Characterization Services
The understanding of any particle process begins with the knowledge of the physical properties of the material of interest. At AVEKA, we are equipped to evaluate your process by tracking the particle characteristics during processing and by evaluating the properties of the powders and dispersions in your final products. AVEKA scientists are available to help you analyze your system to determine the most useful characterization measurements for your project.
Particle Size Distribution
The most widely used characterization method is size analysis and AVEKA can measure particle size from 1 nm to 2 mm. Traditionally, particle size distribution is determined using a series of screens to sieve the particle mixture, weighing the amount retained on each screen and tabulating the percent of the sample above a certain mesh size. This remains the standard method in many industries, especially for measuring larger-sized particles. Currently, laser light scattering methods are now the method of choice for obtaining quick, reproducible particle size measurements, even for particles under a micron in size. AVEKA has a Gilson Sonic Sieve for traditional particle sizing and two light scattering analyzers: the Horiba LB-500 for particles from 3 nm to 6 µm and the Horiba LA-930 for particles from 100 nm to 2 mm. Sample turnaround time is one day and there is no additional charge for analysis in solvents.
Zeta Potential
Zeta potential is a measure of the electrostatic charge on a particle suspended in a liquid that is created by its interaction with the liquid to form an electrical double layer. It provides a key to understanding the stability of particles in a dispersion and is important in the formulation of many coatings, inks, and dispersion products. If the zeta potential value is greater than a threshold value, the particles strongly repel each and do not agglomerate, allowing for a stable particle suspension. By titrating the sample, one can also identify the pH regions where agglomeration is most likely to occur. AVEKA is equipped with a Colloidal Dynamics ZetaProbe for measuring zeta potentials and performing titrations.
Surface Area
Measurements of particle surface area are essential for determining surface properties such as adsorption and catalytic reactivity. The most common method of determining surface area is the BET method, which uses the amount of nitrogen adsorbed onto a powder sample to determine the total particle surface area and the specific surface area (area per unit mass) of the sample. At AVEKA, surface area is determined using the Horiba SA-6200 Surface Area Analyzer.
Helium Pycnometer Density
Pycnometry measures the density of particulate materials by means of displacement of a gas. Unlike tap or powder density measurements which give an effective density of a bulk powder sample (including the air voids in the powder), pycnometry yields the true density of the material(s) making up the powder. The AVEKA Characterization Lab is equipped with a Quantachrome Ultrapycnometer 1000 to characterize polymers, nanocomposites, ceramics, glasses and other materials.
High Performance Liquid Chromatography
HPLC is frequently used to measure the amount of payload released from a microcapsule, the molecular weight distribution of a polymer, the amount of each component in a multi-component mixture or the level of contamination in materials. It can also be used to separate the components of a mixture by using a variety of chemical interactions between the substance being analyzed (analyte) and the chromatography column. In HPLC, the analyte is forced through the chromatography column by pumping a mobile liquid phase through the column, where it is retarded by specific chemical interactions as it flows through the column. The time at which an analyte elutes from the column, called the retention time, provides a way to identify a compound. The response generated by a detector after the column allows calculation of the quantity of material present. Common solvents used include any miscible combinations of water and various organic liquids such as acetonitrile, methanol, or tetrahydrofuran (THF). Completely non-aqueous solvent systems can also be used.
AVEKA, Inc has state-of-the-art HPLC instrumentation made by Agilent Technologies for meeting all your HPLC needs. This equipment can be used in any of the major chromatographic operating modes, including reversed phase, gel permeation chromatography (GPC), and normal phase. Detection options include diode array, refractive index, and fluorescence. Aveka also has extensive experience in method development and method optimization, using our knowledge of the latest developments in column technology to provide our customers with the best answer, in the shortest time, at a reasonable cost.
- Polymer analysis/molecular weight distribution (GPC)
- Formulation analysis (pharmaceutical, pesticide, food, etc.)
- Trace analysis
- Method development
- Method optimization
Differential Scanning Calorimetry
DSC measures the energy loss or gain as a material is heated at a constant rate; these energy changes mark the phase transitions of the material. The heat capacity, glass transition temperature, specific heat and the melting and crystallization temperatures can be determined and used to characterize polymers and other substances with identifiable phase transitions. Other applications include thermal stability and reversibility, blend compatability, heats of vaporization and melting and purity evaluations. AVEKA employs a TA Instruments Q100 Differential Scanning Colorimeter.
Thermogravimetric Analysis
Thermogravimetry measures the change in mass of a sample over changes in time or temperature. The data are used to obtain information about polymerization reactions, the efficiencies of stabilizers and activators and the
thermal stability of a material. TGA also measures the loss of water from hydrates, hydroxides and carbohydrates, the amounts of coatings, the decomposition of organic and inorganic compounds or the oxidative decomposition of organic materials. Other applications include weight loss or gain, drying rate, reactivity in various atmospheres, oxidative degradation, volatilization analysis and compound composition. AVEKA's thermogravimetric analyzer is a TA Instruments Q500.
Solids Analysis
The percent solids or percent volatiles in a sample are measured at AVEKA using the Mettler LJ16 solids analyzer. Common applications of solids analysis are the determination of the water content of a slurry sample and the percent of volatile materials in a powder sample.
Optical Microscopy
For some powder properties, there is no substitute for actually seeing the particles under the microscope. AVEKA employs a Leica optical analysis system for visual particle characterization. This system uses a high quality optical microscope, digital camera and image analysis software to analyze particles from 800 microns down to about one micron in diameter. Using this system various attributes of particles can be obtained including: size, asphericity and surface structure.