<<
>>

THE BASIC MAINTENANCE OF WORK

In introduction the work urgency is proved, the purpose and research problems is formulated, scientific novelty and the practical importance of work are noted.

Chapter 1. The literary review

In chapter 1 the literary review is presented.

The structure and physical and chemical properties PVDF and its copolymers with triftoretilenom, PABI, and also composites on their basis are considered. Reception of films PVDF and PABI is separately considered. The phenomenon segnetoelektrichestva both electrowire properties PVDF and other polymers, and also composites on their basis is discussed.

Chapter 2. Samples and research methods

In the second chapter polymeric materials and segnetookeramika, used for preparation PKM with raised segnetoelektricheskimi properties are specified. The basic objects of research were PVDF, PABI, their mixes, and also composites with segnetoelektricheskim filler НЦТС-1. Polymeric films gibkotsepnogo PVDF moulded in two ways: from a melt and a solution, and films zhestkotsepnogo PABI moulded only from a solution. As solvent in both cases used dimetilatsetamid (DMAA). Films of mix PVDF and PABI received from a solution with general solvent DMAA. Films PKM received introduction in a solution or a polymer melt segnetoelektricheskogo a powder (НЦТС-1) in a certain parity.

In work various physical and chemical methods of research were used. Method IK the Fourier-spectroscopy has allowed to study to the full chemical composition, molecular and supermolecular structure of polymer. Characteristic absorption bands for investigated polymers are resulted in tab. 1.

Table 1. Characteristic absorption bands PVDF and PABI

Polymer Value of characteristic absorption bands, sm-1
PVDF 1431 1270 1073 883 841 510 442
PABI 1255 1119 1075 1018 844

In work two modern techniques of record and processing IK of spectrums are used. According to the first technique (IK spectroscopy in mode Image) received tridimensional (3D IK spectrums) the plotting of distribution of polymers and filler in a polymeric matrix (the "chemical" plotting). By means of the second technique developed in laboratory of spectroscopy TvGU, from IK spectrums took the contribution caused by light scattering on particles of filler in a polymeric matrix. After corresponding processing IK of spectrums of dispersion received the information on the sizes dispersing
Particles. IK spectrums wrote down on IK spectrometer Equinox of 55 firms Bruker. For record 3D IK spectrums of samples in mode Image follow-up used IK microscope Hyperion-3000 of firm Bruker.

Morphology of polymeric materials studied by means of methods of optical microscopy on device Axiovert of firm Carl Zeiss and electronic scanning microscopy on the device of 6610 LV firm JEOL.

Thermal stability of polymeric materials (thermogravimetric analysises) on derivatografe estimated a method of a thermogravimetric analysis F.Paulik, I.Paulik, L.Erden's systems.

Electrophysical properties of samples characterised a method of thermal noise (for measurement of initial inductivity) and a bridge method (for research of an electric hysteresis in a ferroelectric material). Measurement of inductivity for segnetokeramiki НЦТС-1 made in temperature range from 20 to 3000С on frequency 1кГц. For films pure PVDF and the composit mixes containing 10, 20 and 30 % of volume filling (% about.) НЦТС-1, inductivity measurement were made by two ways - a bridge method and a method of thermal noise in temperature range from 20 to 180 0С. The Inductivity defined by a method of thermal noise, has been calculated from noise pressure at the account of calibration of thermal noise on reference resistance and containers. For this purpose it is necessary, that resistance of the sample was much more resistance of the loading resistor connected collaterally to the sample in the course of measurements. The loading resistor has been chosen according to this condition and had resistance 30 clod, that more than on 2 orders there is less than resistance of the sample.

Chapter 3. Reception and a structure of composites

The third chapter is directed on creation PKM on the basis of PVDF, PABI and НЦТС-1, possessing high thermal and segnetoelektricheskimi by properties. To selection of optimum conditions of reception of film samples PKM with necessary properties, and also to the analysis of their structure and morphology.

Films PVDF and PKM on the basis of PVDF.V to work the technique of reception of films PVDF possessing segnetoelektricheskimi properties, as most studied polymer is mastered.

Films of a demanded thickness received, as from a melt, and a polymer solution. The Fig. 1а characterises IK transmittance spectrums of films PVDF received by various methods. In IK transmittance spectrums it is exemplary accurately the absorption bands answering to fluctuations, as СН2-групп (841, 1073 and 1431 sm-1), and СF2-групп (442, 510, 883 and 1270 sm-1) are displayed. Presence

Absorption bands in IK spectrum PVDF with maxima on frequencies of 442 and 510 sm-1 testifies about presence in films of the polar crystal R-phase having segnetoelektricheskie properties. The analysis of intensity of the specified absorption bands testifies to the high maintenance of a crystal R-phase in film PVDF, received of a melt.

