Studies on fracture behavior of tough PA6/PP blends

M. Heino*, P. Hietaoja, J. Seppälä, T. Harmia, K. Friedrich

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    30 Citations (Scopus)


    Fracture toughness of injection-molded PA6/PP blends compatibilized with SEBS-g-MA was studied using deeply double-edge notched tension (DDENT) specimens according to the essential work of fracture procedure. The fracture mechanical studies also included tensile impact tests on the DDENT specimens and characterization of the fracture surfaces by electron microscopy. The results were compared with those of traditional tensile tests and Izod impact tests on single-edge notched samples, and the sensibility of the methods was evaluated. Effects of sample position, ligament length, testing direction, and test speed were studied as well. It was found that the essential work of fracture concept, earlier applied to thin sheets, can also be applied to injection-molded tough blends. High deformation of the skin may, however, interfere with the measurements and cause a "tail" in the load-deformation curves. The plastic work of fracture (Wp) was found to correlate with the impact strength, and thus, it described the toughness. The highest values for work of fracture were recorded for the compatibilized blend with a PA6/PP ratio of 80/20. The essential work of fracture (we) in turn increased with increasing PA6 content and behaved like tensile strength. The test speed was found to affect the fracture behavior substantially: differences between the materials were more pronounced in high-speed tensile impact tests, which revealed signs of cavitation in addition to large-scale plastic deformation for the tough PA6-rich blend compositions.

    Original languageEnglish
    Pages (from-to)2209-2220
    Number of pages12
    JournalJournal of Applied Polymer Science
    Issue number12
    Publication statusPublished - Dec 1997
    MoE publication typeA1 Journal article-refereed


    • Compatibilization
    • Essential work of fracture
    • Fracture toughness
    • Morphology
    • PA6/PP blend
    • Plastic work of fracture


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