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8/6/2019 Polymer Discovery System
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Polymer Discovery System
::: Intelligence in Rheometry
Today, polymers are among the most important materials in
existence as the properties of polymers can be adapted in a
very wide range to fit the field of application. Some polymers
are hard and brittle or tough and shock-resistant, while
other polymers are soft and flexible. The manufacturing and
characterization of polymers is therefore the focus of activity for
numerous industrial companies and research institutes.
IntroductionPlastics are organic or semi-organic substances with a high
molecular weight. The length of the molecular chains and the
entanglement between them are decisive parameters which
influence the properties of the material. Many of the relevant
properties can be characterized using rheological tests.
Polymers have complex chemical and morphological structures
and a wide range of variation in the composition and possibility
of modifying the material. Therefore they show complex
behaviors which need to be taken into consideration whenusing or manufacturing these materials, e.g. the viscoelasticity,
non-Newtonian flow behavior, anisotropy (dependent on
orientation or modification), complex aging behavior and much
more. Describing the properties of polymers requires versatile
procedures in order to obtain the needed information.
Many methods are used for processing and manufacturing
plastics. The majority are forming and reforming procedures
(compression molding, calendering, film extrusion, blow &
injection molding, etc.). Optimizating these procedures and
their quality control is therefore extremely important in the
production of plastics.
Source: accelrys
Models of oxygen and water molecules in an amorphous polymer matrix.
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Material characterization
Molar Mass DistributionRecently, mathematical models have been developed which
allow the determination of the molar mass distribution via
rheological measurement.
Correlations to molar mass distribution or material branching
can be seen in the viscoelastic behavior, which influence
both, the manufacturing process and the properties of
the end product. The molar mass is the most important
structural parameter which affects the flow behavior of
polymers.
Process SimulationCorrelation to manufacturing conditionsMeasurements at low shear rates are mainly used for
analyzing manufacturing problems. Whereas manufacturing
processes such as extrusion or injection molding occur
at high shear rates, differences between the materials are
usually seen at low shear rates. Manufacturing problems
often occur at low shear rates, e.g. delayed die swell with
extrusion or delay due to irregular relaxation during the
cooling phase of injection molded parts. Polymer melts
show pronounced shear thinning behavior, i.e. the viscosity
decreases with increasing shear rate. Flow curves are
important for the manufacturing of polymers to determine the
energy required for the process. Oscillatory measurements
also reveal information about the elasticity of the melt, which
can be correlated with die swell.
The viscosity curve becomes flatter with decreasing shear
rate and the polymer melt shows Newtonian behavior with
a constant viscosity. This region at low shear rates is called
the terminal relaxation zone or the 1st newtonian plateau.
The constant viscosity in this range is called the zero-shear
viscosity 0 and represents an important temperature dependent
material parameter. For most technical polymers, the zero-shear
viscosity is directly proportional to the average molar mass.
The rheological measurement therefore clearly shows small
differences in the molar mass.
At a constant average molar mass, the energy required for shear
thinning in the manufacturing process can be correlated with
the molar mass distribution. Polymers with a wide molar mass
distribution have more of a tendency to shear thinning, even at
low shear rates, than more narrowly distributed materials with
the same average molar mass. Broadening the molar massdistribution aids extrusion and shaping. This means, for example,
that the surface quality of molded plastic parts can be improved
by varying the distribution width. The width of the molar mass
distribution correlates with the cross-over point between the
storage modulus G and the loss modulus G in a frequency
sweep.
Rheological Tests on Polymers
G'
G''
Angular Frequency
> narrow
lower averagemolar mass (MW)
longer / branchedmolecules
GX, X
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BranchingThe number, length and mobility of side chains influence the
rheological properties. If the side chains are not very long,
this leads to increased viscosity at low shear rates and more
pronounced shear thinning compared to the corresponding
linear polymer.
If a polymer has long-chain branching, it will display low
viscosity at low shear rates. The extent of branching can
therefore be used to control manufacturing and product
characteristics.
FillersFillers also influence the manufacturing process and the
properties of the end product. Important factors are size,
form and concentration of the fillers and the interactions
between the particles. Fillers usually lead to an increase in
the melting viscosity and a reduction of die swell. From a
rheological standpoint an increasing filler content results in asmaller so-called linear visco-elastic (LVE) range, which can
be determined in an amplitude or strain sweep.
