Method of measurement of polymers' equilibrium hardness coefficient

FIELD: measuring technique.

SUBSTANCE: while warming sample up, average value of square of voltage of thermal electrical; fluctuations is measured at terminals of measuring converter. Maximal value, which corresponds to glass transition temperature, is measured, at which temperature the value of dielectric permeability is found and value of hardness coefficient is calculated. Method can be used for measurement of equilibrium hardness coefficient of polymer chains for polymers in unit.

EFFECT: improved precision of measurement.

1 dwg, 6 tbl

 

The invention relates to measuring technique and can be used in the production of high-molecular compounds, as well as to predict changes in physical properties of polymers under various conditions of operation.

There is a method of estimating the ratio of the equilibrium rigidity of the polymer chains σ according to the results of viscometric measurements (tverdokhlebova I.I. Conformation of macromolecules (viscometric method of assessment). - M.: Chemistry, 1981. - S). The disadvantage of this method is that to get the result you want to determine the viscosity of polymer solutions and to carry out a large number of calculations. Consequently, measuring the information about the real processes of molecular movements subsystems polymer systems are inadequate to the object.

The closest technical solution of the invention is a method of determining dielectric properties of polymers (see RF Patent №2166768 G 01 R 27/26, G 01 N 27/22, bull. No. 13, 10.05.2001 year).

The method consists in the following. Put the material at a known temperature T in condenser transducer, parallel to the primary Converter with a test material as a dielectric layer to connect the incremental resistance Rdmand changing its value, find and measure Maxi the social value of the mean square voltage fluctuations at the terminals of the Converter ; remove from the transducer of the analyzed sample, set the distance between the electrodes of the transducer, corresponding to the thickness of the sample d, measure the average square of the voltage fluctuations when connected to the invertercalculate the dielectric permittivity ε' and tangent of dielectric loss angle tgδ by the formulas:

where Δf is the frequency, f is the measurement frequency; D is the diameter of the transducer electrodes, With0- own input capacitance of the measuring system,- the average square EMF noise pre-amplifier, k is the Boltzmann constant, ε0- electric constant. The disadvantage of this method is the impossibility of determining the coefficient of rigidity of the polymer chains σ.

The technical result of the invention is the possibility of determining the coefficient of equilibrium rigidity of the polymer chains σ for polymers in the block.

The invention consists in that place, the sample of the polymer system in the primary measuring transducer of the capacitive type, produce heating of the sample in a linear increase of temperature T with speedin% the CoE heating is measured at the terminals of the measuring transducer value of the mean square of the voltage thermal power fluctuations record the maximum value ofcorresponding to the glass transition temperature Tcwhen this temperature determines the value of the dielectric constant without affecting the test sample external electromagnetic fields ε'fcalculate the value of the stiffness coefficient by the formula

where k is Boltzmann's constant, f is the measurement frequency, Δf - frequency band, ε0- electric constant, D is the diameter of the disk electrodes of the transducer, d is the thickness of the polymer sample, With0- capacity measuring system, And is a constant determined by the structure of the polymer.

The invention is illustrated as follows. Between the glass transition temperature of the polymer, Tcand the ratio of the equilibrium rigidity of macromolecules σ there is a ratio (privalko VP Molecular structure and properties of polymers. - Leningrad: Khimiya, 1986. - P.87)

where a is a constant determined by the structure of the polymer (Table 1...6).

