Yield Process of Amorphous Polymers with Different Heat Treatments
Masayoshi KITAGAWA, Sinichi ISHIDA, Kengo SHIBAGAKI and Yoshinori YAMADA
Abstract:It has been shown that the yield process is very different between the annealed and quenched samples of amorphous polymers. Many slip lines appearing just before yielding cause a specimen necking near the peak stress in as-received and annealed samples, while it occurs without visible formation of slip lines in quenched samples. To investigate this difference may promote the understanding on the yield mechanism of amorphous polymers. In this paper, the results mentioned previously were confirmed at tensile and shear tests and some mechanical properties related to the yielding were measured using as-received(AR) and quenched(Q) samples of amorphous polymers, PC, PVC, PMMA and PET. It was shown that (1) the values of tanƒÂ are higher in Q than in AR samples, (2) the diffusion rate of methyl alcohol to PMMA is greater in Q than in AR samples, (3) the specific gravities of Q samples are smaller than those of AR ones and (4) the yield mechanism is very different between AR and Q samples under both tension and shearing. Key Words:Yielding, Slip line, Amorphous polymer, Quench, Loss tangent, Diffusion