which indicate the occurrence of interfacial, adhesive interaction in modified polyamide-6, ensuring the growth of ordered regions, leads to an increase in the degree of crystallinity of the polymer (Table 4).
The influence of the filler on the formation of the structure of the polymer matrix results in a change in physical-mechanical properties of polyamide-6 filled with potassium tetrathitanate. As can be seen from Table 5 there is a tendency to increase its physical-mechanical properties. Thus, for a composite with a 10 % potassium tetrathionate content, the breaking stress increases by 50 % during compression, the material hardness increases by 36 %, and its heat resistance increases by 23 °C.
In the traditional combination of potassium tetrathitanate with the polyamide-6 granulate, it was technologically possible to introduce filler in an amount of up to 30 %, which ensures the production of a composite material with enhanced properties at 10 % potassium tetrathitanate content (Table 6).
A comparative analysis of the properties of polyamide-6 filled by different methods (Fig. 3)
Table 3
The effect of basalt on physical-mechanical properties of epoxide compositions modified with trichloroethylphosphate in the proportion 70epoxy-20 pbw + 15 Polyethylenepolyamines pbw +
+ 30 trichloroethylphosphate pbw
Basalt, pbw Impact strength, kJ/m2 Brinell hardness, MPa Breaking bending stress, MPa Water absorption, % Vicat heat resistance, °С
- 34 130 45 0.20 114
1 37 134 50 0.17 124
30 39 185 77 0.10 180
50 55 253 122 0.07 206
Table 4
Parameters of the supermolecular structure of the investigated composition
Degree of crystallinity, %
Polymer Crystallite size, À
by IRS by X-ray diffraction
17.4 42
40.5 28
Note: the numerator - samples synthesized in the laboratory; the denominator - samples based on granulated polyamide-6.
Й О
— H
«*» SSM üöo и« Ma Hü> 1С« TT „-1
V, cm
Fig. 2. IR spectra:
1 - polyamide-6; 2 - potassium tetrathionate; 3 - polyamide-6 (granulate) + 1 % potassium tetrathionate; 4 - polyamide-6+1% potassium tetrathionate, introduced at the stage of polyamide synthesis
indicates that the introduction of potassium tetrathitanate in both cases provides an increase in the basic physical-mechanical properties of the composite.
3
2
1
. 17.7
PA-6 435
21.4
PA-6 modified 50 5
Table 5
Physical-mechanical properties of polymerization-filled polyamide-6
Filler content, % mass kl Density, kg/m3 Breaking bending stress, MPa Brinell hardness, MPa Vicat heat resistance, °C Water absorption for 24 h, %
- 1090 36 64 180 1.3
10 1157 70 87 203 4.4
20 1320 59 97 168 5.2
30 1444 54 24 200 8.9
40 1564 116 110 194 9.9
Table 6 Deformation-strength properties of polyamide-6 filled with potassium tetrathitanate
Filler content, % Ultimate tensile stress, MPa Elastic modulus at tension, % Breaking bending stress, MPa Impact strength, kJ/m2 Brinell hardness, MPa
- 38.5 36.0 73.5 19.0 143.0
10 42.5 43.0 106.0 25.5 176.5
20 41.5 42.0 105.0 26.0 154.0
30 43.0 31.5 105.5 27.0 -
1240
12 4 5 Melt Flow Index, g/10min
1050-
1000
Density, kg/m
210
210 200 190180 170 160
1 2 4 5. Vicat heat resistance, °C
Brinell hardness, MPa
Fig. 3. Physical-mechanical properties of filled polyamide-6:
1 - polyamide-6 without fillers; 2 - polyamide-6 + 10% potassium tetrathitanate (synthesis stage); 3 - PA-6 (granulate) + 10% potassium tetrathitanate; 4 - polyamide-6 + 1% potassium tetrathitanate (synthesis stage); 5 - polyamide-6 (granulate) + 1% potassium tetrathitanate
Complex studies of the processes of structure formation in composite materials based on a polyamide matrix and a submicrosized filler - potassium tetrathitanate, the study of the effect of potassium te-trathitanate and submicro-size basalt on the kinetics of
the curing process and the physical and mechanical properties of epoxy composites have made it possible to formulate the main conclusions characterizing the specific regulation of structure and performance properties PMCM:
- Kinetic studies of the curing process of epoxy binder modified by trichloroethylphosphate in the presence of submicrometer additives (potassium tetra-thitanate, dispersed basalt) both as modifiers and as fillers indicate their significant influence on process parameters. At the same time, this is manifested to a greater extent in the increase in the curing time, which creates the conditions for preferential growth of the linear chains of the macromolecule, which results in an increase in the toughness, breaking bending stresses, and the hardness of the composite, while increasing the oxygen index.
- The study of the structural features of polyamide 6, modified at the stage of synthesis by submi-cron-size potassium tetrathitanate, also confirms its active influence on the formation of the polymer matrix, which results in an increase in the degree of crys-tallinity of the polymer and an improvement in its physical and mechanical properties.
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