The mechanical properties of some binders used in tableting

Abstract
Films of acacia, gelatin, methylhydroxyethyl cellulose, polyvinylpyrrolidone (PVP) and starch have been prepared with moisture levels of 2·0 to 20·0% w/w obtained by equilibration at relative humidities from 0 to 90%. Tensile strengths of 60 mm × 2 mm strips of these films have been determined by stressing to failure at a constant rate of 6·6 times 10−5 ms−1 in a tensile strength apparatus. From the stress-strain curves the modulus of elasticity, yield strength and the work done in breaking unit cross-sectional area of the films have been calculated. This has given an indication of the binders’ mechanical behaviour over the range of moisture contents likely to be encountered in tableting.