Across industry, powders are routinely handled at elevated temperature. For example, Additive Manufacturing (AM) build chambers are heated to reduce warpage and thermally induced stress in the finished component, while catalysts typically operate at elevated temperature to achieve maximum productivity. Pasteurisation and dehydration are good examples of heat treatment processes applied to extend the shelf life of products by reducing microbial populations or preventing fungal growth, particularly within the food industry. The pharmaceutical sector relies on melt granulation and hot melt extrusion to achieve target bioavailability and controlled release rates in solid dosage forms.
The importance of characterising powders under process relevant conditions has become increasingly well-established over recent years, but most testing is still carried out at ambient temperature. As a result, powders may exhibit unpredictable performance in many unit operations, leading to issues such as stoppages, downtime, and out-of-specification products. At elevated temperature solid particles may deform elastically or plastically, moisture will migrate, and the density of entrained gas will reduce. These and other changes directly impact bulk powder properties such as flowability, compressibility, and permeability that define process and product performance.
In an article with Powder Bulk Solids, we consider how temperature affects powder behaviour and the requirements for elevated temperature testing. Experimental data is presented that quantifies the extent to which temperature changes the flowability of two powders – a pharmaceutical excipient and a polymer powder for AM. The results highlight the difficulty of predicting such changes and the need for appropriate testing.
Please click here to read the article in full – Testing Powders at Elevated Temperatures.