Format:
Online-Ressource
ISSN:
1521-4117
Content:
Abstract: Dry powder coating is a powerful method for modifying the surface properties of particles whilst retaining their essential bulk properties. The coating of a host powder by guest particles can be achieved via different means ranging from simple stirring together of the two components, to high energy impact coating in devices such as a Nara Hybridizer or Turbula Mixer. The quality of the powder coating resulting from such methods is an important parameter, which depends both on the force of the mechanical action used, and also the physico‐chemical interactions between the host and guest particles. Here, a method for evaluating the strength of host‐guest interactions based on particle size analysis using a standard Malvern Mastersizer with dry powder feed is presented. Basically, the liberation of small guest particles from host particles can be achieved by increasing the air pressure, and the presence of liberated fine particles mixed with guest particles can be detected from differences in volume and number distributions. Complementary examination is undertaken using an environmental scanning electron microscope (ESEM). This technique has been used to evaluate the interaction strength of a coating of hydrophobic magnesium stearate on a herbal extract (Harpagophytum). It is shown that effective coating can be achieved by three different means: simple stirring, a Turbula Mixer and by using a Nara Hybridizer. The respective strength of the coatings is greater with increasing mechanical force used for the process. The method is proposed as a simple means of evaluating powder‐powder coating processes.
Content:
The coating of ‘host’ particles with much smaller ‘guest’ particles is a versatile method to dramatically change the behaviour of powders. Here, a method for evaluating the strength of host‐guest interactions based on standard particle size analysis is presented. It is shown that the strength of the coating is related to the mechanical forces during the coating process.
In:
volume:23
In:
number:2
In:
year:2006
In:
pages:127-132
In:
extent:6
In:
Particle & particle systems characterization, Weinheim : Wiley-VCH, 1984-, 23, Heft 2 (2006), 127-132 (gesamt 6), 1521-4117
Language:
English
DOI:
10.1002/ppsc.200601020
URN:
urn:nbn:de:101:1-2023081305324442908710
URL:
https://doi.org/10.1002/ppsc.200601020
URL:
https://nbn-resolving.org/urn:nbn:de:101:1-2023081305324442908710
URL:
https://d-nb.info/1299144918/34
URL:
https://doi.org/10.1002/ppsc.200601020
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