CC BY
11
Вестник технологического университета. 2015. Т.18, №8 УДК541.64: 539.2: 537.5
S. G. Karpova, Yu. A. Naumova, L. P. Lyusova, A. A. Popov, G. E. Zaikov
PROBE MOBILITY DYNAMICS, CRYSTAL STRUCTURE OF FILM AND NONWOVEN FIBER MATERIALS PREPARED FROM POLYURETHANE AND STYRENE ACRYLONITRILE
Keywords: EPR microprobe, TEMPO stable radical, time correlation.
Structural and dynamic analysis, combining thermophysical measurements by differential scanning calorimetry and measurements of segmental mobility by the EPR microprobe technique, is performed for films and nonwoven fiber materials prepared from polyurethane (PU) and a styrene-acrylonitrile copolymer (SAN), as well as mixed compositions thereof. The effect of the tetrahydrofuran, ethyl acetate, and acetone solvents on the structure and molecular dynamics of films and matrices based on ultrathin PU and SAN fibers is examined. A weak effect of solvent on the molecular dynamics of chains in the PU film and nonwoven materials and a strong influence on the molecular mobility in SANfilms and films of mixed compositions with a high SAN content are observed. For fibers, such influence is negligible. In PU and PU/SAN mixed formulations, mesomorphic structures are formed in both the film and nonwoven materials. The temperature dependence of the rotational correlation time t of the probe exhibits a kink at temperatures close to the melting point of the mesomorphic structures in the PU/SAN mixtures. All the studied dependences for both the films and fibers feature a kink at PU/SAN = 50/50, which is associated with phase inversion in the compositions. The probe measurements show the impact of an oxidant (ozone) on the amorphous phase in these polymers. Measuring the rotational dynamics of the probe before and after exposure to ozone of the film and ltrafine fiber materials showed that, for both the PU films and fibers, ozonation produces practically no effect on the molecular dynamics, while for PU/SAN compositions and pure SAN, t changes significantly.
Ключевые слова: микрозондовый ЭПР, стабильные радикалы ТЕМПО, время корреляции.
Представлены результаты исследования методом структурно - динамического анализа в комбинации с теплофизическими измерениями методом дифференциальной сканирующей калориметрии и измерениями сегментной подвижности методом микрозондового ЭПР, выполненные для пленок и нетканых волокнистых материалов, полученных из полиуретана (ПУ) и сополимера стирола с акрилонитрилом (САН), а также смесевых композиций на их основе. Рассматривается эффект тетрагидрофурана, этилацетата, ацетона на структуру и молекулярную динамику цепей в пленках и матрицах на основе ультратонкого ПУ и волокон САН. Наблюдается слабое влияние растворителя на молекулярную динамику цепей в пленке ПУ и нетканых материалах и сильное влияния на молекулярную подвижность в пленках САН и пленках смесевых композиций с высоким содержанием САН. Для волокон такое влияние незначительно. В смесевых составах ПУ и ПУ/САН жидкокристаллические структуры формируются как в пленке, так и в нетканых материалах. Температурная зависимость времени корреляции вращения зонда t имеет излом при температурах близких к точке плавления жидкокристаллических структур в смесях ПУ/САН. Все изученные зависимости, как для пленок, так и для волокон имеют излом при соотношении ПУ/САН=50/50, что связано с инверсией фаз в композициях. Зондовые измерения показали влияние окислителя (озона) на аморфную фазу в этих полимерах. Измерение вращательной динамики зонда до и после экспозиции в озоне пленки и ультрадисперсного волокнистого материала показали, что, как для пленок, так и для волокон ПУ, озонирование практически не производит эффекта на молекулярную динамику, в то время как для композиций ПУ/САН и чистого САН, изменения t значительны.
Introduction
Development and synthesis of new polymers is a long-term and expensive process. One effective way of solving the problem is to use of mixtures of existing polymers. By varying the composition of the mixture and types of constituent components, it is possible to prepare the required material.
Another aspect affecting the properties of polymers is the method for their processing. One of the most important ways of processing of polymers is to treat them in solutions. Structurization in solution is controlled by the nature of the solvent used, with the main reason for differences in the structure of the obtained materials being the influence of the thermodynamic quality of the solvent on the mode of interaction of polymer macromolecules with solvent molecules and, as a consequence, on the interaction between macromolecules themselves [1-4].
