Failure Characterization of Polypropylene Block Copolymer Welded Joint

L. FASCE; A.P. CISILINO; P. FRONTINI; B. MARCZIS; T.CZIGNAVY

POLYMER ENGINEERING AND SCIENCE

Wiley

Año: 2007 vol. 47 p. 1062 - 1069

0032-3888

Double- V welded joints were performed on polypropylene block copolymer using an automated hot gas welding machine, which was able to independently control welding parameters leading to reproducible welded joints. The failure behavior of welded joints coming up from three hot gas temperatures in the range of 230 to 260ºC was investigated. Uniaxial tensile tests, fracture mechanics experiments, several microscopy techniques and complementary FEM analysis allowed the assessment of the quality of filler rods and welding interfaces. The performed welded joints achieved joint efficiencies about 65%. Relative weak interfaces were developed as a consequence of segregation of polymer chains during the welding process. However, the welding temperature had a marked effect on the failure behavior of the welds. Weld strength as well as interface toughness increased with increasing the welding temperature, because polymer chains diffuse quickly into the parent material enlarging the distance of penetration and hence the deformation capability of the joint.