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Measurement of Viscosity of Aqueous Solutions of Hypromellose by Rotating Viscometer Method (CAT#: STEM-PPA-0018-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

The principle of the rotating viscometer method to measure the force acting on a rotor (torque) when it rotates at a constant angular velocity (rotational speed) in a liquid. Rotating viscometers are used for measuring the viscosity of Newtonian (shear-independent viscosity) or non-Newtonian liquids (shear dependent viscosity or apparent viscosity). Rotating viscometers can be divided in 2 groups, namely absolute and relative viscometers. In absolute viscometers the flow in the measuring geometry is well defined.
The measurements result in absolute viscosity values, which can be compared with any other absolute values. In relative viscometers the flow in the measuring geometry is not defined. The measurements result in relative viscosity values, which cannot be compared with absolute values or other relative values if not determined by the same relative viscometer method. Different measuring systems are available for given viscosity ranges as well as several rotational speeds.

Applications

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

Procedure

1. Pour the liquid into the measuring cup.
2. Insert the spindle into the liquid.
3. Rotate the spindle and measure the resistance.

Materials

• Sample Type: liquid, gel-like, or semi-solid everyday substances
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