Abstract
In this paper, in order to obtain three kinds of fracture toughness K_c, K_d, K_<arr> of engineering plastics namely PC, PBT and PEEK, the brittle fracture toughness test is performed on load time from 5 × 10_<-5> s to 1000 s by the method of using instrument Charpy impact test machine and ordinary tensile test machine. The brittle fracture toughness test were performed in the wide range of stress intensity factor rate K/t from 0.1 to 10^6 MPa・mm^<1/2>/s. It is cleared by these tests that (a) fracture toughness K_c, K_d, K_<arr> of PC are 220, 200 〜 100 and 60 MPa-mm^<1/2> and (b)K_c K_d, of PBT are 200 and 170〜70 MPa・mm^<1/2> and (c) K_c, K_d of PEEK are 250 and 200 〜 120 MPa・mm^<1/2>. These rate tendencies of brittle fracture toughness of engineering plastics are similar to those of general metal materials.