Fig. 1. And - IK transmittance spectrums of film PVDF received by melt spinning (1) and solution (2); - IK transmittance spectrums of composites on a basis

Matrixes from PVDF from 30 % maintenance НЦТС-1 received by melt spinning

(1) and a solution (2).

The high maintenance of a polar phase is caused by mechanical influence (pressing) on a sample in the course of its melt spinning. In a film, received from a solution, intensity of these absorption bands much less. It is possible to conclude, that film crystallisation in this case occurs mainly to formation of a non-polar phase (fig. 1).

The Fig. 1б shows, that introduction segnetoelektricheskogo filler in film PVDF causes essential decrease in size propuskanija at the expense of light scattering in both cases - films received as from a melt, and a solution.

Composite microphotos yield us visual representation about the form and distribution of particles of filler in a polymeric matrix (fig. 2). It is important to notice uniform distribution of particles НЦТС-1 in a polymeric matrix for a melt case, that considerably improves physical-mechanical properties of a material. At moulding PKM from a solution uniform distribution of grains of filler in a polymeric matrix also is observed. However in this case there is some aggregation of particles of filler in a polymeric matrix.

By means of method IK the Fourier-spectroscopy in mode Image it is possible to characterise chemical composition and morphology of polymeric mixes and composites. Presented on fig. 3 3D IK the spectrum yields visual representation about dimensional distribution of components in PKM. The Color scale located to the right of a spectrum on fig. 3 yields the information on quantitative composition of components in a composite. Figures on this scale correspond to concentration of this or that component in a composite.

Fig. 2. Microphotos PKM from PVDF from 30 % maintenance НЦТС-1, received by melt spinning () and a solution ().

The Fig. 3 also characterises distribution of particles segneto - ceramics in a polymeric matrix (segnetokeramike answers

Red colour). It is visible, that in a matrix on the basis of PVDF ceramics particles are distributed evenly on all volume of the sample.

Films PABI and PKM on the basis of PABI. The Fig. 4 characterises chemical composition (and,) and morphology () film PABI received from a solution.

In IK a spectrum of the sample (fig. 4а) characteristic absorption bands PABI on frequencies 844, 1018, 1119 and 1255 sm-1 are distinctly displayed. Film PABI is practically homogeneous (fig. 4в), however is observed the relief of a surface connected with distinction in thickness of the sample.

3D IK an absorption spectrum of received film PABI (fig. 4б) mainly has green colour, but includes some more undertints. Presence of insignificant colour scale testifies to uniformity of a film on a thickness practically on all surface.

Data IK of spectral analysis PKM on the basis of PABI characterises fig. 5а on which characteristic absorption bands PABI on frequencies 843 are accurately displayed, 1017, 1117 and 1255 sm-1 (compare about fig. 4а). Besides, in IK a spectrum the significant is observed

9


Effect of dispersion on the filler particles, expressed in essential decrease svetopropuskanija through a sample. The spectral analysis also shows, that in PABI at composite reception there are no chemical transfomations, and between a mat

ritsej and filler it is not observed significant chemical interactions. Hence, as well as in a case with PKM on the basis of PVDF, we

We receive a material with coherence 0-3 types. As a result of it electric properties received PKM will depend exclusively on properties of initial filler as polymer is a dielectric and does not represent interest from the point of view of presence segnetoelektricheskih properties.

The composite microphoto (fig. 5в) shows us uniform distribution of grains НЦТС-1 in polymer volume, but, as well as in a case with PKM on the basis of PVDF (fig. 2б), is observed insignificant aggregation of particles of filler.

On fig. 5б it is presented 3D IK a spectrum of film PKM written down in the field of 1345-1210 sm-1. At the analysis following characteristic absorption bands have been chosen: 1255 sm-1 - for PABI and 599 sm-1 - for НЦТС-1. As well as for PKM with matrix PVDF (fig. 3а) in 3D a composite spectrum various colour shades are observed. PABI in a composite it is characterised by green and dark blue colour. Presence of dark blue and green colour for one substance is caused by heterogeneity of a film of a composite on a thickness that has been shown above (see fig. 4б). Pink and
Red colour is characterised by distribution and the size of aggregates from filler particles in volume of a polymeric matrix.

In a concrete case it is possible to speak about presence of one large centre of formation of aggregate to what pink colour in a spectrum testifies.

