Polymer characterization
Encyclopedia
Polymer characterization is the analytical branch of polymer science
.
The discipline is concerned with the characterization of polymeric materials on a variety of levels. The characterization typically has as a goal to improve the performance of the material which implies that the characterization should ideally also be linked to the parameters that are related to the desirable properties of the material such as strength, impermeability, toughness, optical properties and the like.
like size exclusion chromatography
often in combination with Low-angle laser light scattering
(LALLS) and or viscometry can be used to determine the molecular weight distribution as well as the degree of long chain branching of a polymer, provided a suitable solvent can be found. Copolymers with short chain branching such as linear low-density polyethylene (a copolymer of ethylene and a higher alkene such as hexene or octene) require a different approach. Analytical Temperature Rising Elution Fractionation (ATREF) techniques can reveal how the short chain branches are distributed over the various molecular weights.
, particularly Differential scanning calorimetry
. Changes in the compositional and structural parameters of the material usually affect its melting transitions or glass transitions and these in turn can be linked to many performance parameters. For semicrystalline polymers it is an important method to measure crystallinity. Thermogravimetric analysis
can also give an indication of polymer thermal stability and the effects of additives such as flame retardants.
are essentially extensions of thermal analysis that can reveal more subtle transitions with temperature as they affect the complex modulus or the dielectric function of the material.
in combination with staining techniques, but also Scanning Electron Microscopy, Scanning probe microscopy
and other forms of microscopy
are important tools to optimize the morphology of materials like polybutadiene
-polystyrene
polymers and many polymer blends.
X-ray diffraction is generally not as powerful for this class of materials as they are either amorphous or poorly crystallized. The Small-angle scattering
like Small-angle X-ray scattering
(SAXS) can be used to measure the long periods of semicrystalline polymers.
Polymer science
Polymer science or macromolecular science is the subfield of materials science concerned with polymers, primarily synthetic polymers such as plastics...
.
The discipline is concerned with the characterization of polymeric materials on a variety of levels. The characterization typically has as a goal to improve the performance of the material which implies that the characterization should ideally also be linked to the parameters that are related to the desirable properties of the material such as strength, impermeability, toughness, optical properties and the like.
Chemical structure
The chemical structure of many polymers is rather complex because the polymerization reaction does not necessarily produce identical molecules as in the case in the DNA-coded synthesis of biopolymers. A polymeric material typically consists of a distribution of molecular sizes and sometimes also of shapes. Chromatographic methodsChromatography
Chromatography is the collective term for a set of laboratory techniques for the separation of mixtures....
like size exclusion chromatography
Size exclusion chromatography
Size-exclusion chromatography is a chromatographic method in which molecules in solution are separated by their size, and in some cases molecular weight . It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers...
often in combination with Low-angle laser light scattering
Low-angle laser light scattering
Low-angle laser light scattering or LALLS is an application of light scattering that is particularly useful in conjunction with the technique of Size exclusion chromatography, one of the most powerful and widely-used techniques to study the molecular weight distribution of a polymer.Typically the...
(LALLS) and or viscometry can be used to determine the molecular weight distribution as well as the degree of long chain branching of a polymer, provided a suitable solvent can be found. Copolymers with short chain branching such as linear low-density polyethylene (a copolymer of ethylene and a higher alkene such as hexene or octene) require a different approach. Analytical Temperature Rising Elution Fractionation (ATREF) techniques can reveal how the short chain branches are distributed over the various molecular weights.
Thermal properties
A true workhorse for polymer characterization is thermal analysisThermal analysis
Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature. Several methods are commonly used - these are distinguished from one another by the property which is measured:...
, particularly Differential scanning calorimetry
Differential scanning calorimetry
Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature...
. Changes in the compositional and structural parameters of the material usually affect its melting transitions or glass transitions and these in turn can be linked to many performance parameters. For semicrystalline polymers it is an important method to measure crystallinity. Thermogravimetric analysis
Thermogravimetric analysis
Thermogravimetric analysis or thermal gravimetric analysis is a type of testing performed on samples that determines changes in weight in relation to change in temperature. Such analysis relies on a high degree of precision in three measurements: weight, temperature, and temperature change...
can also give an indication of polymer thermal stability and the effects of additives such as flame retardants.
Mechanical and dielectric spectroscopy
Dynamic mechanical spectroscopy and Dielectric spectroscopyDielectric spectroscopy
Dielectric spectroscopy , and also known as electrochemical impedance spectroscopy, measures the dielectric properties of a medium as a function of frequency...
are essentially extensions of thermal analysis that can reveal more subtle transitions with temperature as they affect the complex modulus or the dielectric function of the material.
Morphology
Morphological parameters, particularly on a mesoscale (nanometers to micrometers) are very important for the mechanical properties of many materials. Transmission Electron MicroscopyTransmission electron microscopy
Transmission electron microscopy is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through...
in combination with staining techniques, but also Scanning Electron Microscopy, Scanning probe microscopy
Scanning probe microscopy
Scanning Probe Microscopy is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. An image of the surface is obtained by mechanically moving the probe in a raster scan of the specimen, line by line, and recording the probe-surface interaction as a...
and other forms of microscopy
Microscopy
Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...
are important tools to optimize the morphology of materials like polybutadiene
Polybutadiene
Polybutadiene is a synthetic rubber that is a polymer formed from the polymerization process of the monomer 1,3-butadiene.It has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production...
-polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
polymers and many polymer blends.
X-ray diffraction is generally not as powerful for this class of materials as they are either amorphous or poorly crystallized. The Small-angle scattering
Small-angle scattering
Small-angle scattering is a scattering technique based on the deflection of a beam of particles, or an electromagnetic or acoustic wave, away from the straight trajectory after it interacts with structures that are much larger than the wavelength of the radiation. The deflection is small hence...
like Small-angle X-ray scattering
Small-angle X-ray scattering
Small-angle X-ray scattering is a small-angle scattering technique where the elastic scattering of X-rays by a sample which has inhomogeneities in the nm-range, is recorded at very low angles...
(SAXS) can be used to measure the long periods of semicrystalline polymers.
Other techniques
- Solid state NMRNMRNMR may refer to:Applications of Nuclear Magnetic Resonance:* Nuclear magnetic resonance* NMR spectroscopy* Solid-state nuclear magnetic resonance* Protein nuclear magnetic resonance spectroscopy* Proton NMR* Carbon-13 NMR...
- Spectroscopic techniquesSpectroscopySpectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
: FTIR etc. - ACOMP
- MFIMelt Flow IndexMelt flow index or MFI is a measure of the ease of flow of the melt of a thermoplastic polymer. It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for...
- Dual polarisation interferometryDual Polarisation InterferometryDual polarization interferometry is an analytical technique that can probe molecular scale layers adsorbed to the surface of a waveguide by using the evanescent wave of a laser beam confined to the waveguide...
- Matrix-assisted laser desorption/ionizationMatrix-assisted laser desorption/ionizationMatrix-assisted laser desorption/ionization is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules and large organic molecules , which tend to be fragile and fragment when ionized by more conventional ionization methods...