FRACTURE-TOUGHNESS DETERMINATION OF ABS POLYMERS USING THE J-METHOD

The suitability of J-R curve fitting methods proposed by ASTM E 813-81 and E 813-87 metal standards in fitting ABS J-R curves is discussed. Tests were carried out at room temperature on one commercial grade ABS resin in three-point bending. Specimens were precracked with a razor blade and tests were performed over a X20 range of crosshead rate in the quasistatic regime. Specimens of different geometric relationships (B/W, a/W, smooth specimens of different thickness, and side-grooved specimens) were assayed. The two ASTM fitting procedures were also checked against data reported by other authors for other ABS type resins. Model appropriateness was checked by statistical analysis. Results appeared to be geometrically independent for deeply notched specimens. No significant variation in the J-R curve was found for changes in the displacement rate. Both J-R curve fittings appeared to be adequate. The ASTM E 813-87 procedure led to less conservative critical initiation J(IC) values.