DSpace

King Saud University Repository >
King Saud University >
COLLEGES >
Science Colleges >
College of Engineering >
College of Engineering >

Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/13359

Title: Uniaxial strain rate effects in pharmaceutical powders during cold compaction
Authors: Es-Saheb, M.
Keywords: Uniaxial compression, low-strain-rate tests
Issue Date: 1992
Publisher: Kluwer Academic Publishers
Citation: Journal of Materials Science Volume 27, Issue 15, August 1992, Pages 4151-4159
Abstract: The results of uniaxial compression tests on some pharmaceutical powders subjected to strain rates of between 10-3 and 105 s-1 are given. The tests fall into three main categories: low-strain-rate tests (10-3-10 s-1) performed on a servohydraulic variable speed-compression machine at constant compression rate; medium-strain-rate tests (102-103 s-1) carried out on a drop hammer; and high strain rate tests (103-105 s-1) performed on a high-pressure air projectile launcher compaction apparatus. Axial and radial pressures, as well as displacement-time measurements, are made. Powders tested include: Dipac sugar; sodium chloride; potassium bromide; lactose; paracetamol d.c.; avicel; calcium phosphate; and copper sulphate. The influence of compression rate on the form of the characteristic pressure-density and radial-axial pressure relationships during uniaxial straining is presented. The investigation showed that the general tendency for all powders tested, except for paracetamol d.c., is to exhibit increased compaction pressure with strain rate up to 105 s-1. Due to morphological and compositional effects, paracetamol d.c. softens with the rate of straining up to about 102 s-1 and at higher rates it behaves like other powders. Also the mean radial pressure at the die wall (obtained by a pin-type transducer) shows that the friction conditions are variable during the process, and their effect tends to decrease as the speed of compaction increases, resulting in more uniform density compacts. Finally, by observing the decay of both axial and radial pressures with time under constant volume conditions, a reasonably linear behaviour is obtained for all materials tested, particularly the axial relaxation curves, over the period recorded.
URI: http://hdl.handle.net/123456789/13359
ISSN: 00222461
Appears in Collections:College of Engineering

Files in This Item:

File Description SizeFormat
12.docx19.83 kBMicrosoft Word XMLView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

DSpace Software Copyright © 2002-2007 MIT and Hewlett-Packard - Feedback