Measurements on solidsWith the appropriate accessories, a rheometer can be used
to perform dynamic mechanical thermal analysis (DMTA)
on solid samples by measuring the samples in torsion.
The solid properties are usually determined as a function
of the temperature and the results give insight into the
morphological properties and behavior of the polymer when
in use. Measurement of the glass transition temperature
(Tg) and storage modulus (G) below the glass transition
temperature gives information on the maximum service
temperature and the impact strength, embrittlement and
stiffness of the material. For crystalline or partially-crystalline
polymers the melting temperature (Tm) is another important
material parameter accessible with such a DMTA test.
Conversion and analysis methods
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Applications
Fig. 1: FLOW AND VISCOSITY CURVE or
how to get information about the flowability of athermoplastic:Flow and viscosity curves give information about the flowability of
thermoplastics under different shear and process conditions. The zero-
shear viscosity 0 at low shear rates is an important material property
and is directly proportional to the average molar mass Mw. In order to
determine a viscosity curve over a broad range of shear rates a master
curve can be constructed using time temperature superposition in
combination with the conversion method according to Cox Merz. In
addition, conversions from transient tests and a direct measurement
with controlled shear rate provides the whole spectrum of shear rates.
Powerful regression methods may help to calculate the zero-shear
viscosity 0 and the infinite-shear viscosity inf in a shear range where
all the molecules are totally disentangled and oriented.
Fig. 3: CROSS OVER POINT Gx or how tocompare the molar mass of thermoplastics within10 minutes:Within 10 minutes, the molecular structure can be analyzed with
respect to the average molar mass Mw and the molar mass distribution
MMD. A powerful and model free method is given for a relative
comparison of thermoplastics. A qualitative measure for the average
molar mass is expressed by the horizontal position of the cross-over
point Gx while the vertical position of Gx indicates the MMD. In addition
the degree of branching can lead to a horizontal shift of Gx while
comparing polymers of the same type.
Fig. 2: TIME TEMPERATURE SUPERPOSITIONTTS or looking deep into the macromolecularstructure of a polymer melt:The Dynamic mechanical analysis (DMA) in torsion, determined
via time temperature superposition TTS, provides shear and
time dependent information about the viscoelastic properties of
a material. Predictions regarding "Die Swell are possible. All the
information about the polymeric macro-structure and its short
and long term behavior is already included in the "Master Curve.
Comparative average molar mass and molar mass distribution,
as well as the calculation of their absolute values, are supported.
Conversions into transient and oscillatory material functions are
applicable.
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Fig. 4: MOLAR MASS CALCULATION a method
used not only for short or narrow distributedpolymer melts:Processability and product performance depend very much on the
molecular structure of the polymer melt, so it is important to analyze
thermoplastics with respect to their molecular structure. A rheological
dynamic mechanical measurement (DMA) in combination with the
latest sophisticated MMD analysis methods has major advantages
and is still easy to use. The thermoplastic material can be measured
as molten material and does not need to be diluted in an aggressive
solvent. The method has no upper limits regarding length and
distribution of the molecules; rather there are advantages due to
the higher sensitivity with increasing average molar mass Mw. Input
data for the method include a frequency sweep showing zero-shear
viscosity and cross-over point Gx.
Fig. 6: TRANSIENT TEST TYPES (Creep, StressRelaxation and Stress Growth Tests) find outmore about the time response of your material:Step stress (creep & recovery), step strain (stress relaxation) and
step rate (stress growth / start up flow) experiments are typically
performed to measure the time (transient) response of a material to
a given constant shear stress, shear strain or shear rate. Analysis
methods enable the calculation of important material constants such
as zero-shear viscosity, plateau modulus, creep compliance and the
conversion from the transient material functions to oscillatory material
functions - G(), G(). In Figure 6, a stress growth experiment is
presented.
Fig. 5: DYNAMIC MECHANICAL THERMALANALYSIS (DMTA) in TORSION or how todetermine phase transitions of thermoplastics,thermosets and elastomers:This test provides the essential information about the materials
phase transitions. Glass transition (Tg), melting (Tm) and
crystallization temperature (Tc) can be determined with high
precision using the environmental chamber CTD 600. Information
about the degree of crystallinity or cross-linking is expressed in the
slope of the material functions G and G. With the film and fibre
fixture, DMA and DMTA tests in tension can be performed even on
soft polymeric films and fibres. In figure 5, a multiwave experiment
is presented with the determination of the glass transition
temperature, expressed as the maximum in tan(). As can be seen,
Tg is a function of the applied frequency.
