Rapid measurements of elastic modulus and density in polypropylene sheet during aging

摘要

AbstractNew methods for rapidly obtaining elastic modulus and density measurements during isothermal polymer aging are given. The elastic measurements are performed using a Rockwell hardness tester. In this case, the elastic recovery is measured. Rapid density measurements are performed using a “double drop” density gradient columan method. Here, a fully aged and a freshly quenched specimen are dropped simultaneously into the column. Simultaneous column height differences directly measure the density difference of the two specimens. The results of these two experiments extend previously reported aging measurements to relatively low times of aging. A log (time) law for both properties is found to the smallest times measu