Table 1
The group of polymersAnd,
and115,0
b84,0
in62,5
g51,5
d40,0
Table 2Table 3
Group aGroup b
Polybutene-1
PolytetramethylenePolypropylene
PolyethylenePolybutylmethacrylate
PolypropyleneoxidePolychlorotrifluoroethylene
PolydioxanonePoly-n-methylsterol
PolyoxyethylenePoly-2,5-dichlorostyrene
Poly-ε-caprolactonPolystyrene
PolyethyleneiminePoly-n-Postira
Polyvinylidene fluoridePoly-n-chloresterol
PolyxystraPoly-o-methylsterol
Polyvinyl alcohol : Poly-3,4-dichlorostyrene
Poly-α-methylsterol

Table 4Table 5
GroupGroup g
Natural rubberPaleoclimate-1
Poly-CIS-isoprenePolyisobutylene
PolymethylacrylateP is divinelyinspired
PolymethylacrylatePolypenco-1
The polyvinyl acetatePolyvinylbutyral
PolymethylmethacrylatePolyvinylbutyral
isotacticPolyvinylether
atacticPolyvinyl pyrrolidone
Polyvinyl chloridePoly-m-chloresterol
PolyacrylonitrilePolyacrylamide
Poly-m-forsteraPolyvinylidene
Poly-o-chloresterol
Poly-1-vinylnaphthalene
Poly-2-vinylnaphthalene
Table 6
Group d
Polyhexes-1
Politicalit
Polyacrylnitrile
Polyacrylnitrile
Polipoprotein
Polycyclohexylene
Polybutylcyanoacrylate
Polyphenylmethyl
Polybutylmethacrylate

For the average of the square of the voltage of the electromagnetic fluctuations of the polymer system, placed in the primary measuring transducer of the capacitive type, with the proviso that the magnitude of the signal is much larger than the noise in the measurement system, we can write the following expression

where 1/Rxactive conductivity of the transducer, 1/RIactive conductivity measuring system, k is Boltzmann's constant, f is the measurement frequency, Δf - frequency band, ε0- electric constant, D is the diameter of the disk electrodes of the transducer, d is the thickness of the polymer sample, With0- capacity measuring system, ε'f- the dielectric constant of the polymer, determined without affecting the test sample external electromagnetic fields.

For non-crystalline polymer systems dependtemperature has the form of a curve with a maximum. The maximumcan be observed only in the case when the real part of the complex conductivity of the transducer is equal to the imaginary, ie,

For the glass transition temperature of the expression (5) can be represented in the form

Given the fact allows you to get a definite relationship between dielectric constant ε 'f, the maximum mean square voltage of the electromagnetic fluctuations at the terminals of the primary Converterwhen the glass transition temperature Tcconstructive parameters of the transducer D, d, C0and the ratio of the equilibrium stiffness of polymer

The drawing shows a measuring device for determining the activation energy of the processes of molecular mobility in polymer systems. The sample 1 is placed in the primary measuring transducer of the capacitive type 2, located in the electromagnetic screen 6. The sample temperature is measured by thermocouple 4 and the potentiometer 3. Heat mode is set by the block 5. The signal measurement data is amplified broadband amplifier 7 and supplied to the processing unit 8, which includes the ADC 9 and the personal computer 10.

The proposed method of determining the coefficient of rigidity of polymeric materials can significantly extend the experimental analysis of high-molecular compounds.

The method of determining the coefficient of the equilibrium stiffness of polymers, namely, that put the sample polymer system at the primary measuring transducer of the capacitive type, measured at the terminals of measuring the transformation of the of the motor is the average of the square of the voltage thermal power fluctuations determine the value of the dielectric constant without affecting the test sample external electromagnetic fields ε'f, characterized in that produce heating of the sample in a linear increase of temperature T with speedin the process of heating is measured at the terminals of the measuring transducer value of the mean square of the voltage thermal power fluctuationsrecord the maximum value ofcorresponding to the glass transition temperature Twithwhen this temperature determines the value of the dielectric constant without affecting the test sample external electromagnetic fields ε'fcalculate the value of the stiffness coefficient by the formula

where k is Boltzmann's constant, f is the measurement frequency, Δf - frequency band, ε0- electric constant, D is the diameter of the disk electrodes of the transducer, d is the thickness of the polymer sample, With0- capacity measuring system, And is a constant determined by the structure of the polymer.



 

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