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Polymer nanocomposites consist of a polymer matrix and reinforcing particles that have at least one dimension under 100 nm. The processing of nanocomposite polymers is the most important stage, determining the final properties of nanocomposites. Nanocomposites are now preferentially prepared by melt-mixing using conventional compounding processes such as twin-screw extrusion. Many processing parameters (polymer matrix type, content and type of nanofiller, barrel temperature, screw speed, number and shape of extruder screws, etc.) affect the properties of nanocomposites. This research work represents an investigation of the influence of processing parameters (amount of nanoclay filler, the screw rotation speed, and extruder barrel temperature) on the flexural properties of polyamide 12/nanoclay-reinforced nanocomposite. From the test results, it is apparent that an increase in nanoclay content from 1 to 8% significantly increases flexural strength. The obtained nanocomposite has a 19% higher flexural strength and a 56% higher flexural modulus than pure PA12. Mathematical models that show the dependence of flexural strength and flexural modulus on the processing parameters used were obtained as a result of this analysis.

It is well known that pipes or tubes due to their geometry are not suitable for producing standard specimens for fracture toughness testing (e. g. Single Edge Notched Bend (SENB) specimens or Compact Tension specimens. This is especially evident in thin walled pipes or tubes. We propose a new type of specimen, called Pipe Ring Notched Bend (PRNB) specimen, which is ideal for pipes or tubes due to its ring geometry. In the recent years, the authors have made a lot of research on this type of specimen, but cut out from a plate, not from pipes, where some imperfections in the geometry, material, residual stresses, etc. are present. Within this paper, two PRNB specimens (designations PRNB1 and PRNB2) are cut out from pipe which is used in boilers and made from 16Mo3 steel. From the same pipe, four SENB specimens (designations SENB1, SENB2, SENB3 and SENB4) are also made in order to compare the fracture behaviour of standard SENB and newly proposed PRNB specimens.

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