- Surface Area & Gas Adsorption
- Pore Size
- Representative Sampling
- Particle Size
- Particle Shape
- Dynamic Vapor Sorption (DVS)
- Zeta Potential
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Density, True Density & Tapped Density
Different Methods of Density measurements
Density is defined as mass per unit volume.
Analysis of sample mass can be simply and accurately performed using a balance, but analysis of sample volume, particularly of powders or irregularly shaped materials can be difficult and can be perceived and measured in more than one way:
- as bulk volume with corresponding bulk density - includes volume of solid phase, plus volume of inter-particular space and pores within particles
- as apparent/envelope/geometric volume giving apparent/envelope density - includes volume of solid phase plus pores within the particle
- as true/skeletal volume for true density measurement - includes volume of solid phase only and any closed pores within that are not open to the outside surface
Corresponding measuring methods are:
- Bulk Density - volume determined by the use of graduated cylinder, the cylinder can be tapped giving a measure of the so called Tapped Density
- Apparent/envelope Density - volume of large geometric shapes easy to measure (ruler, calipers), volume of irregular shapes measured by powder pycnometry using a free flowing powder, volume of small, irregular shapes measured by mercury displacement
- True Density - For regular shapes this is easy to measure using an accurate balance and a ruler, for irregular or fractured shapes we employ the Archimedean principle of fluid/gas displacement to measure the volume. The gas pycnometry operating principle is Gas Law: PV = nRT Where P is the gas pressure, V is the volume containing the gas, n is the number of moles of the gas, R is the universal gas constant and T is the temperature of the gas. Introducing a sample into an analysis chamber of a known volume we determine the volume of a gas displaced by the sample and true volume of the analysed material. Most commonly used gas is helium but other gasses are also possible.
- True Density measurement is one of the simplest and most economical methods of Quality Control, the measurement takes few minutes and can be highly automated.
- Pycnometric or True Density analysis combined with Mercury porosimetry can provide a measure of materials’ porosity.
- Gas Pycnometry can be used to determine percentage of solids in the slurry
- Specialist applications allow the determination of open and closed cell porosity of rigid and semi rigid foams.
For more information contact us.
Density Research Papers
Review recent papers citing use of Quantachrome true density instruments:
TITLE: Hydration of high alumina cement–silica fume composite with addition of Portland cement or sodium polyphosphate under hydrothermal treatment
AUTHORS: Palou, Bágeľ, Živica, Kuliffayová, Ifka - Slovak Academy of Sciences, Slovak Republic
INSTRUMENT: Pentapyc 5200e
USAGE: density of materials was determined by the gas pycnometry technique
TITLE: X-ray diffraction parameters and reaction rate modeling for gasification and combustion of chars derived from inertinite-rich coals
AUTHORS: Everson, Okolo, Neomagus, dos Santos - North-West University, South Africa
USAGE: the skeletal density was determined, using helium gas
TITLE: CO2 rock physics as part of the Weyburn-Midale geological storage project
AUTHORS: Njiekak, Schmitt, Yam, Kofman - University of Alberta, Canada
USAGE: The petrophysics tests included (i) He pycnometry for the determination of the sample's grain density and estimation of bulk porosity
TITLE: The micro-sandblasting technique as a new tool for the evaluation of the state of conservation of natural stone and mortar surfaces
AUTHORS: Rescic, Tiano, Fratini & Manganelli Del Fà - CNR Institute for Conservation and Valorization of Cultural Heritage (ICVBC), Italy
USAGE: perform measurements with the helium pycnometer in order to determine the real density before and after the micro-sandblasting tests
TITLE: Evaluation of material properties and compression characteristics of Assam Bora rice flours as a directly compressible vehicle in tablet formulation
AUTHORS: Zaki Ahmad, Akhter, Dhiman, Sharma & Verma - Dreamz College of Pharmacy, India
INSTRUMENT: Ultrapyc 1200e
USAGE: True density was obtained on a helium pycnometer. The data generated from bulk density and true density were utilized for calculating the porosity of powder mass
TITLE: A study of the oxidation of ZrB2 powders during high-energy ball-milling in air
AUTHORS: Ortiz, Zamora and Rodríguez-Rojas - University of Extremadura, Spain
USAGE: The density measurements were made by helium pycnometry
TITLE: Oxidative torrefaction of biomass residues and densification of torrefied sawdust to pellets
AUTHORS: Wang, Peng, Li, Bi, Legros, Lim, Sokhansanj - Guangzhou Institute of Energy Conversion, China
USAGE: The particle density was measured
TITLE: Protein spheres prepared by drop jet freeze drying
AUTHORS: Eggerstedt, Dietzel, Sommerfeld, Süverkrüp, Lamprecht - University of Bonn, Germany
INSTRUMENT: Ultrapycnometer 1000
USAGE: The particle density of pure substances was analyzed with a helium pycnometer and the density of formulations was calculated.
TITLE: Characterization of internal structure, polymer erosion and drug release mechanisms of biodegradable poly(ester anhydride)s by X-ray microtomography
AUTHORS: Mönkäre, Pajander, Hakala, Savolainen, Järveläinen, Korhonen, Seppälä, Järvinen - University of Eastern Finland, Finland
INSTRUMENT: Multipycnometer MVP-1
USAGE: densities were measured by a pycnometer using helium as the measuring gas