The solvent plays a significantly more complicated role in solvent-polymer 1-polymer 2
systems. How the solvent affects the structure of films and nanoscale fibrous structures (fibers, filaments, networks, and porous fibrous matrices) is of considerable interest. Currently, ultrathin fibers and products thereof are extensively used in biomedicine, cell engineering, separation and filtration processes, in creating reinforced composites, in electronics, chemical analysis, sensory diagnostics, and a number of other innovative areas [5-13].
The choice of polymers is associated with a wide use of polyurethane (PU) in medicine and the light industry, for example, for producing fibers and non-woven micro- and nanofibrous materials, adhesive compositions, varnishes, paints, protective agents, sealing materials, artificial leather, suede, filtering materials for respirators, and rubberized fabrics. In medicine, it used to cultivate cells of various tissues and to manufacture bone prostheses, connections of nerve fibers, osmotic dialysis filters, artificial heart components, artificial blood vessels, catheters, and matrices for drug delivery. At present, mixed
compositions are widely used as filtering fiber materials for personal respiratory protection.
A high hemocompatibility and mechanical properties of these polymers put them above competition with respect to other polymeric implants. The structure and properties of PU were studied in [1416]. In addition, mixed compositions of PU with chitosan [17, 18], polyhydroxybutyrate [19], and styrene-acrylonitrile (SAN) copolymer [20] were investigated.
Thus, the selection of the components of mixtures of polymers and solvent for their processing in solutions makes it possible to widely change the set of physicomechanical properties of the tested film and fibrous materials, leading to creation of products with valuable consumer qualities.
Subjects and methods
The objects of study were films were prepared from Desmocoll 400 polyurethane thermoplastic (Bayer, Mw = 1.0 x 105), SAN 350N styrene-acrylonitrile copolymer (Kumho, Mw = 1.0 x 105), and mixed compositions thereof at PU/SAN ratios (wt %) of 10/90, 30/70, 50/50, and 80/20 in the film material and 25/75, 50/50, 75/25 in the nonwoven fiber materials. The films were dissolved in organic solvents of different chemical classes: ethyl acetate (EA), tetrahydrofuran (THF), and acetone (A). The concentrations of the test solutions ranged within 0.1-2.0 g/100 mL. The films were prepared in Petri dishes by casting from 10 wt % polymer solutions, with subsequent evaporation of the solvent at constant temperature and humidity.
We also studied polymeric nonwoven materials with a fiber diameter of 1-10 ^m prepared by electrospinning from Desmocoll 400, SAN, and mixtures thereof. The material has a mass per unit area of 20-70 g/m2 and an aerodynamic resistance of 3-30 Pa at an air flow rate of 1 cm/s. At present, fibers are produced by means of an original technology based on electrospinning (ES), which enables to manufactureultrathin fibers and nonwoven materials. The nonwoven materials tested in the present work were prepared by electrospinning, more specifically by the "nanospider" method, a patented technology of highvoltage capillary-free electrospinning of fibers [6]. Electrospinning process was carried out at a temperature of 20°C and a relative humidity of 60%. The distance to the receiving electrode was 0.2-0.3 m.
Thermal analysis of the test materials was performed on a DTAS-1300 thermal analyzer at temperatures from -90 to 140°C. The heating rate was 20 K/min. The temperature was measured to within ±0.5°C.
The molecular mobility in the samples was studied by the paramagnetic probe method. The probe was 2,2,6,6-tetramethylpiperidine-1-oxyl, a stable nitroxyl radical. The latter was introduced into the films and nonwoven materials with low and high SAN contents from the vapor phase at temperatures of respectively 40 and 70°C until a concentration of 10-310-4 mol/L was reached. The EPR spectra were recorded in the absence of saturation, which was verified by examining the dependence of the signal intensity on the
micro-wave field power. The probe rotational correlation time t was evaluated from EPR spectra by the formula [21]
it
where A + is the width the spectral components located in the weak field; !+/!_ is the ratio of the intensities of the components in the weak and strong fields, respectively. The error in determination of t was ±5%.
Results and discussion
Study of the Influence of the Solvent on the Crystalline Phase in Mixed PU/SAN Compositions
Differential scanning calorimetry (DSC) was used to study the structure of films and fibers of PU/SAN mixed compositions formed in THF solvent (Fig. 1). It was found that the dependences the fraction of mesomorphic structures and their melting points on the mixture composition are different for films and fibers.
