Physical Characterisation

Physical characterisation refers to the process of measuring and analysing various physical properties of materials. Some common techniques used for physical characterisation are:

Thermal Services

X-Ray Diffraction

Particle Size Distribution

Rheology and Viscosity

Texture

Specific Surface Area (SSA, BET) and Density

Powder Flowability

Volume measurement

Benchtop low resolution NMR

Thermal Services

DSC and TGA can be applied in a broad range of ways to elucidate the number of polymorphs, hydrated forms, melting point, Tg, degradation behaviour, polymorphic conversion, recrystallisation and heat capacity. DVS is used to study the response of material to changes in humidity, it is essential in understand physico-chemical behaviours such as stability and microbiological activity. XRD is a complimentary technique (see XRD offering).

Equipment

• Mettler Toledo DSC 5+ (Differential Scanning Calorimetry)
• TA Discovery DSC2500 (Differential Scanning Calorimetry)
• TA TGA 5500 (Thermogravimetric analysis)
• SDT650 (TGA/DSC combined)
• Surface Measurement Systems DVS (Dynamic Vapour Sorption)

X-Ray Diffraction

The physical form of ingredients used in both food and pharmaceuticals can have a major impact on the desired properties for finished products. X-Ray Powder Diffraction (XRPD) is a powerful technique both on its own and in combination – DSC, TGA etc. XRPD can help to determine which available polymorph is most desired.

Equipment

• Bruker D8 Advance, with temperature and humidity stage.

Particle Size Distribution

Particle size distribution (PSD) is a fundamental measurement in the product life cycle. The link between particle size and product performance are known to affect dissolution rate, absorption rates and content uniformity. The processability and stability of a formulation are all dependent on PSD.

During formulation of a product the flow and packing properties, tablet and capsule fill volumes, compression, dissolution and blend uniformity can all be affected by PSD. At RSSL we have a series of instruments that allow the measurement of PSD and particle shape/morphology. We are also highly experienced in method development and validation.

Equipment

• Malvern Mastersizer 2000 and Mastersizer 3000
• Zetasizer ZSP (Zetapotential and DLS)
• Sieving
• Lumisizer (emulsion stability) (Analytical centrifuge to monitor accelerated stability of multi-phase samples.)

Rheology and Viscosity

Rheological testing examines the flow and deformation behaviour of materials under different shear conditions, while viscosity measurements quantify resistance to flow. These properties are key in assessing the handling, processability, and sensory characteristics of semi-solids and liquids, such as sauces, creams, gels, and pastes.

Rheology data help optimise texture, stabilise emulsions, and predict shelf-life performance, ensuring products meet both functional and consumer expectations.

Equipment

• Netzsch Kinexus
• Haake Viscotester iQ (VTIQ)
• Brookfield LV
• Brookfield RV
• U-tube viscometry
• TA DHR-1
• TA ARES-G2

Texture

Texture analysis is a scientific method used to quantify and characterise the physical properties of materials in terms of their tactile and structural attributes. This technique is commonly applied to a wide range of products, including food, cosmetics, pharmaceuticals, and various materials, to understand how they feel and behave under mechanical stress. Texture analysis helps manufacturers ensure consistent product quality and optimise formulations. 

Equipment

• Stable Micro Systems TA.XT Texture analyser

Specific surface area (SSA, BET) and Density

Density and surface area measurements provide critical insight into the physical characteristics of powders and porous materials. Bulk and tapped density assessments help evaluate packing behaviour, flow properties, and compressibility — all of which affect manufacturing efficiency and product uniformity. Specific surface area is determined using the Brunauer-Emmett-Teller (BET) method, which measures the amount of gas adsorbed onto the material's surface.

This technique is particularly valuable for characterising materials such as food powders, functional ingredients, and active packaging components, where surface area can influence reactivity, solubility, shelf-life, and texture. Together, these measurements support formulation optimisation, quality control, and process development.

Equipment

• TriStar II 3020
• Tapped Density
• Bulk density
• Gas Pycnometry
• Oscillating U-tube

Powder Flowability

Powder flowability refers to the ease with which a bulk powder material flows or moves when subjected to external forces such as gravity. It is a critical property in various industries, including pharmaceuticals, food processing, chemicals, and manufacturing, where powders are handled, transported, and processed in various ways. Poor powder flowability can lead to issues such as clogging, inconsistent dosing, and inefficient processing. 

Equipment

• Brookfield Powder Flow
• FT4 Powder rheometer

Volume measurement

Accurate volume measurement is important for evaluating product uniformity, aeration, and overall presentation — especially in bakery, confectionery, and puffed products. Techniques such as displacement or laser-based scanning allow for the precise determination of volume and density. This data supports product development, quality control, and packaging optimisation, helping to ensure compliance with labelling requirements and consumer expectations.

Equipment

• Stable Micro Systems Volscan profiler

Benchtop low resolution NMR

Benchtop low-resolution Nuclear Magnetic Resonance (NMR) spectroscopy is a rapid, non-destructive method used to measure moisture, fat, and solid content in food matrices. It operates by detecting hydrogen nuclei responses in magnetic fields, providing reliable compositional data without the need for extensive sample preparation.

This technique is ideal for routine quality control, offering consistent and repeatable measurements for high-throughput environments such as production lines or formulation screening.

Equipment

• Bruker NMR Minispec MQ