Fig. 5. IK transmittance spectrum PKM on the basis of PABI from 30 % maintenance НЦТС-1 (); 3D IK absorption spectrum PKM ();

Surface microphoto

Films PKM ().

It is positioned, that the centre size of aggregates from filler particles in film PKM makes ≈ 4 microns while initial particle size makes ≈ 2,2 microns.

Films on the basis of mix PVDF and PABI and PKM on the basis of this mix. Special interest in the present work was represented by reception of a polymeric matrix from mix PVDF and PABI and a composite on its basis. The matrix in the form of a film managed to be received by moulding in the general solvent (DMMA). The matrix Spectral analysis has shown (fig. 6а), that in IK spectrums absorption bands on frequencies 510, 840 and 1273 sm - 1 which are characteristic for the polar crystal R-phase PVDF possessing segnetoelektricheskimi properties are displayed. At a spectrum also there are absorption bands, characteristic for PABI (840, 1017, 1117 and 1255 sm-1). Possibly, that macromolecules PABI possess essentially higher rigidity of chains, in comparison with PVDF, crystallisation in a polymeric mix causes orientation of macromolecules PVDF and formation of a crystal polar R-phase.

Presented on fig. 6б 3D IK the absorption spectrum of a film from polymer blend yields visual representation about dimensional distribution of components, thus green colour answers PABI, and blue - PVDF. As characteristic IK absorption bands
PABI the strip on frequency of 1650 sm-1, and PVDF - 1273 sm - 1 (pκc has been used. 6б). The Fig. 6б shows, that the yielded polymers well mix up. Making a start from colour scale of a spectrum it is possible to present visually a relative positioning of polymers in a film. Presence in a spectrum of red and yellow colour testifies to aggregation of molecules PVDF or PABI.

And

Fig. 6. And - IK transmittance spectrums of films PVDF (1), PABI (2) and ПАБИ+ПВДФ (3); - 3D IK an absorption spectrum of film ПВДФ+ПАБИ of composition 1:1 on the area of the sample 2.5х2.5 мм2.

IK transmittance spectrum PKM on the basis of mix PVDF and PABI (fig. 7а) shows presence of characteristic absorption bands, as for PVDF (443, 511 and 1278 sm-1) responsible for presence crystal polar β - a phase, and for PABI (1075 and 840 sm-1). Character of a spectrum testifies that between polymers and segnetoelektricheskim filler is not observed essential chemical interaction. Hence, both segnetokeramichesky filler, and PVDF which has polar β a-phase will bring it is additive the contribution in segnetoelektricheskie properties PKM. Besides, presence PABI in PKM can lead to substantial increase of its thermal stability.

On fig. 7б it is presented 3D IK an absorption spectrum of a film ternary PKM. As characteristic absorption bands absorption bands of 1278 sm-1 - for PVDF, 1117 sm-1 - for PABI and 1126 sm-1 - for НЦТС-1 have been chosen. Red colour in a spectrum is responsible for presence PVDF in the sample, green - PABI, and pink - segnetoelektrichesky filler.

Blue colour answers PVDF and characterises area of a film with the depressed thickness. As well as in a case with composites on the basis of a matrix from PABI or PVDF, in sample PKM aggregation of initial components is observed.

Experimental data about particle size of filler in PKM, received by means of various methods (spectral and microscopic) have shown quite good coincidence. Absence of essential aggregation of initial grains НЦТС-1 in PKM can testify that filler particles just occupy the pores formed as a result of moulding of a film from a solution, about answering to the size of individual grain.

Carried out researches PKM by means of optiko-spectral methods have allowed to define their structure and morphology on which essentially physical and chemical properties of a material, in turn, should depend.

Fig. 7. And - IK a transmittance spectrum of film PKM on the basis of matrix ПВДФ+ПАБИ (1:1) from 30 % maintenance НЦТС-1; - 3D IK an absorption spectrum of film sample PKM.

Chapter 4. Physical and chemical properties of composites

The fourth chapter is devoted studying of physical and chemical properties PKM. Owing to creation of a new polymeric material from a mix gibkotsepnogo and zhestkotsepnogo polymers, and PKM on its basis it is expedient to study thermal and segnetoelektricheskie properties of these materials.

