Flexible polyurethane foam scrap was chemically decomposed via glycolysis. Optimal reaction conditions for glycolysis were determined: temperature, 2208C, polyurethane/glycol ratio, 1:1; reaction time, 2.5 hr; diethylene glycol or dipropylene glycol as reagents. Two types of polyurethane scrap were tested; both gave the recycled polyols having the same properties, which is advantageous for possible applications on a commercial scale. A mixture of the virgin and recycled polyols (up to 36 wt%) was used to manufacture rigid polyurethane foams. No undesirable influence of the recyclates on process parameters (cream time, gel time) was found. The end-use properties of the rigid foams were practically the same in the whole range of tested concentrations of recyclates. A fine cellular structure of all tested foams was found.

SynopsisThree types of fracture energies, i.e., for initiation, propagation, and the work of fracture, were measured for an ammonium perchlorate/polybutadiene composite propellant. The testing employed the "trouser leg" specimen configuration. The effect of an accelerated aging process on these energy values was also investigated, showing that such a process ultimately results in a reduction in the fracture energies.