The DSC data (Table 1) showed that the fractions of mesomorphic structures a in the PU films and fibers are similar, being characterized by 45-47 J/g (melting enthalpy). While a small increase in the SAN content significantly reduces the fraction of mesomorphic structures in the films (Fig. 1a), an identical increase in the fibers produces an extremely small change (Fig. 1b). At PU/SAN = 50/50, no mesomorphic structures are formed in films and only small fraction in fibers. At a higher SAN content in the mixed composition (over 50%), the fraction of mesomorphic structures in the films increases dramatically, while in the fibers, a remains almost unchanged.
Fig. 1 - Dependence of the enthalpy of melting of mesomorphic structures in the (a) film and (b) nonwoven materials and of the melting temperature of mesomorphic structures in the (a') film and (b') nonwoven materials on the mixture composition
Thus, for the films and fibers, the fraction a differently depends on the composition of the formulation, but their common feature is a kink in the dependences at 50% PU, which is associated, in our opinion, with a phase inversion. The different behavior
of the dependence of a on the mixture composition for the films and fibers can be explained, in our opinion, by a difference in the morphology of the tested mixed compositions.
The dependences of the melting temperature Tm on the composition for the films and fibers prepared from these polymers are also different. While the melting point of the films and fibers decreases with increasing SAN content (up to 50%), at higher SAN content in the mixture, Tm for the films increases, but, on the contrary, decreases sharply for the fibers. The observed patterns are also indicative of phase inversion in both the films and fibers at PU/SAN = 50/50. A comparison of the data on Tm and a reveals that they change similarly. For example, as the SAN content in the composition increases, so does the concentration of defects in the mesomorphic structures of PU in thefilms, which, in turn, reduces a and Tm. In the fibers, no appreciable change in a is observed (with the exception of the 50/50 composition), so Tm decreases slightly in mixed compositions containing up to 50% SAN. In PU/SAN = 50/50 compositions, phase inversion takes place, with a higher degree of entanglement of chains preventing the formation of mesomorphic structures. As a result, no mesomorphic structures are formed in films, while their proportion in fibers is negligibly small. In mixed compositions, in which the SAN component forms a continuous phase, increasingly perfect PU mesomorphic structures arise in films, which leads to an increase in a and Tm; however, in fibers (probably due to a high speed of spinning), they do not have time to form. Characteristically, the melting point of the films is higher than that of the fibers. For example, while Tm = 51.4°C for the PU/SAN = 30/70 films, Tm = 39°C for the fibers of the same composition; for the PU films and fibers, Tm = 60.3 and 48.5°C, respectively (analogous data were obtained for other compositions), which is also indicative of more imperfect mesomorphic formations in the fibers compared with the films.
[fe.li of the ratio oftlh? polynicf* <ul T-) jifkJ (Ik type ofvohcnl an f, ami C) an kikIkiJ by DSC
fttms
So«WlH Pll PU/SAN SAN
M/20 ÜÍ/S0 30/70 tu/40
Tn T, Г» r, 7, Tt Tm Tt 7,
THF 60.3 -as S7 -M - SO su - Si -30 HQ
EA .4 - 5J -20 - ts- 56 m 77 !»
A я -40 •w - - » - 7Ь 70 It5
ПГн'л
PU/SAN
SoJwiil 75/35 Jfl/Jtl 25/75
Tm T, Tm T, r„ T, r„ 7i 7,
THF «.J -40 -II) 42 •>5 und —JÍ « SS ItO
A characteristic feature is the fact that, while the glass transition temperature Tg for the SAN films is 80°C, it is 110°C for the fibers. In the mixedcomposition films, no glass transition of SAN was observed in the temperature range covered (from -90 to 140°C), except for the PU/SAN = 50/50 composition, whereas the glass transition of the SAN occurs in the fibers of compositions PU/SAN = 25/75 and 50/50, indicative of a more rigid amorphous phase in fibers. The lack of grass transition in mixed formulations (except the above) is suggestive of a plasticizing effect
of PU on the structure of mixtures and of a sufficiently high compatibility of these polymers.