Thermal properties PKM. Results of a thermogravimetric analysis of film samples of a polymeric matrix and PKM are presented on fig. 8. It is positioned, that appreciable loss of weight of the sample as for a matrix (fig. 8а), and for PKM occurs at 400 0С, that essentially above, than at separately taken polymers (PABI - 3500C) and PVDF (3000C). Possibly, at mixture PVDF and PABI a relative positioning polymeric (rigid and flexible) chains and intermolecular interaction between them in a polymeric matrix yields more thermally sound structure, in comparison with separately taken polymers (the synergism phenomenon). The Fig. 8а also shows, that for films ПВДФ+ПАБИ the second basic droop on weight is observed at temperature ~ 950 0C, caused by material destruction. It is important to notice, that for PKM (fig. 8б) at thermal heating of the sample in 13

To the inert environment to 1000 0С it is not revealed appreciable droop on weight and essential destruktsionnyh processes. Film PKM conserved the initial form and colouring. By means of method IK of spectroscopy also it is not positioned appreciable destruktsionnyh processes in the sample.

Fig. 8 Derivatogrammy films ПВДФ+ПАБИ of composition 1:1 () and ПВДФ+ПАБИ+НЦТС-1 (30 weights. %) (). A thermogravimetric analysis - a thermogravimetric analysis, DTG - a differential thermogravimetric analysis

Segnetoelektrichesky svojstvaplenok PVDF and mixes ПВДФ+ПАБИ and PKM on their basis. Segnetoelektrichesky properties of the received polymeric films and films PKM characterised two methods - to roadways and a method of thermal noise. Thickness of films PKM on the basis of PVDF, received of a melt, and value of inductivity (ε) at temperature 200С, measured in two ways, are resulted in tab. 2. From the table follows, that the above the maintenance segnetokeramiki in the sample, the below its inductivity.

Table 2 the Thickness of films PKM on the basis of PVDF and values of inductivity

The maintenance of powder НЦТС-1, %об. Thickness of the sample, micron Inductivity, ε
Bridge method Method of thermal noise
0 25 10 10
10 36 10 11
20 30 10 12
30 38 9 4

The Fig. 9 characterises the frequency profile of inductivity and loss angle for films PKM on the basis of PVDF with concentration НЦТС-1 10, 20 and 30 % about., received in a range of frequencies ν from 10 to 106Гц. With increase in frequency inductivity decreases in 1.5 times for all concentration segnetokeramiki. The Loss angle has a minimum in a range of frequencies 103 106Гц.

Temperature dependence of inductivity of films PVDF with concentration НЦТС-1 10, 20 and 30 % about. (Fig. 10) it has been received by two methods (to roadways and thermal noise). At temperature 130 0С

Fig. 9. The Frequency profile of inductivity and loss angle for films PVDF with concentration НЦТС-1 10, 20 and 30 % about. (Т=25°С, a bridge method).

For inductivity the strongly pronounced maximum (fig. 10а) which decreases with increase in concentration of filler is observed. On temperature dependence of the inductivity received by a method of thermal noise (fig. 10б), the temperature of this maximum makes close value (140 0С). In the field of temperature 150 0С one more small maximum (fig. 10а) which, obviously, is magnetic transformation temperature of filler is visible.

Fig. 10 Temperature dependence of inductivity of films PVDF with concentration НЦТС-1 10, 20 and 30 % about. At frequency 10 kgts: and - a bridge method;

- Method of thermal noise.

On fig. 11 (and,) temperature dependences are presented

Inductivity and loss angle of films PVDF with concentration НЦТС-1 of 30 % about. For different frequencies. On these dependences two accurate maxima are traced at temperatures 130 and 160 0С. Temperature dependence of the dielectric

To permeability for a polymeric matrix of composition ПВДФ+ПАБИ (1:1), received by a bridge method it is presented on fig. 12. On a drawing accurately expressed maximum is observed at 135 0C then the curve goes on droop. The maximum on temperature dependence answers magnetic transformation temperature for PVDF, however at the yielded temperature we receive value of inductivity for PKM bolshee (ε =184), than for a film pure PVDF (ε =120). It is possible to explain such divergence to that at moulding of a composite matrix (ПВДФ+ПАБИ), we receive bolshee the maintenance polar kris tallicheskoj v-phases.

And

Fig. 11. Temperature dependences of inductivity of films PVDF with concentration НЦТС-1 of 30 % on different frequencies () and loss angle (), received by means of a bridge method.

Possibly, increase in the maintenance of a polar phase svjazanno with distinction in rigidity

Polymeric chains of the yielded polymers. ZHestkotsepnoj PABI affects in the course of crystallisation on conformstion of chains gibkotsepnogo PVDF. As a result of it crystallisation PVDF in a matrix occurs mainly to formation of a polar phase.

On the inductivity frequency profile in

Areas low frequencies (since 4Гц) sharp growth of inductivity was observed. At frequency of 100 Hz value of inductivity was stabilised and reached values 160. After that with increase in frequency value of inductivity practically did not change.

