Brittleness of Hard Gel Capsules
brittleness, hardness, firmness, pliability
The brittleness, hardness and flexibility of hard gel capsules impacts their ability to be filled and to withstand variable storage conditions. Compressive tests on hard gel capsules do not always adequately distinguish between formulations which are known to experience brittle-related failures and those formulations which perform acceptably. In particular, the early modulus and yield strength of compression tests on hard gel capsules often articulate only slight differences between the extremely different expected behaviors. This study examines three sets of hard gel capsules which were treated and stored under different conditions and which were tested using a separating rod method. The method stresses the capsules in tension until the capsules fail, typically in a catastrophic manner.