Thus, the preparation of films from solution is slow enough, so equilibrium is established in the system, and addition of SAN (in small amounts) to PU reduces the fraction of PU mesomorphic structures due to the intermolecular interaction between PU and SAN molecules, as was shown in [5]. At higher (over 50%) SAN content, at which the PU forms a dispersed phase, PU inclusions with a dense surface composed of straightened chains arise. The fraction of PU mesomorphic structures in the film material increases at high SAN content (>50%) due to a lesser chain entanglement in the dispersed phase as compared to the dispersion phase. In the fibers, apparently due to a high rate of formation, the structure has no time to come to an equilibrium state, which makes the fraction of PU mesomorphic structures in mixed fiber compositions with high PU content extremely small (Fig. 1a).
Effect of Solvent on the Dynamics and Structure of the Amorphous Phase in Films and Fibers Prepared from PU, SAN, and Mixed Compositions Thereof
To examine the complex evolution of the mobility of the probe, we used the model of binary distribution of segments in less dense and more dense intercrystalline regions, characterized, respectively, by a morerapid and less rapid rotation of TEMPO stable radicals. Studies of molecular dynamics in the films and fibers prepared from PU/SAN mixed compositions revealed that the amorphous phase (except PU, Fig. 2) is heterogeneous. The heterogeneity of amorphous phase indicates the presence therein of structures with a sufficiently low and high mobility. In what follows, the time correlation was calculated only for the fast component.
32Ktf Л.4>n 333CJ 3340 < Л-П ■<I
Magnciit; Huld Ktrciijith. t.;
(hl
32Ж> 33CIÏ t • .'11 3340 I <r.O 33KlI 34ÍHI Magnetic field strength. О
Fig. 2 - EPR spectra of the PU/SAN = 50/50 material formed in the THF solvent: (a) film material and (b) nonwoven material
Studies of the influence of the type of solvent showed that the solvent produces a sufficiently strong effect on the rotational mobility of the probe, and consequently, on the molecular mobility of the polymer
chains (Fig. 3). Figure 3a shows that the highest probe mobility is observed for the films formed in the THF solvent, while the lowest in acetone. The solvent does not significantly affect the molecular mobility in the fibers (Fig. 3b). Introduction of SAN into the polymer matrix causes the growth of t. Note that, with increasing content of SAN in the composition up to 50%, no significant change in the correlation time is observed: only at higher SAN content in the mixture, when the SAN component forms a continuous phase, a sharp rise in t occurs, indicative of an increase in the rigidity of the amorphous regions. The observed dependence of t on the composition of the films can be explained by the structure of the interfacial regions (Fig. 4). To process and quantitatively interpret the data obtained by EPR spectroscopy, we used the Bruker "Winer" and "Simfonia" software codes. These programs enabled to calculate the molecular mobility in the interfacial regions of the studied mixed compositions. Figure 4a shows that, in the films, most dense interfacial regions are formed in mixtures containing small amounts of SAN, so that the transport of radicals through this layer is hampered, which explains why the change in t upon adding SAN (up to 50%) is small. The interfacial layer in compositions with a high content of SAN is characterized by a lower value of t, indicating that the interfacial interlayer is looser, i.e., more permeable for the radical. In the fibers, irrespective of the composition, the interfacial layer is characterized by a rather low t, which indicates its high permeability for the radical and manifests itself through the composition dependence of t (Fig. 3b). For both the films and the fibers, the composition dependences of t feature a kink at PU/SAN = 50/50, a result that confirms the above conclusion about phase inversion at this ratio of the contents of the polymers.
20 40 60 tU 100
eu, s
Fig. 3 - Dependence of t on the composition of the formulation in the (1) A, (2), EA, and (3) THF solvents for the (a) film and (b) nonwoven materials
It should be noted that the correlation times t for PU samples formed in various solvents, be it films or fibers, differ insignificantly, while for SAN films these differences are significant. Thus, the solvent changes the structure of the amorphous regions in the
SAN component to a larger extent than it does in the PU component.
According to [5], for a given mixed composition, the thermodynamic qualities of the solvents change from "good" to "poor" in the order THF > EA > A. In "poof' solvents, the degree of interaction between the polymer and solvent is much higher than in "good" ones; therefore, solvents differing in quality create different polymeric structures in the solution, which persist after removal of the solvent. Differences in the interaction of the polymers in solutions lead to distinctions in the properties of the films and nonwoven fibrous materials prepared from solutions, since the structure formed in the solution in part survives.