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Physica rheometers for polymer testing
Electrical Temperature Device P-ETD 4004 Electrical resistance heating
4 Specially suited for samples which are measured at high temperatures
4Very rapid heating rates
4The special design enables water cooling (liquid circulator) as well as
electrical heating
4 Use of liquid nitrogen for temperatures as low as -130 C
Electrical Temperature Device H-ETD 4004 Electrically heated hood
4Active heating of the sample area and measuring system
4An essential accessory for preventing temperature gradients in the
sample
4The hood can be purged with inert gas to prevent oxidation or otherchemical reactions
Convection Temperature Device CTD 6004 Extremely small temperature gradients
4 No temperature overshoots
4 Measured temperature always represents the sample temperature
4 No ice formation at low temperatures
4 Compact, robust design
4Automatic adjustment of liquid nitrogen consumption
4 Easy to open, good sample access
4 Sample observation during the measurement is possible
4 Chamber can be touched at all test temperatures
4Wide range of accessories: torsion and film/fibre tool, UV-option,
disposable plates, etc.
Environmental SystemsSince temperature has a great influence on the rheological
behavior of all polymeric samples, precise temperature
control is crucial to obtaining reliable rheological data.
However, in practical tests, inaccurate temperature control
is still responsible for a large number of measurement
uncertainties and errors. To address these issues, our
engineers have taken great care to develop various
temperature control systems based on different principles.
These systems fulfill the requirement of accurate temperature
control in all respects and are still commercially affordable,
putting Anton Paar in the lead position with respect to
temperature control in rheology. Numerous patents and
scientific reports about the performance of the various
environmental system have been published. Some key
features include the broadest temperature range available
(-150 C to 1000 C) for a standard rheometer, proof of
performance, i.e. as results of temperature gradient testing,
and the availability of certified temperature sensors which
allow software controlled automatic temperature calibration in
a broad temperature range.
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Included:
Trimming tool for easy
sample trimming on
all sides
Included:
Filling ring for melting
and molding polymer
granuls
Simple to remove
before measurement
Included:
Scraper for fast and
effective cleaning
Option:
Stamping press
This press enables the
production of sample
discs in a thickness
up to 2 mm and in
diameters of 25, 12
and 8 mm.
Helpfull accessories for the CTD 600
Systems Polymer Discovery System Polymer Melt Rheometer
Rheometer Physica MCR Series incl. Toolmaster Physica MCR Series incl. Toolmaster
Temp.-Control System:
Convection Temperature Control Device CTD 600
incl. accessories for polymer handling
Temperature Calibration Sensor CS/CTD
Electrically Heated Temperature Device ETD 400
Measuring System:
Measuring Plate PP25
Lower Measuring Plate PP25 with built-in
temperature probe
Measuring Plate PP25
Software:
RheoPlus SoftwareRotation and Oscillation
DSO Direct Strain Oscillation
Polymer Analysis Package consisting of:Master curves, Relaxation Time Spectra,Retardation Time Spectra,Molar Mass Distribution
RheoPlus SoftwareRotation and Oscillation
Options:
Solid Torsion Bar Fixture STBF
Film and Fibre Fixture
Tool for Extensional Rheology
Low Temperature Option (LN2 Evaporation Unit EVU), TruGap
DSO Direct Strain Oscillation
Polymer Analysis Package consisting of:
Master curves, Relaxation Time Spectra,
Retardation Time Spectra, Molar MassDistribution
Temperature Calibration Sensor CS/CTD
8/6/2019 Polymer Discovery System
8/802/04 B61IP08-B
Specifications
subject to change
without notice
Fotos: Croce & Wir
Anton PaarGmbH
Anton-Paar-Str. 20
A-8054 Graz
Austria - Europe
Tel.: +43 (0)316 257-0
Fax: +43 (0)316 257 257
E-mail: [email protected]
Web: www.anton-paar.com
International Product
Management:
Anton Paar Germany GmbH
Helmuth-Hirth-Str. 6
D-73760 OstfildernGermany - Europe
Tel.: +49 (0)711 72091-0
Fax: +49 (0)711 72091-630
E-mail: [email protected]
Web: www.anton-paar.com
Instruments for:
Density and concentration
measurement
Rheometry and viscometry
Sample preparation
Colloid science
Microhardness testing
X-ray structure analysis
CO2 measurement
High-precision temperature
measurement