Estimation of upper limit of AP content in AP/HTPB composite propellant - a consideration based on flow characteristics of AP/HTPB suspension

Because of the requirements for the preparation of ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) composite propellant, there is an upper limit content, φmax(wt%), of AP contained propellant. It is necessary for the design of AP/HTPB composite propellant to estimate φmax. In this study, an attempt was made to find out the universal powder property of AP which can determine φmax, from the standpoint of the viscosity of AP/HTPB suspension. The results are as follows: 1) Concerning AP/HTPB suspensions prepared in this study, the relationship between the relative viscosity, ηr(-), and the volume fraction, φv(vol%), can be represented by the Mori-Ototake equation, k and φvc which are constant in the Mori-Ototake equation are dependent on specific surface area, Swp(m2/kg), measured by the air-permeability method. It is found that ηr can be represented as the function of φv and Swp 2) ηr of AP/HTPB suspension containing φmax was almost constant. 3) φmax increases with decreasing Swp. The relationship between φmax and Swp can be represented by the following equation. φmax = 85-0.01 Swp (40 m2/kg&leSwp&le1200 m2/kg). It is found that φmax can be estimated from Swp.