In constant electric field the studied polymeric matrix behaved ambiguously. During the initial moment of time, at delivering on 16

The sample of electric field, there was an insignificant falling of container of the sample, but eventually (≈ 20 sek) value

It is stabilised.

For polymeric matrix PVDF-PABI of composition (1:1) (fig. 13) was possible to find out loops of a dielectric hysteresis in electric fields with intensity to 0,70 kv/mm at various frequencies of electric field. Presence of loops of a dielectric hysteresis testifies that the yielded samples possess segnetoelektricheskimi properties. The sated loops to observe it was not possible, as at big fields there was a break-down of a film.

Fig. 13. The loops of a dielectric hysteresis observed in electric field of 0,67 kv/mm, for a polymeric matrix of composition ПВДФ+ПАБИ (1:1) at various frequencies.

On fig. 14а frequency profiles perekljuyochaemoj are presented polarisation at different values of intensity

Electric field. Apparently from drawing with growth of frequency of a put field size of switched over polarisation

Decreases. It is possible to explain the received results to that at high frequencies polymeric chains have not time to be rearranged at change of electric field and, thereof, the polymeric matrix is in stable state, i.e., in the most polymeric matrix there are no rearrangements of polymeric chains.

Fig. 14. And - the Frequency profile of switched over polarisation in electric field Е=0,43 kv/mm; - dependence of polarisation on time in the field Е=0,86 kv/mm and у=20Гц.

Ageing of a polymeric matrix at ambient temperature and one value of variable electric field conducted to a relaxation

Polarisation (fig. 14), that is caused thermal razorientatsiej electric dipoles and transferring of the sample in an equilibrium state. However it is necessary to notice, that the induced value of polarisation did not disappear completely, and made ~ 6 мКл/м2.

On fig. 15 temperature dependences of inductivity for PKM on the basis of a matrix from polymer blend PVDF and PABI (1:1) with the maintenance segnetokeramiki 10, 20 and 30 % weight are presented., received by a bridge method. Values of inductivity have appeared considerably above, than at PKM, received on the basis of a matrix from PVDF with the same maintenance segnetokeramiki (tab. 3 see).

Influence two components: properties

Fig. 15. Temperature dependence dielekt - richeskoj permeability of film PKM with various maintenance НЦТС-1.

In PKM on presence segnetoelektricheskih properties render segnetoelektricheskogo filler (in this case powder НЦТС-1) and properties of the most polymeric matrix. In our case two kinds of polymeric matrixes are presented is a singl-component matrix from PVDF and bipropellant of ПВДФ+ПАБИ. Unlike PVDF, PABI is a typical dielectric and in segnetoelektricheskie property of the contribution does not bring. The essential divergence in values dielectric the maintenance segnetokeramiki is faster

Permeability in the considered

Composites

With the identical

Table 3

Value of inductivity in PKM on the basis of matrix PVDF and

ПВДФ+ПАБИ

The powder maintenance

НЦТС-1, %

Inductivity
PVDF ПВДФ+ПАБИ, a parity 1:1
10 10 74
20 10 54
30 9 72

Fig. 16. The loops of a dielectric hysteresis observed in electric field with intensity Е=0,57 kv/mm, for PKM composition ПВДФ+ПАБИ (1:1) at various frequencies.

In total the maintenance is caused by that in a polymeric matrix on the basis of polymer blend

Crystal polar β - phases PVDF it is significant above, than in composites on the basis of a singl-component matrix.

At a polymeric matrix (ПВДФ+ПАБИ) at frequencies ν

<< | >>
A source: Danilov Anatoly Jurevich. RECEPTION of POLYMERIC COMPOSITES With HIGH SEGNETOELEKTRICHESKY And THERMAL PROPERTIES. The dissertation AUTOABSTRACT on competition of a scientific degree of a Cand.Chem.Sci. Tver - 2015. 2015

More on topic THE BASIC MAINTENANCE OF WORK:

  1. THE BASIC MAINTENANCE OF WORK
  2. the Basic maintenance of work
  3. THE BASIC MAINTENANCE OF WORK
  4. THE BASIC MAINTENANCE OF WORK
  5. the BASIC MAINTENANCE of WORK
  6. THE BASIC MAINTENANCE OF WORK
  7. THE BASIC MAINTENANCE OF WORK
  8. THE BASIC MAINTENANCE OF WORK
  9. THE BASIC MAINTENANCE OF WORK
  10. II. THE BASIC MAINTENANCE OF WORK
  11. the Basic maintenance of work
  12. THE BASIC MAINTENANCE OF WORK
  13. THE BASIC MAINTENANCE OF WORK