In terms of thermodynamics, "good" and "poor" solvents differ only in their interaction with the polymer, resulting in a different interaction of macromolecules with each other. A higher degree of coiling of macromolecules in "poor" solvents favors an increase in the number of contacts not only between like but also between unlike macromolecules [11]. Thus, the solvent greatly influences the structure and molecular mobility of the polymer it dissolves. In THF, the most "good" solvent, the structure of the polymer composition is close to the equilibrium. In passing to the "bad" solvent, the structure becomes increasingly nonequilibrium, the density of chains grows, and as a result, the rigidity of the macromolecules increases in the series of solvents THF, EA, and A (Fig. 3a). For the fibers, the effect of the solvent on the amorphous structure of the polymers is much weaker (Fig. 3b).
Fig. 4 - Dependence of t for interphase layers in the (a) film and (b) nonwoven materials the composition of the formulation in the (1) A, (2), EA, and (3) THF solvents
Figure 5a demonstrates how the fraction of macromolecules comprising the dense amorphous regions in the film compositions (evaluated from , Fig. 5) increases in going from the "good" to the "poor" solvent. It can be seen that the increase of the PE content in the mixture causes a decrease in the fraction of regions with hindered motion, so that, for mixed compositions with low SAN content (less than 50%), only one spectrum is observed. In the fibers, these
differences manifest themselves in a lesser extent (Fig. 5b); however, a double spectrum is observed for mixed compositions with high PU content. Note that the kink in these dependences is also observed at PU/SAN = 50/50 (Fig. 5b).
W-l
U 2(1 41) 60 Ktl PU.»
Fig. 5 - Dependence of on the composition of the formulation in the (1) A, (2), EA, and (3) THF solvents for the (a) film and (b) nonwoven materials
, , in)
Cx III5, null/tin'
<b)
4.5
pu, %
Fig. 6 - Dependence of the concentration of the radical on the composition of the formulation in the (1) A, (2), EA, and (3) THF solvents for the (a) film and (b) nonwoven materials
The solvent determines the concentration of radicals in the studied polymers. That the density of the amorphous phase in PU, as well as in the compositions formed in the different solvents (Fig. 6), is seen from the decrease in the concentration of the radical in passing from the "good" to the "poor" solvent, in both the films and the fibers prepared from the mixtures studied. However, an analysis of the concentration of the radical in the mixed compositions formed, for example, in the THF solvent shows that the observed changes in the films can be attributed to the growth of the density of the samples in going from PU to SAN and to the decrease of the fraction of amorphous phase accessible to the radical, factors that cause a reduction in the concentration of the radical in the samples (Fig. 6a). Different dependences were observed for the
PU/SAN fibers (Fig. 6b). The composition of the fiber produced no significant effect on the concentration of the radical, as it happens in the films. Only for the PU/SAN = 50/50 samples, a jump in the dependence of the radical concentration on the composition was observed, indicative of the most loose packing of the chains in these fibers. Characteristically, that the extreme point was observed PU/SAN = 50/50 also supports the conclusion on phase inversion at these ratio of the contents of the polymers.
We also studied how the correlation time for films and fibers prepared from these mixtures depends on temperature. It was shown that these dependences have a kink at 45-55°C, which is apparently due to the "unfreezing" of mesomorphic structures (Fig. 1). A linear dependence was observed only for PU/SAN = 50/50 films; i.e., for compositions without mesomorphic structures (in the fiber samples, their fraction is negligibly small).
The activation energy was found to change differently, depending on the composition of the polymer mixture, type of solvent, and method of preparation of the polymeric material (Fig. 7). Calculation of the activation energy for the rotational mobility of the probe in the tested polymers showed that, for the PU films, the effect of solvent on the value of Ea is small; adding SAN (up to 50%) reduces the activation energy, which is apparently due to a decrease in the density of the mixed composition (Fig. 7a). At higher SAN content in the mixture, changes in Ea were not so conspicuous for any of the solvents. Note that the activation energy increases in passing from the "good" to the "poor" solvent.
