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Measurement of Viscosity of Aqueous Solutions of Hypromellose by Capillary Viscometer (CAT#: STEM-PPA-0008-YJL)

Introduction

Cellulose derivatives have an irreplaceable role as pharmaceutical excipients with a wide use in the pharmaceutical industry, including manufacturing of current medicines and development of new dosage forms (DF) and modern pharmaceutical manufaturing processes. Hydroxypropyl methylcellulose, also called Hypromellose (HPMC) belongs to one of the most common hydrophilic cellulose derivatives used in the pharmaceutical industry and development of new oral and oromucosal matrix DF with controlled drug release.
HPMC molecule is based on a linear polysaccharide cellulose chain with ether-linked methoxyl and hydroxypropyl side groups. The types of HPMC differ by their chemical structure (substitution degrees and ratios), resulting molecular weight, viscosity and particle size. HPMC also provides a broad offer of viscosity grades and robust mechanism of drug release from various DF. Single-point comparison becomes topical in consequence to the pharmacopoeial requirement that the apparent viscosity of 2% hypromellose solution should be read at the shear rate of approximately 10 s(-1).




Principle

A capillary viscometer is an instrument used to measure the viscosity, or thickness, of a liquid by measuring how long it takes the liquid to flow through a small-diameter tube, or capillary. The flow, or efflux, time is directly proportional to the liquid's kinematic viscosity, and may be converted directly to viscosity by use of a conversion factor unique to each instrument. Viscosity is generally temperature dependent, so the capillary viscometer is usually used in a controlled-temperature water bath set to a specific temperature.
The capillary method is used to determine the viscosity of a Newtonian fluid (a liquid with a viscosity independent of the shearing stress or rate of shear). Capillary viscometer calculations are performed using suspended level capillary viscometers and Ostwald-type capillary viscometers.

Applications

Mineral oil industry; Food industry; Cosmetic/pharmaceutical industry; Petroleum industry

Procedure

1. Select the capillary viscometer and load the sample.
2. Adjust the bath temperature.
3. Determine the efflux time of the sample.

Materials

• Sample Type: Newtonian fluid
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