Etj. kJ/nio[
(в)
(Ь)
■til
Fig. 7 - Dependence of Ea on the composition of the formulation in the (1) A, (2), EA, and (3) THF solvents for the (a) film and (b) nonwoven materials
In the case of the fiber samples, the activation energy behaves differently (Fig. 7b). Like a (Fig. 1b), Ea for the mixtures with <50% PU practically does not change, at 50% PU, Ea decreases sharply, whereas for the compositions with higher SAN content, the activation energy increases slightly. Note that the values of Ea for the fibrous polymers formed in the different solvents (except for acetone) are similar, while for the
films, these differences are significant (Fig. 7a). It is important that, for all the mixed compositions (except for 50/50), the temperature dependences of the correlation time exhibit a kink within 45-55°C, temperatures close to the melting point of the mesomorphic structures. Therefore, we explain the observed kinks in the temperature dependences of t by the unfreezing of mesomorphic structures. That the activation energy Ea increases at temperatures above 50°C can be attributed to the fact that the activation energy for the mesomorphic structures is higher.
Using the microprobe method, we demonstrated that the oxidant (ozone) influences the amorphous phase of the above polymers. Studies have shown that, regardless of the method of preparation, the polymeric compositions with high SAN content were oxidized. Polyurethane and mixtures thereof with small amounts SAN were more resistant to the impact of ozone (Fig. 8).
For the PU and PU/SAN = 80/20 samples, the correlation time changed only slightly after ozonation of the films and fibers formed in THF. In the mixed formulations with high SAN content, t for both the films and fibers increased after a short exposure to ozone (up to 2 h). Further oxidation with ozone decreased t, with these changes manifesting themselves most clearly for the PU/SAN = 25/75 composition (PU/SAN = 30/70 for the film sample). Oxidation processes are known to involve the physical and chemical crosslinking of macromolecules, as well as the degradation of chains. At the initial stage of the oxidation, crosslinking processes prevail, leading to a decrease in molecular mobility and, consequently, to an increase in t. At longer exposures to ozone, the processes of degradation of chains begin to dominate, causing a decrease in t. Thus, we can conclude that SAN is most strongly susceptible to ozone oxidation. Similar patterns were obtained for the samples formed in the A and EA media.
241» 411
Fig. 8 - Dependence of t on the duration of treatment in ozone of the (a) film (PU/SAN = (1) 30/70, (2) 50/50, (3) 80/20, and (4) 100/0) and (b) nonwoven (PU/SAN = (1) 25/75, (2)50/50, (3) 75/25, and (4) 100/0) materials
- --# «.«6
1(1 15 Time, li
Fig. 9 - Dependence of on the duration of exposure to ozone of the (a) film (PU/SAN = (1) 30/70 and (2) 50/50) and (b) nonwoven (PU/SAN = (1) 25/75, (2) 50/50, and (3) 75/25) materials
A comprehensive study of film and nonwoven materials made it possible to analyze changes in the molecular mobility of the polymer molecules in early stages of their interaction with oxidizing aggressive media. We also examined how the ratio changes with the duration of treatment in ozone of the fibers formed in THF. Figure 9 shows that, in the initial stage of exposure to ozone (up to 2 h), this quantity increases, but later reduces. The growth of indicates an increase in the fraction of dense amorphous domains, which is apparently associated with the physical crosslinking of macromolecules during the ozonation, so the decrease of this parameter indicates the destruction of these regions. Like the correlation time, the parameter symbatically, which confirms the conclusion on the dominant role of crosslinks between chains at the initial stage of ozone oxidation.
Conclusions
Thus, we have shown that the formation of the structure of a polymer in solution is determined by the nature of the solvent, with the main reason for differences in structure being the thermodynamic affinity between the solvent and solute.
The strongest influence of the type of solvent on the structure and molecular dynamics was observed for SAN and mixed compositions with a high content of the latter.
It was shown that mesomorphic structures are formed in both the film and the nonwoven materials.
At the PU/SAN = 50/50 ratio, the dependences of т, Еа, the concentration of the radical, and the fraction of mesomorphic structures on the composition of the film and nonwoven materials exhibit kinks because of phase inversion.
Using the probe method, we revealed the influence of an oxidant (ozone) on the amorphous phase in the film and nonwoven materials. It was shown that, irrespective of the mode of formation of compositions, those with a high SAN content are more readily
oxidized. Polyurethane and mixtures thereof with small amounts of SAN are more resistant to the effect of ozone.
While for the film material, the type of solvent greatly affects the molecular mobility, for the nonwoven fabric, this effect is significantly smoothed.
It has also been shown that, while in the films, the concentration of the radial decreases by almost an order of magnitude in substituting SAN for PU, in the nonwoven material, these changes are small.
References
1. A. A. Tager, Physical Chemistry of Polymers (Scientific World, Moscow, 2007) [in Rus.].
2. L. S. Krokhina, Macromolecular compounds. 18, 663 (1976).
3. V. N. S. Pendyala and S. F. Xavier, Polymer 38, 3565 (1997).
4. Yu. N. Filatov, I. A. Kapustin, I. Yu. Filatov, and M. S. Yakushkin, Life Safety, No. 54, 6 (2011).
5. M. Yu. Boksha, Thesis PhD (Lomonosov Moscow State Univ. Fine Chem. Technol., Moscow, 2010).
6. A. Pocius, Adhesion and Adhesives Technology (Hanser, Munchen, 2012).
7. A. A. Ol'khov, O. V. Staroverova, Yu. N. Filatov, et al., Gazette Kazan Technological University, 16 (8), 157 (2013).
8. I. A. Kapustin, I. Yu. Filatov, and Yu. N. Filatov, Chemical Fiber, No. 5, 37 (2012).
9. Y. Filatov, A. Budyka, and V. Kirichenko, Electrospinning of Micro- and Nanofibers: Fundamentals in Separation and Filtration Processes (Begell House, New York, 2007).
10. A. K. Budyka and N. B. Borisov, Fiber Filters for Control of Air Pollution (IzdAT, Moscow, 2008) [in Rus.].
11. Yu. N. Filatov, I. Yu. Filatov, and M. Yu. Nebratenko, RF Patent No. 2357785, Byull. Izobret. No. 16 (2009).
12. Yu. A. Naumova, L. R. Lyusova, S. G. Karpova, et al., Rubber, No. 4, 48 (2013).
13. A. Greiner and J. H. Wendoff, Adv. Polym. Sci. 219, 107 (2008).
14. M. I. Shtilman, Polymers of Medical Biological Purposes (Akadembook, Moscow, 2006) [in Rus.].
15. S. G. Karpova, A. L. Iordanskii, N. S. Klenina, A. A. Popov, S. M. Lomakin, N. G. Shilkina, and A. V. Rebrov, Russ. J. Phys. Chem. B 7, 225 (2013).
16. T. Ikejima and Y. Inoue, Carbohydr. Polym. 41, 351 (2000).
17. S. G. Karpova, A. L. Iordanskii, S. N. Chvalun, M. A. Shcherbina, S. M. Lomakin, N. G. Shilkina, S. Z. Rogovina, V. S. Markin, A. A. Popov, and A. A. Berlin, Reports Phys. Chem. 446, 176 (2012).
18. S. G. Karpova, A. L. Iordanskii, A. A. Popov, N. G. Shilkina, S. M. Lomakin, M. A. Shcherbin, S. N. Chvalun, and A. A. Berlin, Russ. J. Phys. Chem. B 6, 72 (2012).
19. M. Ratzsch, G. Haudel, G. Pompe, and E. Meyer, J. Macromol. Sci. Chem. A 27, 1631 (1990).
20. S. G. Karpova, Yu. A. Naumova, Yu. K. Lukanina, L. R. Lyusova, and A. A. Popov, Polymer Sci., Ser. A 56, 472 (2014).
21. A. M. Vasserman and A. L. Kovarskii, Spin Labels and Probes in Physical Chemistry of Polymers (Science, Moscow, 1986) [in Rus.].
© S. G. Karpova - Ph. D., senior researcher, N.Emanuel Institute of Biochemical Physics. RAS, [email protected]; Yu. A. Naumova - Ph. D., Senior Fellow,Lomonosov Moscow State Univ., [email protected]; L. P. Lyusova - prof, chief researcher, Lomonosov Moscow State Univ., [email protected]; A. A. Popov - prof., head of laboratory, N.Emanuel Institute of Biochemical Physics, RAS, [email protected]; G. E. Zaikov - prof, deparnent of TPM KNRTU, [email protected].
© С. Г. Карпова - ст. науч. сотр., Института Биохимической физики им. Н.М.Эмануэля, [email protected]; Ю. А. Наумова - канд. хим. наук, с.н.с. Московского госуд. ун-та им. М.В.Ломоносова, [email protected]; А. А. Попов - проф., зав. лаб. Института Биохимической физики им. Н.М.Эмануэля, [email protected]; Г. Е. Заиков - д-р хим. наук, проф. каф. ТПМ КНИТУ, [email protected].
